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Postnatal Day (postnatal + day)
Selected AbstractsSpatial conditional discrimination learning in developing ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2005Kevin L. Brown Abstract The present study established an effective procedure for studying spatial conditional discrimination learning in juvenile rats using a T-maze. Wire mesh located on the floor of the maze as well as a second, identical T-maze apparatus served as conditional cues which signaled whether a left or a right response would be rewarded. In Experiment 1, conditional discrimination was evident on Postnatal Day (PND) 30 when mesh,+,maze or maze-alone were the conditional cues, but not when mesh-alone was the cue. Experiment 2 confirmed that mesh-alone was sufficiently salient to support learning of a simple (nonconditional) discrimination. Its failure to serve as a conditional cue in Experiment 1 does not reflect its general ineffectiveness as a stimulus. Experiment 3 confirmed that the learning shown in Experiment 1 was indeed conditional in nature by comparing performance on conditional versus nonconditional versions of the task. Experiment 4 showed that PND19 and PND23 pups also were capable of performing the task when maze,+,mesh was the cue; however, the findings indicate that PND19 subjects do not use a conditional strategy to learn this task. The findings suggest postnatal ontogeny of conditional discrimination learning and underscore the importance of conditional cue salience, and of identifying task strategies, in developmental studies of conditional discrimination learning. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 46: 97,110, 2005. [source] Contextual modulation of spatial discrimination reversal in developing ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 1 2005Jerome H. Pagani Abstract Reversal of discrimination learning is influenced by manipulation of the training context. In adult and developing rats, contextual changes made between acquisition and reversal aid the learning of the new discrimination, possibly by serving to release proactive interference from the originally acquired discrimination (M. E. Bouton & D. C. Brooks, 1993; N. Spear, G. Smith, R. Bryan, & W. Gordon, 1980). The present study sought to examine this effect in an appetitive T-maze task, as a function of different contextual manipulations. Rats of three ages, Postnatal Day (PND) 19, PND23, and PND30, were tested for their ability to acquire and reverse a position habit in a T-maze. Contextual changes were made between acquisition and reversal sessions and consisted of one of three manipulations: (a) texture; the texture of the maze floor was changed via the addition or subtraction of wire mesh; (b) maze; subjects were reversed in a different maze that was identical in construction to the training maze, but differed in spatial location; (c) texture and maze; subjects were shifted to the new maze, the floor of which differed in texture from the training maze but was otherwise identical in construction. Results showed that the texture,maze combination was an effective aid to reversal learning at all ages tested. The texture alone, however, was not effective at any age. The maze alone also was an effective cue for reversal, but proved to have the greatest effect for PND30 subjects. During ontogeny, the contextual modulation of reversal learning is importantly influenced by the nature and the salience of the contextual cue. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 46: 36,46, 2005. [source] Causal Links between Brain Cytokines and Experimental Febrile Convulsions in the RatEPILEPSIA, Issue 12 2005James G. Heida Summary:,Purpose: Despite the prevalence of febrile convulsions (FCs), their pathophysiology has remained elusive. We tested the hypothesis that components of the immune response, particularly the proinflammatory cytokine interleukin-1, (IL-1,) and its naturally occurring antagonist interleukin-1 receptor antagonist (IL-1ra) may play a role in the genesis of FC. Methods: Postnatal day 14 rats were treated with lipopolysaccharide (LPS; 200 ,g/kg, i.p.) followed by a subconvulsant dose of kainic acid (1.75 mg/kg, i.p.). Brains were harvested at and 2 h after onset of FCs to measure brain levels of IL-1, and IL-1ra. Separate groups of animals were given intracerebroventricular (ICV) injections of IL-1,, or IL-1ra in an attempt to establish a causal relation between the IL-1,/IL-1ra system and FCs. Results: Animals with FCs showed increased IL-1, in the hypothalamus and hippocampus but not in the cortex compared with noFC animals that also received LPS and kainic acid. This increase was first detected in the hippocampus at onset of FCs. No detectable difference in IL-1ra was found in brain regions examined in either group. When animals were treated with IL-1, ICV, a dose-dependant increase was noted in the proportion of animals that experienced FCs, whereas increasing doses of IL-1ra, given to separate groups of animals, were anticonvulsant. Conclusions: Our results suggest that excessive amounts of IL-1, may influence the genesis of FCs. This may occur by overproduction of IL-1,, or by alteration in the IL-1,/IL-1ra ratio in the brain after an immune challenge. [source] Differential long-term neurotoxicity of HIV-1 proteins in the rat hippocampal formation: A design-based stereological studyHIPPOCAMPUS, Issue 2 2008Sylvia Fitting Abstract The human immunodeficiency virus type 1 (HIV-1) proteins, gp120 and Tat, are believed to play a role in mediating central nervous system (CNS) pathology in HIV-1 infected patients. Using design-based stereology, we examined the role of neonatal intrahippocampal injections of gp120 and Tat on the adult hippocampus (,7½ month). Postnatal day (P)1-treated Sprague-Dawley rats were bilaterally injected with vehicle (VEH, 0.5 ,l sterile buffer), gp120 (100 ng), Tat (25 ,g) or combined gp120 + Tat (100 ng + 25 ,g). Using Nissl-stained tissue sections, we quantified total neurons in five subregions of the rat hippocampus [granual layer (GL), hilus of the dentate gyrus (DGH), cornu ammonis fields (CA)2/3, CA1, and subiculum (SUB)], and total glial cells (astrocytes and oligodendrocytes) in two subregions (DGH and SUB). Estimates of cell area and cell volume were taken in the DGH. There was a significant reduction of neuron number in the CA2/3 subfield by Tat and gp120, and a significant reduction in the DGH by Tat only. For glial cells, numbers of astrocytes in the DGH and SUB were increased by the Tat protein, whereas no effects were noted for gp120. Finally, for oligodendrocytes Tat increased cell number in the DGH but not in any other region; gp120 had no detectable effect in any brain region. Estimates of cell area and cell volume of the three different cell types revealed no significant differences between treatments. Collectively, these results suggest differential effects of gp120 and Tat on the estimated total number of neurons, as well as on the number of glial cells. © 2007 Wiley-Liss, Inc. [source] Death and survival of heterozygous Lurcher Purkinje cells In vitroDEVELOPMENTAL NEUROBIOLOGY, Issue 8 2009Hadi S. Zanjani Abstract The differentiation and survival of heterozygous Lurcher (+/Lc) Purkinje cells in vitro was examined as a model system for studying how chronic ionic stress affects neuronal differentiation and survival. The Lurcher mutation in the ,2 glutamate receptor (GluR,2) converts an orphan receptor into a membrane channel that constitutively passes an inward cation current. In the GluR,2+/Lc mutant, Purkinje cell dendritic differentiation is disrupted and the cells degenerate following the first week of postnatal development. To determine if the GluR,2+/Lc Purkinje cell phenotype is recapitulated in vitro, +/+, and +/Lc Purkinje cells from postnatal Day 0 pups were grown in either isolated cell or cerebellar slice cultures. GluR,2+/+ and GluR,2+/Lc Purkinje cells appeared to develop normally through the first 7 days in vitro (DIV), but by 11 DIV GluR,2+/Lc Purkinje cells exhibited a significantly higher cation leak current. By 14 DIV, GluR,2+/Lc Purkinje cell dendrites were stunted and the number of surviving GluR,2+/Lc Purkinje cells was reduced by 75% compared to controls. However, treatment of +/Lc cerebellar cultures with 1-naphthyl acetyl spermine increased +/Lc Purkinje cell survival to wild type levels. These results support the conclusion that the Lurcher mutation in GluR,2 induces cell autonomous defects in differentiation and survival. The establishment of a tissue culture system for studying cell injury and death mechanisms in a relatively simple system like GluR,2+/Lc Purkinje cells will provide a valuable model for studying how the induction of a chronic inward cation current in a single cell type affects neuronal differentiation and survival. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009 [source] Changes in hyporesponsiveness to acute amphetamine and age differences in tyrosine hydroxylase immunoreactivity in the brain over adolescence in male and female ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 5 2009Iva 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] Postnatal stress in mice: Does "stressing" the mother have the same effect as "stressing" the pups?DEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2004A. Moles Abstract Short- and long-term effects of brief maternal separation, maternal exposure to novel male odor, and standard rearing were compared in NMRI mice. The first condition consisted of 15 min of daily exposure of pups to clean bedding (CB), and the second condition consisted of 15 min of mothers' exposure to the odor of strange males (SM), for 14 days after birth starting from postnatal Day 1. Thus, both conditions entailed the same period of maternal separation. A control mother,offspring group was left undisturbed (nonhandled, N-H). Corticosterone levels of mothers and pups were measured at the end of the last manipulation session. Corticosterone levels were higher in SM mothers, differing from both those of CB and of control dams; CB pups showed the highest corticosterone levels in comparison with the pups belonging to the other groups. Maternal behavior observed as furthest as possible from the daily separation session did not differ among the three groups. The behavioral response to 0.5 mg/kg of apomorphine in 15-day-old pups was enhanced in both CB and SM animals, which suggests an alteration of dopaminergic functioning. Finally, adult CB and SM male mice showed an increase in the percentage of time and entries into the open arms of the plus-maze in comparison to nonhandled males. This study indicates that exposure to ecologically relevant stimuli elicited a stress response in lactating dams. This "social stress" brings about short- and long-term effects in the offspring, even in the absence of any direct manipulation of the pups. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 44: 230,237, 2004. [source] Repeated exposures to gustatory stimuli produce habituation or positive contrast effects in perinatal ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 3 2004G. Andrew Mickley Abstract Adult rats exhibit a decrease in consummatory responses following repeated presentations of a taste (habituation) and an increase in consummatory responses if they experience an upward shift in the magnitude or intensity of a gustatory stimulus (e.g., sucrose or saccharin). These responses do not represent a direct sensorimotor reaction to a gustatory cue, but rather reflect a change in responding based on the memory of a previous taste. Here, we sought to determine if fetal rats could (like adults) adjust their orofacial motor responses based on a memory of recent gustatory experience. Embryonic Day 18 (E18) or Day 19 (E19) rat fetuses received oral lavage with either 0.15 or 0.30% saccharin (SAC). Subsequently, observations of orofacial movements (mouthing and licking) following oral lavage with 0.30% SAC were made 50 min later, 24 hr later, or on postnatal Day 3 (P3). Thus, some animals were in a "shifted" condition in which they first experienced a relatively low concentration of SAC and then a higher one while control rats ("nonshifted") received 0.30% SAC during both taste exposures. Fetuses exhibited evidence of both habituation (with repeated presentation of the 0.30% SAC) and positive contrast effects (PCEs) (following an upward shift in SAC concentration) when retested 50 min after their first exposure to SAC on E19. However, these animals did not exhibit PCEs 24 hr later or 5 days later (on P3). Contrast effects were not observed when the initial SAC exposure was on E18, and habituation responses were variable depending on the time interval between the taste presentations to these animals. Rats with a 5- to 6-day latency between the two taste presentations showed neither PCEs nor habituation. Our data indicate that PCEs and habituation effects emerge at different ages, and their demonstration is dependent upon the latency between the taste presentations. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 44: 176,188, 2004. [source] Maternally separated rats show deficits in maternal care in adulthoodDEVELOPMENTAL PSYCHOBIOLOGY, Issue 1 2001Vedran Lovic Abstract Although there is considerable research on the phenomenology, neuroendocrinology, neuroanatomy, and sensory control of maternal behavior, little is known about the influences of early postnatal and postweaning experiences on the development of maternal behavior. The purpose of this study was to assess how early life separation from the mother rat affects development of the offspring's juvenile and adult maternal behavior. From postnatal Days 1 to 17, 3 female rats within each litter were separated (SEP) from the mother and the rest of the litter for 5 hr daily while 3 of their sisters were not maternally separated (NSEP). On postnatal Day 21, all subjects were weaned and randomly assigned to one of three juvenile conditions. One female from both SEP and NSEP groups was either isolated (I), given a social conspecific (S), or given 1- to 4-day-old pups (P) for 5 consecutive days. Maternal behavior of SEP and NSEP animals was assessed and recorded on each of the 5 days. Once all animals reached adulthood, they were mated, gave birth, and were assessed for their maternal behavior. We found that the effects of maternal separation on juvenile maternal-like behaviors were minimal. On the other hand, maternal separation reduced adult maternal licking and crouching over pups. In addition, there was a significant interaction between postnatal and juvenile experience on maternal crouching in maternal animals. These results are discussed in terms of the variety of possible behavioral, endocrine, and neurochemical mechanisms that mediate the effects of early life experiences on adult maternal behavior. © 2001 John Wiley & Sons, Inc. Dev Psychobiol 39: 19,33, 2001 [source] The birth process initiates an acute phase reaction in the fetus-newborn infantACTA PAEDIATRICA, Issue 9 2000G Marchini Our goal was to investigate whether the normal birth process stimulated an acute phase response in healthy infants with physiological changes in the circulating levels of acute phase cytokines and acute phase proteins. We also monitored body temperature, body weight and behavioural state in order to investigate if clinical signs of acute phase reaction were present. We made cross-sectional measurements of interleukin-1,, interleukin-6, C-reactive protein, serum amyloid A, procalcitonin, prealbumin, body weight, body temperature and the duration of the sleeping period during the first four postnatal days. We found an increase in interleukin-6 (p < 0.001) during the first day, followed by an increase in C-reactive protein, serum amyloid A and procalcitonin on the second postnatal day (p < 0.01). The level of prealbumin fell after birth and reached its lowest value at 3 d of age (p < 0,001). Interleukin-l p remained unchanged. The duration of the sleeping period was longer during the first day (p < 0.01). There was an increase in body temperature during the first day (p < 0.01). Maximal weight loss was during the first 2 d. Conclusions: The normal birth process and extra-uterine adaptation stimulates an acute phase reaction in the newborn infant with a release of interleukin-6 and acute phase proteins and a depression of prealbumin. This reaction, as the body's first line inflammatory defence system, probably affects the infant's behaviour, nutritional state as well as the regulation of body temperature. [source] Dietary exposure to low doses of bisphenol A: Effects on reproduction and development in two generations of C57BL/6J miceCONGENITAL ANOMALIES, Issue 3 2010Kenichi Kobayashi Abstract The present study was conducted to examine the effects of low-dose exposure to bisphenol A on reproduction and development in two generations of mice. Pregnant female C57BL/6J mice (F0) were fed a diet containing low doses of bisphenol A (0, 0.33, 3.3, or 33 ppm) from gestational day 6 through postnatal day 22, and the weanlings (F1 and F2) from each F0 and F1 dam group, respectively, were also fed these same concentrations of bisphenol A ad libitum until sacrifice. There were no treatment-related changes in body weight, body weight gain, food consumption, gestation length, or the number of live births on postnatal day 1 in F0 dams between the control group and bisphenol A groups. Sex ratio and viability were similar in all F1 pups. No treatment-related changes were observed in body weight, food consumption, developmental parameters, anogenital distance, or weight of any of the organs (liver, kidney, heart, spleen, thymus, testis, ovary, or uterus) in F1 and F2 adults in either sex. The epididymis weight was slightly higher with 0.33 and 3.3 ppm in F1 males, but this slight increase was neither dose dependent nor seen across generations. There were no treatment-related effects of bisphenol A on cauda epididymal sperm count or sperm motility in F1 or F2 males. These findings indicate that dietary exposure to bisphenol A between 0.33 and 33 ppm does not adversely affect reproduction or development as assessed in two generations of mice. [source] Gene expression in the efferent ducts, epididymis, and vas deferens during embryonic development of the mouseDEVELOPMENTAL DYNAMICS, Issue 9 2010Elizabeth M. Snyder Abstract The tissues of the male reproductive tract are characterized by distinct morphologies, from highly coiled to un-coiled. Global gene expression profiles of efferent ducts, epididymis, and vas deferens were generated from embryonic day 14.5 to postnatal day 1 as tissue-specific morphologies emerge. Expression of homeobox genes, potential mediators of tissue-specific morphological development, was assessed. Twenty homeobox genes were identified as either tissue-enriched, developmentally regulated, or both. Additionally, ontology analysis demonstrated cell adhesion to be highly regulated along the length of the reproductive tract. Regulators of cell adhesion with variable expression between the three tissues were identified including Alcam, various cadherins, and multiple integrins. Immunofluorescence localization of the cell adhesion regulators POSTN and CDH2 demonstrated cell adhesion in the epithelium and mesenchyme of the epididymis may change throughout development. These results suggest cell adhesion may be modulated in a tissue-specific manner, playing an important role in establishing each tissue's final morphology. Developmental Dynamics 239:2479,2491, 2010. © 2010 Wiley-Liss, Inc. [source] Identification of novel genes expressed during mouse tooth development by microarray gene expression analysisDEVELOPMENTAL DYNAMICS, Issue 8 2007Trevor J. Pemberton Abstract To identify genes heretofore undiscovered as critical players in the biogenesis of teeth, we have used microarray gene expression analysis of the developing mouse molar tooth (DMT) between postnatal day (P) 1 and P10 to identify genes differentially expressed when compared with 16 control tissues. Of the top 100 genes exhibiting increased expression in the DMT, 29 were found to have been previously associated with tooth development. Differential expression of the remaining 71 genes not previously associated with tooth development was confirmed by quantitative reverse transcription-polymerase chain reaction analysis. Further analysis of seven of the latter genes by mRNA in situ hybridization found that five were specific to the developing tooth in the craniofacial region (Rspo4, Papln, Amtn, Gja1, Maf). Of the remaining two, one was found to be more widely expressed (Sp7) and the other was found to be specific to the nasal serous gland, which is close to, but distinct from, the developing tooth (Vrm). Developmental Dynamics 236:2245,2257, 2007. © 2007 Wiley-Liss, Inc. [source] Zic4, a zinc-finger transcription factor, is expressed in the developing mouse nervous systemDEVELOPMENTAL DYNAMICS, Issue 3 2005Carles Gaston-Massuet Abstract Zic genes comprise a family of transcription factors, characterized by the presence of a zinc-finger domain containing two cysteines and two histidines (C2-H2). Whereas the embryonic expression patterns of Zic1, 2, 3, and 5 have been described in detail, Zic4 has not yet received close attention. We studied the expression of Zic4 by in situ hybridization during mouse embryogenesis. Zic4 mRNA was first detected at low intensity at embryonic day (E) 9 and, by E10.5, expression was up-regulated in the dorsal midline of the forebrain with a strong, expanded expression domain at the boundary between the diencephalon and telencephalon, the septum, and the lamina terminalis. The choroid plexus of the third ventricle expresses Zic4, as does the dorsal part of the spinal neural tube, excluding the roof plate. The dorsal sclerotome and the dorsomedial lip of the dermomyotome also express Zic4 whereas dorsal root ganglia are negative. At E12.5, Zic4 continues to be expressed in the midline of the forebrain and in the dorsal spinal neural tube. Postnatally, Zic4 is expressed in the granule cells of the postnatal day 2 cerebellum, and in the periventricular thalamus and anterior end of the superior colliculus. We conclude that Zic4 has an expression pattern distinct from, but partly overlapping with, other members of the Zic gene family. Developmental Dynamics 233:1110,1115, 2005. © 2005 Wiley-Liss, Inc. [source] Developmental changes in neurite outgrowth responses of dorsal root and sympathetic ganglia to GDNF, neurturin, and arteminDEVELOPMENTAL DYNAMICS, Issue 3 2003H. Yan Abstract The ability of glial cell line,derived neurotrophic factor (GDNF), neurturin, and artemin to induce neurite outgrowth from dorsal root, superior cervical, and lumbar sympathetic ganglia from mice at a variety of development stages between embryonic day (E) 11.5 and postnatal day (P) 7 was examined by explanting ganglia onto collagen gels and growing them in the presence of agarose beads impregnated with the different GDNF family ligands. Artemin, GDNF, and neurturin were all capable of influencing neurite outgrowth from dorsal root and sympathetic ganglia, but the responses of each neuron type to the different ligands varied during development. Neurites from dorsal root ganglia responded to artemin at P0 and P7, to GDNF at E15.5 and P0, and to neurturin at E15.5, P0, and P6/7; thus, artemin, GDNF, and neurturin are all capable of influencing neurite outgrowth from dorsal root ganglion neurons. Neurites from superior cervical sympathetic ganglia responded significantly to artemin at E15.5, to GDNF at E15.5 and P0, and to neurturin at E15.5. Neurites from lumbar sympathetic ganglia responded to artemin at all stages from E11.5 to P7, to GDNF at P0 and P7 and to neurturin at E11.5 to P6/7. Combined with the data from previous studies that have examined the expression of GDNF family members, our data suggest that artemin plays a role in inducing neurite outgrowth from young sympathetic neurons in the early stages of sympathetic axon pathfinding, whereas GDNF and neurturin are likely to be important at later stages of sympathetic neuron development in inducing axons to enter particular target tissues once they are in the vicinity or to induce branching within target tissues. Superior cervical and lumbar sympathetic ganglia showed temporal differences in their responsiveness to artemin, GDNF, and neurturin, which probably partly reflects the rostrocaudal development of sympathetic ganglia and the tissues they innervate. Developmental Dynamics 227:395,401, 2003. © 2003 Wiley-Liss, Inc. [source] Chronological gene expression of ADAMs during testicular development: Prespermatogonia (gonocytes) express fertilin , (ADAM2)DEVELOPMENTAL DYNAMICS, Issue 3 2003Carolina Rosselot Abstract Immediately after birth, primordial germinal cell-derived prespermatogonia (PSG), located in the center of the testicular cords, migrate between adjacent Sertoli cells to establish contact with the cord basal lamina. PSG migration suggests continued assembly and disassembly of cell,cell contacts by a molecular mechanism that may involve integrins and their ligands, the disintegrin domain of spermatogenic cell-specific plasma membrane proteins called ADAMs. We have analyzed the temporal gene expression of selected ADAMs in intact fetal, early postnatal, and pubertal rat testis and Sertoli,spermatogenic cell cocultures by reverse transcriptase-polymerase chain reaction, in situ hybridization, and immunocytochemistry. We report that several ADAM transcripts are expressed in fetal, neonatal, and prepubertal testes. Cyritestin (ADAM3), ADAM5, ADAM6, and ADAM15 are expressed in day 17 fetal testes. In contrast, no expression of fertilin , (ADAM1) and fertilin , (ADAM 2) was detected in fetal testes. Fertilin , gene expression starts after postnatal day 2, subsequent to the expression of fertilin ,, which occurs on postnatal day 1. After postnatal day 2, all the indicated ADAMs, including the fertilin , and fertilin ,, continue to be expressed. Transcripts of spermatogenic cell-specific fertilin ,, fertilin ,, ADAM3, and ADAM5 were detected during the coculture of PSG with Sertoli cells for up to 72 hr after plating. The presence of fertilin , mRNA and protein in cocultured PSG was visualized by in situ hybridization and immunocytochemistry, respectively. These observations indicate that PSG in coculture with Sertoli cells provide a suitable approach for analyzing cell,cell adhesive responses involving spermatogenic cell-specific ADAMs. Development Dynamics 458,467, 2003. © 2003 Wiley-Liss, Inc. [source] Single cause, polymorphic neuronal migration disorders: an animal modelDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 10 2000Glenn D Rosen PhD Injury to the developing cortical plate can result in a variety of neuronal migration disorders. The results are reported of experimental research aimed at determining whether these different types of neocortical malformations are the consequence of comparable injury of varying intensity. Freezing probes were placed on the skulls of 44 newborn rats (age equivalent to 4 to 5 months of gestation in humans) and induced either one or two freezing injuries of durations ranging from 2 to 20 seconds. A variety of cortical malformations including minor laminar dysplasias, molecular layer ectopias, microgyria, and porencephalic cysts were seen in the brains of these animals when they were examined on postnatal day (P)2, P21, and P60. The severity of the malformation was directly related to the strength (number of hits and duration) of the freezing injury. These results suggest that a single etiologic event of varying severity during neuronal migration to the neocortex can induce widely disparate malformations of the cortex. [source] Elevated corticosterone levels in stomach milk, serum, and brain of male and female offspring after maternal corticosterone treatment in the ratDEVELOPMENTAL NEUROBIOLOGY, Issue 10 2010Susanne Brummelte Abstract Early influences such as maternal stress affect the developmental outcome of the offspring. We created an animal model of postpartum depression/stress based on giving high levels of corticosterone (CORT) to the rat dam, which resulted in behavioral and neural changes in the offspring. This study investigated whether highly elevated levels of maternal CORT during pregnancy or the postpartum result in higher levels of CORT in the stomach milk, serum, and brain of offspring. Dams received daily injections of CORT (40 mg/kg) or oil (control) either during pregnancy (gestational days 10,20) or the postpartum (Days 2,21). Pups that were exposed to high gestational maternal CORT had higher CORT levels in serum, but not in stomach milk or brain, on postnatal day (PND) 1. However, on PND7, pups that were exposed to high postpartum maternal CORT had higher CORT levels in stomach milk and brain, but not in serum. Conversely on PND18, pups that were exposed to high postpartum maternal CORT had higher CORT levels in serum, but not in brain (prefrontal cortex, hypothalamus, or hippocampus). Moreover, 24 h after weaning, there were no significant differences in serum CORT levels between the groups. Thus, CORT given to the dam during pregnancy or the postpartum results in elevated levels of CORT in the offspring, but in an age- and tissue-dependent manner. Developmental exposure to high CORT could reprogram the HPA axis and contribute to the behavioral and neural changes seen in adult offspring. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 70: 714,725, 2010 [source] The role of cell death in sexually dimorphic muscle development: Male-specific muscles are retained in female bax/bak knockout miceDEVELOPMENTAL NEUROBIOLOGY, Issue 11 2008Dena A. Jacob Abstract The bulbocavernosus (BC) and levator ani (LA) muscles are present in males but absent or severely reduced in females, and the fate of these muscles controls the survival of motoneurons in the sexually dimorphic spinal nucleus of the bulbocavernosus. However, the mechanism underlying the sex difference in BC and LA development has been controversial. We examined the role of cell death in sexual differentiation of the bulbocavernosus BC/LA muscles in mice. Muscle development was mapped from embryonic day 16 (E16) to postnatal day 5 (P5). A sex difference (male > female) first arose on E17 (BC) or E18 (LA), and increased in magnitude postnatally. TUNEL labeling revealed dying cells in the BC and LA muscles of both sexes perinatally. However, females had a significantly higher density of TUNEL-positive cells than did males. A role for the proapoptotic factors, Bax and Bak, in BC/LA development was tested by examining mice lacking one or both of these proteins. In females lacking either Bax or Bak, the BC was absent and the LA rudimentary. Deletion of both bax and bak genes, however, rescued the BC, increased LA size ,20-fold relative to controls, and virtually eliminated TUNEL-positive cells in both muscles. We conclude that cell death plays an essential role in sexual differentiation of the BC/LA muscles. The presence of either Bax or Bak is sufficient for cell death in the BC/LA, whereas the absence of both prevents sexually dimorphic muscle cell death. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008. [source] Glutamate AMPA/kainate receptors, not GABAA receptors, mediate estradiol-induced sex differences in the hypothalamusDEVELOPMENTAL NEUROBIOLOGY, Issue 3 2007Brigitte J. Todd Abstract Sex differences in brain morphology underlie physiological and behavioral differences between males and females. During the critical perinatal period for sexual differentiation in the rat, gonadal steroids act in a regionally specific manner to alter neuronal morphology. Using Golgi-Cox impregnation, we examined several parameters of neuronal morphology in postnatal day 2 (PN2) rats. We found that in the ventromedial nucleus of the hypothalamus (VMN) and in areas just dorsal and just lateral to the VMN that there was a sex difference in total dendritic spine number (males greater) that was abolished by treating female neonates with exogenous testosterone. Dendritic branching was similarly sexually differentiated and hormonally modulated in the VMN and dorsal to the VMN. We then used spinophilin, a protein that positively correlates with the amount of dendritic spines, to investigate the mechanisms underlying these sex differences. Estradiol, which mediates most aspects of masculinization and is the aromatized product of testosterone, increased spinophilin levels in female PN2 rats to that of males. Muscimol, an agonist at GABAA receptors, did not affect spinophilin protein levels in either male or female neonates. Kainic acid, an agonist at glutamatergic AMPA/kainate receptors, mimicked the effect of estradiol in females. Antagonizing AMPA/kainate receptors with NBQX prevented the estradiol-induced increase in spinophilin in females but did not affect spinophilin level in males. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007 [source] Sex differences in the level of Bcl-2 family proteins and caspase-3 activation in the sexually dimorphic nuclei of the preoptic area in postnatal ratsDEVELOPMENTAL NEUROBIOLOGY, Issue 13 2006Shinji Tsukahara Abstract In developing rats, sex differences in the number of apoptotic cells are found in the central division of the medial preoptic nucleus (MPNc), which is a significant component of the sexually dimorphic nucleus of the preoptic area, and in the anteroventral periventricular nucleus (AVPV). Specifically, male rats have more apoptotic cells in the developing AVPV, whereas females have more apoptotic cells in the developing MPNc. To determine the mechanisms for the sex differences in apoptosis in these nuclei, we compared the expression of the Bcl-2 family members and active caspase-3 in postnatal female and male rats. Western blot analyses for the Bcl-2 family proteins were performed using preoptic tissues isolated from the brain on postnatal day (PD) 1 (day of birth) or on PD8. In the AVPV-containing tissues of PD1 rats, there were significant sex differences in the level of Bcl-2 (female > male) and Bax (female < male) proteins, but not of Bcl-xL or Bad proteins. In the MPNc-containing tissues of PD8 rats, there were significant sex differences in the protein levels for Bcl-2 (female < male), Bax (female > male), and Bad (female < male), but not for Bcl-xL. Immunohistochemical analyses showed significant sex differences in the number of active caspase-3-immunoreactive cells in the AVPV on PD1 (female < male) and in the MPNc on PD8 (female > male). We further found that active caspase-3-immunoreactive cells of the AVPV and MPNc were immunoreactive for NeuN, a neuronal marker. These results suggest that there are sex differences in the induction of apoptosis via the mitochondrial pathway during development of the AVPV and MPNc. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006 [source] Developmental shift in bidirectional functions of taurine-sensitive chloride channels during cortical circuit formation in postnatal mouse brainDEVELOPMENTAL NEUROBIOLOGY, Issue 2 2004Mika Yoshida Abstract Taurine (2-aminoethanesulfonic acid) is the most abundant free amino acid in the developing mammalian cerebral cortex, however, few studies have reported its neurobiological functions during development. In this study, by means of whole-cell patch-clamp recordings, we examined the effects of taurine on chloride channel receptors in neocortical neurons from early to late postnatal stages, which cover a critical period in cortical circuit formation. We show here that taurine activates chloride channels in cortical neurons throughout the postnatal stages examined (from postnatal day 2 to day 36). The physiological effects of taurine changed from excitatory to inhibitory due to variations in the intracellular Cl, concentration during development. An antagonist blocking analysis also demonstrated a developmental shift in the receptor target of taurine, from glycine receptors to GABAA receptors. Taken together, these results may reflect genetically programmed, bidirectional functions of taurine. At the early developmental stage, taurine acting on glycine receptors would serve to promote cortical circuit formation. As cortical circuit has to be regulated in the later stages, taurine would serve as a safeguard against hyperexcitable circuit. © 2004 Wiley Periodicals, Inc. J Neurobiol 60: 166,175, 2004 [source] Nipple preference and contests in suckling kittens of the domestic cat are unrelated to presumed nipple qualityDEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2009Robyn Hudson Abstract We studied the development of suckling behavior and weight gain in 11 litters (52 kittens) of free-ranging domestic cats until postnatal day 28 just before the start of weaning. In six of these litters, we also recorded milk intake and contests for access to nipples. Already within 12 hr of birth kittens showed a preference for posterior nipples, and by postnatal day 3 each had developed a preference for particular nipples. In fact, 86% of kittens used one particular nipple most often, and even when the mother changed the side she lay on to nurse. Contests for access to nipples occurred throughout the study period at an average rate of one to two contests per kitten per hour of nursing. Contrary to suggestions in the literature that kittens compete for more productive nipples, we found no relation between kittens' use of particular nipples and their weight gain, milk intake, or involvement in contests during suckling. We suggest that kittens' preference for posterior nipples as well as their establishment of an individual "teat order" might function to optimize the number of nipples remaining productive across lactation, and to reduce energetically costly scrambles and potentially injurious contests among littermates. © 2009 Wiley Periodicals, Inc. Dev. Psychobiol 51: 322,332, 2009. [source] Differential development of body equilibrium among littermates in the newborn rabbitDEVELOPMENTAL PSYCHOBIOLOGY, Issue 1 2009Edith Muciño Abstract Interest is growing among psychobiologists and behavioral ecologists in the role of sibling relations in shaping individual development and life histories. In litters of domestic rabbits Oryctolagus cuniculus the heaviest pups at birth are more likely to survive the critical first postnatal week, they compete more effectively with littermates for milk and well-insulated positions in the litter huddle, and are the heaviest at weaning. Here we report that high birth weight pups are also better able to maintain body equilibrium. Testing pups' ability to maintain equilibrium when placed on a 15° ramp for 2 min each day during the first postnatal week, we found that pups showed a continual daily improvement in their ability to maintain balance while moving on the ramp, rarely lost balance by postnatal day 8, and that heavier pups could maintain balance better and earlier than their lighter littermates. Better ability to maintain body equilibrium, however achieved, may help explain heavier pups' advantage in competing for vital resources such as milk and in gaining access to better-insulated positions in the litter huddle. It also provides further support for the usefulness of birth weight, not only as an absolute measure but also relative to the weight of other littermates, as a predictor of different developmental trajectories, behavioral and physiological, among same-age siblings in this mammal. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 51: 24,33, 2009 [source] Cross-Modal transfer of the conditioned eyeblink response during interstimulus interval discrimination training in young ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 7 2008Kevin L. Brown Abstract Eyeblink classical conditioning (EBC) was observed across a broad developmental period with tasks utilizing two interstimulus intervals (ISIs). In ISI discrimination, two distinct conditioned stimuli (CSs; light and tone) are reinforced with a periocular shock unconditioned stimulus (US) at two different CS,US intervals. Temporal uncertainty is identical in design with the exception that the same CS is presented at both intervals. Developmental changes in conditioning have been reported in each task beyond ages when single-ISI learning is well developed. The present study sought to replicate and extend these previous findings by testing each task at four separate ages. Consistent with previous findings, younger rats (postnatal day,PD23 and 30) trained in ISI discrimination showed evidence of enhanced cross-modal influence of the short CS,US pairing upon long CS conditioning relative to older subjects. ISI discrimination training at PD43,47 yielded outcomes similar to those in adults (PD65,71). Cross-modal transfer effects in this task therefore appear to diminish between PD30 and PD43,47. Comparisons of ISI discrimination with temporal uncertainty indicated that cross-modal transfer in ISI discrimination at the youngest ages did not represent complete generalization across CSs. ISI discrimination undergoes a more protracted developmental emergence than single-cue EBC and may be a more sensitive indicator of developmental disorders involving cerebellar dysfunction. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 647-664, 2008. [source] Domperidone interferes with conditioned disgust reactions but not taste avoidance evoked by a LiCl-paired taste in infant ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2008Ricardo Marcos Pautassi Abstract Rats exhibit taste avoidance and conditioned disgust reactions when stimulated with a tastant paired with lithium chloride (LiCl). Lithium-mediated activation of chemoreceptor nuclei at the brainstem appears to determine the acquisition of conditioned taste aversion (CTA) in adult rodents. Domperidone (DOM), an anti-emetic drug that does not cross the blood,brain barrier, was employed to analyze mechanisms underlying LiCl-mediated CTA in infant rats. On postnatal day 13 animals were given DOM followed by a pairing between intraoral saccharin and LiCl. Saccharin consumption at testing was lower in lithium-treated pups than in controls. DOM did not interfere with this LiCl-mediated taste avoidance but significantly decreased LiCl-mediated disgust reactions (head-shaking and wall climbing). Activation of the emetic system of the brainstem does not seem necessary for the acquisition of LiCl-mediated conditioned taste avoidance. Yet, these centers seem to be involved in the palatability shift resulting from taste-LiCl pairings. These results indicate an early dissociation between conditioned disgust reactions and conditioned taste avoidance. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 343,352, 2008. [source] Early adolescents show enhanced acute cocaine-induced locomotor activity in comparison to late adolescent and adult ratsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2008Kimberly A. Badanich Abstract Initiation of drug use during adolescence is associated with an increased probability to develop a drug addiction. The present study examined dose,response effects of cocaine (0, 5, 10, or 20 mg/kg, i.p.) on locomotor activity in early adolescent (postnatal day (PND) 35), late adolescent (PND 45), and young adults (PND 60) by measuring total distance moved (TDM) and frequency of start,stops. In response to 20 mg/kg cocaine, early adolescents showed the greatest cocaine-induced increase in TDM in comparison to late adolescent and adult rats. At this same dose, early adolescents showed the greatest cocaine-induced attenuation of start,stops relative to older rats. Results suggest that early adolescents engage in more cocaine-induced locomotor activity and less stationary behavior indicating that early adolescents are more sensitive to locomotor activating effects of high dose cocaine than older rats. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 127,133, 2008. [source] Therapeutic effects of complex rearing or bFGF after perinatal frontal lesionsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2008Wendy Comeau Abstract We investigated the effects of an enriched environment and/or basic fibroblast growth factor (bFGF) on recovery from neonatal frontal injury in rats. Rats received medial frontal lesions, or sham surgery, on postnatal day (P) 2/3. In the first set of experiments (Experiments 1 and 2), rats were housed in enriched environments that consisted of a large enclosure with multiple objects (or standard housing) for 90 days beginning at weaning (P22) or in adulthood (P110). In Experiment 3, the rats either received 7 days of subcutaneous bFGF beginning on the day after surgery or bFGF plus enriched housing beginning at weaning. After the 90-day housing period, the animals were tested on a spatial navigation task and a skilled reaching task. Early lesions of the medial frontal cortex caused severe impairments in spatial learning but this deficit was markedly reduced with enriched housing, bFGF, or a combination of both, with the latter being most effective. The housing effects varied with age, however: the earlier the experience began, the better the outcome. Enriched housing increased dendritic length in cortical pyramidal neurons, an effect that was greater in the lesion than the control animals, and enriched housing reversed the lesion-induced decrease in spine density. Enriched environment increased the thickness of the cortical mantle in both lesion and controls whereas bFGF had no effect. Experience thus can affect functional and anatomical outcome after early brain injury but the effects vary with age at experience and may be facilitated by treatment with bFGF. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 134,146, 2008. [source] Extinction in the developing rat: An examination of renewal effectsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 6 2007Carol S.L. Yap Abstract In the present series of experiments the context-specificity of extinction was examined from a developmental perspective. For postnatal day (PN) 23 rats, renewal of freezing to an aversive odor conditioned stimulus (CS) was observed when rats were conditioned in Context A, extinguished in Context B, and tested in Context A (i.e., ABA renewal). This effect was not observed in PN16 rats, which is consistent with previous studies suggesting that rats <,PN20 are impaired in encoding contextual information [i.e., Carew and Rudy [1991]. Developmental Psychobiology, 24, 191,209]. Subsequent experiments demonstrated that for rats conditioned at PN16 and tested at PN23, contextual regulation of extinction performance depended on the age at which extinction occurred. Specifically, ABA renewal was observed in rats given extinction training at PN22 but not in rats given extinction training at PN17. These latter results show that whether or not context regulates the expression of an ambiguous memory is determined by the animal's age when the memory becomes ambiguous. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 565-575, 2007. [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] | ||||||||||||||||||||||||||||||||||