Neuroinflammation, blood-brain barrier dysfunction, hippocampal atrophy and delayed neurodevelopment: Contributions for a rat model of congenital Zika syndrome.

The congenital Zika syndrome (CZS) has been characterized as a set of several brain changes, such as reduced brain volume and subcortical calcifications, in addition to cognitive deficits. Microcephaly is one of the possible complications found in newborns exposed to Zika virus (ZIKV) during pregnancy, although it is an impacting clinical sign. This study aimed to investigate the consequences of a model of congenital ZIKV infection by evaluating the histopathology, blood-brain barrier, and neuroinflammation in pup rats 24 h after birth, and neurodevelopment of the offspring. Pregnant rats were inoculated subcutaneously with ZIKV-BR at the dose 1 × 107 plaque-forming unit (PFU mL-1) of ZIKV isolated in Brazil (ZIKV-BR) on gestational day 18 (G18). A set of pups, 24 h after birth, was euthanized. The brain was collected and later evaluated for the histopathology of brain structures through histological analysis. Additionally, analyses of the blood-brain barrier were conducted using western blotting, and neuroinflammation was assessed using ELISA. Another set of animals was evaluated on postnatal days 3, 6, 9, and 12 for neurodevelopment by observing the developmental milestones. Our results revealed hippocampal atrophy in ZIKV animals, in addition to changes in the blood-brain barrier structure and pro-inflammatory cytokines expression increase. Regarding neurodevelopment, a delay in important reflexes during the neonatal period in ZIKV animals was observed. These findings advance the understanding of the pathophysiology of CZS and contribute to enhancing the rat model of CZS.

Olive oil-rich diet during pregnancy/lactation attenuated the early life stress effects on depressive-like behavior and altered energy metabolism in the dorsal hippocampus in a sex-specific manner.

METHODS: and results: Pregnant Wistar rats received diets enriched in soybean oil (SO) or OO during gestation/lactation. At birth, litters were subdivided into MS or intact groups. After weaning, the pups received standard chow until adulthood, when they were subjected to behavioral tasks. At PND90 biochemical analyses were performed. Maternal OO-enriched diet prevented MS-induced higher weight gain, and decreased MS-induced anhedonic behavior. Increased latency to immobility and shorter immobility time were observed in the maternal OO-enrich diet groups. Maternal OO-enrich diet groups also presented reduced reactive oxygen species and increased activity of antioxidant enzymes. In addition, this diet showed sex-specific effects, by decreasing mitochondrial mass and potential, reducing AMPK activation, and increasing synaptophysin and PSD-95 immunocontent in the DH of male rats. Early stress, on the other hand, decreased production of free radicals and decreased levels of SIRT1 in the DH of male rats. In females, OO prevented the anhedonic behavior induced by MS. CONCLUSIONS: Maternal OO-enrich diet attenuated MS-induced depressive behavior in both sexes. In addition, it affected energy metabolism in the DH of male rats, favored synaptic plasticity, and contributed to reducing pathophysiological conditions.

Hypoxia-Inducible Factor-1α (HIF-1α) Inhibition Impairs Retinoic Acid-Induced Differentiation in SH-SY5Y Neuroblastoma Cells, Leading to Reduced Neurite Length and Diminished Gene Expression Related to Cell Differentiation.

Neuroblastoma is the most common extracranial solid tumour in childhood, originated from cells of the neural crest during the development of the Sympathetic Nervous System. Retinoids are vitamin-A derived differentiating agents utilised to avoid disease resurgence in high-risk neuroblastoma treatment. Several studies indicate that hypoxia-a common feature of the tumoural environment-is a key player in cell differentiation and proliferation. Hypoxia leads to the accumulation of the hypoxia-inducible factor-1α (HIF-1α). This work aims to investigate the effects of the selective inhibition of HIF-1α on the differentiation induced by retinoic acid in human neuroblastoma cells from the SH-SY5Y lineage to clarify its role in cell differentiation. Our results indicate that HIF-1α inhibition impairs RA-induced differentiation by reducing neuron-like phenotype and diminished immunolabeling and expression of differentiation markers. HIF1A is involved in Retinoic Acid (RA) induced differentiation in SH-SY5Y neuroblastoma cells. siRNA HIF1A gene silencing leads to a weaker response to RA, demonstrated by changes in the neuro-like phenotype and diminished expression of differentiation markers.

Life-course effects of early life adversity exposure on eating behavior and metabolism.

Environmental variations in early life influence brain development, making individuals more vulnerable to psychiatric and metabolic disorders. Early life stress (ELS) has a strong impact on the development of eating behavior. However, eating is a complex behavior, determined by an interaction between signals of energy homeostasis, neuronal circuits involved in its regulation, and circuits related to rewarding properties of the food. Although mechanisms underlying ELS-induced altered feeding behavior are not completely understood, evidence suggest that the effects of ELS on metabolic, mood, and emotional disorders, as well as reward system dysfunctions can contribute directly or indirectly to altered feeding behavior. The focus of this chapter is to discuss the effects of ELS on eating behavior and metabolism, considering different factors that control appetite such as energy homeostasis, hedonic properties of the food, emotional and cognitive status. After highlighting classic studies on the association between ELS and eating behavior alterations, we discuss how exposure to adversity can interact with genetics characteristics to predict variable outcomes.

Chronic high-fat diet affects food-motivated behavior and hedonic systems in the nucleus accumbens of male rats.

Environmental variations can influence eating and motivated behaviors, as well as the brain's feeding circuits to predisposing overweight and obesity. The identification of mechanisms through which a long-term consumption of caloric-dense palatable foods and its association with early life stress can cause neuroadaptations and possible modify motivational behaviors are relevant to elucidate the mechanisms associated with obesity. Here, we investigated the long-term effects of a chronic high-fat diet (HFD), and its interaction with early social isolation on hedonic feeding responses in adult rats. Rats were subjected, or not, to social isolation between postnatal days 21-28 and were fed a control diet or HFD, for 10 weeks post weaning. Hedonic feeding behavior was evaluated during adulthood and parameters related to the dopaminergic, cannabinoid, and opioid systems were measured in the nucleus accumbens. Animals with chronic HFD intake were less motivated to obtain sweet palatable foods. This reduced motivation did not appear to be associated with less pleasure upon tasting sweet food, as no alteration in reactivity to sweet taste was observed. Interestingly, the animals receiving HFD presented decreased immunocontents of the D1 and CB1 receptors, while the stressed group displayed a reduction in dopamine turnover. In summary, chronic HFD causes a significant motivational impairment for sweet palatable foods; these changes may be associated with a decreased dopaminergic and cannabinoid neurotransmission in the nucleus accumbens. In contrast, a brief social isolation during the prepubertal period was unable to alter the behavioral parameters studied but caused a decreased dopaminergic turnover in the nucleus accumbens of adult rats. These findings highlight the importance of long-term HFD exposure on the modulation of hedonic feeding behavior and related neurochemical systems.

Consumption of a palatable diet rich in simple sugars during development impairs memory of different degrees of emotionality and changes hippocampal plasticity according to the age of the rats.

We investigated the effect of a chronic palatable diet rich in simple sugars on memory of different degrees of emotionality in male adult rats, and on hippocampal plasticity markers in different stages of development. On postnatal day (PND) 21, 45 male Wistar rats were divided in two groups, according to their diet: (1-Control) receiving standard lab chow or (2-Palatable Diet) receiving both standard chow plus palatable diet ad libitum. At PND 60, behavioral tests were performed to investigate memory in distinct tasks. Hippocampal plasticity markers were investigated at PND 28 in half of the animals, and after the behavioral tests. Palatable diet consumption induced an impairment in memory, aversive or not, and increased Na+ , K+ -ATPase activity, both at PND 28, and in the adulthood. Synaptophysin, brain-derived neurotrophic factor (BDNF), and protein kinase B (AKT), and phosphorylated AKT were reduced in the hippocampus at PND 28. However, at PND 75, this diet consumption led to increased hippocampal levels of synaptophysin, spinophilin/neurabin-II, and decreased BDNF and neuronal nitric oxide synthase. These results showed a strongly association of simple sugars-rich diet consumption during the development with memory impairments. Plasticity markers are changed, with results that depend on the stage of development evaluated.

Neurometabolic effects of sweetened solution intake during adolescence related to depressive-like phenotype in rats.

OBJECTIVE: Exposure to artificial sweeteners, such as aspartame, during childhood and adolescence has been increasing in recent years. However, the safe use of aspartame has been questioned owing to its potentially harmful effects on the developing brain. The aim of this study was to test whether the chronic consumption of aspartame during adolescence leads to a depressive-like phenotype and to investigate the possible mechanisms underlying these behavioral changes. METHODS: Adolescent male and female rats were given unlimited access to either water, solutions of aspartame, or sucrose in their home cages from postnatal day 21 to 55. RESULTS: Forced swim test revealed that both chronic aspartame and sucrose intake induced depressive-like behaviord, which was more pronounced in males. Additionally, repeated aspartame intake was associated with increased cerebrospinal fluid (CSF) aspartate levels, decreased hippocampal neurogenesis, and reduced activation of the hippocampal leptin signaling pathways in males. In females, we observed a main effect of aspartame: reducing PI3K/AKT one of the brain-derived neurotrophic factor pathways; aspartame also increased CSF aspartate levels and decreased the immunocontent of the GluN2A subunit of the N-methyl-d-aspartic acid receptor. CONCLUSION: The findings revealed that repeated aspartame intake during adolescence is associated with a depressive-like phenotype and changes in brain plasticity. Interestingly, males appear to be more vulnerable to the adverse neurometabolic effects of aspartame than females, demonstrating a sexually dimorphic response. The present results highlighted the importance of understanding the effects caused by the constant use of this artificial sweetener in sensitive periods of development and contribute to regulation of its safe use.

Animal Models of Metabolic Disorders in the Study of Neurodegenerative Diseases: An Overview.

The incidence of metabolic disorders, as well as of neurodegenerative diseases-mainly the sporadic forms of Alzheimer's and Parkinson's disease-are increasing worldwide. Notably, obesity, diabetes, and hypercholesterolemia have been indicated as early risk factors for sporadic forms of Alzheimer's and Parkinson's disease. These conditions share a range of molecular and cellular features, including protein aggregation, oxidative stress, neuroinflammation, and blood-brain barrier dysfunction, all of which contribute to neuronal death and cognitive impairment. Rodent models of obesity, diabetes, and hypercholesterolemia exhibit all the hallmarks of these degenerative diseases, and represent an interesting approach to the study of the phenotypic features and pathogenic mechanisms of neurodegenerative disorders. We review the main pathological aspects of Alzheimer's and Parkinson's disease as summarized in rodent models of obesity, diabetes, and hypercholesterolemia.

Sex-dependent effect on mitochondrial and oxidative stress parameters in the hypothalamus induced by prepubertal stress and access to high fat diet.

OBJECTIVE: Some factors related to lifestyle, including stress and high-fat diet (HFD) consumption, are associated with higher prevalence of obesity. These factors can lead to an imbalance between ROS production and antioxidant defenses and to mitochondrial dysfunctions, which, in turn, could cause metabolic impairments, favoring the development of obesity. However, little is known about the interplay between these factors, particularly at early ages, and whether long-term sex-specific changes may occur. Here, we evaluated whether social isolation during the prepubertal period only, associated or not with chronic HFD, can exert long-term effects on oxidative status parameters and on mitochondrial function in the whole hypothalamus, in a sex-specific manner. METHODS: Wistar male and female rats were divided into two groups (receiving standard chow or standard chow + HFD), that were subdivided into exposed or not to social isolation during the prepubertal period. Oxidative status parameters, and mitochondrial function were evaluated in the hypothalamus in the adult age. RESULTS: Regarding antioxidant enzymes activities, HFD decreased GPx activity in the hypothalamus, while increasing SOD activity in females. Females also presented increased total thiols; however, non-protein thiols were lower. Main effects of stress and HFD were observed in TBARS levels in males, with both factors decreasing this parameter. Additionally, HFD increased complex IV activity, and decreased mitochondrial mass in females. Complex I-III activity was higher in males compared to females. CONCLUSION: Stress during the prepubertal period and chronic consumption of HFD had persistent sex-specific effects on oxidative status, as well as on its consequences for the cell and for mitochondrial function. HFD had more detrimental effects on females, inducing oxidative imbalance, which resulted in damage to the mitochondria. This HFD-induced imbalance may be related to the development of obesity.

Neonatal handling impairs intradimensional shift and alters plasticity markers in the medial prefrontal cortex of adult rats.

Stress response can be modulated by neonatal/childhood events. Neonatal handling (NH) is an animal model in which the animals are subjected to brief separations from the dam during the first days of life, and it leads to lower emotionality and behavioral changes in adulthood. The aim of this study was to observe if early events, such as (NH), may program associative learning and behavioral flexibility in adult male rats and if these changes could be related to altered neurochemistry in the medial prefrontal cortex (mPFC). We evaluated proteins related to synaptic plasticity (brain-derived neurotrophic factor [BDNF] and synaptophysin [SYP]) as well as Na+/K+-ATPase activity. Additionally, we evaluated proteins related to the dopaminergic system (tyrosine hydroxylase [TH] and phosphorylated TH [pTH]), since this system appears to be affected in some neonatal interventions. Neonatally handled animals exhibited impairment in simple discrimination and intradimensional shift but not in reversal or compound discrimination; in addition, no alteration in switching from an egocentric spatial to a cued strategy was observed. These effects were accompanied by a decrease in SYP levels and Na+/K+-ATPase activity, suggesting reduced synaptic function. These results indicate that NH increases attention to irrelevant stimuli and/or impairs associative learning, and this is accompanied by neurochemical alterations in the (mPFC).

Sex-specific effects of prepubertal stress and high-fat diet on leptin signaling in rats.

OBJECTIVE: Both stress exposure and high-fat diet (HFD) are contributors to the alarming prevalence of obesity. Leptin is secreted from adipose tissue and regulates appetite and body weight via the JAK-STAT3 pathway in the hypothalamus; it also regulates the hypothalamic-pituitary-thyroid axis, modulating energy homeostasis. Leptin signaling may be impaired by HFD intake, and here we investigate whether social isolation during the prepubertal period, associated with chronic HFD, can exert long-term effects on metabolic parameters in a sex-specific manner. METHODS: Wistar male and female rats were divided into two groups (receiving standard chow or standard chow and HFD), which were subdivided into (1) exposed to social isolation during the prepubertal period or (2) not exposed. RESULTS: HFD induced sex-specific effects on leptin signaling and on the hypothalamic-pituitary-thyroid axis; males receiving HFD presented increased T4 but a reduced T3:T4 ratio and higher caloric efficiency during development. A stress × diet interaction was noted for leptin signaling in males, where pSTAT3 was higher when these factors were applied together. On the other hand, females were more susceptible to early stress, which reduced pSTAT3 in the hypothalamus. CONCLUSION: Both stress during the prepubertal period and chronic consumption of HFD had long-term sex-specific effects on hormonal signaling related to energy balance. However, the effects of HFD were more pronounced in males, whereas prepubertal stress had greater effects on leptin signaling in females.

Impact of High-Fat Diet and Early Stress on Depressive-Like Behavior and Hippocampal Plasticity in Adult Male Rats.

During development, the brain goes through fundamental processes, including organization of neural networks and plasticity. Environmental interventions may change initial brain programming, leading to long-lasting effects and altering the susceptibility to psychopathologies, including depression disorder. It is known that depression is a psychiatric disorder with a high prevalence worldwide, including high rates among adolescents. In this study, we evaluated whether social isolation in the prepubertal period and chronic use of high-fat diet (HFD) may induce depressive-like behavior in male adult rats. We also investigated hippocampal plasticity markers and neurotransmitter systems. We found both social isolation and HFD induced a depressive-like behavior in the forced swimming task. Moreover, chronic HFD reduced synaptic markers in hippocampus, demonstrated by reductions in ßIII-tubulin (neuronal marker), PSD-95, SNAP-25, and neurotrophin-3. The HFD group also presented decreased glutamatergic and GABAergic receptors subunits. On the other hand, stress affected hippocampal brain-derived neurotrophic factor (BDNF) signaling pathways, and increased expression of subunit of the NMDA receptor (NR2A). Both factors (stress and diet) decreased GR in the hippocampus without affecting plasma corticosterone at basal levels. Interactions between early stress and HFD access were observed only in the BNDF receptor (tropomyosin receptor kinase B; TrkB) and synaptophysin. In summary, these findings showed that a brief social isolation and chronic HFD, during a sensitive developmental period, cause depressive-like behavior in adulthood. The mechanisms underlying these behavioral effects may involve changes in the levels of synaptic proteins in hippocampus: HFD consumption appears to affect synaptic markers, while social isolation affected BDNF signaling more significantly.

Short post-weaning social isolation induces long-term changes in the dopaminergic system and increases susceptibility to psychostimulants in female rats.

Childhood and adolescence are sensitive periods of development, marked by high brain maturation and plasticity. Exposure to early life stress, such as social isolation, is able to prompt changes in sensitive brain circuitries, essentially in the mesolimbic dopaminergic system and increase the risk for addictive behaviors later in life. Post-weaning social isolation can stimulate the consumption of rewarding substances, like drugs of abuse and palatable foods. However, most studies analyze long periods of social isolation and very little is known about the effects of a brief social isolation in a sensitive period of development and its association with palatable food on the reward system sensitization. Furthermore, females are more susceptible to the reinforcing effect of drugs than males. Therefore, the aim of this study was to analyze the effects of a short post-weaning social isolation combined with a free access to a chronic high sugar diet (HSD) on the dopaminergic system, oxidative status and behavioral response to an amphetamine-like drug in adulthood. We used female Wistar rats that were socially isolated from post-natal days (PD) 21 to 35 and received free access to a HSD until PD 60. On PD 65, animals were submitted to a challenge with diethylpropion (DEP), an amphetamine-like drug and different responses were analyzed: locomotor activity, immmunocontent of dopamine related proteins, and the oxidative status in the striatum, before and after the DEP challenge. We showed that a short post-weaning social isolation (SI) increased the locomotor response to DEP, when compared with previous saline administration. Social isolation also increased dopamine transporter, tyrosine hydroxylase, and decreased dopamine D2 receptor immunocontent. Additionally, SI increased the overall oxidative status parameters after the challenge with DEP. Interestingly, the exposure to a HSD prevented the SI effects on locomotor response, but did not interfere in the dopaminergic parameters evaluated, despite having modified some oxidative parameters. This study showed for the first time that a short post-weaning social isolation was able to induce long-term changes in the striatal dopaminergic system and increased the response to psychostimulants. These results emphasize the importance of stressful experiences during a short period of development on programming susceptibility to psychostimulants later in life.

Neonatal interventions differently affect maternal care quality and have sexually dimorphic developmental effects on corticosterone secretion.

Neonatal handling (H) and maternal separation (MS) both induce changes in maternal care, but the contribution of these changes to the behavioral and neurochemical outcomes of the offspring remains unclear, as studies often find opposite results concerning the frequency of maternal behaviors, particularly in the MS paradigm. In this study, behavior displayed by H, MS and non-handled (NH) Wistar rat dams were observed during the first 10days after birth. A tentative assessment of the quality of maternal care was made, using a previously reported score that reflects behavior fragmentation and inconsistency. Central oxytocin levels and hippocampal synaptic plasticity markers were also evaluated in dams, immediately after litter weaning. In adulthood, male and female offspring were subjected to a contextual stress-induced corticosterone challenge to provide further information on the impact of early interventions on neuroendocrine parameters. We found that while both H and MS interventions induced an increase in the amount of pup-directed behavior, MS dams displayed a more fragmented and inconsistent pattern of care, reflecting poorer maternal care quality. Interestingly, an increase in oxytocin levels was observed only in H dams. While H offspring did not differ from NH, MS males and females showed marked differences in corticosterone secretion compared to controls. Our results suggest that briefly removing the pups from the nest alters maternal care quantity but not quality and increases central oxytocin, while long separations appear to increase low quality maternal care and change neuroendocrine responses in adult offspring in a sex-specific manner.

Early life adversities or high fat diet intake reduce cognitive function and alter BDNF signaling in adult rats: Interplay of these factors changes these effects.

Environmental factors, like early exposure to stressors or high caloric diets, can alter the early programming of central nervous system, leading to long-term effects on cognitive function, increased vulnerability to cognitive decline and development of psychopathologies later in life. The interaction between these factors and their combined effects on brain structure and function are still not completely understood. In this study, we evaluated long-term effects of social isolation in the prepubertal period, with or without chronic high fat diet access, on memory and on neurochemical markers in the prefrontal cortex of rats. We observed that early social isolation led to impairment in short-term and working memory in adulthood, and to reductions of Na(+),K(+)-ATPase activity and the immunocontent of phospho-AKT, in prefrontal cortex. Chronic exposure to a high fat diet impaired short-term memory (object recognition), and decreased BDNF levels in that same brain area. Remarkably, the association of social isolation with chronic high fat diet rescued the memory impairment on the object recognition test, as well as the changes in BDNF levels, Na(+),K(+)-ATPase activity, MAPK, AKT and phospho-AKT to levels similar to the control-chow group. In summary, these findings showed that a brief social isolation period and access to a high fat diet during a sensitive developmental period might cause memory deficits in adulthood. On the other hand, the interplay between isolation and high fat diet access caused a different brain programming, preventing some of the effects observed when these factors are separately applied.

Neonatal handling causes impulsive behavior and decreased pharmacological response to methylphenidate in male adult wistar rats.

Neonatal handling has an impact on adult behavior of experimental animals and is associated with rapid and increased palatable food ingestion, impaired behavioral flexibility, and fearless behavior to novel environments. These symptoms are characteristic features of impulsive trait, being controlled by the medial prefrontal cortex (mPFC). Impulsive behavior is a key component of many psychiatric disorders such as attention deficit hyperactivity disorder (ADHD), manic behavior, and schizophrenia. Others have reported a methylphenidate (MPH)-induced enhancement of mPFC functioning and improvements in behavioral core symptoms of ADHD patients. The aims of the present study were: (i) to find in vivo evidence for an association between neonatal handling and the development of impulsive behavior in adult Wistar rats and (ii) to test whether neonatal handling could have an impact on monoamine levels in the mPFC and the pharmacological response to MPH in vivo. Therefore, experimental animals (litters) were classified as: "non-handled" and "handled" (10[Formula: see text]min/day, postnatal days 1-10). After puberty, they were exposed to either a larger and delayed or smaller and immediate reward (tolerance to delay of reward task). Acute MPH (3[Formula: see text]mg/Kg. i.p.) was used to suppress and/or regulate impulsive behavior. Our results show that only neonatally handled male adult Wistar rats exhibit impulsive behavior with no significant differences in monoamine levels in the medial prefrontal cortex, together with a decreased response to MPH. On this basis, we postulate that early life interventions may have long-term effects on inhibitory control mechanisms and affect the later response to pharmacological agents during adulthood.

Mitochondrial and Oxidative Stress Aspects in Hippocampus of Rats Submitted to Dietary n-3 Polyunsaturated Fatty Acid Deficiency After Exposure to Early Stress.

Chronic dietary long-chain polyunsaturated fatty acids (PUFAs) deficiency may lead to changes in cortex and hippocampus neuronal membrane phospholipids, and may be linked to impaired central nervous system function. Particularly docosahexaenoic acid deficiency appears to be involved in neuropsychiatric disorders. On the other hand, adverse events early in life may also profoundly affect brain development, leading to long-lasting effects on neurophysiology, neurobiology and behavior. This research assessed if neonatal stress and a dietary n-3 PUFAs deficiency could interact to produce hippocampal alterations related to mitochondrial functions in adult rats. There were no effects of diet, neonatal intervention or interactions on superoxide dismutase or catalase enzymatic activities, mitochondrial membrane potential and respiratory chain complexes. Rats fed n-3 PUFAs deficient diet displayed higher levels of glutathione peroxidase and catalase activity, higher free radicals production and higher thiol content compared to rats fed n-3 PUFAs adequate diet. There were interactions among diets and neonatal stress, since glutathione peroxidase, free radicals production and thiol content were increased in groups that were subjected to neonatal interventions fed n-3 PUFAs deficient diet. Additionally, reduced mitochondrial potential was observed in handled animals. Total thiol revealed a neonatal stress effect, since animals subjected to neonatal interventions displayed lower thiol content. In conclusion, we observed that a chronic treatment with deficient n-3 PUFAs diet, from the puberty period on, increased free radicals production and imbalanced antioxidant enzymes activities, and these increases were higher in animals subjected to neonatal interventions.

Variations in the neonatal environment modulate adult behavioral and brain responses to palatable food withdrawal in adult female rats.

BACKGROUND/OBJECTIVES: Early handling alters adult behavioral responses to palatable food and to its withdrawal following a period of chronic exposure. However, the central mechanisms involved in this phenomenon are not known. Since neonatal handling has persistent effects on stress and anxiety responses, we hypothesized that its involvement in the aforementioned association may be associated with differential neuroadaptations in the amygdala during withdrawal periods. METHODS: Litters were randomized into two groups: handled (H, removed from their dam for 10min per day from the first to the tenth postnatal day and placed in an incubator at 32°C) and non-handled (NH). Experiment 1: on PNDs 80-100, females were assigned to receive palatable food+rat chow for 15 or 30 days, and these two groups were compared in terms of palatable food preference, body weight and abdominal fat deposition. In Experiment 2, H and NH rats were exposed to a chronic diet of palatable food+rat chow for 15 days, followed by (a) no withdrawal, (b) 24h withdrawal from palatable food (receiving only rat chow) or (c) 7-day withdrawal from palatable food (receiving only rat chow). Body weight, 10-min rebound palatable food intake, abdominal fat deposition, serum corticosterone as well as TH and pCREB levels in the amygdala were then compared between groups. RESULTS: Experiment 1-chronic exposure to palatable food induces comparable metabolic effects after 15 and 30 days. Experiment 2-neonatal handling is associated with a peculiar response to palatable food withdrawal following chronic exposure for 15 days. Rats exposed to early handling ingested less of this food after a 24h withdrawal period, and displayed increased amygdala TH and pCREB levels. CONCLUSIONS: Variations in the neonatal environment affect both behavioral responses and amygdala neuroadaptation to acute withdrawal from a palatable diet. These findings contribute to the comprehension of the mechanisms that link early life events and altered feeding behavior and related morbidities such as obesity in adulthood.

How postnatal insults may program development: studies in animal models.

During the postnatal period, the nervous system is modified and shaped by experience, in order to adjust it to the particular environment in which the animal will live. This plasticity, one of the most remarkable characteristics of the nervous system, promotes adaptive changes, but it also makes brain more vulnerable to insults. This chapter will focus on the effects of interventions during the postnatal development in animal models of neonatal handling (usually up to 15 min of handling) and maternal separation (usually at least for 3 h). Sex-specific changes and effects of prepubertal stress such as social isolation later on in life were also considered. These interventions during development induce long-lasting traces in the pups' nervous system, which will be reflected in changes in neuroendocrine functions, including the hypothalamus-pituitary-adrenal and hypothalamus-pituitary-gonadal axes; anxiety and cognitive performance; and feeding, sexual, and social behavior. These enduring changes may be adaptive or maladaptive, depending on the environment in which the animal will live. The challenge researchers facing now is to determine how to reverse the deleterious effects that may result from early-life stress exposure.

Resveratrol treatment has neuroprotective effects and prevents cognitive impairment after chronic cerebral hypoperfusion.

OBJECTIVE: The present study investigated the neuroprotective effects of Resveratrol (RSV) in rats submitted to chronic cerebral hypoperfusion (CCH) in a model of permanent two-vessel occlusion (2VO). METHODS: For this purpose, adult Wistar rats received daily i.p. injections of RSV (20 mg/kg) for 7 days, starting 1 hour after the 2VO procedure. Behavioral testing was run between the 30th and 45th days after the 2VO surgery. Accordingly, spatial working memory function in the Morris water maze was evaluated. At the end of the behavioral assessment (45th day post-surgery) part of experimental animals underwent transcardiac perfusion for histological analysis. Another group was euthanized on the 3rd, 14th, and 45th days post-surgery for nerve growth factor (NGF) evaluation. RESULTS: Resveratrol treatment along 7 days after CCH significantly attenuated pyramidal cell death in the CA1 hippocampal subfield and prevented both spatial working and reference memory impairments. Our results revealed an enhancement of NGF expression 3 days after CCH in all ischemic animals. A late increase in hippocampal NGF levels was detected after 45 days only in CCH-RSV treated animals. CONCLUSIONS: Results presented here show morphological and functional neuroprotective actions of RSV treatment for CCH, as well as support the inducing effects of RSV on the expression of NGF and its possible association to the neuroprotective action in this rodent model of vascular dementia.