Short periods of prenatal stress affect growth, behaviour and hypothalamo–pituitary–adrenal axis activity in male guinea pig offspring

Prenatal stress can have profound long-term influences on physiological function throughout the course of life. We hypothesized that focused periods of moderate prenatal stress at discrete time points in late gestation have differential effects on hypothalamo–pituitary–adrenal (HPA) axis function in adult guinea pig offspring, and that changes in HPA axis function will be associated with modification of anxiety-related behaviour. Pregnant guinea pigs were exposed to a strobe light for 2 h on gestational days (GD) 50, 51, 52 (PS50) or 60, 61, 62 (PS60) (gestation length ∼70 days). A control group was left undisturbed throughout pregnancy. Behaviour was assessed in male offspring on postnatal day (PND)25 and PND70 by measurement of ambulatory activity and thigmotaxis (wall-seeking behaviour) in a novel open field environment. Subsequent to behavioural testing, male offspring were cannulated (PND75) to evaluate basal and activated HPA axis function. Body weight was significantly decreased in adult PS50 and PS60 offspring and this effect was apparent soon after weaning. The brain-to-body-weight ratio was significantly increased in adult PS50 males. Basal plasma cortisol levels were elevated in PS50 male offspring throughout the 24 h sampling period compared with controls. In response to an ACTH challenge and to exposure to an acute stressor, PS60 male offspring exhibited elevated plasma cortisol responses. Plasma testosterone concentrations were strikingly decreased in PS50 offspring. Thigmotaxis in the novel environment was increased in PS50 male offspring at PND25 and PND70, suggesting increased anxiety in these animals. In conclusion, prenatal stress during critical windows of neuroendocrine development programs growth, HPA axis function, and stress-related behaviour in adult male guinea pig offspring. Further, the nature of the effect is dependant on the timing of the maternal stress during pregnancy.     

Alterations induced by gestational stress in brain morphology and behaviour of the offspring.

Retrospective studies in humans suggest that chronic maternal stress during pregnancy, associated with raised plasma levels of CRH, ACTH and cortisol may increase the likelihood of preterm birth, developmental delays and behavioural abnormalities in the children. In adulthood, it may contribute to the significant association between the incidence of schizophrenia, increased left or mixed handedness, reduction in cerebral asymmetry and anomalies in brain morphology. Our studies and others have shown that prenatal stress in rats can mimic these developmental and behavioural alterations. These rats show a reduced propensity for social interaction, increased anxiety in intimidating or novel situations and a reduction in cerebral asymmetry and dopamine turnover, consistent with those in schizophrenic humans. Prenatally-stressed (PS) rats also show behaviour consistent with depression, including a phase-shift in their circadian rhythm for corticosterone, sleep abnormalities, a hedonic deficit and greater acquisition of learned helplessness under appropriate conditions. These behavioural abnormalities are associated with impaired regulation of the hypothalamic-pituitary-adrenal axis response to stress and increased CRH activity. PS males may show demasculinisation and feminisation of their sexual behaviour. The developmental and behavioural abnormalities in PS offspring could occur through sensitisation of the foetal brain by maternal stress hormones to the action of glucocorticoid and CRH and to neurotransmitters affected by them. This may have long-lasting consequences and could explain the precipitation of depressive symptoms or schizophrenia by psychosocial stress in later life. The character of the behavioural abnormalities probably depends on the timing of the maternal stress in relation to development of the particular neuronal systems.     

Variations in the postnatal maternal environment in mice: effects on maternal behaviour and behavioural and endocrine responses in the adult offspring

According to the maternal mediation hypothesis, brain and behavioural development in rodents is affected by environment-dependent variations in maternal care. Thus, it has been shown that early handling results in reduced behavioural and neuroendocrine responses to stressors and that these effects are associated with increased maternal care received during infancy. To investigate this further in mice, we chose a less artificial paradigm that is not confounded by human manipulation and reflects a more natural form of early environmental variation. We housed lactating C57BL/6 dams and their litters in cage systems composed of a nest cage (NC) and a foraging cage (FC) connected by a tunnel, and varied the dams' access to food by providing food either in the NC (NC dams) or FC (FC dams) until postnatal day 14. FC dams were more frequently observed in the FC than NC dams, and although the frequency of the dams being in physical contact with the pups did not differ between the two treatments, FC dams showed lower levels of active nursing than NC dams during the first week of lactation. These environment-dependent variations in maternal behaviour had sex-specific effects on the adult offspring's behavioural and HPA responses to stressors and altered their social behaviour in the home cage, with NC offspring showing higher levels of socio-positive behaviours than FC offspring. These results provide further independent evidence for the maternal mediation hypothesis and demonstrate that even subtle variations of the maternal environment can affect maternal care and induce persistent changes in offspring phenotype.     

Fetal programming of autonomic and HPA function: do people who were small babies have enhanced stress responses?

Studies in several species have demonstrated that an adverse early environment can influence the development of the autonomic nervous system and hypothalamic–pituitary–adrenal (HPA) axis. The autonomic nervous system and HPA axis are key components of the neuroendocrine response to stress and many of these animal models show altered biological responses to stress. Recent research now suggests that these processes operate in humans. An adverse early environment, as evidenced by reduced birth or infant weight, is associated with enhanced autonomic and HPA responses to experimental psychological stress. However, there appear to be marked sex differences in the mechanisms involved. Epidemiological studies demonstrate that physiological changes in these neuroendocrine systems may predispose to cardiovascular disease through their influence on risk factors such as plasma glucose and lipid concentrations and blood pressure. Thus the combination of enhanced stress susceptibility and the psychosocial stressors to which people are exposed may be an important component of the disease risk in human populations.     

Effects of maternal prenatal stress on offspring development: a commentary

Pregnancy is associated with major physiological changes and adaptation to these changes is crucial for normal fetal development. Heightened emotional stress during pregnancy may interfere with the necessary adaptation and lead to dysregulation of the two major stress response systems: the Hypothalamic-Pituitary-Adrenal (HPA) Axis and the Autonomic Nervous System (ANS). Negative effects on the fetus of such maladaptation have been documented in both animals and humans and range from poor birth outcomes to negative impacts on neurodevelopment, as well as long term emotional and behavioural disturbances. Conversely, it has been hypothesized that low levels of maternal prenatal stress may actually have an adaptive value for the offspring. Investigation of these associations employing physiological markers and repeated measures throughout pregnancy and postpartum of both the mother and the offspring, is required in order to understand the various effects of prenatal stress on the development of the offspring. It is also crucial to explore the possibility of variable periods of vulnerability throughout gestation. The aim of this commentary is to reexamine the current literature on the ill-effects of maternal stress during pregnancy on the offspring and to explore avenues for future treatment and prevention.     

Effects of rat odour and shelter on maternal behaviour in C57BL/6 dams and on fear and stress responses in their adult offspring

Recent studies in rats and mice suggest that developmental plasticity of HPA-stress and fear responses could be mediated by environment-dependent variations in maternal behaviour. The present study was designed to examine this question further by varying the adversity of the maternal environment to study its effects on nest-attendance and maternal care and on the HPA and fear responses in the adult offspring. C57BL/6 dams and their litter were housed in a cage system composed of a nest cage (NC) and a foraging cage (FC) connected by a tunnel. Using a 2 x 2 factorial design, we varied the maternal foraging environment (FC) by the presence or absence of rat odour (feces) and shelters (MouseHouse and tube) from postnatal days 1-14 and assessed the adult offspring's corticosterone response to isolation/novelty stress and their behaviour in three tests of fearfulness (elevated-O-maze, open-field, free exploration). While the presence of shelters in the FC reduced time spent in the NC (nest site attendance), the presence of rat odour in the FC increased active maternal care without altering nest site attendance. Alterations of the offspring's HPA and fear responses were rather subtle. The presence of shelters in the dam's foraging environment decreased fearfulness in the offspring in the free exploration test. In addition, males reared by dams exposed to rat odour were less fearful in the open-field test, and both males and females reared by dams without shelters and rat odour in the FC showed a greater corticosterone response to isolation/novelty stress. Multiple regression analysis indicated a negative relationship between maternal licking/grooming and fearfulness in males and a positive relationship between nest site attendance and fearfulness in females. Taken together, these results indicate that mouse dams adjust specific aspects of maternal behaviour in response to the specific properties of their environment, and that active maternal care and nest site attendance are two aspects of maternal behaviour that may affect the offspring's stress and fear systems independent of each other and in a sex-specific way.     

Long-term consequences of early maternal deprivation in serotonergic activity and HPA function in adult rat

Increasing body of evidence indicates that early life stressful events may induce permanent alterations in neurodevelopment, which in turn, could lead to the development of psychopathologies in adulthood. In particular, maternal deprivation (MD) for 24 h in rats has been associated with several abnormalities in brain and behaviour during adulthood, relevant to the neurobiological substrate of anxiety disorders. The aim of the present study was to clarify the long-term effects of MD, on hypothalamo–pituitary–adrenal (HPA) axis activity and serotonergic (5-HT) function, in adulthood, subjects that have not been yet thoroughly investigated. For this purpose, Wistar rat pups were deprived from their mothers for a 24-h single period at postnatal day 9 (pnd 9) and were examined when aged 69–90 days. Plasma corticosterone and ACTH levels along with the animal's behaviour in an open field were used as indices of stress. Moreover, serotonergic activity was estimated in hypothalamus and hippocampus, key structures in the coordination of neuroendocrine and behavioural responses to stress. Interestingly, in adulthood, MD rats compared to controls, displayed decreased body weight, increased serotonergic activity and “anxiety” related behaviour, as well as elevated plasma corticosterone and ACTH levels. The findings of this study showed that MD results in long-term modifications in HPA axis and serotonergic activity indicating a clear relationship between early life stressful events and the development of anxiety-like disorders later in adulthood.     

Neuroendocrine function and chronic inflammatory stress

The factors regulating susceptibility and severity of autoimmune diseases are poorly understood. That neuroendocrine factors are critical modulators in this regard is self-evident. For example, there are major gender differences in susceptibility with women at greater risk than men of, for example, rheumatoid arthritis (RA) and multiple sclerosis (MS). The hypothalamo-pituitary-adrenal (HPA) axis has rightly attracted a considerable amount of attention. Of particular interest has been the hypothesis that susceptibility to autoimmune disease may be related to an impaired responsiveness of the HPA axis; that is, an inability to mount an appropriate cortisol response with which to down-regulate the immune system might allow the immune system to rampage unchecked and attack self. This hypothesis links regulation of the release from the adrenal gland of the potent anti-inflammatory glucocorticoids to the disease process. Endogenous glucocorticoids are crucial for the regulation of the severity of the disease process. The hypothesis proposing a link between a hyporesponsive HPA axis and susceptibility to disease is compelling. However, evidence from a number of sources has suggested that this may not be the entire story and alterations in the activity of the HPA axis have not been consistently observed in patients with RA. This review will concentrate on recent findings concerning the HPA axis in determining susceptibility to, and in regulating the severity of, inflammatory processes in autoimmune disease. These studies have revealed that a single exposure to endotoxin can confer protection to subsequent development of inflammation in an arthritis model in both neonatal and adult rats. Behavioural differences within a single population of rats are associated with differences in the plasma corticosterone responses to stress. However, relative hyporesponsiveness is not reflected by an increase in the severity of inflammation. In humans with RA the dexamethasone-corticotrophin-releasing factor (CRF) test has revealed two distinct sub-populations of patients. Studies in patients with MS have shown that this is not related to depression but rather to the severity of the disease. A better understanding of these complex neuroendocrine interactions may lead to novel clinical interventions.     

产前应激对子代的影响及潜在作用机制

Inappropriate diet and stress in maternal pregnancy may affect the development of the offspring. Brain dysfunction and some chronic diseases such as obesity and diabetes in offspring are associated with the factors during maternal pregnancy. Many researches focused on how prenatal stress affected cognitive function and behavior of the offspring and how nutritional modulation might prevent the pathogenesis of such diseases. Here we summarize the effects of prenatal stress on the offspring and the potential mechanism, like hypothalamus-pituitary-adrenal axis(HPA), oxidative stress, apoptosis and inflammation, and the prevention of nutrient to offspring dysfunction by prenatal stress, based on our previous work and some existing references.     

A spoonful of sugar: feedback signals of energy stores and corticosterone regulate responses to chronic stress

To begin to understand the effects of chronic stress on food intake and energy stores, the effects of increased activity in the hypothalamo-pituitary-adrenal (HPA) axis and glucocorticoids (GCs) on the body and brain must first be understood. We propose two major systems that are both GC sensitive: a metabolic feedback that is inhibitory and a direct central GC drive. Under basal conditions, the metabolic feedback signal to brain is dominant, although infusion of GC into a lateral brain ventricle blocks the effects of the metabolic feedback. Chronic stress activates GC secretion and brain nuclear GC receptor occupancy, markedly changing the normal relationships between these two major corticosteroid-activated systems. The stressor-induced switch in the relative strengths of these signals determines subsequent brain regulation of stress responses (behavioral, neuroendocrine and autonomic outflows). The metabolic feedback effects of GCs are mimicked by voluntary sucrose ingestion in adrenalectomized rats, and experiments suggest that the metabolic feedback also inhibits the stressor-induced direct GC drive on brain. We speculate that the interaction between peripheral and central GC-sensitive signaling systems may be coupled through the inhibitory actions of endogenous opiatergic inputs on corticotropin-releasing factor (CRF) neurons.     

Adrenocortical and behavioural response to chronic restraint stress in neurokinin-1 receptor knockout mice

Brain substance P and its receptor (neurokinin-1, NK1) have a widespread brain distribution and are involved in an important number of behavioural and physiological responses to emotional stimuli. However, the role of NK1 receptors in the consequences of exposure to chronic stress has not been explored. The present study focused on the role of these receptors in the hypothalamic-pituitary-adrenal (HPA) response to daily repeated restraint stress (evaluated by plasma corticosterone levels), as well as on the effect of this procedure on anxiety-like behaviour, spatial learning and memory in the Morris water maze (MWM), a hippocampus-dependent task. Adult null mutant NK1-/- mice, with a C57BL/6J background, and the corresponding wild-type mice showed similar resting corticosterone levels and, also, did not differ in corticosterone response to a first restraint. Nevertheless, adaptation to the repeated stressor was faster in NK1-/- mice. Chronic restraint modestly increased anxiety-like behaviour in the light-dark test, irrespective of genotype. Throughout the days of the MWM trials, NK1-/- mice showed a similar learning rate to that of wild-type mice, but had lower levels of thigmotaxis and showed a better retention in the probe trial. Chronic restraint stress did not affect these variables in either genotype. These results indicate that deletion of the NK1 receptor does not alter behavioural susceptibility to chronic repeated stress in mice, but accelerates adaptation of the HPA axis. In addition, deletion may result in lower levels of thigmotaxis and improved short-term spatial memory, perhaps reflecting a better learning strategy in the MWM.     

Dysregulation of the stress response in asthmatic children

The stress system co-ordinates the adaptive responses of the organism to stressors of any kind. Inappropriate responsiveness may account for increased susceptibility to a variety of disorders, including asthma. Accumulated evidence from animal models suggests that exogenously applied stress enhances airway reactivity and increases allergen-induced airway inflammation. This is in agreement with the clinical observation that stressful life events increase the risk of a new asthma attack. Activation of the hypothalamic–pituitary–adrenal (HPA) axis by specific cytokines increases the release of cortisol, which in turn feeds back and suppresses the immune reaction. Data from animal models suggest that inability to increase glucocorticoid production in response to stress is associated with increased airway inflammation with mechanical dysfunction of the lungs. Recently, a growing body of evidence shows that asthmatic subjects who are not treated with inhaled corticosteroids (ICS) are likely to have an attenuated activity and/or responsiveness of their HPA axis. In line with this concept, most asthmatic children demonstrate improved HPA axis responsiveness on conventional doses of ICS, as their airway inflammation subsides. Few patients may experience further deterioration of adrenal function, a phenomenon which may be genetically determined.     

Prenatal immobilization stress and postnatal maternal separation cause differential neuroendocrine responses to fasting stress in adult male rats

Prenatal immobilization stress (PNS) and postnatal maternal separation (MS180) are two widely used rodent models of early-life stress (ELS) that affect the hypothalamus–pituitary–adrenal (HPA) axis, cause behavioral alterations, and affect glucose tolerance in adults. We compared anxiety-like behavior, coping strategies, and HPA axis activity in PNS and MS180 adult (4-month-old) male rats and assessed their glucose tolerance and HPA axis response after mild fasting stress. Both PNS and MS180 induced a passive coping strategy in the forced swimming test, without affecting anxiety-like behavior in the elevated plus-maze. Moreover, both PNS and MS180 increased the hypothalamic corticotropin-releasing hormone expression; however, only MS180 increased the circulating corticosterone levels. Both early life stressors increased fasting glucose levels and this effect was significantly higher in PNS rats. MS180 rats showed impaired glucose tolerance 120 min after intravenous glucose administration, whereas PNS rats displayed an efficient homeostatic response. Moreover, MS180 rats showed higher circulating corticosteroid levels in response to fasting stress (overnight fasting, 12 hr), which were restored after glucose administration. In conclusion, early exposure to postnatal MS180, unlike PNS, increases the HPA axis response to moderate fasting stress, indicating a differential perception of fasting as a stressor in these two ELS models.     

Stress, eating and the reward system

An increasing number of people report concerns about the amount of stress in their life. At the same time obesity is an escalating health problem worldwide. Evidence is accumulating rapidly that stress related chronic stimulation of the hypothalamic-pituitary-adrenal (HPA) axis and resulting excess glucocorticoid exposure may play a potential role in the development of visceral obesity. Since adequate regulation of energy and food intake under stress is important for survival, it is not surprising that the HPA axis is not only the 'conductor' of an appropriate stress response, but is also tightly intertwined with the endocrine regulation of appetite. Here we attempt to link animal and human literatures to tease apart how different types of psychological stress affect eating. We propose a theoretical model of Reward Based Stress Eating. This model emphasizes the role of cortisol and reward circuitry on motivating calorically dense food intake, and elucidating potential neuroendocrine mediators in the relationship between stress and eating. The addiction literature suggests that the brain reward circuitry may be a key player in stress-induced food intake. Stress as well as palatable food can stimulate endogenous opioid release. In turn, opioid release appears to be part of an organisms' powerful defense mechanism protecting from the detrimental effects of stress by decreasing activity of the HPA axis and thus attenuating the stress response. Repeated stimulation of the reward pathways through either stress induced HPA stimulation, intake of highly palatable food or both, may lead to neurobiological adaptations that promote the compulsive nature of overeating. Cortisol may influence the reward value of food via neuroendocrine/peptide mediators such as leptin, insulin and neuropeptide Y (NPY). Whereas glucocorticoids are antagonized by insulin and leptin acutely, under chronic stress, that finely balanced system is dysregulated, possibly contributing to increased food intake and visceral fat accumulation. While these mechanisms are only starting to be elucidated in humans, it appears the obesity epidemic may be exacerbated by the preponderance of chronic stress, unsuccessful attempts at food restriction, and their independent and possibly synergistic effects on increasing the reward value of highly palatable food.     

Animal models of social stress: effects on behavior and brain neurochemical systems.

Social interactions serve as an evolutionarily important source of stress, and one that is virtually ubiquitous among mammalian species. Animal models of social stress are varied, ranging from a focus on acute, intermittent, or chronic exposure involving agonistic behavior, to social isolation. The relative stressfulness of these experiences may depend on the species, sex, and age of the subjects, and subject sex also appears to influence the value of hypothalamic--pituitary--adrenal (HPA) axis activity as a general criterion for stress response: higher glucocorticoid levels are typically found in dominant females in some species. Social stress models often produce victorious and defeated, or dominant and subordinate, animals that may be compared to each other or to controls, but the appropriateness of specific types of comparisons and the interpretations of their differences may vary for the different models. Social stress strongly impacts behavior, generally reducing aggression and enhancing defensiveness, both inside and outside the stress situation. Social and sexual behaviors may be reduced in subordinate animals, as is activity and responsivity to normally rewarding events. However, some components of these changes may be dependent on the presence of a dominant, rather than representing a longer-term and general alteration in behavior. Social stress effects on brain neurotransmitter systems have been most extensively investigated, and most often found in serotonin and noradrenergic systems, with changes also reported for other monoamine and for peptidergic systems. Morphological changes and alterations of neogenesis and of cell survival particularly involving the hippocampus and dentate gyrus have been reported with severe social stress, as have longer-term changes in HPA axis functioning. These findings indicate that social stress models can provide high magnitude and appropriate stressors for research, but additionally suggest a need for caution in interpretation of the findings of these models and care in analysis of their underlying mechanisms.     

Brain oxytocin: differential inhibition of neuroendocrine stress responses and anxiety-related behaviour in virgin, pregnant and lactating rats

The involvement of brain oxytocin in the attenuated responsiveness of the hypothalamo-pituitary-adrenal axis and the oxytocin systems to external stressors found in pregnant and lactating rats has been studied, including both neuroendocrine and behavioural aspects. Intracerebroventricular infusion of an oxytocin receptor antagonist (0.75 microg/5 microl), but not of vehicle, elevated basal corticotropin and corticosterone secretion into blood of virgin female, but not of late pregnant or lactating rats. Oxytocin antagonist treatment further elevated the stress-induced (exposure to the elevated plus-maze or forced swimming) secretion of both corticotropin and corticosterone, but only in virgin and not in pregnant or lactating rats. Thus, corticotropin and corticosterone plasma concentrations remained attenuated in antagonist-treated pregnant and lactating animals. In contrast, infusion of the oxytocin antagonist significantly elevated the stress-induced secretion of oxytocin into blood in pregnant and lactating, but not in virgin, animals, indicating an autoinhibitory influence of intracerebral oxytocin on neurohypophysial oxytocin secretion induced by non-reproduction-related stimuli. Treatment with oxytocin antagonist 10 min prior to behavioural testing on the elevated plus-maze significantly reduced the anxiety-related behaviour in both pregnant and lactating rats, without exerting similar effects in virgin female rats. The results demonstrate a tonic inhibitory effect of endogenous oxytocin on corticotropin and, consequently, corticosterone secretion in virgin female rats, an effect which is absent in the peripartum period. In contrast, an anxiolytic action of endogenous oxytocin was detectable exclusively in pregnant and lactating rats. Therefore, we conclude that the actions of intracerebral oxytocin include independent effects on the responses of the hypothalamo-pituitary-adrenal axis and oxytocin systems to stressors and the anxiety-related behaviour which are modulated by the reproductive state of the animals.     

Impact of maternal trauma-related psychopathology and life stress on HPA axis stress response

To understand and curb intergenerational transmission of stress-related disorder, it is important to identify how trauma-related psychopathology in mothers impacts their psychophysiological stress regulation, particularly in the context of parenting their infants. In this study we investigated associations between mothers’ trauma-related psychopathology and life stress and HPA axis response to a personally relevant stressor (infant separation stress) in a non-clinical sample followed longitudinally postpartum. A community sample of low-income mothers (n = 73) and their infants completed laboratory sessions at 3, 6, 12, and 18 months postnatal, and salivary cortisol samples collected before and after dyadic stress tasks at the latter three sessions. These tasks were used to assess HPA function. A three-level hierarchical linear model of repeated cortisol measures nested within sessions within mother-infant dyads did not reveal significant main effects of trauma-related psychopathology on maternal cortisol response, but there was evidence that both a clinical interviewer-rated diagnosis of PTSD and ongoing self-reported trauma symptoms blunted effects of life events on cortisol reactivity. Region of significance analyses indicated that current life stress predicted more pronounced cortisol reactivity only among mothers without trauma-related psychopathology; for those with trauma-related psychopathology, life stress did not relate to cortisol response. Effects held when controlling for childhood trauma and previous (prenatal) maternal distress symptoms, suggesting they did not reflect ongoing impacts of past trauma exposure and/or psychopathology. Blunting effects of trauma-related psychopathology on maternal life stress responsiveness may help clarify how stress sensitivities and mental health are transmitted from parent to child.

     

Distress conditions during pregnancy may lead to pre-eclampsia by increasing cortisol levels and altering lymphocyte sensitivity to glucocorticoids

Psychological stress may affect up to 18% of all pregnant women, altering the function of both neuroendocrine and immune systems. Distress conditions may directly change the hypothalamic-pituitary-adrenal (HPA) axis, leading to increased cortisol levels and associated changes in cellular immunity. Psychological events such as high stress levels, anxiety or depression may directly or indirectly affect pregnancy and may thus lead to pre-eclampsia (PE). Here, we suggest that distress conditions during pregnancy may lead the development of PE by enhancing in vivo cortisol levels. High cortisol levels are associated with hypertension and endothelial dysfunction, features often observed in patients with PE. Lymphocytes from patients with high cortisol levels may have a reduced sensitivity to the synthetic glucocorticoid dexamethasone (DEX). Stress-related steroid resistance may disrupt the HPA axis, leading to post-natal detrimental effects such as increased allostatic load, increased pro-inflammatory cytokine levels and even depression in the offspring.     

Impact of aging on stress-responsive neuroendocrine systems

Throughout life organisms are challenged with various physiological and psychological stressors, and the ability to handle these stressors can have profound effects on the overall health of the organism. In mammals, the effects of stressors on the aging process and age-related diseases are complex, involving the nervous, endocrine and immune systems. Certain types of mild stress, such as caloric restriction, may extend lifespan and reduce the risk of diseases, whereas some types of psychosocial stress are clearly detrimental. We now have a basic understanding of the brain regions involved in stress responses, their neuroanatomical connections with neuroendocrine pathways, and the neuropeptides and hormones involved in controlling responses of different organ systems to stress. Not surprisingly, brain regions involved in learning and memory and emotion play prominent roles in stress responses, and monoaminergic and glutamatergic synapses play particularly important roles in transducing stressful sensory inputs into neuroendocrine responses. Among the neuropeptides involved in stress responses, corticotropin-releasing hormone appears to be a pivotal regulator of fear and anxiety responses. This neuropeptide is responsible for activation of the hypothalamic-pituitary-adrenal (HPA) axis, which is critical for mobilizing energy reserves and immune responses, and improper regulation of the HPA axis mediates many of the adverse effects of chronic physical and psychosocial stress. In the brain, for instance, stress may contribute to disease processes by causing imbalances in cellular energy metabolism and ion homeostasis, and by inhibiting neuroprotective signaling pathways. There is considerable evidence that normal aging impacts upon neuroendocrine stress responses, and studies of the molecular and cellular mechanisms underlying the pathogenic actions of mutations that cause age-related neurological disorders, such as Alzheimer's disease, are revealing novel insight into the involvement of perturbed neuroendocrine stress responses in these disorders.