Nutritional aspects modulating brain development and the responses to stress in early neonatal life

Maternal rat prenatal and neonatal treatment with pequi pulp reduces anxiety and lipid peroxidation in brain tissue of rat offspring at adolescence

The Pequi fruit (Caryocar Brasiliense cambess), typical of the Brazilian cerrado or savannah, is a source of essential fatty acids, carotenoids, and phenolic compounds. The aim of this study was to analyze the effects of consuming this fruit on anxiety behavior and lipid peroxidation in the brains of rats whose mothers were treated (by gavage) during pregnancy and lactation with Pequi fruit (pulp or nuts) at 2000 mg/kg of body weight. Anxiety parameters were assessed using the open field (OF), elevated plus maze (EPM), and light/dark box (LDB) tests. The brain was removed to measure malondialdehyde (MDA) levels. Data were analyzed using One-way Anova (p < 0.05). In the OF, the animals in the pulp group presented more time spent in the central area (20.37 ± 0.73 vs Control: 12.51 ± 0.39; Nuts: 8.28 ± 0.40) and increased locomotion (159.7 ± 6.10) compared to the other groups (Control: 127.3 ± 5.54; Nuts: 139.08 ± 6.57). In the EPM, the pulp group entered into the open arms (8.57 ± 0.36) and stayed more time in the central area (19.44 ± 1.17) compared to the Nuts group (7.14 ± 0.34; 13.00 ± 1.57). In the LDB the pulp group entered more (8.00 ± 0.42 vs Control: 7.16 ± 0.16 and Nuts: 7.42 ± 0.75) and stayed longer in the clear light side (92.18 ± 6.42) than all the other groups (Control: 71.44 ± 3.53; Nuts: 80.57 ± 6.50), respectively. Pulp group presented lower MDA in the brain (55.34 ± 3.04) compared to Control (72.06 ± 4.66) and Nuts (66.57 ± 2.45). We conclude that Pequi pulp consumption during pregnancy and lactation reduces lipid peroxidation in brain tissue and induces anxiolytic-like behavior in rat offspring. These effects were not observed in the Pequi nuts group.

Impact of Early Nutrition, Physical Activity and Sleep on the Fetal Programming of Disease in the Pregnancy: A Narrative Review

Early programming is the adaptation process by which nutrition and environmental factors alter development pathways during prenatal growth, inducing changes in postnatal metabolism and diseases. The aim of this narrative review, is evaluating the current knowledge in the scientific literature on the effects of nutrition, environmental factors, physical activity and sleep on development pathways. If in utero adaptations were incorrect, this would cause a mismatch between prenatal programming and adulthood. Adequate caloric intake, protein, mineral, vitamin, and long-chain fatty acids, have been noted for their relevance in the offspring brain functions and behavior. Fetus undernutrition/malnutrition causes a delay in growth and have detrimental effects on the development and subsequent functioning of the organs. Pregnancy is a particularly vulnerable period for the development of food preferences and for modifications in the emotional response. Maternal obesity increases the risk of developing perinatal complications and delivery by cesarean section and has long-term implications in the development of metabolic diseases. Physical exercise during pregnancy contributes to overall improved health post-partum. It is also interesting to highlight the relevance of sleep problems during pregnancy, which influence adequate growth and fetal development. Taking into account these considerations, we conclude that nutrition and metabolic factors during early life play a key role of health promotion and public health nutrition programs worldwide to improve the health of the offspring and the health costs of hospitalization.

Repeated exposure to sucrose for procedural pain in mouse pups leads to long-term widespread brain alterations

Oral sucrose is administered routinely to reduce pain of minor procedures in premature infants and is recommended as standard care in international guidelines. No human or animal studies on effects of early repeated sucrose exposure on long-term brain development have been done in the context of pain. We evaluated the effects of repeated neonatal sucrose treatment before an intervention on long-term brain structure in mouse pups. Neonatal C57Bl/6J mice (n = 109) were randomly assigned to one of 2 treatments (vehicle vs sucrose) and one of 3 interventions (handling, touch, or needle-prick). Mice received 10 interventions daily from postnatal day 1 to 6 (P1-6). A dose of vehicle or 24% sucrose was given orally 2 minutes before each intervention. At P85-95, brains were scanned using a multichannel 7.0 T MRI. Volumes of 159 independent brain regions were obtained. Early repetitive sucrose exposure in mice (after correcting for whole brain volume and multiple comparisons) lead to smaller white matter volumes in the corpus callosum, stria terminalis, and fimbria (P < 0.0001). Cortical and subcortical gray matter was also affected by sucrose with smaller volumes of hippocampus and cerebellum (P < 0.0001). These significant changes in adult brain were found irrespective of the type of intervention in the neonatal period. This study provides the first evidence of long-term adverse effects of repetitive sucrose exposure and raises concerns for the use of this standard pain management practice during a period of rapid brain development in very preterm infants.

Nutritional Supplement of Hatchery Eggshell Membrane Improves Poultry Performance and Provides Resistance against Endotoxin Stress

Eggshells are significant part of hatchery waste which consist of calcium carbonate crust, membranes, and proteins and peptides of embryonic origins along with other entrapped contaminants including microbes. We hypothesized that using this product as a nutritional additive in poultry diet may confer better immunity to the chickens in the paradigm of mammalian milk that enhances immunity. Therefore, we investigated the effect of hatchery eggshell membranes (HESM) as a short term feed supplement on growth performance and immunity of chickens under bacterial lipopolysaccharide (LPS) challenged condition. Three studies were conducted to find the effect of HESM supplement on post hatch chickens. In the first study, the chickens were fed either a control diet or diets containing 0.5% whey protein or HESM as supplement and evaluated at 5 weeks of age using growth, hematology, clinical chemistry, plasma immunoglobulins, and corticosterone as variables. The second and third studies were done to compare the effects of LPS on control and HESM fed birds at 5 weeks of age following at 4 and 24 h of treatment where the HESM was also sterilized with ethanol to deplete bacterial factors. HESM supplement caused weight gain in 2 experiments and decreased blood corticosterone concentrations. While LPS caused a significant loss in body weight at 24 h following its administration, the HESM supplemented birds showed significantly less body weight loss compared with the control fed birds. The WBC, heterophil/lymphocyte ratio, and the levels of IgG were low in chickens fed diets with HESM supplement compared with control diet group. LPS challenge increased the expression of pro-inflammatory cytokine gene IL-6 but the HESM fed birds showed its effect curtailed, also, which also, favored the up-regulation of anti-inflammatory genes compared with control diet fed chickens. Post hatch supplementation of HESM appears to improve performance, modulate immunity, and increase resistance of chickens to endotoxin.

Dairy fat blend improves brain DHA and neuroplasticity and regulates corticosterone in mice

Mimicking the breast milk lipid composition appears to be necessary for infant formula to cover the brain's needs in n-3 PUFA. In this study, we evaluated the impact of partial replacement of vegetable oil (VL) in infant formula by dairy fat (DL) on docosahexaenoic acid (DHA) brain level, neuroplasticity and corticosterone in mice. Mice were fed with balanced VL or balanced DL diets enriched or not in DHA and arachidonic acid (ARA) from the first day of gestation. Brain DHA level, microglia number, neurogenesis, corticosterone and glucocorticoid receptor expression were measured in the offsprings. DL diet increased DHA and neuroplasticity in the brain of mice at postnatal day (PND) 14 and at adulthood compared to VL. At PND14, ARA and DHA supplementation increased DHA in VL but not in DL mice brain. Importantly, DHA and ARA supplementation further improved neurogenesis and decreased corticosterone level in DL mice at adulthood. In conclusion, dairy lipids improve brain DHA level and neuroplasticity.

Modulation of prenatal stress via docosahexaenoic acid supplementation: implications for child mental health

Pregnant women living in poverty experience chronic and acute stressors that may lead to alterations in circulating glucocorticoids. Experimental evidence from animal models and correlational studies in humans support the hypothesis that prenatal exposure to high levels of glucocorticoids can negatively affect the developing fetus and later emotional and behavioral regulation in the offspring. In this integrative review, recent findings from research in psychiatry, obstetrics, and animal and human experimental studies on the role of docosahexaenoic acid in modulation of the stress response and brain development are discussed. The potential for an emerging field of nutritionally based perinatal preventive interventions for improving offspring mental health is described. Prenatal nutritional interventions may prove to be effective approaches to reducing common childhood mental disorders.

Early-life adversity programs emotional functions and the neuroendocrine stress system: the contribution of nutrition, metabolic hormones and epigenetic mechanisms

Clinical and pre-clinical studies have shown that early-life adversities, such as abuse or neglect, can increase the vulnerability to develop psychopathologies and cognitive decline later in life. Remarkably, the lasting consequences of stress during this sensitive period on the hypothalamic-pituitary-adrenal axis and emotional function closely resemble the long-term effects of early malnutrition and suggest a possible common pathway mediating these effects. During early-life, brain development is affected by both exogenous factors, like nutrition and maternal care as well as by endogenous modulators including stress hormones. These elements, while mostly considered for their independent actions, clearly do not act alone but rather in a synergistic manner. In order to better understand how the programming by early-life stress takes place, it is important to gain further insight into the exact interplay of these key elements, the possible common pathways as well as the underlying molecular mechanisms that mediate their effects. We here review evidence that exposure to both early-life stress and early-life under-/malnutrition similarly lead to life-long alterations on the neuroendocrine stress system and modify emotional functions. We further discuss how the different key elements of the early-life environment interact and affect one another and next suggest a possible role for the early-life adversity induced alterations in metabolic hormones and nutrient availability in shaping later stress responses and emotional function throughout life, possibly via epigenetic mechanisms. Such knowledge will help to develop intervention strategies, which gives the advantage of viewing the synergistic action of a more complete set of changes induced by early-life adversity.

Early repetitive pain in preterm infants in relation to the developing brain

Infants born preterm (<37 weeks of gestation) are particularly vulnerable to procedural stress and pain exposure during neonatal intensive care, at a time of rapid and complex brain development. Concerns regarding effects of neonatal pain on brain development have long been expressed. However, empirical evidence of adverse associations is relatively recent. Thus, many questions remain to be answered. This review discusses the short- and long-term effects of pain-related stress and associated treatments on brain maturation and neurodevelopmental outcomes in children born preterm. The current state of the evidence is presented and future research directions are proposed.

Neuroimaging, a new tool for investigating the effects of early diet on cognitive and brain development

Nutrition is crucial to the initial development of the central nervous system (CNS), and then to its maintenance, because both depend on dietary intake to supply the elements required to develop and fuel the system. Diet in early life is often seen in the context of "programming" where a stimulus occurring during a vulnerable period can have long-lasting or even lifetime effects on some aspect of the organism's structure or function. Nutrition was first shown to be a programming stimulus for growth, and then for cognitive behavior, in animal studies that were able to employ methods that allowed the demonstration of neural effects of early nutrition. Such research raised the question of whether nutrition could also programme cognition/brain structure in humans. Initial studies of cognitive effects were observational, usually conducted in developing countries where the presence of confounding factors made it difficult to interpret the role of nutrition in the cognitive deficits that were seen. Attributing causality to nutrition required randomized controlled trials (RCTs) and these, often in developed countries, started to appear around 30 years ago. Most demonstrated convincingly that early nutrition could affect subsequent cognition. Until the advent of neuroimaging techniques that allowed in vivo examination of the brain, however, we could determine very little about the neural effects of early diet in humans. The combination of well-designed trials with neuroimaging tools means that we are now able to pose and answer questions that would have seemed impossible only recently. This review discusses various neuroimaging methods that are suitable for use in nutrition studies, while pointing out some of the limitations that they may have. The existing literature is small, but examples of studies that have used these methods are presented. Finally, some considerations that have arisen from previous studies, as well as suggestions for future research, are discussed.

Poor nutrition during pregnancy and lactation negatively affects neurodevelopment of the offspring: evidence from a translational primate model

BACKGROUND

Studies of the effects of prenatal nutrition on neurodevelopment in humans are complicated because poor nutrition occurs in the context of psychosocial stressors and other risk factors associated with poor developmental outcomes.

OBJECTIVE

Under controlled experimental conditions, we tested an effect of prenatal nutrition on neurodevelopmental outcomes in the nonhuman primate.

DESIGN

Juvenile offspring of 19 female baboons, whose diets were either restricted [maternal nutrition restriction (MNR)] or who were fed ad libitum (control), were administered the progressive ratio task from the Cambridge Neuropsychological Test Automated Battery. Activity, persistence, attention, and emotional arousal were coded from videotapes. These established, reliable methods were consistent with those used to assess individual differences in the behaviors of school-age children.

RESULTS

MNR offspring (3 female and 4 male offspring) had significantly fewer responses and received fewer reinforcements on the progressive ratio task than did control offspring (8 female and 4 male offspring). MNR offspring showed a more variable activity level and less emotional arousal than did control offspring. Female MNR offspring showed more variable and lower levels of persistence and attention than did female control offspring. Thus, under controlled experimental conditions, data support a main effect of prenatal nutrition on highly translatable neurodevelopmental outcomes.

CONCLUSIONS

Nutritional interventions during pregnancy have been successfully used to target neurodevelopmental problems, such as increasing folic acid intake during pregnancy to decrease the incidence of neural tube defects. Results from the current study can be used to support the testing of nutritional preventive interventions for the most-common childhood behavior problems.

Leptin regulates dopamine responses to sustained stress in humans

Neural systems that identify and respond to salient stimuli are critical for survival in a complex and changing environment. In addition, interindividual differences, including genetic variation and hormonal and metabolic status likely influence the behavioral strategies and neuronal responses to environmental challenges. Here, we examined the relationship between leptin allelic variation and plasma leptin levels with DAD2/3R availability in vivo as measured with [(11)C]raclopride PET at baseline and during a standardized pain stress challenge. Allelic variation in the leptin gene was associated with varying levels of dopamine release in response to the pain stressor, but not with baseline D2/3 receptor availability. Circulating leptin was also positively associated with stress-induced dopamine release. These results show that leptin serves as a regulator of neuronal function in humans and provides an etiological mechanism for differences in dopamine neurotransmission in response to salient stimuli as related to metabolic function. The capacity for leptin to influence stress-induced dopaminergic function is of importance for pathological states where dopamine is thought to play an integral role, such as mood, substance-use disorders, eating disorders, and obesity.

The evolutionary origin and significance of menopause

Contemporary women have long life expectancy (81 y, United States), especially relative to the age at menopause (51 y, United States). Menopause is a consequence of reproductive aging and follicular depletion (ovarian failure), yielding very low circulating estrogen serum concentrations and biologically disadvantageous metabolic alterations. Stated in terms of antagonistic pleiotropy, the ongoing hypoestrogenic endocrine environment, beneficial during lactation, results in acceleration of several age-related illnesses after menopause (ie, late postmenopausal osteoporosis, cardiovascular disease, and cognitive decline). Specifically, the similar hypoestrogenic hormonal milieu present during postpartum lactation provides biologic advantages (fitness) to both mother and newborn. These precepts of evolutionary medicine encourage a reassessment of hormone therapy, and on the basis of data presented the authors propose additional opportunities for disease prevention and morbidity reduction in postmenopausal women.

Gender differences in the long-term effects of chronic prenatal stress on the HPA axis and hypothalamic structure in rats

Stress during pregnancy can impair biological and behavioral responses in the adult offspring and some of these effects are associated with structural changes in specific brain regions. Furthermore, these outcomes can vary according to strain, gender, and type and duration of the maternal stress. Indeed, early stress can induce sexually dimorphic long-term effects on diverse endocrine axes, including subsequent responses to stress. However, whether hypothalamic structural modifications are associated with these endocrine disruptions has not been reported. Thus, we examined the gender differences in the long-term effects of prenatal and adult immobilization stress on the hypothalamic-pituitary-adrenocortical (HPA) axis and the associated changes in hypothalamic structural proteins. Pregnant Wistar rats were subjected to immobilization stress three times daily (45 min each) during the last week of gestation. One half of the offspring were subjected to the same regimen of stress on 10 consecutive days starting at postnatal day (PND) 90. At sacrifice (PND 180), serum corticosterone levels were significantly higher in females compared to males and increased significantly in females subjected to both stresses with no change in males. Prenatal stress increased pituitary ACTH content in males, with no effect in females. Hypothalamic CRH mRNA levels were significantly increased by prenatal stress in females, but decreased in male rats. In females neither stress affected hypothalamic cell death, as determined by cytoplasmic histone-associated DNA fragment levels or proliferation, determined by proliferating cell nuclear antigen levels (PCNA); however, in males there was a significant decrease in cell death in response to prenatal stress and a decrease in PCNA levels with both prenatal and adult stress. In all groups BrdU immunoreactivity colocalized in glial fibrillary acidic protein (GFAP) positive cells, with few BrdU/NeuN labelled cells found. Furthermore, in males the astrocyte marker S100β increased with prenatal stress and decreased with adult stress, suggesting affectation of astrocytes. Synapsin-1 levels were increased by adult stress in females and by prenatal stress in males, while, PSD95 levels were increased in females and decreased in males by both prenatal and adult stress. In conclusion, hypothalamic structural rearrangement appears to be involved in the long-term endocrine outcomes observed after both chronic prenatal and adult stresses. Furthermore, many of these changes are not only different between males and females, but opposite, which could underlie the gender differences in the long-term sequelae of chronic stress, including subsequent responses to stress.

Considerations for using sucrose to reduce procedural pain in preterm infants

Preterm and critically ill newborns admitted to a NICU undergo repeated skin-breaking procedures that are necessary for their survival. Sucrose is rapidly becoming the accepted clinical standard nonpharmacologic intervention for managing acute procedural pain for these infants. Although shown to be safe in single doses, only 4 studies have evaluated the effects of repeated doses of sucrose over relatively short periods of time. None has examined the use of sucrose throughout the NICU stay, and only 1 study evaluated the neurodevelopmental outcomes after repeated doses of sucrose. In that study, infants born at <31 weeks' gestational age and exposed to >10 doses per day in the first week of life were more likely to show poorer attention and motor development in the early months after discharge from the NICU. Results of studies in animal models have suggested that the mechanism of action of sucrose is through opioid pathways; however, in human infants, little has been done to examine the physiologic mechanisms involved, and the findings reported thus far have been ambiguous. Drawing from the growing animal literature of research that has examined the effects of chronic sugar exposure, we describe alternative amine and hormone pathways that are common to the processing of sucrose, attention, and motor development. In addition, a review of the latest research to examine the effects of repeated sucrose on pain processing is presented. These 2 literatures each can inform the other and can provide an impetus to initiate research to examine not only the mechanisms involved in the calming mechanisms of sucrose but also in the long-term neurodevelopmental effects of repeated sucrose in those infants born extremely preterm or critically ill.

Maternal dietary fat determines metabolic profile and the magnitude of endocannabinoid inhibition of the stress response in neonatal rat offspring

Endocannabinoids (eCBs) are products of phospholipid (PL)-derived arachidonic acid (AA) that regulate hypothalamus-pituitary-adrenal axis activity. We hypothesized that differences in the quality and quantity of maternal dietary fat would modulate the PL AA content in the neonatal brain affecting stress responsiveness via differences in eCB production and activity in stress-activated brain areas. Pregnant rats were fed a 5% [control (C)] or 30% fat [high fat (HF)] diet rich in either n-6 (HF-n-6) or n-3 (HF-n-3) fat during the last week of gestation and lactation. Postnatal d 10 offspring were tested for metabolic hormones, AA (n-6) and eCB brain content, and hormonal effects of eCB receptor antagonism (AM251, 1 or 3 mg/kg ip) on stress responses. Like maternal diet, milk from HF-n-3 mothers had a reduced n-6/n-3 fat ratio compared with that of C and HF-n-6 mothers. Hypothalamic and hippocampal levels of PL AA were diet specific, reflecting the maternal milk and dietary n-6/n-3 ratio, with HF-n-3 offspring displaying reduced AA content relative to C and HF-n-6 offspring. Plasma corticosterone and insulin were elevated in HF-fed pups, whereas leptin was increased only in HF-n-6 pups. Basal eCB concentrations were also diet and brain region specific. In C pups, eCB receptor antagonist pretreatment increased stress-induced ACTH secretion, but not in the HF groups. Stress-induced corticosterone secretion was not sensitive to AM251 treatment in HF-n-3 pups. Thus, the nature of preweaning dietary fat differentially influences neonatal metabolic hormones, brain PL AA levels, and eCB, with functional consequences on hypothalamus-pituitary-adrenal axis modulation in developing rat pups.

Administration of human leptin differentially affects parameters of cortisol secretion in socially housed female rhesus monkeys

Chronic exposure to psychosocial stress may lead to a dysregulation of the limbic-hypothalamic-pituitary-adrenal axis that results in a number of adverse health outcomes. The fat-derived hormone leptin has been indicated as a potential key component to maintaining homeostasis by enhancing glucocorticoid negative feedback. Using an established model of nonhuman primate social stress, notably social subordination, this study examined the effects of continuous leptin administration on cortisol secretion in female rhesus monkeys. The 20 subjects were maintained in stable five-member social groups with established dominance hierarchies. All females were ovariectomized but received estradiol throughout the study to maintain serum concentrations at early follicular phase levels. Three parameters of cortisol secretion were examined in dominant and subordinate females during control and leptin-treatment conditions: diurnal cortisol secretion; response to a dexamethasone suppression test; and response to a brief separation from their social group. We hypothesized that leptin supplementation would attenuate the hypercortisolemia characteristic of subordinate females. During baseline conditions, subordinate female rhesus monkeys had significantly lower levels of serum leptin compared with more dominant monkeys and were less sensitive to glucocorticoid negative feedback. Exogenous administration of leptin improved glucocorticoid negative feedback in subordinate females and decreased morning cortisol in all animals. However, there were no status differences in response to a social separation test and diurnal rhythm in cortisol during baseline conditions. However, leptin administration did not attenuate the increase in cortisol in response to a social separation. The data presented in this study demonstrate that leptin can attenuate several parameters of cortisol secretion in female rhesus monkeys and thus may play a role in the response of the adrenal glands to socio-environmental stimuli.

Breastfeeding is an essential complement to vaccination

AIM

This article explores the role of breastfeeding in different aspects of vaccination in the first 6 months when infants are still developing: (1) pain management; (2) immunomodulation of infants' vaccine responses; (3) metabolism of thimerosal.

METHODS

Major databases were searched for studies that addressed outcomes of related issues.

RESULTS

Studies reveal that breastfeeding can: (1) help mothers and infants to cope with the stressful situations that accompany parenteral vaccines; (2) improve response to vaccines in the still maturing immunologic and enterohepatic systems of infants; (3) influence physiologic parameters that can change metabolism of ethylmercury derived from some vaccines.

CONCLUSION

Health promotion that supports vaccinations should also emphasize early initiation and maintenance of exclusive breastfeeding up until 6 months for maximum protection of the infants with a possible beneficial effect on the vaccine response. Paediatric professionals should inform mothers of the proven benefits of breastfeeding and its importance in complementing vaccination and lowering stress and the risk of untoward reactions on susceptible infants.

Effects of prenatal ethanol exposure on hypothalamic-pituitary-adrenal function across the estrous cycle

BACKGROUND

Rats prenatally exposed to ethanol (E) typically show increased hypothalamic-pituitary-adrenal (HPA) responses to stressors in adulthood. Importantly, prenatal ethanol may differentially alter stress responsiveness in male and female offspring, suggesting a role for the gonadal hormones in mediating the effects of ethanol on HPA activity. We investigated the role of ethanol-induced changes in hypothalamic-pituitary-gonadal (HPG) activity in the differential HPA regulation observed in E compared to control females across the estrous cycle.

METHODS

Peripheral hormones and changes in central neuropeptide mRNA levels were measured across the estrous cycle in adult female offspring from E, pair-fed (PF) and ad libitum-fed control (C) dams.

RESULTS

Ethanol females showed normal estrous cyclicity (vaginal smears) but delayed sexual maturation (vaginal opening). Both HPG and HPA activity were differentially altered in E (and in some cases, PF) compared to control females as a function of estrous cycle stage. In relation to HPG activity, E and PF females had higher basal and stress estradiol (E(2)) levels in proestrus compared to other phases of the cycle, and decreased GnRH mRNA levels compared to C females in diestrus. Further, E females had greater variation in LH than PF and C females across the cycle, and in proestrus, only E females showed a significant LH increase following stress. In relation to HPA activity, both basal and stress CORT levels and overall ACTH levels were greater in E than in C females in proestrus. Furthermore, AVP mRNA levels were increased overall in E compared to PF and C females.

CONCLUSIONS

These data demonstrate ethanol-induced changes in both HPG and HPA activity that are estrous phase-specific, and support the possibility that changes in HPA activity in E females may reflect differential sensitivity to ovarian steroids. E females appear to have an increased HPA sensitivity to E(2), and a possible shift toward AVP regulation of HPA activity. That PF were similar to E females on some measures suggests that nutritional effects of diet or food restriction played a role in mediating at least some of the changes observed.

Perinatal maternal fat intake affects metabolism and hippocampal function in the offspring: a potential role for leptin

Both undernutrition and overnutrition of the mother during pregnancy and lactation produce a syndrome of altered energy balance in the offspring and has long-lasting consequences on CNS systems regulating food intake, metabolism, and food reward. Homeostatic circulating factors like insulin, glucocorticoids, and leptin that are generally increased by exposure to high fat/high caloric diets constitute important signals in these processes. They trigger functional activation of specific intracellular cascades mediating cellular sensitivity, survival, and synaptic plasticity. Using a model whereby the late fetal and neonatal rat is exposed to increased high fat (HF) via HF feeding of the mother, we investigated the proximal (neonatal) and distal (adult) consequences on metabolism and hippocampal function in the offspring. Adult offspring of HF-fed mothers displayed several of the physiological and behavioral changes susceptible to leading to metabolic complications. These include elevated circulating concentrations of leptin and corticosterone, increased body weight gain and food intake, modest preference for fat-containing food types, as well as the onset of hypothalamic leptin resistance. In the hippocampus, HF-fed offspring or neonates treated with leptin show similar increases in neurogenesis and survival of newborn neurons. We identified some of the direct effects of leptin to increase synaptic proteins, N-methyl-d-aspartate (NMDA), and glucocorticoid receptors, and to reduce long-term potentiation (LTP) prior to weaning. While these studies have documented effects in animal models, concepts can easily be translated to human nutrition in order to help design better perinatal diets and nutritional preventive measures for mothers in a coordinated effort to curb the obesity trend.

Predation threat exerts specific effects on rat maternal behaviour and anxiety-related behaviour of male and female offspring

Differences in the rate of maternal behaviours received by rodent offspring are associated with differential programming of molecular and behavioural components of anxiety and stress-related functions. To determine the degree to which maternal behaviours are sensitive to environmental conditions, Long-Evans rat dams were exposed to the odour of a predator (cat) at two different time points during the first week postpartum. Exposure on the day of birth (DOB), but not the third day following birth, increased levels of maternal care in predator-exposed dams relative to dams exposed to a control condition across the first 5 days post-partum. As adults, female offspring of dams exposed on DOB exhibited a less-anxious phenotype in a novel open-field, spending more time in the center and less time displaying thigmotaxis. In contrast, under the same conditions, male offspring showed the opposite behavioural response, consistent with an increasingly anxious phenotype. Results from a subsequent stressor test (response to a predator odour) were consistent with the notion that the rearing effects were specific to anxiety-related behaviours in offspring. Accordingly, we showed that rearing conditions did not affect GR mRNA or NGFI-A expression in the hippocampus of offspring or cross-fostered offspring. The dissociation between stress and anxiety, as well as the sex-specific alterations in behaviour, may reflect the specificity inherent to neural programming in the face of naturalistic early life conditions.

The role of polyunsaturated fatty acids (PUFAs) in development, aging and substance abuse disorders: review and propositions

The polyunsaturated fatty acids (PUFAs), especially omega-3 and -6, play an important role in the functioning of membranes. Therefore, changes in their physical properties might entail impairment of the neurotransmission between cells. Studies emphasize the importance of omega-3 intakes, but they also highlight the need of a balance between omega-6 and -3, whose ideal ratio should be 4:1. The Western diet has very high amounts of saturated fat and omega-6, which might contribute, at least partially, to physiopathologies and high incidence as well as prevalence of psychiatric and neurodegenerative diseases. This narrow review aimed at systematizing the studies on the importance of PUFAs in some particular cases, that is, the extremes of life: pre- and post-natal development, and cognitive aging. Additionally, it aimed at studying the association between PUFAs and substance abuse disorders. We used the databases LILACs, MEDLINE and PUBMED.

Sex and diet affect the behavioral response of rats to chronic mild stressors

To investigate the interaction between sex, stressors, and dietary choice in rats, a preferred diet under the influence of chronic mild stressors was empirically determined to consist of soybeans and cookies in addition to lab chow. This preferred mixed diet was then tested for its influence on several behavioral tests at the end of prolonged exposure to the potential stressors. Rats of both sexes decreased their frequency of rearing but increased their attention to novelty in response to stressors. In the elevated plus maze, diet interacted with exposure to stressors to influence time spent in the open arm in females but not males. In the forced swim test, females but not males fed the mixed diet showed increased immobility, whether exposed to stressors or not. Finally, females but not males showed a differential effect of diet under stressors on the sucrose preference test, but this result was confounded by estrus cycling, demonstrating the importance of this factor in analyzing behavior in females. These results suggest that male and female rats differ in their susceptibility to the behavioral-modifying influences of stressors. And to the extent that diet serves as a coping mechanism, it does so differently in males and females.

Determinants of early life leptin levels and later life degenerative outcomes

The early (intrauterine and neonatal) life environment plays an important role in programming the susceptibility in later life to chronic degenerative diseases, such as obesity, cardiovascular diseases, diabetes mellitus, cancer and osteoporosis. Among other hormones, leptin plays a major role in the regulation of the overall metabolism and has multiple neuroendocrine (adeno- and neuro-hypophysis axes and the hypothalamus-pituitary-adrenal axis) and immune functions. The hormone exerts its actions beginning in the early life time period, regulating the intrauterine and early extrauterine life growth and development, as well as the adaptation to extrauterine life, neonatal thermogenesis and response to stress. Recent findings also support a role of leptin in the process of fetal bone remodeling and brain development. Therefore, it is of interest to explore the physiology of leptin in early life, as well as those factors that may perturb the balance of the hormone with pathological consequences in terms of confining an increased risk for disease in later life. This review aims to summarize reported findings concerning the role of leptin in early life, as well as the association of fetal, maternal and placental factors with leptin levels, while attempting to speculate mechanisms through which these factors may influence the risk for developing chronic diseases in later life.