Effects of prenatal malnutrition and postnatal nutritional rehabilitation on CA3 hippocampal pyramidal cells in rats of four ages

Gestational protein restriction alters early amygdala neurochemistry in male offspring

BACKGROUND

Gestational protein intake restriction-induced long-lasting harmful outcomes in the offspring's organs and systems. However, few studies have focused on this event's impact on the brain's structures and neurochemical compounds.

AIM

The present study investigated the effects on the amygdala neurochemical composition and neuronal structure in gestational protein-restricted male rats' offspring.

METHODS

Dams were maintained on isocaloric standard rodent laboratory chow with regular protein [NP, 17%] or low protein content [LP, 6%]. Total cells were quantified using the Isotropic fractionator method, Neuronal 3D reconstruction, and dendritic tree analysis using the Golgi-Cox technique. Western blot and high-performance liquid chromatography performed neurochemical studies.

RESULTS

The gestational low-protein feeding offspring showed a significant decrease in birth weight up to day 14, associated with unaltered brain weight in youth or adult progenies. The amygdala cell numbers were unchanged, and the dendrites length and dendritic ramifications 3D analysis in LP compared to age-matched NP progeny. However, the current study shows reduced amygdala content of norepinephrine, epinephrine, and dopamine in LP progeny. These offspring observed a significant reduction in the amygdala glucocorticoid (GR) and mineralocorticoid (MR) receptor protein levels. Also corticotrophin-releasing factor (CRF) amygdala protein content was reduced in 7 and 14-day-old LP rats.

CONCLUSION

The observed amygdala neurochemical changes may represent adaptation during embryonic development in response to elevated fetal exposure to maternal corticosteroid levels. In this way, gestational malnutrition stress can alter the amygdala's neurochemical content and may contribute to known behavioral changes induced by gestational protein restriction.

Severe Gestational Low-Protein Intake Impacts Hippocampal Cellularity, Tau, and Amyloid-β Levels, and Memory Performance in Male Adult Offspring: An Alzheimer-Simile Disease Model?

Background:

Maternal undernutrition has been associated with psychiatric and neurological disorders characterized by learning and memory impairment.

Objective:

Considering the lack of evidence, we aimed to analyze the effects of gestational protein restriction on learning and memory function associated with hippocampal cell numbers and neurodegenerative protein content later in life.

Methods:

Experiments were conducted in gestational low- (LP, 6% casein) or regular-protein (NP, 17% casein) diet intake offspring. Behavioral tests, isolated hippocampal isotropic fractionator cell studies, immunoblotting, and survival lifetime were observed.

Results:

The birthweight of LP males is significantly reduced relative to NP male progeny, and hippocampal mass increased in 88-week-old LP compared to age-matched NP offspring. The results showed an increased proximity measure in 87-week-old LP compared to NP offspring. Also, LP rats exhibited anxiety-like behaviors compared to NP rats at 48 and 86-wk of life. The estimated neuron number was unaltered in LP rats; however, non-neuron cell numbers increased compared to NP progeny. Here, we showed unprecedented hippocampal deposition of brain-derived neurotrophic factor, amyloid-β peptide (Aβ), and tau protein in 88-week-old LP relative to age-matched NP offspring.

Conclusion:

To date, no predicted studies showed changes in hippocampal morphological structure in maternal protein-restricted elderly offspring. The current data suggest that gestational protein restriction may accelerate hippocampal function loss, impacting learning/memory performance, and supposedly developing diseases similar to Alzheimer’s disease (AD) in elderly offspring. Thus, we propose that maternal protein restriction could be an elegant and novel method for constructing an AD-like model in adult male offspring.

The neural basis of attentional alterations in prenatally protein malnourished rats

Protein malnutrition during gestation alters brain development and produces specific behavioral and cognitive changes that persist into adulthood and increase the risks of neuropsychiatric disorders. Given evidence for the role of the prefrontal cortex in such diseases, it is significant that studies in humans and animal models have shown that prenatal protein malnutrition specifically affects functions associated with prefrontal cortex. However, the neural basis underlying these changes is unclear. In the current study, prenatally malnourished and control rats performed a sustained attention task with an unpredictable distractor, a task that depends on intact prefrontal cortical function. Radiolabeled 2-deoxyglucose was used to measure neural and brain network activity during the task. Results confirmed that adult prenatally malnourished rats were more distractible than controls and exhibited lower functional activity in prefrontal cortices. Thus, prefrontal activity was a predictor of task performance in controls but not prenatally malnourished animals. Instead, prenatally malnourished animals relied on different brain networks involving limbic structures such as the hippocampus. These results provide evidence that protein reduction during brain development has more wide-reaching effects on brain networks than previously appreciated, resulting in the formation of brain networks that may reflect compensatory responses in prenatally malnourished brains.

The enduring effect of prenatal protein malnutrition on brain anatomy, physiology and behavior

There is increasing evidence that the maternal environment exerts enduring influences on the fetal brain. In response to certain environmental stimuli such as reduced protein content, the fetus changes the course of its brain development, which leads to specific and programed changes in brain anatomy and physiology. These alterations produce a brain with a fundamentally altered organization, which then translates to alterations in adult cognitive function. The effects on brain and behavior may be linked, such that a prenatal stimulus relays a signal to alter brain development and encourage the selection and development of brain circuits and behaviors that would be beneficial for the environment in which the animal was anticipated to emerge. At the same time, the signal would deselect behaviors unlikely to be adaptive. We draw on evidence from rodent models to suggest that the brain that develops after a reduction in protein during the prenatal phase is not uniformly dysfunctional, but simply different. This perspective has implications for the role of prenatal factors in the production and expression of behavior, and may account for the elevation of risk factors for neurological and psychiatric illnesses.

Reduced Midbrain Dopamine Neuron Number in the Adult Non-human Primate Brain after Fetal Radiation Exposure

Early gestation is a neurodevelopmental period that is especially vulnerable to environmental insult and one in which neurogenesis features prominently. Prenatal perturbation during early gestation has been linked to neuropsychiatric illnesses such as autism and schizophrenia, and severe environmental insult during this period can result in profound mental impairment. Midbrain dopamine neurons are generated during early gestation and play a key role in the motor, cognitive and reward circuitries implicated in neuropsychiatric disease and addiction. This study examined the impact of curtailing neurogenesis in early gestation on neuron number in the midbrain dopamine group, i.e., the substantia nigra and contiguous ventral tegmental area. Rhesus macaque monkeys were exposed in utero on embryonic days 39-41 to x-irradiation (3-4 exposures of 50 cGy over 3-7 days totalling <200 cGy) and allowed to mature to full adulthood. Stereologic cell counts of tyrosine hydroxylase-positive neurons in the midbrain dopamine group were performed in adult monkeys, as were measurements of somal size. Mean total neuron number in the irradiated monkeys was significantly reduced on average by 33% compared to that of the control group. Somal size did not differ between the groups, suggesting that the integrity of survivor populations was not impacted. Reduced midbrain dopamine neuron number in fetally irradiated, adult monkeys indicates that radiation exposure during the critical period of neurogenesis results in an enduring reduction of this population and underscores the susceptibility of early neurodevelopmental processes to irreversible damage from environmental exposures.

Role of astaxanthin in the modulation of brain-derived neurotrophic factor and spatial learning behavior in perinatally undernourished Wistar rats

Objective: Maternal health and nutrition during the perinatal period is the predominant factor influencing the functional development of the brain. Maternal malnutrition during the perinatal period causes retardation of brain development. The current study investigates the role of Astaxanthin (AsX) in spatial learning and memory and BDNF in perinatally undernourished Wistar rats.Methods: The albino wistar rats were perinatally undernourished and administered with different dosages of AsX. The spatial learning and memory performance and BDNF level were assessed. Data were collected and analysed.Results: The % Correct choice during the acquisition phase, performance at the end of the acquisition phase and the mean BDNF level at the Hippocampus, Cerebellum, and Cerebral cortex showed significant decline (P<0.001) in the PUN group and significantly high (P<0.001) in the PUNA2 group compared to the control. However, the mean RME and mean WME during different days of the acquisition phase were significantly high (P<0.001) in the PUN group and insignificant (P>0.05) in PUNA2 compared to the control.Discussion: The results showed that AsX effectively modulated the cognitive deficit that occurred in perinatally undernourished rats. This can be attributed to BDNF upregulation as evidenced by the significant increase of the BDNF level.

Structural Neuroimaging of Anorexia Nervosa: Future Directions in the Quest for Mechanisms Underlying Dynamic Alterations

Anorexia nervosa (AN) is a serious eating disorder characterized by self-starvation and extreme weight loss. Pseudoatrophic brain changes are often readily visible in individual brain scans, and AN may be a valuable model disorder to study structural neuroplasticity. Structural magnetic resonance imaging studies have found reduced gray matter volume and cortical thinning in acutely underweight patients to normalize following successful treatment. However, some well-controlled studies have found regionally greater gray matter and persistence of structural alterations following long-term recovery. Findings from diffusion tensor imaging studies of white matter integrity and connectivity are also inconsistent. Furthermore, despite the severity of AN, the number of existing structural neuroimaging studies is still relatively low, and our knowledge of the underlying cellular and molecular mechanisms for macrostructural brain changes is rudimentary. We critically review the current state of structural neuroimaging in AN and discuss the potential neurobiological basis of structural brain alterations in the disorder, highlighting impediments to progress, recent developments, and promising future directions. In particular, we argue for the utility of more standardized data collection, adopting a connectomics approach to understanding brain network architecture, employing advanced magnetic resonance imaging methods that quantify biomarkers of brain tissue microstructure, integrating data from multiple imaging modalities, strategic longitudinal observation during weight restoration, and large-scale data pooling. Our overarching objective is to motivate carefully controlled research of brain structure in eating disorders, which will ultimately help predict therapeutic response and improve treatment.

Preserved white matter microstructure in young patients with anorexia nervosa?

A massive but reversible reduction of cortical thickness and subcortical gray matter (GM) volumes in Anorexia Nervosa (AN) has been recently reported. However, the literature on alterations in white matter (WM) volume and microstructure changes in both acutely underweight AN (acAN) and after recovery (recAN) is sparse and results are inconclusive. Here, T1-weighted and diffusion-weighted MRI data in a sizable sample of young and medication-free acAN (n = 35), recAN (n = 32), and age-matched female healthy controls (HC, n = 62) were obtained. For analysis, a well-validated global probabilistic tractography reconstruction algorithm including rigorous motion correction implemented in FreeSurfer: TRACULA (TRActs Constrained by UnderLying Anatomy) were used. Additionally, a clustering algorithm and a multivariate pattern classification technique to WM metrics to predict group membership were applied. No group differences in either WM volume or WM microstructure were detected with standard analysis procedures either in acAN or recAN relative to HC after controlling for the number of performed statistical tests. These findings were not affected by age, IQ, or psychiatric symptoms. While cluster analysis was unsuccessful at discriminating between groups, multivariate pattern classification showed some ability to separate acAN from HC (but not recAN from HC). However, these results were not compatible with a straightforward hypothesis of impaired WM microstructure. The current findings suggest that WM integrity is largely preserved in non-chronic AN. This finding stands in contrast to findings in GM, but may help to explain the relatively intact cognitive performance of young patients with AN and provide the basis for the fast recovery of GM structures. Hum Brain Mapp 37:4069-4083, 2016. © 2016 Wiley Periodicals, Inc.

Protein malnutrition during gestation and early life decreases neuronal size in the medial prefrontal cortex of post-pubertal rats

Retrospective studies in human populations indicate that protein deprivation during pregnancy and early life (early protein malnutrition, EPM) is associated with cognitive impairments, learning disabilities and may represent a risk factor for the late onset of some psychiatric disorders, fundamentally schizophrenia, a condition where the prefrontal cortex plays an important role. The purpose of this study was to analyze whether EPM affects structural aspects of the rat medial prefrontal cortex (mPFC), such as cortical volume, neuronal density and neuronal soma size, which seem altered in patients with schizophrenia. For this, a rat model of EPM (5% casein from conception to postnatal day 60) was adopted and the rat mPFC volume, total number of neurons and average neuronal volume were evaluated on postnatal day 60 (post-pubertal animals) by histo- and immunohistochemical techniques using unbiased stereological analysis. EPM did not alter the number of NeuN+ neurons in the rat mPFC. However, a very significant decrease in mPFC volume and average neuronal size was observed in malnourished rats. Although the present study does not establish causal relationships between malnutrition and schizophrenia, our results may indicate a similar structural phenomenon in these two situations.

Weight restoration therapy rapidly reverses cortical thinning in anorexia nervosa: A longitudinal study

Structural magnetic resonance imaging studies have documented reduced gray matter in acutely ill patients with anorexia nervosa to be at least partially reversible following weight restoration. However, few longitudinal studies exist and the underlying mechanisms of these structural changes are elusive. In particular, the relative speed and completeness of brain structure normalization during realimentation remain unknown. Here we report from a structural neuroimaging study including a sample of adolescent/young adult female patients with acute anorexia nervosa (n=47), long-term recovered patients (n=34), and healthy controls (n=75). The majority of acutely ill patients were scanned longitudinally (n=35): at the beginning of standardized weight restoration therapy and again after partial weight normalization (>10% body mass index increase). High-resolution structural images were processed and analyzed with the longitudinal stream of FreeSurfer software to test for changes in cortical thickness and volumes of select subcortical regions of interest. We found globally reduced cortical thickness in acutely ill patients to increase rapidly (0.06 mm/month) during brief weight restoration therapy (≈3 months). This significant increase was predicted by weight restoration alone and could not be ascribed to potentially mediating factors such as duration of illness, hydration status, or symptom improvements. By comparing cortical thickness in partially weight-restored patients with that measured in healthy controls, we confirmed that cortical thickness had normalized already at follow-up. This pattern of thinning in illness and rapid normalization during weight rehabilitation was largely mirrored in subcortical volumes. Together, our findings indicate that structural brain insults inflicted by starvation in anorexia nervosa may be reversed at a rate much faster than previously thought if interventions are successful before the disorder becomes chronic. This provides evidence drawing previously speculated mechanisms such as (de-)hydration and neurogenesis into question and suggests that neuronal and/or glial remodeling including changes in macromolecular content may underlie the gray matter alterations observed in anorexia nervosa.

NADPH-diaphorase Histochemical Labeling Patterns in the Hippocampal Neuropil and Visual Cortical Neurons in Weaned Rats Reared during Lactation on Different Litter Sizes

Tissue distribution of nitric oxide-synthases was investigated in the rat hippocampus and visual cortex under nutritional changes induced by modification of the litter size. Young (30-45-days-old) rats, suckled in litters formed by 3,6 or 12 pups (called small, medium and large litters, respectively), were studied by using nicotine-adenine-dinucleotide phosphate-diaphorase histochemistry (shortly, diaphorase), a simple and robust procedure to characterize tissue distribution of nitric oxide-synthases. We assessed morphometric features of the diaphorase-positive cells in visual cortex, and the neuropil histochemical activity in hippocampal CA1 and dentate gyrus using densitometry analysis. In the large-litter group, the labeled-cell density in white matter of area 17 was higher, as compared to the small-litter group. There was a clear trend, in the large-litter group, to lower values of soma area, dendritic field and branches per neuron, but the differences were not significant. Densitometry analysis of hippocampus revealed a significant increase in the relative neuropil histochemical activity of the dentate gyrus molecular layer in the larger litters, which may be associated to increased compensatory blood flow in the hippocampus. The pathophysiological mechanisms of the observed changes remain to be investigated.

The effects of prenatal and postnatal environmental interaction: prenatal environmental adaptation hypothesis

Adverse antenatal maternal environments during pregnancy influence fetal development that consequently increases risks of mental health problems including psychiatric disorders in offspring. Therefore, behavioral and brain alterations caused by adverse prenatal environmental conditions are generally considered as deficits. In this article, we propose a novel hypothesis, along with summarizing a body of literatures supporting it, that fetal neurodevelopmental alterations, particularly synaptic network changes occurring in the prefrontal cortex, associated with adverse prenatal environmental conditions may be adaptation to cope with expected severe postnatal environments, and therefore, psychiatric disorders may be able to be understood as adaptive strategies against severe environmental conditions through evolution. It is hoped that the hypothesis presented in this article stimulates and opens a new venue on research toward understanding of biological mechanisms and therapeutic treatments of psychiatric disorders.

Gestational protein restriction induces CA3 dendritic atrophy in dorsal hippocampal neurons but does not alter learning and memory performance in adult offspring

Studies have demonstrated that nutrient deficiency during pregnancy or in early postnatal life results in structural abnormalities in the offspring hippocampus and in cognitive impairment. In an attempt to analyze whether gestational protein restriction might induce learning and memory impairments associated with structural changes in the hippocampus, we carried out a detailed morphometric analysis of the hippocampus of male adult rats together with the behavioral characterization of these animals in the Morris water maze (MWM). Our results demonstrate that gestational protein restriction leads to a decrease in total basal dendritic length and in the number of intersections of CA3 pyramidal neurons whereas the cytoarchitecture of CA1 and dentate gyrus remained unchanged. Despite presenting significant structural rearrangements, we did not observe impairments in the MWM test. Considering the clear dissociation between the behavioral profile and the hippocampus neuronal changes, the functional significance of dendritic remodeling in fetal processing remains undisclosed.

Malnutrition and brain development: an analysis of the effects of inadequate diet during different stages of life in rat

Protein malnutrition or undernutrition can result in abnormal development of the brain. Depending on type, age at onset and duration, different structural and functional deficits can be observed. In the present review, we discuss the neuroanatomical, behavioral, neurochemical and oxidative status changes associated with protein malnutrition or undernutrition at different ages during prenatal and immediately postnatal periods as well as in adult rat. Analysis of all data suggests that protein malnutrition as well as undernutrition induced impaired learning and retention when imposed during the immediately postnatal period and in adulthood, whereas hyperactivity including increased impulsiveness and greater reactivity to aversive stimuli occurred when malnutrition or undernutrition was imposed either pre or postnatally. This general state of hyperreactivity may be linked essentially to an alteration in dopaminergic system. Hence, the present review shows that in spite of the attention devoted in the literature to prenatal effects, cognitive deficits are more serious following malnutrition or undernutrition after birth. We thus clearly establish a special vulnerability to malnutrition after weaning in rats.

The environment and susceptibility to schizophrenia

In the present article the putative role of environmental factors in schizophrenia is reviewed and synthesized. Accumulating evidence from recent studies suggests that environmental exposures may play a more significant role in the etiopathogenesis of this disorder than previously thought. This expanding knowledge base is largely a consequence of refinements in the methodology of epidemiologic studies, including birth cohort investigations, and in preclinical research that has been inspired by the evolving literature on animal models of environmental exposures. This paper is divided into four sections. In the first, the descriptive epidemiology of schizophrenia is reviewed. This includes general studies on incidence, prevalence, and differences in these measures by urban-rural, neighborhood, migrant, and season of birth status, as well as time trends. In the second section, we discuss the contribution of environmental risk factors acting during fetal and perinatal life; these include infections [e.g. rubella, influenza, Toxoplasma gondii (T. gondii), herpes simplex virus type 2 (HSV-2)], nutritional deficiencies (e.g., famine, folic acid, iron, vitamin D), paternal age, fetal/neonatal hypoxic and other obstetric insults and complications, maternal stress and other exposures [e.g. lead, rhesus (Rh) incompatibility, maternal stress]. Other putative neurodevelopmental determinants, including cannabis, socioeconomic status, trauma, and infections during childhood and adolescence are also covered. In the third section, these findings are synthesized and their implications for prevention and uncovering biological mechanisms, including oxidative stress, apoptosis, and inflammation, are discussed. Animal models, including maternal immune activation, have yielded evidence suggesting that these exposures cause brain and behavioral phenotypes that are analogous to findings observed in patients with schizophrenia. In the final section, future studies including new, larger, and more rigorous epidemiologic investigations, and research on translational and clinical neuroscience, gene-environment interactions, epigenetics, developmental trajectories and windows of vulnerability, are elaborated upon. These studies are aimed at confirming observed risk factors, identifying new environmental exposures, elucidating developmental mechanisms, and shedding further light on genes and exposures that may not be identified in the absence of these integrated approaches. The study of environmental factors in schizophrenia may have important implications for the identification of causes and prevention of this disorder, and offers the potential to complement, and refine, existing efforts on explanatory neurodevelopmental models.

Nutrition and neurodevelopment: mechanisms of developmental dysfunction and disease in later life

Nutrition plays a central role in linking the fields of developmental neurobiology and cognitive neuroscience. It has a profound impact on the development of brain structure and function and malnutrition can result in developmental dysfunction and disease in later life. A number of diseases, including schizophrenia, may be related to neurodevelopmental insults such as malnutrition, hypoxia, viruses or in utero drug exposure. Some of the most significant findings on nutrition and neurodevelopment during the last three decades, and especially during the last few years, are discussed in this review. Attention is focused on the underlying cellular and molecular mechanisms by which diet exerts its effects. Randomized intervention studies have revealed important effects of early nutrition on later cognitive development, and recent epidemiological findings show that both genetics and environment are risk factors for schizophrenia. Particularly important is the effect of early nutrition on development of the hippocampus, a brain structure important in establishing learning and memory, and hence for cognitive performance. A major aim of future research should be to elucidate the molecular mechanisms underlying nutritionally-induced impairment of neurodevelopment and specifically to determine the mechanisms by which early nutritional experience affects later cognitive performance. Key research objectives should include: (1) increased understanding of mechanisms underlying the normal processes of ageing and neurodegenerative disorders; (2) assessment of the role of susceptibility genes in modulating the effects of early nutrition on neurodevelopment; and (3) development of nutritional and pharmaceutical strategies for preventing and/or ameliorating the adverse effects of early malnutrition on long-term programming.

Effects of postnatal malnutrition and senescence on learning, long-term memory, and extinction in the rat

There is a wealth of information indicating that the hippocampal formation is important for learning and memory consolidation. The hippocampus is very sensitive to ageing and developmentally stressful factors such as prenatal malnutrition, which produces anatomical alterations of hippocampal pyramidal cells as well as impaired spatial learning. On the other hand, there are no reports about differential effects of postnatal malnutrition, installed at birth and maintained all through life in young and aged rats, on learning and memory of active avoidance, a task with an important procedural component. We now report that learning and long-term retention of this task were impaired in young malnourished animals, but not in young control, senile control, and senile malnourished Sprague-Dawley rats; young and senile rats were 90 and 660 days of age, respectively. Extinction tests showed, however, that long-term memory of the malnourished groups and senile control animals is impaired as compared with the young control animals. These data strongly suggest that the learning and long-term retention impairments seen in the young animals were due to postnatal malnutrition; in the senile groups, this cognitive alteration did not occur, probably because ageing itself is an important factor that enables the brain to engage in compensatory mechanisms that reduce the effects of malnutrition. Nonetheless, ageing and malnutrition, conditions known to produce anatomic and functional hippocampal alterations, impede the maintenance of long-term memory, as seen during the extinction test.

Prenatal protein deprivation alters dopamine-mediated behaviors and dopaminergic and glutamatergic receptor binding

Epidemiological evidence indicates that prenatal nutritional deprivation may increase the risk of schizophrenia. The goal of these studies was to use an animal model to examine the effects of prenatal protein deprivation on behaviors and receptor binding with relevance to schizophrenia. We report that prenatally protein deprived (PD) female rats showed an increased stereotypic response to apomorphine and an increased locomotor response to amphetamine in adulthood. These differences were not observed during puberty. No changes in haloperidol-induced catalepsy or MK-801-induced locomotion were seen following PD. In addition, PD female rats showed increased (3)H-MK-801 binding in the striatum and hippocampus, but not in the cortex. PD female rats also showed increased (3)H-haloperidol binding and decreased dopamine transporter binding in striatum. No statistically significant changes in behavior or receptor binding were found in PD males with the exception of increased (3)H-MK-801 binding in cortex. This animal model may be useful to explore the mechanisms by which prenatal nutritional deficiency enhances risk for schizophrenia in humans and may also have implications for developmental processes leading to differential sensitivity to drugs of abuse.

Can a reward-based behavioural test be used to investigate the effect of protein-energy malnutrition on hippocampal function?

Our laboratory is investigating the effects of protein-energy malnutrition (PEM) on cognitive outcome following global ischemia. Here, we investigated whether PEM independently impairs working memory in the T-maze and if the associated food reward reverses PEM. Gerbils were fed 12.5% (control diet) or 2% protein. A loss of body weight (20.1%) in the 2% protein group and decreased food intake and serum albumin concentration compared to controls (17.5% and 18.2%, respectively) indicated that PEM was achieved. Based on T-maze criterion frequently used in ischemia studies, no difference was observed in the mean (+/- SEM) number of trials required (control 5.2 +/- 0.7; PEM 4.9 +/- 0.4; p = 0.758) or the number of animals reaching criterion (control 10/12; PEM 12/12; p = 0.140). Using more stringent criterion, PEM animals required fewer trials (control 7.3 +/- 0.7; PEM 5.4 +/- 0.4; p = 0.035), and more reached criterion (control 8/12; PEM 12/12; p = 0.028). PEM may increase motivation to obtain a food reward.

Protein malnutrition differentially alters the number of glutamic acid decarboxylase-67 interneurons in dentate gyrus and CA1–3 subfields of the dorsal hippocampus

In 30- and 90-day-old rats, using immunohistochemistry for glutamic acid decarboxylase 67 (GAD-67), we have tested whether malnutrition during different periods of hippocampal development produces deleterious effects on the population of GABA neurons in the dentate gyrus (DG) and cornu Ammonis (CA1-3) of the dorsal hippocampus. Animals were under one of four nutritional conditions: well-nourished controls (Con), prenatal protein malnourished (PreM), postnatal protein malnourished (PostM), and chronic protein malnourished (ChroM). We found that the number of GAD-67-positive (GAD-67+) interneurons was higher in the DG than in the CA1-3 areas of both Con and malnourished groups. Regarding the DG, the number of GAD-67+ interneurons was increased in PreM and PostM and decreased in ChroM at 30 days. At 90 days of age the number of GAD-67+ interneurons was increased in PostM and ChroM and remained unchanged in PreM. With respect to CA1-3, the number of labeled interneurons was decreased in PostM and ChroM at 30 days of age, but no change was found in PreM. At 90 days no changes in the number of these interneurons were found in any of the groups. These observations suggest that 1) the cell death program starting point is delayed in DG GAD-67+ interneurons, and 2) protein malnutrition differentially affects GAD-67+ interneuron development throughout the dorsal hippocampus. Thus, these changes in the number of GAD-67+ interneurons may partly explain the alterations in modulation of dentate granule cell excitability, as well as in the emotional, motivational, and memory disturbances commonly observed in malnourished rats.

Global undernutrition during gestation influences learning during adult life

Intrauterine growth restriction can lead to significant long-term health consequences such as metabolic and cardiovascular disorders, but less is known about its effects on choice and behavioral adaptation in later life. Virgin Wistar rats were time mated and randomly assigned to receive either ad-libitum access to chow or 30% of that level of nutrition during pregnancy to generate growth-restricted offspring. At 60 days of age, 6 female offspring from each group were trained on concurrent variable-interval schedules. Sessions consisted of seven randomly arranged concurrent-schedule components, each with a different reinforcer ratio that varied from 27:1 to 1:27, and each component lasting for 10 reinforcer deliveries. Behavioral change across reinforcers in components, measured by sensitivity to reinforcement, was consistently lower for offspring of undernourished mothers, showing that their behavior was less adaptable to environmental change. These results provide direct experimental evidence for a link between prenatal environmental conditions and reduced behavioral adaptability--learning--in later life.

Asymmetry of neuron numbers in the hippocampal formation of prenatally malnourished and normally nourished rats: a stereological investigation

There is considerable evidence for lateralization of hippocampal function and hemispheric asymmetry in humans. In the rat, studies have reported asymmetries in the thicknesses of layers, the volumes of hippocampal subfields, and the density of cells at specific points along the septotemporal axis. To determine if there is an asymmetry of neuron numbers and whether prenatal malnutrition affects any asymmetries, 90-day old male Sprague-Dawley rats that were either normally nourished or malnourished prenatally were perfused with 4% paraformaldehyde and the brains cut into 30-micro m sections. One interrupted series of sections through the entire hippocampus was analyzed stereologically to estimate the total number of neurons in the hilus of the dentate gyrus, the CA3/CA2 stratum pyramidale (SP), the CA1 SP, and the SP of the prosubiculum/subiculum of both hemispheres. Significant asymmetries (P < 0.05) were found in the CA1 and CA3/CA2 subfields, with the right hemisphere containing 21 and 6% fewer neurons, respectively. Malnutrition reduced neuron numbers in the CA1 subfield by 12%, but did not alter the hemispheric asymmetry. Our findings agree with previous reports of left dominant asymmetries in the rat brain and suggest that this may result from differences in total numbers of neurons.

Organization of olfactory glomeruli in neonatally undernourished rats

Newborn rats maintain mother-litter bonds by using olfactory signals. At birth, units in the olfactory glomeruli (OG) are immature and vulnerable to noxious epigenetic factors like undernutrition. Because little is known about the effects of neonatal undernutrition upon the OG morphological organization, different OG parameters were studied in undernourished Wistar rats at 7, 14 and 21 days of age. The issue was addressed by analyzing the olfactory bulb (OB) cross sectional area, the total number and area of OGs in the OB coronal sections, and the distribution of OG area in dorsal and ventral quadrants. Reductions in the OB and OG cross sectional areas were detected at 7 and 14 days posnatally. OG area comparisons by OB quadrants were reduced along the study in quadrants, with larger effects in medial than in lateral OB quadrants. Current OG cytoarchitectonic modifications may affect the newborn capabilities for odour discrimination by disrupting early mother-litter interactions.

Prenatal malnutrition and sleep states in adult rats: effects of restraint stress

Independently, prenatal malnutrition and psychological/physical stress have been shown to affect sleep architecture in adult rats. As malnutrition and stress commonly co-exist in malnourished human populations, the objective of the present study was to ascertain the combined effects of these two insults by examining sleep-wake parameters following a brief restraint stress in prenatally protein malnourished rats. The male offspring of rats provided with a protein deficient diet (6% casein) for 5 weeks prior to mating and throughout pregnancy were implanted with recording electrodes beginning at postnatal day 90. Polygraph recordings were obtained to quantify sleep states during the first 4 h of the dark phase of the cycle on 2 consecutive days. The first followed a 24-h habituation session to the recording chamber (baseline). The second occurred at the same time of day but followed 20 min of restraint stress in a Plexiglas tube. During baseline, prenatally malnourished rats spent more time in rapid eye movement sleep (REMS) in the first 2 h after "lights off" (block 1), and greater amounts of wakefulness (W) with a corresponding reduction in slow wave sleep (SWS) in the second two hours (block 2), as compared with controls. Following stress, the sleep architecture of both groups of rats remained unaltered in block 1 relative to their baseline day. In block 2, both groups exhibited significant reductions in SWS and REMS with significantly greater reductions being expressed in the prenatally malnourished group (most dramatically, REMS was completely eliminated). These findings suggest that sleep disturbances may be more severe in those malnourished human populations subjected to acutely stressful experiences.

Effect of prenatal protein malnutrition on numbers of neurons in the principal cell layers of the adult rat hippocampal formation

Malnutrition has been associated with a variety of functional and anatomical impairments of the hippocampal formation. One of the more striking of these is widespread loss of hippocampal neurons in postnatally malnourished rats. In the present study we have investigated the effect of prenatal malnutrition on these same neuronal populations, neurons that are all generated during the period of the dietary restriction. In prenatally protein deprived rats, using design-based stereology, we have measured the regional volume and number of neurons in the hilus of the dentate gyrus and the pyramidal cell layers of CA3, CA2, CA1, and the subiculum of 90-day-old animals. These results demonstrated a statistically significant reduction of 20% in neuron numbers in the CA1 subfield, while numbers in the other subfields were unchanged. There was a corresponding significant reduction of 22% in the volume of the CA1 subfield and a significant 14% decrease in the volume of the pyramidal layer of the subiculum. The change in volume of the pyramidal layer of the subiculum without neuron loss may reflect loss of CA1 afferent input to the pyramidal layer. Although the effect of nutritional deprivation on the neuronal population appears to be different in pre- and postnatal malnutrition, both dietary paradigms highlight the vulnerability of key components of the hippocampal trisynaptic circuit (consisting of the dentate granule cell mossy fibers projection to CA3 pyramids and the CA3 projection to the CA1 pyramids), which is an essential circuit for memory and learning.

A “deficient environment” in prenatal life may compromise systems important for cognitive function by affecting BDNF in the hippocampus

The intrauterine environment has the capacity to mold the prenatal nervous system. Particularly, recent findings show that an adverse prenatal environment produces structural defects of the hippocampus, a critical area sub-serving learning and memory functions. These structural changes are accompanied by a disruption in the normal expression pattern of brain-derived neurotrophic factor (BDNF) and its cognate tyrosine kinase B (TrkB) receptor. The important role that the BDNF system plays in neural modeling and learning and memory processes suggests that fetal exposure to unfavorable intrauterine conditions may compromise proper cognitive function in adult life. These findings have implications for disorders that involve a dysfunction in the BDNF system and are accompanied by cognitive deficits.

The mossy fiber system of the hippocampal formation is decreased by chronic and postnatal but not by prenatal protein malnutrition in rats

We tested in 70-day-old Sprague-Dawley rats, whether malnutrition imposed during different periods of hippocampal development produced deleterious effects on the total reference volume of the mossy fiber system. Animals were treated under four nutritional conditions: (a) well nourished; (b) prenatal protein malnourished; (c) chronic protein malnourished and (d) postnatal protein malnourished. Timm's stained material was used in coronal hippocampal sections (40 microm) to estimate--using the Principle of Cavalieri--the total reference volume of the mossy fiber system in each experimental group. Our results show that chronic and postnatal protein malnourished, but not prenatal malnourished rats, decrease the mossy fiber system and the total reference volume of the mossy fiber system are selectively vulnerable to the type of dietary restriction. Thus, chronic and posnatal protein malnutrition produce deleterious effects, but only rats under prenatal protein malnutrition were able to reorganize synapses in this plexus. These findings raise the possibility that chronic malnutrition, as a long-term stressful factor, might be an important paradigm to test structural hippocampal changes that produce physiological and pathophysiological effects, or the possibility to recover its function for nutritional rehabilitation.

Gestational and postnatal malnutrition affects sensitivity of young rats to picrotoxin and quinolinic acid and uptake of GABA by cortical and hippocampal slices

It is widely known that a complex interaction between excitatory and inhibitory systems is required to support the adequate functioning of the brain and that significant alterations induced by early protein restriction are complex, involving many systems. Based on such assumptions, we investigated the effects of maternal protein restriction during pregnancy and lactation followed by offspring protein restriction on some GABAergic and glutamatergic parameters, which mediate inhibitory and excitatory transmission, respectively. The sensitivity of young malnourished rats to convulsant actions of the GABA(A) receptor antagonist picrotoxin (PCT; s.c.) and to N-methyl-d-aspartate (NMDA) receptor agonist quinolinic acid (QA; i.c.v) and also gamma-amino-n-butyric acid (GABA) and glutamate uptake by cortical and hippocampal slices were evaluated in P25 old rats. Early protein malnutrition induced higher sensitivity to picrotoxin, which could be associated with the observed higher GABA uptake by cortical, and hippocampal slices in malnourished rats. In contrast, we observed lower sensitivity to quinolinic acid in spite of unaltered glutamate uptake by the same cerebral structures. Picrotoxin enhanced GABA uptake in hippocampus in well- and malnourished rats; however, it did not affect cortical GABA uptake. Our data corroborate our previous report, showing that malnutrition depresses the glutamatergic activity, and point to altered modulation of GABAergic neurotransmission. Such findings allow us to speculate that malnutrition may affect the excitatory and inhibitory interaction.

Prenatal protein deprivation in rats induces changes in prepulse inhibition and NMDA receptor binding

Epidemiological studies suggest that prenatal malnutrition increases the risk of developing schizophrenia. Animal models indicate that prenatal protein deprivation (PPD) affects many aspects of adult brain function. We tested the hypothesis that PPD in rats would alter prepulse inhibition (PPI), which is an operational measure of sensorimotor gating that is deficient in schizophrenia patients. Additionally, we examined dopaminergic and glutaminergic receptor binding in the striatum and hippocampus, which have been suggested to play a role in the etiology of schizophrenia. Rat dams were fed normal (25%) or low (6%) protein diets beginning 5 weeks prior to, and throughout pregnancy. The pups were tested at postnatal days (PND) 35 and 56 for PPI. Striatal and hippocampal NMDA receptor, and striatal dopamine receptor binding were quantified post-mortem in a subset of these rats. Female rats exposed to PPD had reduced levels of PPI at PND 56, but not PND 35, suggesting the emergence of a sensorimotor gating deficit in early adulthood. Striatal NMDA receptor binding was increased in PPD females. A decrease in initial startle response (SR) was also observed in all PPD rats relative to control rats. These results suggest that PPD causes age- and sex-dependent decreases in PPI and increases in NMDA receptor binding. This animal model may be useful for the investigation of neurodevelopmental changes that are associated with schizophrenia in humans.

Effects of prenatal malnutrition on GABAA receptor α1, α3 and β2 mRNA levels

Exposure of pregnant rats to protein malnutrition throughout pregnancy alters the developing hippocampus, leading to increased inhibition and selective changes in hippocampal-mediated behaviors. Given that GABA mediates most inhibitory neurotransmission, we asked whether selective changes in the levels of GABA receptor subunit mRNAs might result. Quantitative RNase protection profiling of 12 GABAA and GABAB receptor subunit mRNAs show that alpha1 and beta2 decrease in the adult (P90) hippocampal formation of prenatally malnourished rats, while the levels of alpha3 are increased. Moreover, the distribution of alpha1, alpha3 and beta2 mRNAs remains unchanged in CA1 and CA3 hippocampal subfields relative to dentate gyrus. The data suggest that prenatal malnutrition produces global changes of certain GABAA, but not GABAB, receptor mRNAs in the hippocampal formation.

Increased density of hippocampal kainate receptors but normal density of NMDA and AMPA receptors in a rat model of prenatal protein malnutrition

The postnatal development of excitatory amino acid receptor types including kainate, N-methyl-D-aspartate (NMDA), and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) was assessed in the hippocampus, entorhinal cortex, and adjacent neocortex in normal and prenatally protein malnourished rats ages 15, 30, 90, and 220 postnatal days by quantitative autoradiography. Tritiated ligands used to measure binding site density were (3)[H]kainate, (3)[H]MK-801, and (3)[H]AMPA, respectively. Kainate receptors showed statistically significant increases in binding density in stratum lucidum of CA3 (hippocampal mossy fiber zone) in 90- and 220-day-old malnourished rats compared with age- and sex-matched controls but not in 15- or 30-day-old malnourished rats. Compared with previous anatomic studies, these results are mostly in agreement with a significantly decreased hippocampal mossy fiber plexus in 15-, 90-, and 220-day-old rats but not in 30-day-old rats. These results suggested that the increased density of postsynaptic kainate receptors located mainly on proximal apical dendrites of CA3 pyramidal cells may be compensatory to decreased glutamate release due to the reduction in mossy fiber plexus. In contrast, the density of putative NMDA and AMPA receptors quantified in prenatally malnourished rats was comparable to the density quantified in age- and sex-matched control rats, as were all three receptor types in entorhinal cortex and adjacent neocortex. Thus, the selectivity of the compensation of (3)[H]kainate-labeled mossy fiber plexus in adult but not in early postnatal developing malnourished rats may help ensure continued breeding and survival of the species under otherwise adverse environmental conditions.

Prenatal protein malnutrition decreases mossy fibers-CA3 thorny excrescences asymmetrical synapses in adult rats

Prenatal protein malnutrition has deleterious effects on hippocampal structure and function that likely result from decreased synapse number. We thus evaluated long-term effects of prenatal protein malnutrition on the mossy fibers-CA3 thorny excrescences asymmetrical synapses in 220-day-old rats. Protein malnourished rats born from pregnant dams fed with 6% casein diet were cross-fostered to lactating control rats at birth. Control animals were fed with a 25% casein diet. Timm's stained material was used to estimate the total reference volume of the mossy fiber system suprapyramidal bundle by means of stereology. The mossy fiber-CA3 asymmetrical synapse numerical density was obtained by electron microscopy, using the physical disector method. The total number of mossy fiber-CA3 asymmetrical synapses was determined on the basis of the total reference volume of the mossy fiber system suprapyramidal bundle and the mossy fiber-CA3 asymmetrical synapse numerical density. Prenatal protein malnutrition produced long-lasting, significant decreases in the volume of the mossy fiber system suprapyramidal bundle and in the numerical density of mossy fiber-CA3 asymmetrical synapse, suggesting a reduction in the total number of this synapse type. Hence, prenatal protein malnutrition induces long lasting deleterious effects on the progression of developmental programs controlling synaptogenesis and/or synaptic consolidation, likely by affecting a myriad of cellular processes.

Effects of perinatal undernourishment on neuronal development of the facial motor nucleus in the rat

The facial nucleus (FN) of the rat is composed of multipolar neurons generated between gestational days G12 and G15. This nucleus is involved in the mechanisms underlying muscle contraction during the sucking reflex. After birth, the neuronal substrate of this reflex is gradually organized to allow the performance of other functions such as gnawing, chewing, swallowing and drinking. Undernourishment is known to produce different degrees of delayed brain development, the greatest of which are similar to the characteristics of the premature syndrome. Neuronal morphological alterations are associated with sucking-reflex deficiencies, which interfere with feeding by the newborn. The current study shows that perinatal undernourishment leads to dendritic arbor hypoplasia and small alterations of soma size in Golgi--Cox impregnated FN neurons of rats. The data suggest that these morphological alterations of FN neurons, may be associated with shifts in the input and integration of signals, and may finally modify the elaboration of motoneuron discharges partly modulating bucolabial muscle contraction during sucking movements and facial expression. Additionally, neonatal nutritional rehabilitation modifies the effects on FN neuronal development, ameliorating the influence of early adverse nutritional conditions.

Permanent and transitory morphometric changes of NADPH-diaphorase-containing neurons in the rat visual cortex after early malnutrition

We investigated the histochemical positivity to NADPH-diaphorase, which reveals nitric oxide synthase activity, in area 17 of rats malnourished early in life, both in the post-weaning period (group M1), and in adulthood after nutritional recovering (group M2). Control pups (C1 and C2 groups) received ad libitum after weaning the same diets as their mothers. Rats of group M2 were nutritionally recovered by receiving the control diet from post-natal day 42 until adulthood. Aldehyde-fixed sections (200-microm thick) through area 17 were processed for NADPH-diaphorase histochemistry following the malic enzyme indirect method. The features of NADPH-diaphorase-containing neurons of area 17 of malnourished young (M1) and adult (M2) rats were analyzed quantitatively in comparison to the matched groups C1 and C2. Permanent changes, represented by increase in the density and dendritic field areas of NADPH-diaphorase-positive cells, and transitory ones, represented by decreased values of soma areas, were observed in area 17 of the M1 and M2 cases. However, some other features, such as dendritic branch angle and number of dendrites per cell in the gray matter, remained unchanged after malnutrition. Thus, the findings indicate a possible relationship between early malnutrition and alterations in nitric oxide synthase-containing cells in the visual cortex. Physiological implications of these data may be related to synaptic plasticity and refinement of developmental brain circuits.

Prenatal protein malnutrition results in increased frequency of miniature inhibitory synaptic currents in rat CA1 pyramidal cells

There is growing evidence for an effect of prenatal protein malnutrition on the GABAergic neurotransmitter system in the rat hippocampus and associated structures. In the present study, we examined the functional electrophysiological consequences of observed alterations in GABA(A) and benzodiazepine receptor systems. Whole-cell patch clamp recordings of spontaneous and of miniature inhibitory postsynaptic currents (mIPSCs) generated by CA1 pyramidal cells were performed in in vitro hippocampal slices prepared from control and prenatally protein malnourished adult male rats. The characteristics of spontaneous synaptic currents were unaltered by the prenatal insult, as were the amplitudes and kinetics of GABA(A) receptor-mediated mIPSCs. The frequency of mIPSCs, however, was significantly increased in CA1 pyramidal cells in slices prepared from prenatally malnourished vs. control rats. The effect of the benzodiazepine receptor agonist chlordiazepoxide on the characteristics of mIPSCs was also examined and found to be the same in cells from both nutritional groups. The increased frequency of mIPSCs together with the lack of a change in amplitude, kinetics, or modulation by benzodiazepines of mIPSCs in response to prenatal protein malnutrition indicate a presynaptic locus of effect of this insult.

Deficits in operant behavior and alteration of CA1, CA3 hippocampal dendritic arborization due to subicular lesions

The deficits in operant behavior and the alterations in dendritic arborizations of Cornu Ammonis 1 and Cornu Ammonis 3 (CA1 and CA3) hippocampal areas were investigated in subicular lesioned rats. The subjects were female Wistar rats aged 120 days, and were divided into four groups: one serving as age-matched untrained control, a second group received training and sham lesioning, a third group were only trained, and the fourth group were first trained and then subjected to subicular lesions. The rats were food-deprived 24 hours prior to operant behavior training sessions. Two training sessions for operant behavior with continuous reinforcement of 10 minutes duration per day were done during the shaping session, following which rats were allowed 10 minutes of operant food reward for 10 days. On the eleventh day, only the operant behavior and sham-operated rats were used for subicular lesion and sham surgery, respectively. After 72 hours of surgical recovery, operant behavioral testing was performed daily as before for a further period of 10 days. Later, all groups of rats were killed and the hippocampus was processed for rapid Golgi staining. Our results suggest that subicular lesions produce a significant reduction in operant learning. Further, the Golgi studies revealed a reduction in dendritic branching points and intersections of apical and basal CA1, CA3 neurons in lesioned rats.

Self-stimulation rewarding experience induced alterations in dendritic spine density in CA3 hippocampal and layer V motor cortical pyramidal neurons

Self-stimulation rewarding experience induced alterations in the numerical density of spines in CA3 hippocampal and layer V motor cortical pyramidal neurons in adult male Wistar rats was evaluated. Self-stimulation experience was provided 1 h daily over a period of 10 days through stereotaxically implanted bipolar stainless steel electrodes bilaterally in lateral hypothalamus and substantia nigra-ventral tegmental area. After 10 days, rats were killed and the hippocampus and motor cortex were processed for rapid Golgi staining procedure. The dendritic spine densities were studied in CA3 hippocampal and layer V motor cortical pyramidal neurons. The spine densities were quantified in five successive segments of 15.2 microm up to a distance of 76 microm. Apical dendrites were classified as mainshaft, sub branch, oblique shaft-I, oblique shaft-II, primary branch; and basal dendrites as main shaft, primary branch and secondary branch. A grand total of 864 CA3 hippocampal and 1008 layer V motor cortical dendrites were analysed for spine counting in different groups of rats. The results revealed a significant (P<0.001; ANOVA, F-test) increase in the number of spines in all the categories of dendrites in apical and basal regions in both hippocampal and motor cortical neurons in self-stimulation group of rats. Such changes were not observed either in sham control, experimenter-administered or normal control groups of rats. The self-stimulation induced increase in the spine density suggests an increase in the postsynaptic receptive field in CA3 hippocampal and layer V motor cortical neurons. This might enhance the efficacy of synaptic transmission in these neurons. Our study clearly demonstrated the self-stimulation rewarding experience induced postsynaptic plasticity in hippocampal and motor cortical pyramidal neurons.

Undernutrition and Postnatal Development of Brain Oxidative Metabolism in Limbic Structures: A Quantitative Study

The effects of food restriction during gestation, lactation and post-weaning were studied in rat brain structures (14,21 and 30 days). Oxidative metabolism was quantified in neurons from the anterior thalamus and mammillary bodies using a quantitative histochemical method for cytochrome c oxidase (CO). In all the rat brains studied, a significant increase in activity occurred in the control group from 14 to 21 days after birth which then remained constant up to 30 days. A similar pattern was observed in the undernourished group, although in the anterodorsal and anteromedial thalamic nuclei the rise in CO only occurred between day 14 and 30 and there were no significant age-related changes in the lateral mammillary nucleus. Undernutrition produced a significant drop in CO activity after 21 days in all the nuclei except the lateral mammillary nucleus. In the latter nucleus and also in the pars medialis of the medial mammillary nucleus this parameter decreased at 30 days. Our results suggest that undernutrition and nutritional rehabilitation have different effects on the diencephalic regions studied, which depends on age and region.

Alterations in the density of excrescences in CA3 neurons of hippocampus in rats subjected to self-stimulation experience

Self-stimulation (SS) rewarding experience induced alterations in the density of excrescences in the apical dendrites of CA3 neurons were studied in adult male Wistar rats. SS experience was provided daily for an hour over a period of 10 days, through bipolar stainless steel electrodes implanted bilaterally in lateral hypothalamus and substantia nigra-ventral tegmental area. The results revealed a significant (P<0.001) increase in the number of excrescences in both main shaft and sub branches of the apical dendrites in SS experienced group compared to control groups of rats. The increased number of excrescences in CA3 neurons might be due to an enhancement in the synaptic transmission in the mossy fiber pathway following SS experience.

Long-lasting structural changes in CA3 hippocampal and layer V motor cortical pyramidal neurons associated with self-stimulation rewarding experience: a quantitative Golgi study

Self-stimulation (SS) rewarding experience induced structural changes in CA3 hippocampal and layer V motor cortical pyramidal neurons in adult male Wistar rats has been demonstrated. In the present study, whether these structural changes are transient or of a permanent nature was evaluated. Self-stimulation experience was provided for 1 h daily over a period of 10 days through bilaterally implanted bipolar electrodes in the lateral hypothalamus and the substantia nigra-ventral tegmental area. Following 10 days of SS experience, the rats were sacrificed after an interval of 30 and 60 days for the quantitative analysis of the dendritic morphology in Golgi stained CA3 hippocampal and layer V motor cortical pyramidal neurons. The results revealed a significant increase in the dendritic branching points and intersections in apical and basal dendrites in both types of neurons in 30 days post-SS group compared to sham control. The total number of apical and basal dendrites were significantly increased in both 30 and 60 days post-SS groups of rats. This study suggests that SS experience induced structural changes are sustainable, even in the absence of rewarding experience.

Effects of acute prenatal ethanol exposure on Bergmann glia cells early postnatal development

The effects of acute ethanol exposure during the prenatal phase of Bergmann glia cell (Bgc) generation were evaluated in three postnatal days. Ethanol exposed rats showed Bgc with reduced soma size, decreased number and width of their fibers, and increased fiber length, when compared with control animals. These differences, however, were significant at postnatal day 12. Our results demonstrate that acute, prenatal exposure to ethanol during critical stages of brain development disrupts Bgc early postnatal development.

Effects of prenatal protein malnutrition on mossy fibers of the hippocampal formation in rats of four age groups

The present study was undertaken to investigate the effect of prenatal protein deprivation on the postnatal development of the mossy fiber plexus of the hippocampal formation on postnatal (P) days 15, 30, 90, and 220. Although there is extensive information about the effects of malnutrition on cell body and dendrite morphology, little attention has been paid to axons or axon plexuses. The mossy fiber plexus represents the dentate gyrus granule cell axonal projection to areas CA4 and CA3 of the hippocampal formation and is readily demonstrated with Timm's heavy metal stain. With the use of this stain, the plexus was measured at 13 levels throughout the hippocampal complex. There was no effect of the diet on the anatomical distribution of the plexus. The current study, however, does show significant effects of prenatal protein malnutrition on postnatal development of the mossy fiber plexus that are age dependent. The prenatally malnourished rats show significant deficits in the total rostro-caudal extent and volume of the plexus on P15, P90, and P220, with the most marked dietary effect on P220. There was no significant diet effect on P30 in either extent or volume.

Effects of prenatal protein malnutrition on hippocampal CA1 pyramidal cells in rats of four age groups

The present study was undertaken to investigate the effect of prenatal protein deprivation on area CA1 hippocampal pyramidal cells on postnatal (P) days 15, 30, 90 and 220 using Golgi techniques. Age related changes in both groups and diet related changes between groups were assessed. There were significant diet effects at all four ages, with one of 12 different measurements showing a significant diet effect on P15, five on P30, one on P90, and seven on P220. The most marked effect of the diet was on pyramidal cell dendrite spine density in the stratum moleculare and stratum radiatum, with a different pattern of diet effects in the two strata. In pyramidal cell dendrites in the stratum moleculare, there was a deficit in spine density that was significant at three of the four ages and there were similar age-related changes in the two diet groups. Spines on pyramidal cell dendrites in the stratum radiatum showed a lack of synchrony of age-related changes in the two diet groups, with an increased spine density in the malnourished rats on P30 and a widening deficit in this parameter on P90 and P220. The bimodal distribution to these changes, with most marked deficits occurring on P30 and P220, with an intervening period of apparent "catch-up" on P90, is of interest and may be a significant brain adaptation to malnutrition. The present study is the final of three morphometric studies on the effect of prenatal protein restriction on three key neurons in the hippocampal trisynaptic circuit. When compared to our previous studies on the dentate granule cell and the CA3 pyramidal cell, it is noted that there is an effect of the low protein diet on all these neurons, with the most marked effect on the predominantly postnatally generated dentate granule cells.

Effect of chronic restraint stress on dendritic spines and excrescences of hippocampal CA3 pyramidal neurons--a quantitative study

Effect of chronic restraint stress on the number of dendritic spines and excrescences of hippocampal CA3 pyramidal neurons has been investigated. The results revealed a significant increase in the number of dendritic spines of apical and basal dendrites in rats subjected to restraint stress (6 h per day for 21 days). The number of excrescences were also markedly increased in stressed rats. The physiological significance and possible mechanism for increased spine density is discussed.

A classification of sociomedical health indicators: perspectives for health administrators and health planners

The conceptualization and operationalization of measures of health status are considered. Health indicators are conceived as a subset of social indicators, and therefore, as any social indicator, they are viewed as derivative from social issues. The interrelationships of different frames of reference for defining and measuring health that have accompained three distinct health problem patterns in the United States are viewed from a developmental perspective. Mortality and morbidity rates, the traditional health indicators, by themselves no longer serve to assess health status in developed nations. Their deficiencies as indicators serve as background for a classification schema for sociomedical health status indicators that relates health definition frames of reference, measures of health status, and health problems. The role of a group of health indicators-sociomedical heath indicators-in the current formulation of health status measures is assessed.