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Wistar Rats (wistar + rat)
Kinds of Wistar Rats Selected AbstractsMODULATORY EFFECT OF NARINGENIN ON N -METHYL- N, -NITRO- N -NITROSOGUANIDINE- AND SATURATED SODIUM CHLORIDE-INDUCED GASTRIC CARCINOGENESIS IN MALE WISTAR RATSCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 10 2008Ekambaram Ganapathy SUMMARY 1Naringenin is a flavanone that is believed to have many biological actions, including as an anti-oxidant, free radical scavenger and an antiproliferative agent. The global incidence of gastric carcinoma is increasing rapidly, more than for any other cancer. Therefore, in the present study, we tested the effects of naringenin on gastric carcinogenesis induced by N -methyl- N,-nitro- N -nitrosoguanidine (MNNG) and saturated sodium chloride (S-NaCl) in rats. 2Male Wistar rats were divided into five groups and treated over a period of 20 weeks as follows: (i) a control group given corn oil (1 mL/rat, p.o.) daily 20 weeks; (ii) 200 mg/kg, p.o., MNNG on Days 0 and 14 with S-NaCl (1 mL/rat) administered twice a week for the first 3 weeks; (iii) 200 mg/kg, p.o., MNNG on Days 0 and 14, with naringenin (200 mg/kg, p.o., daily) treatment for the entire 20 weeks; (iv) 200 mg/kg, p.o., MNNG on Days 0 and 14, with naringenin treatment (200 mg/kg, p.o., daily) initiated from 6 to 20 weeks; (v) 200 mg/kg, p.o., naringenin alone daily for 20 weeks. 3In Group II rats in which gastric cancer was inducted with MNNG and S-NaCl, there was a significant increase in hydrogen peroxide and lipid peroxidation levels, with decreases in reduced glutathione, oxidized glutathione, glutathione peroxidase, glutathione reductase and glucose 6-phosphate dehydrogenase. In addition, in Group II rats with gastric cancer, there were significant increases in the activity of cytochrome P450, cytochrome b5 and NADPH cytochrome c reductase, with concomitant decreases in the activity of the phase II enzymes glutathione S-transferase and UDP-glucuronosyl transferase. Naringenin treatment (Groups III and IV) restored enzyme activity to near control levels. 4These results indicate that naringenin has a chemopreventive action against MNNG-induced gastric carcinoma in experimental rats. [source] Affective and Adrenocorticotrophic Responses to Photoperiod in Wistar RatsJOURNAL OF NEUROENDOCRINOLOGY, Issue 2 2008B. J. Prendergast The present study tested the hypothesis that seasonal intervals of exposure to modest changes in photoperiod, typical of those experienced by humans living in temperate latitudes (10,14 h light/day), engage changes in emotional behaviour of Wistar rats, a commonly-used animal model for investigations of affective physiology. Short day lengths (, 12 h light/day) induced behavioural despair in a forced-swim test, exploratory anxiety in an open field arena, and anhedonia in a two-bottle sucrose preference task, relative to longer day lengths. Plasma adrenocorticotrophic hormone was lower in short-day relative to long-day rats, but testosterone and corticosterone concentrations were comparable across treatments. In common with animals that engage reproductive responses to day length, reproductively nonresponsive mammals such as Wistar rats exhibit changes in affective state following small changes in day length. Wistar rats may provide an animal model for the study of seasonal mood regulation because the neuroendocrine, depressive, anxious and anhedonic responses of Wistar rats to short days bear similarities to those observed in some human populations. Standard laboratory husbandry practices (exposure to a 12 : 12 h light/dark cycle) may inadvertently deliver a chronic background depressive and anxiogenic stimulus. [source] A Single, Moderate Ethanol Exposure Alters Extracellular Dopamine Levels and Dopamine D2 Receptor Function in the Nucleus Accumbens of Wistar RatsALCOHOLISM, Issue 10 2009Kelle M. Franklin Background:, The nucleus accumbens (NAc) has been implicated in the neurochemical effects of ethanol (EtOH). Evidence suggests that repeated EtOH exposures and chronic EtOH drinking increase dopamine (DA) neurotransmission in the NAc due, in part, to a reduction in D2 autoreceptor function. The objectives of the current study were to evaluate the effects of a single EtOH pretreatment and repeated EtOH pretreatments on DA neurotransmission and D2 autoreceptor function in the NAc of Wistar rats. Methods:, Experiment 1 examined D2 receptor function after a single intraperitoneal (i.p.) injection or repeated i.p. injections of 0.0, 0.5, 1.0, or 2.0 g/kg EtOH to female Wistar rats. Single EtOH pretreatment groups received 1 daily i.p. injection of 0.9% NaCl (saline) for 4 days, followed by 1 day of saline or EtOH administration; repeated EtOH pretreatment groups received 5 days of saline or EtOH injections. Reverse microdialysis experiments were conducted to determine the effects of local perfusion with the D2 -like receptor antagonist (-)sulpiride (SUL; 100 uM), on extracellular DA levels in the NAc. Experiment 2 evaluated if pretreatment with a single, moderate (1.0 g/kg) dose of EtOH would alter levels and clearance of extracellular DA in the NAc, as measured by no-net-flux (NNF) microdialysis. Subjects were divided into the EtOH-naïve and the single EtOH pretreated groups from Experiment 1. Results:, Experiment 1: Changes in extracellular DA levels induced with SUL perfusion were altered by the EtOH dose (p < 0.001), but not the number of EtOH pretreatments (p > 0.05). Post-hoc analyses indicated that groups pretreated with single or repeated 1.0 g/kg EtOH showed significantly attenuated DA response to SUL, compared with all other groups (p < 0.001). Experiment 2: Multiple linear regression analyses yielded significantly (p < 0.05) higher extracellular DA concentrations in the NAc of rats receiving EtOH pretreatment, compared with their EtOH-naïve counterparts (3.96 ± 0.42 nM and 3.25 ± 0.23 nM, respectively). Extraction fractions were not significantly different between the 2 groups. Conclusions:, The present results indicate that a single EtOH pretreatment at a moderate dose can increase DA neurotransmission in the NAc due, in part, to reduced D2 autoreceptor function. [source] Patterns of Ethanol Intake in Preadolescent, Adolescent, and Adult Wistar Rats Under Acquisition, Maintenance, and Relapse-Like ConditionsALCOHOLISM, Issue 4 2009David García-Burgos Background:, Animal behavioral models of voluntary ethanol consumption represent a valuable tool to investigate the relationship between age and propensity to consume alcohol using an experimental methodology. Although adolescence has been considered as a critical age, few are the studies that consider the preadolescence age. This study examines the ethanol consumption/preference and the propensity to show an alcohol deprivation effect (ADE) after a short voluntary ethanol exposure from a developmental perspective. Methods:, Three groups of heterogeneous Wistar rats of both sexes with ad libitum food and water were exposed for 10 days to 3 ethanol solutions at 3 different ontogenetic periods: preadolescence (PN19), adolescence (PN28), and adulthood (PN90). Ethanol intake (including circadian rhythm), ethanol preference, water and food consumption, and ADE were measured. Results:, During the exposure, the 3 groups differed in their ethanol intake; the greatest amount of alcohol (g/kg) was consumed by the preadolescent rats while the adolescents showed a progressive decrease in alcohol consumption as they approached the lowest adult levels by the end of the assessed period. The pattern of ethanol consumption was not fully explained in terms of hyperphagia and/or hyperdipsia at early ages, and showed a wholly circadian rhythm in adolescent rats. After an abstinence period of 7 days, adult rats showed an ADE measured both as an increment in ethanol consumption and preference, whereas adolescent rats only showed an increment in ethanol preference. Preadolescent rats decreased their consumption and their preference remained unchanged. Conclusions:, In summary, using a short period of ethanol exposure and a brief deprivation period the results revealed a direct relationship between chronological age and propensity to consume alcohol, being the adolescence a transition period from the infant to the adult pattern of alcohol consumption. Preadolescent animals showed the highest ethanol consumption level. The ADE was only found in adult animals for both alcohol consumption and preference, whereas adolescents showed an ADE only for preference. No effect of sex was detected in any phase of the experiment. [source] Reinstatement of Ethanol-Seeking Behavior Following Intravenous Self-Administration in Wistar RatsALCOHOLISM, Issue 9 2007Justin T. Gass Background: In animal models of alcoholism, subjects are traditionally trained to self-administer ethanol via the oral route. However, ethanol is also self-administered intravenously (IV), a paradigm which offers several advantages over oral self-administration methods, including immediate delivery to the bloodstream, more rapid onset of pharmacological effects, and elimination of the need to utilize tastants or sweeteners to mask the aversive orosensory properties of ethanol. However, no studies to date have examined reinstatement of ethanol-seeking behavior in animals with a history of IV ethanol self-administration. Methods: Male Wistar rats were implanted with indwelling jugular vein catheters and trained to self-administer ethanol IV (1% v/v solution, equivalent to 1 mg/kg) in an operant lever-pressing paradigm in twice daily 1 hour sessions. Each IV delivery of ethanol was paired with presentation of a light-tone complex stimulus. After stabilization of response patterns, IV self-administration behavior was subjected to extinction procedures. Next, animals were exposed to the three types of stimuli known to reinstate ethanol-seeking behavior: presentation of ethanol-associated cues, a priming dose of ethanol (0.5 g/kg i.p.), or exposure to stress via administration of the anxiogenic compound yohimbine (2.5 mg/kg i.p.) or its corresponding vehicle. Results: During the maintenance phase of self-administration, animals exhibited significantly more presses on the lever that delivered the ethanol solution than the inactive lever, indicating that IV ethanol functioned as a positive reinforcer. Following extinction, it was found that ethanol-seeking behavior could be reinstated by all three types of stimuli (cues, ethanol priming, and yohimbine). Vehicle injection did not affect responding on either lever. Conclusions: Ethanol serves as a reinforcer when self-administered IV, and following extinction, ethanol-seeking behavior can be reinstated by ethanol-associated cues, ethanol priming, or a pharmacological stressor. Thus, reinstatement of ethanol-seeking behavior in animals with a history of IV ethanol self-administration may be a novel animal model of relapse. [source] Effects of Neuropeptide Y on Appetitive and Consummatory Behaviors Associated With Alcohol Drinking in Wistar Rats With a History of Ethanol ExposureALCOHOLISM, Issue 4 2005Annika Thorsell Background: Neuropeptide Y (NPY) reduces ethanol intake under free access conditions in Wistar rats with a history of prolonged ethanol vapor exposure. The current study was designed to determine whether NPY differentially alters ethanol-associated appetitive behavior (i.e., lever pressing) or ethanol consumption in Wistar rats with a history of ethanol vapor exposure. Methods: Wistar rats were first trained to self-administer 10% ethanol in a paradigm that provided 25 min of free access to 10% ethanol after completing a 20,lever press response requirement (i.e., an RR20 schedule). After stable level lever pressing was established, operant sessions were suspended during a 9-week period of ethanol vapor exposure. Self-administration sessions were then reinstituted, and a fixed time (FT) schedule of 10% ethanol access was used to assess the effects of ethanol exposure and NPY on lever pressing and drinking behavior. Under the FT schedule, the maximum number of lever presses emitted within 10 min was assessed before providing access to 10% ethanol. Results: Ethanol vapor exposure did not alter patterns of lever pressing under the RR20 schedule, but lever presses emitted under the FT schedule were reduced after ethanol vapor exposure. Ethanol intake was significantly increased after ethanol vapor exposure. NPY significantly reduced ethanol intake but did not significantly reduce lever pressing under the FT schedule. Conclusions: Taken together, these data suggest that chronic ethanol exposure increases ethanol intake without clearly enhancing its reinforcing value. Furthermore, NPY has a greater impact on the consummatory factors mediating ethanol intake than appetitive factors mediating ethanol seeking. [source] Ultrastructural Features of Myenteric Ganglia of Adult Wistar Rats (Rattus norvegicus)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 6 2000M. R. M. Natali Summary The ultrastructural features of the ganglia of the myenteric plexus exhibit changes according to the animal species. These myenteric ganglia in the duodenum of adult rats of the Wistar strain were characterized ultrastructurally in this work. Those ganglia were depicted as compact structures, composed of neurones and glial cells, forming a dense neuropil surrounded by a continuous basal lamina and collagen fibrils. Glial cell bodies were smaller and apparently more frequent than neuronal cell bodies, being morphologically distinguished by nuclear features. In the neuronal extensions granular and agranular synaptic vesicles of different sizes predominate, in addition to mitochondria and myelinized profiles. Gliofilaments were not observed on the glial extensions of the rats. [source] Tephrosia purpurea Ameliorates N-Diethylnitrosamine and Potassium Bromate-Mediated Renal Oxidative Stress and Toxicity in Wistar RatsBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 6 2001Naghma Khan 1999). The present study was designed to investigate a chemopreventive efficacy of T. purpurea against N-diethylnitrosamine-initiated and potassium bromate-mediated oxidative stress and toxicity in rat kidney. A single intraperitoneal dose of N-diethylnitrosamine (200 mg/kg body weight) one hr prior to the dose of KBrO3 (125 mg/kg body weight) increases microsomal lipid peroxidation and the activity of xanthine oxidase and decreases the activities of renal antioxidant enzymes viz., catalase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase, phase II metabolizing enzymes such as glutathione-S-transferase and quinone reductase and causes depletion in the level of renal glutathione content. A sharp increase in blood urea nitrogen and serum creatinine has also been observed. Prophylactic treatment of rats with T. purpurea at doses of 5 mg/kg body weight and 10 mg/kg body weight prevented N-diethylnitrosamine-initiated and KBrO3 promoted renal oxidative stress and toxicity. The susceptibility of renal microsomal membrane for iron ascorbate-induced lipid peroxidation and xanthine oxidase activities were significantly reduced (P<0.01). The depleted levels of glutathione, the inhibited activities of antioxidant enzymes, phase II metabolizing enzymes and the enhanced levels of serum creatinine and blood urea nitrogen were recovered to a significant level (P<0.01). All the antioxidant enzymes were recovered dose-dependently. Our data indicate that T. purpurea besides a skin antioxidant can be a potent chemopreventive agent against renal oxidative stress and carcinogenesis induced by N-diethylnitrosamine and KBrO3. [source] Dose- and Sex-related Carcinogenesis by N-Bis(2-hydroxypropyl)nitrosamine in Wistar RatsCANCER SCIENCE, Issue 4 2000Eduardo L. T. Moreira An initiation-promotion medium-term bioassay for detection of chemical carcinogens, developed in the male F344 rat, uses 0.1% N-bis(2-hydroxypropyl)nitrosamine (DHPN) among five genotoxic chemicals for the initiation of carcinogenesis in multiple organs. To establish this bioassay in the Wistar strain, the effects of two dose levels of DHPN were evaluated on the main DHPN rat target organs: lung, thyroid gland, kidneys and liver. Four groups of male and female animals were studied: Control,untreated group; Multi-organ initiated group (also referred to as DMBDD, based on the initials of the five initiators),treated sequentially with N-diethylnitrosamine (DEN, i.p.), N-methyl-N-nitrosourea (MNU, i.p.), N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN, drinking water), N, ,N,-dimethylhydrazine (DMH, s.c.) and DHPN (drinking water) for 4 weeks; a third group treated with 0.1% DHPN in drinking water for 2 weeks and the last group treated with 0.2% DHPN in drinking water for 4 weeks. The animals were sacrificed after 30 weeks. DHPN at 0.2% induced preneoplasia in the liver and kidneys of rats of both sexes, the number and area of the putative preneoplastic liver glutathione S-transferase-positive hepatocyte foci being significantly increased in these animals. It also induced benign and malignant tumors in female and in male rats. However, there was no relationship between the increased incidence of preneoplastic lesions and tumor development in the 0.2% DHPN-exposed groups of both sexes. DHPN at 0.1% induced only a few preneoplastic lesions in the liver and kidney and no tumors in both male and female rats. A clear dose and sex-related carcinogenic activity of DHPN was registered, although Wistar rats of both sexes showed a relative resistance to the carcinogenic activity of this compound. [source] A biodegradable copolymer for the slow release of growth hormone expedites scarring in diabetic ratsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2007Francisco García-Esteo Abstract In many diseases wound healing is impaired. This study was designed to establish whether the healing process in diabetes could be improved using a site-specific polymer delivery system containing hGH. The system was first optimized in in vitro experiments performed on cultured fibroblasts taken from healthy and diabetic rats and then tested in an incisional wound model created in the diabetic Wistar rat. In the in vitro experiments using cultured fibroblasts, cell viability, growth, and proliferation were determined, along with polymer degradation, hormone release rates and the expression of TGF,1 in the culture medium. For the in vivo experiments, polymer discs with/without GH were inserted through 3 cm incisions made on the backs of the animals. Wound specimens were obtained 7 and 30 days after surgery to evaluate inflammatory/apoptotic cells, metalloprotease expression and neoangiogenesis using microscopy and immunohistochemical techniques. The local administration of GH using a polymer delivery system did not affect the normal wound healing process. Conversely, when used in diabetic animals, epidermal and dermal repair was expedited. Our findings indicate that GH induces cell proliferation, enhances CD4+ infiltration; increases extracellular matrix protein deposition; stimulates angiogenesis; and diminishes apoptosis at the diabetic wound site. These effects give rise to a comparable wound healing process to that observed in healthy animals. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] 1,8-Cineole induces relaxation in rat and guinea-pig airway smooth muscleJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 3 2009Nilberto Robson Falcão Nascimento Abstract Objectives 1,8-Cineole is a monoterpene with anti-inflammatory, vascular and intestinal smooth muscle relaxant activity. We have evaluated the potential bronchodilatatory activity of this compound. Methods 1,8-Cineole was tested against carbachol, histamine, K+ 80 mM and ovalbumin-induced bronchial contractions in Wistar rat or guinea-pig tissues. Some of the guinea-pigs had been previously sensitized with an intramuscular injection of 5% (w/v) ovalbumin/saline solution. Control animals received 0.3 ml saline. In separate experimental groups the response to 1,8-cineole (1,30 mg/kg), phenoterol (0.05,5 mg/kg) or vehicle (0.3% Tween in saline) was studied. Key findings 1,8-Cineole decreased, in vivo, rat bronchial resistance with similar efficacy as phenoterol (66.7 ± 3.2% vs 72.1 ± 5.3%). On the other hand, the maximal relaxant response to 1,8-cineole in carbachol-precontracted rat tracheas was 85.5 ± 5.7% (IC50 = 408.9 (328,5196) ,g/ml) compared with 80.2 ± 4.8% (IC50 = 5.1 (4.3,6.1) ,g/ml) with phenoterol. The addition of 1,8-cineole to guinea-pig tracheal rings tonically contracted with K+ 80 mM induced a concentration-related relaxation. The maximal relaxation elicited by 1,8-cineole was 113.6 ± 11.7% (IC50 127.0 (115.9,139.2) ,g/ml) compared with 129.7 ± 14.6% (IC50 0.13 (0.12,0.14) ,g/ml) achieved after phenoterol administration. In addition, the incubation of tracheal rings with 1,8-cineole (100, 300 or 1000 ,g/ml), 15 min before inducing phasic contractions with K+ 80 mM, decreased the maximal amplitude of the contraction by 31.6 ± 4.6, 75.7 ± 2.7 and 92.2 ± 1.5%, respectively. In another set of experiments, neither the maximal response nor the IC50 for the 1,8-cineole-induced relaxation were different between normal and ovalbumin-sensitized tissues. Moreover, the relaxation of bronchial rings contracted after exposure to 1 ,g/ml ovalbumin occurred at a faster rate in rings pre-incubated with 1,8-cineole when compared with rings pre-incubated with vehicle only (Tween 0.3%). Therefore, in the first minute after the antigen challenge, the tracheal tissue relaxed after the peak contraction by 6.5, 21.4 (P < 0.05 vs control) and 66.9% (P < 0.05 vs control) in the presence of 100, 300 or 1000 ,g/ml 1,8-cineole, respectively. Conclusions 1,8-Cineole relaxed rat and guinea-pig (nonsensitized and ovalbumin-sensitized) airway smooth muscle by a nonspecific mechanism. [source] Efficacy and irritancy of enhancers on the in-vitro and in-vivo percutaneous absorption of curcuminJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 5 2003Jia-You Fang Curcumin is a predominant compound derived from the rhizomes of Curcuma longa L., and shows antibacterial, anti-inflammatory and antineoplastic activity. The in-vitro and in-vivo skin absorption of curcumin was investigated after application of enhancers using Wistar rat as an animal model. The enhancers selected in this study included terpenes, flavonoids and cholestanol. The irritant profiles of these enhancers were also established by transepidermal water loss (TEWL) and histological observations. Cyclic monoterpenes generally showed stronger enhancement of curcumin permeation than the other enhancers. Modulation of concentration and pretreatment duration of enhancers possibly indicated that the enhancers have varied ability and mechanisms to enhance curcumin permeation. Terpineol produced the highest TEWL values among the enhancers tested, whereas ketocholestanol produced no, or only a negligible, increase in TEWL as compared with control. The results showed that skin disruption and inflammation did not necessarily correspond to the enhancing efficiency of the enhancers. [source] Dosimetric analysis of the carousel setup for the exposure of rats at 1.62 GHzBIOELECTROMAGNETICS, Issue 1 2004Frank Schönborn Abstract The so-called carousel setup has been widely utilized for testing the hypotheses of adverse health effects on the central nervous system (CNS) due to mobile phone exposures in the frequency bands 800,900 MHz. The objectives of this article were to analyze the suitability of the setup for the upper mobile frequency range, i.e., 1.4,2 GHz, and to conduct a detailed experimental and numerical dosimetry for the setup at the IRIDIUM frequency band of 1.62 GHz. The setup consists of a plastic base on which ten rats, restrained in radially positioned tubes, are exposed to the electromagnetic field emanating from a sleeved dipole antenna at the center. Latest generation miniaturized dosimetric E field and temperature probes were used to measure the specific absorption rate (SAR) inside the brain of three rat cadavers of the Lewis strain and two rat cadavers of the Fisher 344 strain. A numerical analysis was conducted on the basis of three numerical rat phantoms with voxel sizes between 1.5 and 0.125 mm3 that are based on high resolution MRI scans of a 300 g male Wistar rat and a 370 g male Sprague,Dawley rat. The average of the assessed SAR values in the brain was 2.8 mW/g per W antenna input power for adult rats with masses between 220 and 350 g and 5.3 mW/g per W antenna input power for a juvenile rat with a mass of 95 g. The strong increase of the SAR in the brain with decreasing animal size was verified by simulations of the absorption in numerical phantoms scaled to sizes between 100 and 500 g with three different scaling methods. The study also demonstrated that current rat phantom models do not provide sufficient spatial resolution to perform absolute SAR assessment for the brain tissue. The variation of the SARbrainav due to changes in position was assessed to be in the range from +15% to ,30%. A study on the dependence of the performance of the carousel setup on the frequency revealed that efficiency, defined as SARbrainav per W antenna input power, and the ratio between SARbrainav and SARbodyav are optimal in the mobile communications frequency range, i.e., 0.8,3 GHz. Bioelectromagnetics 25:16,26, 2004. © 2003 Wiley-Liss, Inc. [source] Kinetics and Efficacy of an Organophosphorus Hydrolase in a Rodent Model of Methyl-parathion PoisoningACADEMIC EMERGENCY MEDICINE, Issue 7 2010Chip Gresham MD ACADEMIC EMERGENCY MEDICINE 2010; 17:736,740 © 2010 by the Society for Academic Emergency Medicine Abstract Objectives:, Organophosphorus (OP) pesticides exert a tremendous health burden, particularly in the developing world. Limited resources, the severity of intentional OP ingestions, and a paucity of beneficial therapies all contribute to the morbidity and mortality of this broad class of chemicals. A novel theoretical treatment for OP poisoning is the use of an enzyme to degrade the parent OP in the circulation after poisoning. The aims of this study were to determine the pharmacokinetics and efficacy of an OP hydrolase (OpdA) in a rodent model of severe methyl-parathion poisoning. Methods:, Two animal models were used. First, Wistar rats were administered two different doses of the hydrolase (0.15 and 1.5 mg/kg), and the ex vivo hydrolytic activity of plasma was determined by a fluorometric method. Second, an oral methyl-parathion animal poisoning model was developed to mimic severe human poisoning, and the efficacy of postpoisoning OpdA (as measured by survival to 4 and 24 hours) was determined. Results:, The half-life of OpdA in the Wistar rat was dependent on the dose administered and ranged between 45.0 and 57.9 minutes. The poisoning model of three times the lethal dose to 50% of the population (3 × LD50) of methyl-parathion resulted in 88% lethality at 4 and 24 hours. Using a single dose of 0.15 mg/kg OpdA 10 minutes after poisoning resulted in 100% survival at 4 hours (p = 0.001 vs. placebo), but 0% at 24 hours postpoisoning (p = NS vs. placebo). Conclusions:, The OP hydrolase OpdA exhibits pharmacokinetics suitable for repeated dosing and increases short-term survival after severe methyl-parathion poisoning. [source] Gene expression profiling of the ageing rat vibrissa follicleBRITISH JOURNAL OF DERMATOLOGY, Issue 1 2005C-L. Yang Summary Background, The application of gene expression profiling to the study of chronological ageing has the potential to illuminate the molecular mechanisms underlying a complex and active process. For example, ageing of the skin and its constituent organs has myriad phenotypic consequences, and a better understanding of the means by which these changes arise has important corollaries for intervention strategies. Objectives, We used a transcriptional profiling approach to investigate changes in gene expression associated with ageing of the large vibrissa follicle of the Wistar rat. Methods, Follicle mRNA isolated from male Wistar rats at 1 and 18 months of age was hybridized to Clontech Atlas 1.2 Rat cDNA macroarrays. Confirmation of array results was provided by the use of Northern blotting and immunohistochemistry. Results, Seven transcripts displayed at least a 1·6-fold increase in expression with age, of which APOD (2·5-fold), GSTM2 (2·0-fold) and NPY (1·8-fold) showed the greatest increases. Decreased expression was found in 19 transcripts, most notably in ALOX12 (13·3-fold) and GAP43 (12·6-fold) expression. Conclusions, Follicular ageing is characterized by transcriptional changes associated with diverse aspects of keratinocyte metabolism, proliferation and development. [source] Stereoselective pharmacokinetics of clausenamide enantiomers and their major metabolites after single intravenous and oral administration to ratsCHIRALITY, Issue 8 2003Chuan Jiang Zhu Abstract The pharmacokinetics of clausenamide (CLA) enantiomers and their metabolites were investigated in Wistar rat. After intravenous and oral administration at a dose of 80 and 160 mg/kg each enantiomer, plasma concentrations of (,)- or (+)-CLA and its major metabolites were simultaneously determined by reverse-phase HPLC with UV detection. Notably, stereoselective differences in pharmacokinetics were found. The mean plasma levels of (+)-CLA were higher at almost all time points than those of (,)-CLA. (+)-CLA also exhibited greater tmax, Cmax, t1/2,, AUC0,12h, and AUC0,, and smaller CL (or CL/F) and Vd (or Vd/F), than its antipode. The (+)/(,) isomer ratios for t1/2,, tmax, AUC0,12 h, and AUC0,,, which ranged from 1.26 to 2.08. The ratio for CL (or CL/F) was about 0.5, and there were significant differences in these values between CLA enantiomers (P < 0.05), implying that the absorption, distribution, and elimination of (,)-CLA were more rapid than those of (+)-CLA. Similar findings for (,)-7-OH-CLA, the major metabolite of (,)-CLA, and (+)-4-OH-CLA, the major metabolite of (+)-CLA, can be also seen in rat plasma. The contributing factors for the differences in stereoselective pharmacokinetics of CLA enantiomers appeared to be involved in their different plasma protein binding, first-pass metabolism and interaction with CYP enzymes, especially with their metabolizing enzyme CYP 3A isoforms. Chirality 15:668,673, 2003. © 2003 Wiley-Liss, Inc. [source] Antiandrogenic effects of dibutyl phthalate and its metabolite, monobutyl phthalate, in ratsCONGENITAL ANOMALIES, Issue 4 2002Makoto Ema ABSTRACT, Developmental toxicity following administration of dibutyl phthalate (DBF) and its major metabolite, monobutyl phthalate (MBuP), by gavage was determined in Wistar rats. DBF on days 0,8 of pregnancy induced an increase in the incidence of preimplantation loss at 1250 mg/kg and higher and postimplantation loss at 750 mg/kg and higher. MBuP on days 0,8 of pregnancy produced an increase in the incidence of pre-and postimplantation loss at 1000 mg/kg. DBF on days 7,15 of pregnancy caused an increase in the incidence of fetuses with malformations at 750 mg/kg. MBuP on days 7,15 of pregnancy produced an increased incidence of fetuses with malformations at 500 mg/kg and higher. DBF on days 15,17 of pregnancy resulted in a decrease in the anogenital distance (AGD) of male fetuses and increase in the incidence of fetuses with undescended testes at 500 mg/kg and higher. MBuP on days 15,17 of pregnancy caused a decreased male AGD and increased incidence of fetuses with undescended testes at 250 mg/kg and higher. No effect of DBF and MBuP on the AGD was found in female offspring. The spectrum of fetal malformations, dependence of gestational days of treatment on the manifestation of teratogenicity, and alterations in development of the male reproductive system observed after administration of DBF were in good agreement with those observed after administration of MBuP. These findings suggest that MBuP may be responsible for the induction of developmental toxic effects of DBP. The doses that produced a decrease in the AGD and undescended testes in male offspring were lower than those producing maternal toxicity, fetal malformations after administration during major organogenesis, and embryonic loss. The male reproductive system may be more susceptible than other organ systems to DBP and MBuP toxicity after maternal exposure. [source] Protein kinase C mRNA and protein expressions in hypobaric hypoxia-induced cardiac hypertrophy in ratsACTA PHYSIOLOGICA, Issue 4 2010M. Uenoyama Abstract Aim:, Protein kinase C (PKC), cloned as a serine/threonine kinase, plays key roles in diverse intracellular signalling processes and in cardiovascular remodelling during pressure overload or volume overload. We looked for correlations between changes in PKC isoforms (levels and/or subcellular distributions) and cardiac remodelling during experimental hypobaric hypoxic environment (HHE)-induced pulmonary hypertension. Methods:, To study the PKC system in the heart during HHE, 148 male Wistar rats were housed for up to 21 days in a chamber at the equivalent of 5500 m altitude level (10% O2). Results:, At 14 or more days of exposure to HHE, pulmonary arterial pressure (PAP) was significantly increased. In the right ventricle (RV): (1) the expression of PKC-, protein in the cytosolic and membrane fractions was increased at 3,14 days and at 5,7 days of exposure respectively; (ii) the cytosolic expression of PKC-, protein was increased at 1,5, 14 and 21 days of exposure; (3) the membrane expressions of the proteins were decreased at 14,21 (PKC-,II), 14,21 (PKC-,), and 0.5,5 and 21 (PKC-,) days of exposure; (4) the expression of the active form of PKC-, protein on the plasma membrane was increased at 3 days of exposure (based on semiquantitative analysis of the immunohistochemistry). In the left ventricle, the expressions of the PKC mRNAs, and of their cytosolic and membrane proteins, were almost unchanged. The above changes in PKC-,, which were strongly evident in the RV, occurred alongside the increase in PAP. Conclusion:, PKC-, may help to modulate the right ventricular hypertrophy caused by pulmonary hypertension in HHE. [source] Impaired contractile function and mitochondrial respiratory capacity in response to oxygen deprivation in a rat model of pre-diabetesACTA PHYSIOLOGICA, Issue 4 2009M. F. Essop Abstract Aim:, Obesity is a major contributor to the global burden of disease and is closely associated with the development of type 2 diabetes and cardiovascular diseases. This study tested the hypothesis that mitochondrial respiratory capacity of the pre-diabetic heart is decreased leading to impaired contractile function and tolerance to ischaemia/reperfusion. Methods:, Eight-week-old male Wistar rats were fed a high caloric diet for 16 weeks after which anthropometric, metabolic, cardiac and mitochondrial parameters were evaluated vs. age-matched lean controls. Cardiac function (working heart perfusions) and mitochondrial respiratory capacity were assessed at baseline and in response to acute oxygen deprivation. Results:, Rats fed the high caloric diet exhibited increased body weight and visceral fat vs. the control group. Heart weights of obese rats were also increased. Triglyceride, fasting plasma insulin and free fatty acid levels were elevated, while high-density lipoprotein cholesterol levels were reduced in the obese group. Contractile function was attenuated at baseline and further decreased after subjecting hearts to ischaemia-reperfusion. Myocardial infarct sizes were increased while ADP phosphorylation rates were diminished in obese rats. However, no differences were found for mtDNA levels and the degree of oxidative stress-induced damage. Conclusions:, These data show that decreased mitochondrial bioenergetic capacity in pre-diabetic rat hearts may impair respiratory capacity and reduce basal contractile function and tolerance to acute oxygen deprivation. [source] DHEA improves impaired activation of Akt and PKC ,/,-GLUT4 pathway in skeletal muscle and improves hyperglycaemia in streptozotocin-induced diabetes ratsACTA PHYSIOLOGICA, Issue 3 2009K. Sato Abstract Aim:, Addition of dehydroepiandrosterone (DHEA) to a cultured skeletal muscle locally synthesizes 5,-dihydrotestosterone (DHT). It induced activation of glucose metabolism-related signalling pathway via protein kinase B (Akt) and protein kinase C zeta/lambda (PKC ,/,)-glucose transporter-4 (GLUT4) proteins. However, such an effect of DHEA in vivo remains unclear. Methods:, Using streptozotocin (STZ)-induced rats with type 1 diabetes mellitus, we tested the hypothesis that a single bout of DHEA injection in the rats improves hyperglycaemia and muscle GLUT4-regulated signalling pathway. After 1 week of STZ injection (55 mg kg,1) with male Wistar rats, fasting glucose concentrations were determined in a blood sample taken from the tail vein. Blood glucose levels were then monitored for 180 min after DHEA or sesame oil (control) was injected (n = 10 for each group). Results:, Blood glucose levels decreased significantly for 30,150 min after 2 mg DHEA injection in the STZ rats. In the skeletal muscle, expression and translocation of GLUT4 protein, phosphorylation of Akt and PKC ,/,, and phosphofructokinase and hexokinase enzyme activities increased significantly by DHEA injection. However, DHEA-induced improvements in Akt and PKC ,/,-GLUT4 pathways were blocked by a DHT inhibitor. Conclusion:, These results suggest that a single bout of DHEA injection can improve hyperglycaemia and activate the glucose metabolism-related signalling pathway via Akt and PKC ,/,-GLUT4 proteins of skeletal muscles in rats. Moreover, these results show that a DHEA-induced increase in muscle glucose uptake and utilization might contribute to improvement in hyperglycaemia in type 1 diabetes mellitus. [source] Protective effects of exercise preconditioning on hindlimb unloading-induced atrophy of rat soleus muscleACTA PHYSIOLOGICA, Issue 1 2009H. Fujino Abstract Aim:, A chronic decrease in the activation and loading levels of skeletal muscles as occurs with hindlimb unloading (HU) results in a number of detrimental changes. Several proteolytic pathways are involved with an increase in myofibrillar protein degradation associated with HU. Exercise can be used to counter this increase in proteolytic activity and, thus, may be able to protect against some of the detrimental changes associated with chronic decreased use. The purpose of the present study was to determine the potential of a single bout of preconditioning endurance exercise in attenuating the effects of 2 weeks of HU on the mass, phenotype and force-related properties of the soleus muscle in adult rats. Methods:, Male Wistar rats were subjected to HU for 2 weeks. One half of the rats performed a single bout of treadmill exercise for 25 min immediately prior to the 2 weeks of HU. Results:, Soleus mass, maximum tetanic tension, myofibrillar protein content, fatigue resistance and percentage of type I (slow) myosin heavy chain were decreased in HU rats. In addition, markers for the cathepsin, calpain, caspase and ATP-ubiquitin-proteasome proteolytic pathways were increased. The preconditioning endurance exercise bout attenuated all of the detrimental changes associated with HU, and increased HSP72 mRNA expression and protein levels. Conclusion:, These findings indicate that exercise preconditioning may be an effective countermeasure to the detrimental effects of chronic decreases in activation and loading levels on skeletal muscles and that an elevation in HSP72 may be one of the mechanisms associated with these responses. [source] Similarity of permeabilities for Ficoll, pullulan, charge-modified albumin and native albumin across the rat peritoneal membraneACTA PHYSIOLOGICA, Issue 4 2009D. Asgeirsson Abstract Aim:, Compared to neutral globular proteins, neutral polysaccharides, such as dextran, pullulan and Ficoll, appear hyperpermeable across the glomerular filtration barrier. This has been attributed to an increased flexibility and/or asymmetry of polysaccharides. The present study investigates whether polysaccharides are hyperpermeable also across the continuous capillaries in the rat peritoneum. Methods:, In anaesthetized Wistar rats, FITC,Ficoll or FITC,pullulan together with 125I-human serum albumin (RISA) or neutralized 125I-bovine serum albumin (nBSA) were given intravenously, after which peritoneal dialysis (PD) using conventional PD fluid (Gambrosol 1.5%) was performed for 120 min. Concentrations of FITC-polysaccharides and radioactive albumin species in plasma and dialysis fluid were analysed with high-performance size exclusion chromatography and a gamma counter respectively. Transperitoneal clearance values were calculated for polysaccharides in the molecular radius range 36,150 Å, and for RISA and nBSA. Results:, Ficoll and pullulan showed more or less identical permeabilities, compared to RISA and nBSA, across the peritoneal membrane. Although RISA-clearance, 5.50 ± 0.28 (,L min,1; ±SEM), tended to be lower than the clearances of Ficoll36Å (6.55 ± 0.25), pullulan36Å (6.08 ± 0.22) and nBSA (6.56 ± 0.23), the difference was not statistically significant. This is in contrast to the hyperpermeability exhibited by polysaccharides across the glomerular filtration barrier and also contrasts with the charge selectivity of the latter. Conclusion:, The phenomenon of molecular flexibility is more important for a macromolecule's permeability through the glomerular filter than across the continuous peritoneal capillary endothelium. Furthermore, it seems that charge plays a subordinate role in the steady-state transport across the combined peritoneal capillary,interstitial barrier. [source] Different adaptations of alpha-actinin isoforms to exercise training in rat skeletal musclesACTA PHYSIOLOGICA, Issue 3 2009Y. Ogura Abstract Aim:, Alpha (,)-actinins are located in the skeletal muscle Z-line and form actin,actin cross-links. Mammalian skeletal muscle has two isoforms: ,-actinin-2 and ,-actinin-3. However, the response of ,-actinin to exercise training is little understood. Therefore, the current study examined the effects of exercise training on the expression level of two ,-actinin isoforms in skeletal muscles. Methods:, Twelve male Wistar rats were assigned randomly to a control (C; n = 6) or exercise training (T; n = 6) group. After T animals were trained on an animal treadmill for 9 weeks, ,-actinin-2 and ,-actinin-3 levels in the plantaris, white and red gastrocnemius muscles were analysed. In addition, changes in the myosin heavy chain (MyHC) composition were assessed, and muscle bioenergetic enzyme activities were measured. Results:, Results show that exercise training increased ,-actinin-2 expression levels in all muscles (P < 0.05). However, no significant difference was found in ,-actinin-3 expression levels between C and T animals. Subsequent MyHC analyses of all muscle showed an MyHC shift with direction from IIb to IIa. Furthermore, enzymatic analysis revealed that exercise training improved enzyme activities related to aerobic metabolism. Conclusion:, The results of this study demonstrate that exercise training alters the expression level of ,-actinin at the isoform level. Moreover, the increase in expression levels of ,-actinin-2 is apparently related to alteration of skeletal muscle: its aerobic capacity is improved. [source] Changes in the contractile properties of motor units in the rat medial gastrocnemius muscle after one month of treadmill trainingACTA PHYSIOLOGICA, Issue 4 2008M. Pogrzebna Abstract Aim:, The influence of 4 weeks treadmill training on the contractile properties of motor units (MUs) in the rat medial gastrocnemius muscle was investigated. Methods:, A population of 18 Wistar rats was divided into two groups: trained on a treadmill (n = 7, locomotion speed 27 cm s,1, 1 km daily, 5 days a week, for 4 weeks) and control (n = 11). The contractile properties of isolated MUs were studied. Functional isolation of units was achieved by electrical stimulation of filaments of the ventral roots. A total of 299 MUs were investigated (142 in the control group and 157 in the trained group). They were divided into fast fatigable (FF), fast resistant to fatigue (FR) and slow (S). Their proportions and parameters of contractions were analysed. Results:, Following training, the number of FF units decreased and the number of FR units increased. The distribution of the fatigue index changed within these two types of fast units. The twitch and tetanus forces increased considerably in fast MUs, mainly in those of the FF type. The contraction and relaxation times shortened in the FR and S MUs. The steep part of the force,frequency curves shifted towards higher stimulation frequencies in FR and S units, while in FF units the shift was in the opposite direction. Conclusion:, The significant change in the proportions of fast MUs following training indicates FF to FR transformation. The various effects of training seen in the different MU types help explain the rationale behind mixed training. [source] Changes in skeletal muscle size, fibre-type composition and capillary supply after chronic venous occlusion in ratsACTA PHYSIOLOGICA, Issue 4 2008S. Kawada Abstract Aim:, We have previously shown that surgical occlusion of some veins from skeletal muscle results in muscle hypertrophy without mechanical overloading in the rat. The present study investigated the changes in muscle-fibre composition and capillary supply in hypertrophied muscles after venous occlusion in the rat hindlimb. Methods:, Sixteen male Wistar rats were randomly assigned into two groups: (i) sham operated (sham-operated group; n = 7); (ii) venous occluded for 2 weeks (2-week-occluded group; n = 9). At the end of the experimental period, specimens of the plantaris muscle were dissected from the hindlimbs and subjected to biochemical and histochemical analyses. Results:, Two weeks after the occlusion, both the wet weight of plantaris muscle relative to body weight and absolute muscle weight showed significant increases in the 2-week-occluded group (,15%) when compared with those in the sham-operated group. The concentrations of muscle glycogen and lactate were higher in the 2-week-occluded group, whereas staining intensity of muscle lipid droplets was lower in the 2-week-occluded group than those in the sham-operated group. The percentage of type I muscle fibre decreased, whereas that of type IIb fibre increased in the 2-week-occluded group when compared with the sham-operated group. Although the expression of vascular endothelial growth factor-188 mRNA increased, the number of capillaries around the muscle fibres tended to decrease (P = 0.07). Conclusion:, Chronic venous occlusion causes skeletal muscle hypertrophy with fibre-type transition towards faster types and changes in contents of muscle metabolites. [source] Skeletal muscle HSP72 response to mechanical unloading: influence of endurance trainingACTA PHYSIOLOGICA, Issue 4 2004D. Desplanches Abstract Aims:, It has been shown that increased contractile activity results in heat shock protein 72 (HSP72) accumulation in various skeletal muscles. By contrast, there is no consensus for muscle HSP72 response to muscle disuse for short duration (5,8 days). On the basis of a greater constitutive HSP72 expression in slow-twitch muscles we tested the hypothesis that mechanical unloading for a longer period (2 weeks) would affect this phenotype to a greater extent. Secondly, we evaluated the effects of a physiological muscle heat shock protein (HSP) enhancer (endurance training) on HSP response to unloading and muscle remodelling. Methods:, Adult male Wistar rats were assigned randomly to four groups: (1) sedentary weight-bearing; (2) hindlimb-unloaded (HU) via tail suspension for 2 week; (3) trained on a treadmill (6 week) and (4) trained 6 week and then HU for 2 week. Results:, Unloading resulted in a preferential atrophy of slow muscles [soleus (SOL), adductor longus (AL)] and a slow-to-fast fibre transition with no change in HSP72 level. HSP72 levels were significantly lower in fast muscles [extensor digitorum longus (EDL) and plantaris (PLA)], and did not change with mechanical unloading. Endurance training was accompanied by a small (SOL) or a large (EDL, PLA) increase in HSP72 level with no change in AL. Training-induced accumulation of HSP72 disappeared with subsequent unloading in the SOL and PLA whereas HSP72 content remained elevated in EDL. Conclusion:, The results of this study indicate that (1) after 2 weeks of unloading no change occurred in HSP72 protein levels of slow-twitch muscles despite a slow-to-fast fibre transition; and (2) the training-induced increase of HSP72 content in skeletal muscles did not attenuate fibre transition. [source] Changes in capillary luminal diameter in rat soleus muscle after hind-limb suspensionACTA PHYSIOLOGICA, Issue 4 2000Kano This study examined the time course change of the capillary luminal diameter and the number of capillaries in the rat soleus muscle during hind-limb suspension. Male Wistar rats were divided into 1 and 3 weeks of hind-limb suspension (HS) groups (HS-1 and HS-3). The HS groups were compared with age-matched control groups. All morphometric parameters with respect to capillary and muscle fibre cross-sectional area were determined in perfusion-fixed soleus muscles. After 1 and 3 weeks of hind-limb suspension, the mean muscle fibre cross-sectional area was significantly decreased in HS-1 (,32.0%) and HS-3 (,59.3%) compared with age-matched control groups. Despite a lower capillary-to-fibre ratio (HS-1, ,19.3%; HS-3, ,21.2%), the capillary density was unchanged in HS-1 and significantly increased in HS-3 compared with age-matched control groups. The mean capillary luminal diameter was significantly smaller in HS-1 (,19.9%) and HS-3 (,21.9%) than in the age-matched control groups. The capillary-to-fibre perimeter ratio which indicates the capillary surface area available for gas exchange between blood and tissue did not significantly differ between control groups and HS groups. In conclusion, the morphometrical adaptations in rat soleus with the suspension involved changes in both the capillary luminal diameter and number of capillaries, and the change in capillary surface area was proportional to the degree of muscle atrophy in HS groups. [source] Dopamine receptors modulate ethanol's locomotor-activating effects in preweanling ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 1 2010Carlos Arias Abstract Near the end of the second postnatal week motor activity is increased soon after ethanol administration (2.5,g/kg) while sedation-like effects prevail when blood ethanol levels reach peak values. This time course coincides with biphasic reinforcement (appetitive and aversive) effects of ethanol determined at the same age. The present experiments tested the hypothesis that ethanol-induced activity during early development in the rat depends on the dopamine system, which is functional in modulating motor activity early in ontogeny. Experiments 1a and 1b tested ethanol-induced activity (0 or 2.5,g/kg) after a D1-like (SCH23390; 0, .015, .030, or .060,mg/kg) or a D2-like (sulpiride; 0, 5, 10, or 20,mg/kg) receptor antagonist, respectively. Ethanol-induced stimulation was suppressed by SCH23390 or sulpiride. The dopaminergic antagonists had no effect on blood ethanol concentration (Experiments 2a and 2b). In Experiment 3, 2.5,g/kg ethanol increased dopamine concentration in striatal tissue as well as locomotor activity in infant Wistar rats. Adding to our previous results showing a reduction in ethanol induced activity by a GABA B agonist or a nonspecific opioid antagonist, the present experiments implicate both D1-like and D2-like dopamine receptors in ethanol-induced locomotor stimulation during early development. According to these results, the same mechanisms that modulate ethanol-mediated locomotor stimulation in adult rodents seem to regulate this particular ethanol effect in the infant rat. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 52: 13,23, 2010 [source] Effects of early weaning on anxiety and prefrontal cortical and hippocampal myelination in male and female wistar ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2008Yuka Kodama Abstract We investigated developmental changes in myelin formation in the prefrontal cortex and the hippocampus, and behavioral effects of early weaning in Wistar rats. Early-weaned rats showed decreased numbers of open-arm entries in an elevated plus-maze in both sexes at 4 weeks old; this effect persisted in males, but ceased in females after this age. Expression of myelin basic protein (MBP) showed both age-dependent increases and sex differences; 4-week-old males exhibited higher MBP levels in the hippocampus, whereas 7-week-old males showed lower MBP levels in the prefrontal cortex compared to females of the same age. There was a tendency for group differences from weaning for the 21.5-kDa isoform in the prefrontal cortex. Although these results suggest that male rats are more vulnerable than females to early-weaning effects on anxiety-related behaviors, further detailed analysis is needed to clarify the functional relationship between myelination and anxiety-related behaviors. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 332,342, 2008. [source] Early weaning decreases play-fighting behavior during the postweaning developmental period of wistar ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2007Michito Shimozuru Abstract We examined the influence of early weaning on the development of play-fighting behaviors and anxiety status in Wistar rats. Pups were divided into two groups, those weaned at postnatal day (PD) 16 (early-weaned group) and those weaned at PD30 (normally weaned group), and were housed in pairs of the same sex. Playful interactions were measured for each pair once a week from 4 to 7 weeks of age. Thereafter, during early adulthood, all the rats were subjected to the elevated plus-maze test. The frequencies of pinning and playful attack were less in the early-weaned group than in the normally weaned group. In the elevated plus-maze test, rat pups in the early-weaned group had higher anxiety levels. The results showed that deprivation of mother,pup interactions during the preweaning period decreases affiliative interactions between cage mates, including play-fighting behaviors during the postweaning developmental period, and increases anxiety levels during early adulthood. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 343,350, 2007. [source] | ||||||||||||||||||||||||||||||||||