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Adolescent Rats (adolescent + rat)

Distribution by Scientific Domains

Medical Sciences	66%
Life Sciences	25%
2 Other Domains	9%

Selected Abstracts

Ethanol-Induced Social Facilitation in Adolescent Rats: Role of Endogenous Activity at Mu Opioid Receptors

ALCOHOLISM, Issue 6 2009
Elena I. Varlinskaya
Background:, Ethanol consumption is considerably elevated during adolescence. Attractiveness of alcohol for humans during the adolescent developmental period is based, in part, on its ability to induce social facilitation,a facilitation of social interactions not only evident in human adolescents but also in adolescent rats. Endogenous opioid systems are among the multiple neural systems implicated in the behavioral and reinforcing effects of ethanol and may play a substantial role in modulating stimulatory effects of low doses of ethanol on social behavior during adolescence. This possibility was explored in the present study through the use of an animal model of peer-directed social behavior. Methods:, Sprague,Dawley rats were challenged early in adolescence with saline or ethanol intraperitoneally (i.p.), placed into an individual holding cage for 30 minutes, and then tested in a familiar situation with a nonmanipulated partner of the same age and sex. In Experiment 1, each test subject was injected subcutaneously with one of the three doses of a nonselective opioid antagonist naloxone (0, 0.05, and 0.1 mg/kg), 5 minutes prior to the social interaction test and 25 minutes following challenge with saline or ethanol (0.5 g/kg), whereas in Experiment 2 animals were challenged with one of the six doses of ethanol (0, 0.25, 0.5, 0.75, 1.0, and 1.25 g/kg) prior to injection of either saline or naloxone (0.05 mg/kg). In Experiment 3, animals were pretreated i.p. with the selective ,-opioid antagonist CTOP (0, 0.01, 0.025, 0.05, and 0.1 mg/kg) 30 minutes prior to challenge with saline or ethanol (0.5 g/kg). Results:, Low doses of ethanol (0.5 and 0.75 g/kg) produced social facilitation, as indexed by significant increases in play fighting and social investigation. Both doses of naloxone and the three highest doses of CTOP blocked the stimulatory effects of ethanol on play fighting but not on social investigation. These effects were not associated with alterations in ethanol pharmacokinetic properties or with shifts in the biphasic ethanol dose,response curve. Conclusions:, Ethanol-induced facilitation of social play behavior seen in adolescent animals is mediated in part through ethanol-induced release of endogenous ligands for the ,-opioid receptor or an ethanol-associated enhancement of sensitivity of these receptors for their endogenous ligands. [source]

Difluoromethylornithine Decreases Long-Lasting Protein Oxidation Induced by Neonatal Ethanol Exposure in the Hippocampus of Adolescent Rats

ALCOHOLISM, Issue 5 2007
Carlos Fernando Mello
Background: Ethanol exposure and withdrawal during central nervous system development can cause oxidative stress and produce severe and long-lasting behavioral and morphological alterations in which polyamines seem to play an important role. However, it is not known if early ethanol exposure causes long-lasting protein oxidative damage and if polyamines play a role in such a deleterious effect of ethanol. Methods: In this study we investigated the effects of early ethanol exposure (6 g/kg/d, by gavage), from postnatal day (PND) 1 to 8, and of the administration of difluoromethylornithine (DFMO, 500 mg/kg, i.p., on PND 8), a polyamine biosynthesis inhibitor, on the extent of oxidative modification of proteins. Indices of oxidative modification of proteins included protein carbonyls, 3-nitrotyrosine (3-NT), and protein bound 4-hydroxynonenal (HNE) in the hippocampus, cerebellum, hypothalamus, striatum, and cerebral cortex of Sprague,Dawley rats at PND 40. Results: Both ethanol and DFMO administration alone increased protein carbonyl immunoreactivity in the hippocampus at PND 40, but the combination of DFMO and ethanol resulted in no effect on protein carbonyl levels. No alterations in the content of protein-bound HNE, 3-NT, or carbonyl were found in any other cerebral structure. Conclusions: These results suggest that the hippocampus is selectively affected by early ethanol exposure and by polyamine synthesis inhibition. In addition, the results suggest a role for polyamines in the long-lasting increase of protein carbonyls induced by ethanol exposure and withdrawal. [source]

Acute Effects of Ethanol on Behavior of Adolescent Rats: Role of Social Context

ALCOHOLISM, Issue 3 2001
Elena I. Varlinskaya
Background: First experiences with alcohol in humans occur predominantly in adolescence, and to a large extent the attractiveness of alcohol at this age is based on its ability to facilitate certain forms of social behavior (social facilitation). Adolescence is strongly marked by a focus on peer relationships, and the social nature of the situation plays an important role in responsiveness to alcohol. Peer-directed social activity of adolescent rats may be a valuable experimental model for the study of ethanol-induced changes in social behavior and assessment of the role of the social context in responsiveness to ethanol. Method: In the present study we used a modified dyad social interaction test to characterize acute effects of ethanol on different forms of social behavior (social investigation, contact behavior, and play) and social motivation (preference/avoidance of a peer) in adolescent rats. Ethanol effects on behavior directed toward a peer were compared with those induced by exposure to an inanimate novel object. Results: In the social context, the effects of ethanol were dose-dependent and biphasic. Low doses of ethanol (0.25,0.75 g/kg) produced apparent social facilitation (increased social activity and enhanced social preference), whereas higher doses (3 and 4 g/kg) caused social inhibition (decreased social activity and avoidance of a peer). This pattern was not observed for a nonsocial stimulus: Although overall activity in the nonsocial context was suppressed by 2 and 3 g/kg of ethanol, 0.5 g/kg of ethanol did not activate overall activity directed to the inanimate object. Conclusions: These findings demonstrate that the social nature of the testing situation plays an important role in responsiveness to alcohol in adolescence, especially to its activating effects. The results suggest also that the study of ethanol effects on social behavior of adolescent rats may be an effective tool for the study of adolescent alcohol use and abuse. [source]

Activity-based anorexia during adolescence does not promote binge eating during adulthood in female rats

INTERNATIONAL JOURNAL OF EATING DISORDERS, Issue 8 2008
Wenli Cai
Abstract Objective: Given the frequency of transition from anorexia nervosa to bulimia nervosa, this study investigated whether a history of activity-based anorexia (ABA) during adolescence would promote binge eating during adulthood in female rats. Method: Adolescent rats were given 1-h unlimited access to chow and ad libitum access to a running wheel until body weight reached <80%, indicating the development of ABA. During adulthood, all groups were given 21 days of access to a palatable food for 2 h/day and ad libitum access to chow. Results: During adolescence, rats in the ABA paradigm developed increased wheel running and decreased food intake, reaching <80% of body weight after 3 days. However, there were no significant differences between groups in the amount of binge food consumed during adulthood. Conclusion: A brief episode of ABA during adolescence did not lead to increased binge eating later in life. Longer-term models are needed to determine whether a propensity toward binge eating may result from more sustained ABA during adolescence. © 2008 by Wiley Periodicals, Inc. Int J Eat Disord 2008 [source]

Sensitization, Duration, and Pharmacological Blockade of Anxiety-Like Behavior Following Repeated Ethanol Withdrawal in Adolescent and Adult Rats

ALCOHOLISM, Issue 3 2009
Tiffany A. Wills
Background:, Repeated ethanol withdrawal sensitizes anxiety-like behavior in adult rats and causes anxiety-like behavior and decreased seizure thresholds in adolescent rats. Current experiments determined if adolescent rats exhibit sensitized anxiety-like behavior, the duration of this effect, if drug pretreatments blocked these effects, and if these effects differed from those seen in adults. Methods:, Male adolescent rats received three 5-day cycles of 2.5% ethanol diet (ED) separated by two 2-day withdrawal periods, continuous 15 days of 2.5%ED, or a single 5-day cycle of 2.5%ED. Male adult rats received three 5-day cycles of either 2.5% or 3.5%ED. These groups were tested 5 hours into the final withdrawal for social interaction (SI) deficits (an index of anxiety-like behavior). Ethanol intake was monitored throughout and blood concentrations were obtained from separate groups of rats. Additionally, adolescent rats were tested for SI 1, 2, 7, 14, and 18 days and adults 1 and 2 days after the final withdrawal. Some adolescent rats were also pretreated with the CRF1 antagonist CP-154,526, the 5-HT1A agonist buspirone, or the benzodiazepine receptor antagonist flumazenil during the first 2 withdrawals. Results:, SI was reduced in adolescent rats following repeated withdrawals of 2.5%ED while neither a continuous or single cycle ED exposure caused this effect. Adult rats also had reduced SI following repeated withdrawals from both 2.5% and 3.5%ED. This effect was present up to 1 week following the final withdrawal in adolescents but returned to baseline by 1 day in adults. CP-154,526, buspirone, or flumazenil prevented this reduction in SI in adolescent rats. Conclusions:, Adolescent rats exhibit sensitized anxiety-like behavior following repeated withdrawals at ED concentrations similar to those used in adults. However, this effect is longer lasting in adolescent rats. Drugs modulating CRF, 5-HT, or GABA systems during initial withdrawals prevent the development of anxiety-like behavior otherwise manifest during a final withdrawal in adolescent rats. [source]

Differential Dietary Ethanol Intake and Blood Ethanol Levels in Adolescent and Adult Rats: Effects on Anxiety-Like Behavior and Seizure Thresholds

ALCOHOLISM, Issue 8 2008
Tiffany A. Wills
Background:, Adult rats exhibit increased anxiety-like behavior after exposure to repeated cycles of chronic ethanol and withdrawal. While adolescent rats have differential responses to both acute and chronic ethanol treatments, the potential differences in the effects of repeated withdrawals in this population have yet to be determined. Methods:, Male adult and adolescent rats received three 5-day cycles of either a 4.5% or 7% ethanol diet (ED) separated by two 2-day withdrawal periods. Five hours into the final withdrawal, rats were tested for social interaction (SI) deficits (an index of anxiety-like behavior) and then assessed for seizure thresholds (audiogenic and bicuculline-induced). Ethanol intake was monitored throughout, and blood ethanol concentrations (BEC) were obtained from a separate group of rats. Results:, Adolescent rats have reduced SI during the final withdrawal from either ED and exhibit a greater reduction in SI compared to adult rats when exposed to a 7%ED. Audiogenic seizures were not increased during withdrawal from either ED in adult rats, but adolescent rats that received 7%ED displayed increased seizures. The bicuculline seizure thresholds were decreased in both ages exposed to a 7%ED, but only adolescent rats showed this decreased threshold after 4.5%ED. Ethanol intakes and BECs were higher in adolescent rats compared to similarly treated adults. However, ethanol intakes and BECs were comparable between 4.5%ED-treated adolescent and 7%ED-treated adult rats. Conclusions:, Behavioral results from the 7%ED-treated groups suggested that adolescent rats may be more vulnerable to repeated withdrawals from ethanol than adults; however, differences in ethanol intake and BECs may be at least in part responsible. When ethanol intakes and BECs were similar between 4.5%ED-treated adolescent and 7%ED-treated adult rats, behavioral effects were not different. Importantly, these data illustrated that adolescent rats can exhibit anxiety and reduced seizure thresholds following this repeated withdrawal paradigm. [source]

Chronic Intermittent Injections of High-Dose Ethanol During Adolescence Produce Metabolic, Hypnotic, and Cognitive Tolerance in Rats

ALCOHOLISM, Issue 10 2003
Janelle M. Silvers
Background: Many humans are first exposed to ethanol during adolescence, the time at which they are most likely to binge drink ethanol. Chronic intermittent ethanol (CIE) exposure produces ethanol tolerance in adolescent rodents. Recent studies suggested that adolescent animals administered CIE experienced increased cognitive impairment following an ethanol challenge. These studies further explore development of ethanol tolerance caused by CIE in adolescence, and whether CIE during adolescence leads to altered ethanol response in adulthood. Methods: Beginning postnatal day (P) 30, adolescent rats were administered 5.0 g/kg ethanol or saline every 48 hours for 20 days. In experiment I, animals were tested for differential weight gain. In experiment II, loss of righting reflex (LORR) was observed after each injection, then at completion of pretreatment all animals were tested with 5.0 g/kg ethanol and LORR was observed. In experiment III, blood ethanol levels were observed and elimination rates calculated after the first and fifth pretreatments. All animals were tested with 5.0 g/kg at completion of pretreatment and elimination rates were recalculated. In experiment IV, animals were trained on the spatial version of the Morris Water Maze Task (MWMT) on non-treatment days. Following completion of pretreatment and training, animals were tested after receiving an ethanol (1.0, 1.5, or 2.0 g/kg), or saline. Tests for experiments II, III, and IV were repeated in the same animals following 12 ethanol-free days. Results: Chronic intermittent ethanol exposure during adolescence caused differential weight gain (experiment I). Adolescent rats developed tolerance to ethanol-induced LORR (experiment II) and metabolic tolerance to ethanol (experiment III). This tolerance was seen after 12 ethanol-free days. CIE also attenuated ethanol-induced spatial memory deficits in the MWMT (experiment IV). This effect was not long-lasting. Conclusions: Following CIE pretreatment during adolescence, tolerance developed to the hypnotic and cognitive impairing effects of ethanol, along with increased metabolic rate and decreased weight gain. These results further emphasize the ability of CIE to produce a variety of effects during adolescence, some having long-lasting consequences. [source]

Changes in hyporesponsiveness to acute amphetamine and age differences in tyrosine hydroxylase immunoreactivity in the brain over adolescence in male and female rats

DEVELOPMENTAL PSYCHOBIOLOGY, Issue 5 2009
Iva Z. Mathews
Abstract We investigated hyposensitivity after amphetamine in early (postnatal Day 30; P30) and late (P45) adolescent rats compared to adults (P70) in experiment 1. Locomotor activity was measured for 1,hr after the first (acute) and second (24,hr later) injection of amphetamine (0.5 or 1.5,mg/kg). P30 and P45 rats were transiently hypoactive compared to adults, as indicated by reduced locomotor activity after acute amphetamine and enhanced activity after the second injection in adolescents only. In experiment 2, ovariectomy did not alter locomotor activity during habituation at any age compared to intact rats, and, as for intact adolescents, ovariectomized adolescents continued to be less active after amphetamine than adults, suggesting gonadal immaturity alone cannot account for age differences in experiment 1. However, ovariectomy attenuated the increase in activity after the second treatment. In experiment 3 involving untreated rats, tyrosine hydroxylase immunoreactivity was reduced in P30, P40, and P50 compared to P90 rats in the nucleus accumbens core and the medial prefrontal cortex. Thus, adolescents may have an increased threshold of behavioral activation that can be overcome with either a higher dose or with repeated amphetamine treatment, and may be related to changes in the dopamine system over development. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 417,428, 2009. [source]

PRECLINICAL STUDY: Atypical development of behavioural sensitization to 3,4-methylenedioxymethamphetamine (MDMA, ,Ecstasy') in adolescent rats and its expression in adulthood: role of the MDMA chirality

ADDICTION BIOLOGY, Issue 1 2010
Nora Von Ameln
ABSTRACT Despite the great popularity of 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy) as a drug of abuse, not much is known about the detailed mechanisms of the acute and subchronic effects of the drug. There is especially a lack of information about the distinct behavioural effects of its optical isomers (enantiomers) R- and S-MDMA compared with the racemic RS-MDMA. For this purpose, adolescent rats were repetitively treated during two treatment stages (stage 1: days 1,10; stage 2: days 15, 17, 19) with RS-MDMA (5 or 10 mg/kg) or each of the respective enantiomers (5 mg/kg). The repeated treatment started on postnatal day (PND) 32 and locomotor activity was measured on each day by means of a photobeam-equipped activity box system. RS-MDMA or S-MDMA administration led acutely to massive hyperlocomotion and subchronically, to the development of behavioural sensitization after a short habituation period. R-MDMA was free of hyperactivating effects and even decreased locomotor behaviour upon repeated treatment. Nevertheless, co-administration of R-MDMA increased the hyperactivity of S-MDMA and made the S-MDMA induced behavioural sensitization state-dependent. The animals pre-treated with R-MDMA showed a sensitized response in adulthood when tested with RS-MDMA. Our results indicated that even in the absence of substantial neurotoxicity, both MDMA enantiomers can lead to long-term changes in brain circuitry and concomitant behavioural changes when repeatedly administered in adolescence. The sensitization development was most pronounced in the animals treated with S- and RS-MDMA; the animals with R-MDMA did not develop sensitization under repeated treatment but expressed a sensitized response when challenged with RS-MDMA. [source]

PRECLINICAL STUDY: Amphetamine- and nicotine-induced cross-sensitization in adolescent rats persists until adulthood

ADDICTION BIOLOGY, Issue 3 2009
Gabriela C. Santos
ABSTRACT Nicotine and psychostimulants are often abused in combination and drug abuse often begins during adolescence and can have long-term consequences. Behavioral sensitization has been suggested as an animal model of neuroplasticity implicated in the development of drug addiction. We evaluated whether the pretreatment with nicotine (0.4 mg/kg; s.c.) or amphetamine (5.0 mg/kg; i.p.) in adolescent rats [from postnatal day (P) 28 to P34] could induce cross-sensitization to nicotine and amphetamine when animals were challenged during both adolescence (P37) and adulthood (P70), in separate groups of animals. Adolescent animals pretreated with amphetamine displayed behavioral sensitization to nicotine, which persisted until adulthood. Moreover, adolescent animals pretreated with nicotine showed sensitized locomotor response to amphetamine in the adulthood. These data suggest that adolescents who abuse nicotine may be particularly susceptible to the effects of amphetamine and vice versa. Moreover, this increased vulnerability may persist through their development until adulthood. [source]

Methylphenidate to adolescent rats drives enduring changes of accumbal Htr7 expression: implications for impulsive behavior and neuronal morphology

GENES, BRAIN AND BEHAVIOR, Issue 3 2009
D. Leo
Methylphenidate (MPH) administration to adolescent rodents produces persistent region-specific changes in brain reward circuits and alterations of reward-based behavior. We show that these modifications include a marked increment of serotonin (5-hydroxy-tryptamine) receptor type 7 (Htr7) expression and synaptic contacts, mainly in the nucleus accumbens, and a reduction of basal behavioral impulsivity. We show that neural and behavioral consequences are functionally related: administration of a selective Htr7 antagonist fully counteracts the MPH-reduced impulsive behavior and enhances impulsivity when administered alone in naive rats. Agonist-induced activation of endogenous Htr7 significantly increases neurite length in striatal neuron primary cultures, thus suggesting plastic remodeling of neuronal morphology. The mixed Htr (1a/7) agonist, 8-OH-DPAT, reduces impulsive behavior in adolescent rats and in naive adults, whose impulsivity is enhanced by the Htr7 antagonist. In summary, behavioral pharmacology experiments show that Htr7 mediates self-control behavior, and brain primary cultures experiments indicate that this receptor may be involved in the underlying neural plasticity, through changes in neuronal cytoarchitecture. [source]

Cerebellar granule cells cultured from adolescent rats express functional NMDA receptors: an in vitro model for studying the developing cerebellum

JOURNAL OF NEUROCHEMISTRY, Issue 2 2008
R. Lisa Popp
Abstract In the developing rat cerebellum functional NMDA receptors (NMDARs) expressing the NR2C subunit have been identified on or after postnatal day 19. We obtained primary cultured cells from 19- to 35-day-old rat cerebellum that expressed few oligodendrocytes or astrocytes. Cultured cells were immunoreactive for neuron-specific proteins thus indicating a neuronal population. The primary neuron present was the granule cell as indicated by immunofluorescence for the GABAA alpha 6 subunit. Whole-cell patch-clamp experiments indicated that functional NMDARs were present. Functional characteristics of NMDARs expressed in cerebellar granule cells (CGCs) obtained from adolescent animals were similar to those previously reported for NMDARs expressed in CGCs obtained from neonatal rats. Cultured CGCs obtained from older animals contained NMDARs that were inhibited by EtOH and were less sensitive to the NR2B subunit-specific antagonist Ro 25-6981. Furthermore, NMDA-induced currents were smaller than those observed in CGCs. Western blot analysis indicated the presence of the NMDA NR2A and NR2C subunits, but not the NR2B in cultures obtained from the adolescent rats. CGCs obtained from adolescent rats express functional NMDARs consistent with a developmental profile observed in vivo. [source]

Isoflurane-induced depolarization of neural mitochondria increases with age

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2009
RAVI BAINS
Background and objectives: The mitochondrial membrane potential (,,m) drives the three fundamental functions of mitochondria, namely adenosine triphosphate (ATP) generation, Ca2+ uptake/storage, and generation/detoxification of ROS. Isoflurane depolarizes neural mitochondria. The sensitivity for general anesthetics increases with age, but the mechanism for this age-related sensitivity is still unknown. We compared the effect of isoflurane on [Ca2+]i and ,,m in isolated pre-synaptic terminals (synaptosomes) from neonatal, adolescent, and adult rats and the influence of interventions in the respiratory chain was assessed. Methods: Synaptosomes were loaded with the fluorescent probes fura-2 ([Ca2+]i) and JC-1 (,,m) and exposed to isoflurane 1 and 2 minimum alveolar concentration (MAC). The effect on the electron transport chain was investigated by blocking complexes I and V. Results: In neonatal rats isoflurane had no significant effect on ,,m. In adolescent and adult synaptosomes, however, isoflurane 1 and 2 MAC decreased ,,m. Isoflurane 2 MAC increased [Ca2+]i in neonatal and adolescent rats, but not in adult synaptosomes. In Ca2+ -depleted medium, isoflurane still decreased ,,m, while [Ca2+]i remained unaltered. By blocking complex V of the respiratory chain, the isoflurane-induced mitochondrial depolarization was enhanced in all age groups. Blocking complex I depolarized the mitochondria to the same extent as isoflurane 2 MAC, but without any additive effect. Conclusions: The depolarizing effect of isoflurane on neural mitochondria is more pronounced in the adolescent and adult than in neonatal synaptosomes. The increased mitochondrial sensitivity with age seems to be related to the reversed function of the ATP synthase of the electron transport chain. [source]

Interactions of Stress and CRF in Ethanol-Withdrawal Induced Anxiety in Adolescent and Adult Rats

ALCOHOLISM, Issue 9 2010
Tiffany A. Wills
Background:, Repeated stress or administration of corticotropin-releasing factor (CRF) prior to ethanol exposure sensitizes anxiety-like behavior in adult rats. Current experiments determined whether adolescent rats were more sensitive to these challenges in sensitizing ethanol withdrawal-induced anxiety and altering CRF levels in brain during withdrawal. Methods:, Male adult and adolescent Sprague,Dawley rats were restraint stressed (1 hour) twice 1 week apart prior to a single 5-day cycle of ethanol diet (ED; stress/withdrawal paradigm). Other rats received control diet (CD) and three 1-hour restraint stress sessions. Rats were then tested 5, 24, or 48 hours after the final withdrawal for anxiety-like behavior in the social interaction (SI) test. In other experiments, adolescent rats were given two microinjections of CRF icv 1 week apart followed by 5 days of either CD or ED and tested in social interaction 5 hours into withdrawal. Finally, CRF immunoreactivity was measured in the central nucleus of the amygdala (CeA) and paraventricular nucleus (PVN) after rats experienced control diet, repeated ethanol withdrawals, or stress/withdrawal. Results:, Rats of both ages had reduced SI following the stress/withdrawal paradigm, and this effect recovered within 24 hours. Higher CRF doses were required to reduce SI in adolescents than previously reported in adults. CRF immunohistochemical levels were higher in the PVN and CeA of CD-exposed adolescents. In adolescent rats, repeated ethanol withdrawals decreased CRF in the CeA but was not associated with decreased CRF cell number. There was no change in CRF from adult treatments. Conclusions:, In the production of anxiety-like behavior, adolescent rats have equal sensitivity with stress and lower sensitivity with CRF compared to adults. Further, adolescents had higher basal levels of CRF within the PVN and CeA and reduced CRF levels following repeated ethanol withdrawals. This reduced CRF within the CeA could indicate increased release of CRF, and future work will determine how this change relates to behavior. [source]

Ethanol-Induced Social Facilitation in Adolescent Rats: Role of Endogenous Activity at Mu Opioid Receptors

Patterns of Ethanol Intake in Preadolescent, Adolescent, and Adult Wistar Rats Under Acquisition, Maintenance, and Relapse-Like Conditions

ALCOHOLISM, Issue 4 2009
David 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]

Sensitization, Duration, and Pharmacological Blockade of Anxiety-Like Behavior Following Repeated Ethanol Withdrawal in Adolescent and Adult Rats

Proteomic Analysis Demonstrates Adolescent Vulnerability to Lasting Hippocampal Changes Following Chronic Alcohol Consumption

ALCOHOLISM, Issue 1 2009
Garth A. Hargreaves
Background:, Excessive teenage alcohol consumption is of great concern because alcohol may adversely alter the developmental trajectory of the brain. The aim of the present study was to assess whether chronic intermittent alcohol intake during the adolescent period alters hippocampal protein expression to a greater extent than during adulthood. Methods:, Adolescent [postnatal day (PND) 27] and adult (PND 55) male Wistar rats were given 8 hours daily access to beer (4.44% ethanol v/v) in addition to ad libitum food and water for 4 weeks. From a large subject pool, subgroups of adolescent and adult rats were selected that displayed equivalent alcohol intake (average of 6.1 g/kg/day ethanol). The 4 weeks of alcohol access were followed by a 2-week alcohol-free washout period after which the hippocampus was analyzed using 2-DE proteomics. Results:, Beer consumption by the adult group resulted in modest hippocampal changes relative to alcohol naïve adult controls. The only changes observed were an up-regulation of citrate synthase (a precursor to the Krebs cycle) and fatty acid binding protein (which facilitates fatty acid metabolism). In contrast, adolescent rats consuming alcohol showed more widespread hippocampal changes relative to adolescent controls. These included an increase in cytoskeletal protein T-complex protein 1 subunit epsilon (TCP-1) and a decrease in the expression of 10 other proteins, including glyceraldehyde-3-phosphate dehydrogenase (GAPDH), triose phosphate isomerise, alpha-enolase, and phosphoglycerate kinase 1 (all involved in glycolysis); glutamate dehydrogenase 1 (an important regulator of glutamate); methylmalonate-semialdehyde dehydrogenase (involved in aldehyde detoxification); ubiquitin carboxyl-terminal hydrolase isozyme L1 (a regulator of protein degradation); and synapsin 2 (involved in synaptogenesis and neurotransmitter release). Conclusions:, These results suggest the adolescent hippocampus is more vulnerable to lasting proteomic changes following repeated alcohol exposure. The proteins most affected include those related to glycolysis, glutamate metabolism, neurodegeneration, synaptic function, and cytoskeletal structure. [source]

Differential Dietary Ethanol Intake and Blood Ethanol Levels in Adolescent and Adult Rats: Effects on Anxiety-Like Behavior and Seizure Thresholds

Enhanced Prepulse Inhibition Following Adolescent Ethanol Exposure in Sprague-Dawley Rats

ALCOHOLISM, Issue 10 2005
Craig J. Slawecki
Abstract: Objectives: Recent studies have demonstrated that ethanol exposure differentially affects adolescents and adults. The current studies were designed to compare the effects of 2-week exposure to ethanol during adolescence or adulthood on the acoustic startle response (ASR) and prepulse inhibition (PPI) Methods: Male Sprague-Dawley rats were exposed to ethanol vapor 12 hr/d (on from 6 pm to 6 am) for 14 days during adolescence or adulthood. Six days after the cessation of ethanol vapor exposure, the ASR and PPI were assessed. Results: During ethanol treatment, overall blood alcohol levels averaged 230 to 250 mg/dl in the adolescent and adult treatment groups. Assessment of the ASR revealed that latency to startle was more rapid in adolescents than in adults, but ASR latency was not altered by ethanol exposure. In addition, ASR magnitude was lower in adolescents and was decreased in ethanol-exposed rats on startle trials. Ethanol exposure significantly enhanced PPI, but only after adolescent exposure Conclusions: These data further demonstrate a differential sensitivity of adolescents and adults to the effects of ethanol exposure. Specifically, a 2-week period of ethanol exposure during adolescence selectively enhanced PPI, a neurobehavioral index of sensorimotor gating. However, ASR magnitude was decreased by ethanol exposure regardless of age. On the basis of previous studies, the effects of ethanol exposure on PPI data could indicate that adolescent rats exposed to ethanol are more likely to exhibit behavioral inflexibility and that ethanol exposure acts as a more potent physical stressor in adolescent rats. [source]