Early environmental enrichment prevents cognitive impairments and developing addictive behaviours in a mouse model of prenatal psychological and physical stress

Environmental enrichment (EE) has shown remarkable effects in improving cognition and addictive behaviour. We tested whether EE could help recover from prenatal stress exposure. Mature Swiss Webster male and virgin female mice were placed together until vaginal plugs were detectable. Next, pregnant rodents were randomized into the control, physically and psychologically stressed groups. The application of stress was initiated on the 10th day of pregnancy and persisted for a week to induce stress in the mice. Open field and elevated plus-maze (EPM) tests were utilized as explorative and anxiety assays, respectively. A passive avoidance shuttle-box test was carried out to check anxiety-modulated behaviour. Morris water maze (MWM) test was undertaken to evaluate spatial learning and memory. Conditioned place preference (CPP) test was selected for evaluation of tendency to morphine consumption. Our results showed that prenatal stress elevated anxiety-like behaviour in the offspring which EE could significantly alleviate after weaning. We also found a higher preference for morphine use in the physical stress and psychological stress offspring group. However, no difference was observed among the genders. Application of EE for the stress group improved several parameters of the cognitive behaviour significantly. Although prenatal stress can lead to detrimental behavioural and cognitive outcomes, it can in part be relieved by early exposure to EE. However, some outcomes linked to prenatal stress exposure may not be diminished by EE therapy. In light of such irreversible effects, large-scale preventive actions promoting avoidance from stress during pregnancy should be advised.

Developmental Origins of Stress and Psychiatric Disorders

Over the last few decades, evidence has emerged that the pathogenesis of psychiatric disorders such as schizophrenia can involve perturbations of the hypothalamic-pituitary-adrenal (HPA) axis and other neuroendocrine systems. Variations in the manifestation of these effects could be related to differences in clinical symptoms between affected individuals and to differences in treatment response. Such effects can also arise from the complex interaction between genes and environmental factors. Here, we review the effects of maternal stress on abnormalities in HPA axis regulation and the development of psychiatric disorders such as schizophrenia. Studies in this area may prove critical for increasing our understanding of the multidimensional nature of mental disorders and could lead to the development of improved diagnostics and novel therapeutic approaches for treating individuals who suffer from these conditions.

Models of stress in nonhuman primates and their relevance for human psychopathology and endocrine dysfunction

Stressful life events have been linked to the onset of severe psychopathology and endocrine dysfunction in many patients. Moreover, vulnerability to the later development of such disorders can be increased by stress or adversity during development (e.g., childhood neglect, abuse, or trauma). This review discusses the methodological features and results of various models of stress in nonhuman primates in the context of their potential relevance for human psychopathology and endocrine dysfunction, particularly mood disorders and dysregulation of the hypothalamic-pituitary-adrenocortical (HPA) system. Such models have typically examined the effects of stress on the animals' behavior, endocrine function (primarily the HPA and hypothalamic-pituitary-gonadal systems), and, in some cases, immune status. Manipulations such as relocation and/or removal of an animal from its current social group or, alternatively, formation of a new social group can have adverse effects on all of these outcome measures that may be either transient or more persistent depending on the species, sex, and other experimental conditions. Social primates may also experience significant stress associated with their rank in the group's dominance hierarchy. Finally, stress during prenatal development or during the early postnatal period may have long-lasting neurobiological and endocrine effects that manifest in an altered ability to cope behaviorally and physiologically with later challenges. Whereas early exposure to severe stress usually results in deficient coping abilities, certain kinds of milder stressors can promote subsequent resilience in the animal. We conclude that studies of stress in nonhuman primates can model many features of stress exposure in human populations and that such studies can play a valuable role in helping to elucidate the mechanisms underlying the role of stress in human psychopathology and endocrine dysfunction.

Os efeitos do estresse na função do eixo hipotalâmico-pituitário-adrenal em indivíduos com esquizofrenia

Nas últimas décadas, têm surgido evidências sugerindo que a patogênese de desordens psiquiátricas, tais como a esquizofrenia, pode envolver perturbações no eixo hipotalâmico-pituitário-adrenal (HPA). Variações na manifestação desses efeitos poderiam estar relacionadas a diferenças em sintomas clínicos entre os indivíduos afetados, assim como a diferenças na resposta ao tratamento. Tais efeitos podem também ser originados de complexas interações entre genes e fatores ambientais. Aqui, revisamos os efeitos do estresse maternal em anormalidades na regulação do eixo HPA e desenvolvimento de desordens psiquiátricas, incluindo a esquizofrenia. Estudos nessa área podem gerar o aumento do nosso entendimento da natureza multidimensional da esquizofrenia. Posterior pesquisa nesse campo poderia, em última instância, levar ao desenvolvimento de melhores diagnósticos e novas abordagens terapêuticas para essa debilitante condição psiquiátrica.

Early-life stress and cognitive outcome

RATIONALE

Early-life stress is associated with later neuropsychiatric illness. While the association between early-life stress and brain development is well recognized, relatively few studies have examined the association between exposure to early-life stress and cognitive outcome.

OBJECTIVES

The objective of this paper is to examine the association between early-life stress and cognitive outcome in animal models and humans.

METHODS

In this article, we review alterations in cognitive function associated with early-life stress in animals and then discuss the association of early-life stress and cognitive function in humans.

RESULTS

Findings suggest that early-life stress is associated with abnormal cognitive function in animals and humans. Furthermore, cognitive deficits associated with exposure to early-life stress in humans may persist into at least early adulthood, although animal models of enriched environments and studies of children adopted from institutionalized care into foster families suggest that certain social factors may at least partially reverse cognitive deficits following exposure to early-life stress.

CONCLUSIONS

Exposure to stress in early life may be associated with later deficits in cognitive function.

Perinatal risk factors in the development of aggression and violence

Over the past several decades, the relative contribution of both environmental and genetic influences in the development of aggression and violence has been explored extensively. Only fairly recently, however, has it become increasingly evident that early perinatal life events may substantially increase the vulnerability toward the development of violent and aggressive behaviors in offspring across the lifespan. Early life risk factors, such as pregnancy and birth complications and intrauterine exposure to environmental toxins, appear to have a profound and enduring impact on the neuroregulatory systems mediating violence and aggression, yet the emergence of later adverse behavioral outcomes appears to be both complex and multidimensional. The present chapter reviews available experimental and clinical findings to provide a framework on perinatal risk factors that are associated with altered developmental trajectories leading to violence and aggression, and also highlights the genetic contributions in the expression of these behaviors.

Prenatal stress and brain development

Prenatal stress (PS) has been linked to abnormal cognitive, behavioral and psychosocial outcomes in both animals and humans. Animal studies have clearly demonstrated PS effects on the offspring's brain, however, while it has been speculated that PS most likely affects the brains of exposed human fetuses as well, no study has to date examined this possibility prospectively using an independent stressor (i.e., a stressful event that the pregnant woman has no control over, such as a natural disaster). The aim of this review is to summarize the existing animal literature by focusing on specific brain regions that have been shown to be affected by PS both macroscopically and microscopically. These regions include the hippocampus, amygdala, corpus callosum, anterior commissure, cerebral cortex, cerebellum and hypothalamus. We first discuss the mechanisms by which the effects of PS might occur. In particular, we show that maternal and fetal hypothalamic-pituitary-adrenal (HPA) axes, and the placenta, are the most likely candidates for these mechanisms. We see that, although animal studies have obvious advantages over human studies, the integration of findings in animals and the transfer of these findings to human populations remains a complex issue. Finally, we show how it is possible to circumvent these challenges by studying the effects of PS on brain development directly in humans, by taking advantage of natural or man-made disasters and assessing the impact and consequences of such stressful events on pregnant women and their offspring prospectively.

Hair cortisol predicts object permanence performance in infant rhesus macaques (Macaca mulatta)

Although high circulating levels of glucocorticoids are associated with impaired cognitive performance in adults, less is known about this relationship in infancy. Furthermore, because studies have relied on acute cortisol measures in blood plasma or saliva, interpretation of the results may be difficult as acute measures may in part reflect emotional responses to testing procedures. In this study we examined whether hair cortisol, an integrated measure of hypothalamic-pituitary-adrenal (HPA) axis functioning, predicted performance of nursery-reared (NR) infant rhesus monkeys (n = 32) on Piagetian object permanence tasks. Testing of NR infants began at 19.8 +/- 2.2 (mean +/- SE) days of age and continued for the next several months. Hair cortisol concentrations from the 32 NR monkeys were compared to those of 20 mother-peer-reared (MPR) infants. Hair was shaved at Day 14, allowed to regrow, and obtained again at month 6, thus representing integrated cortisol over a 5.5-month period of time. NR and MPR infants did not differ in month 6 hair cortisol values (t((50)) = 0.02, p = 0.98). Linear regression revealed that hair cortisol predicted object permanence performance in the NR infants. Infants with higher hair cortisol reached criterion at later ages on the well (p < 0.01), screen (p < 0.05), and A-not-B (p < 0.05) tasks and required more test sessions to complete the well (p < 0.01) and screen tasks (p < 0.05). These data are the first to implicate hair cortisol as a reliable predictor of early cognitive performance in infant macaque monkeys.

Prenatal maternal stress from a natural disaster predicts dermatoglyphic asymmetry in humans

Dermatoglyphic asymmetry of fingertip ridge counts is more frequent in schizophrenia patients than normal controls, and may reflect disruptions in fetal development during Weeks 14–22 when fingerprints develop. However, there are no data in humans linking specific adverse events at specific times to dermatoglyphic asymmetries. Our objective was to determine whether prenatal exposure to a natural disaster (1998 Quebec ice storm) during Weeks 14–22 would result in increased dermatoglyphic asymmetry in children, and to determine the roles of maternal objective stress exposure, subjective stress reaction, and postdisaster cortisol. Ridge counts for homologous fingers were scored for 77 children (20 target exposed [Weeks 14–22] and 57 nontarget exposed [exposed during other gestation weeks]). Children in the target group had more than 0.50 SD greater asymmetry than the nontarget group. Within the target group, children whose mothers had high subjective ice storm stress had significantly greater asymmetry than those with lower stress mothers, and maternal postdisaster cortisol had a significant negative correlation with the children's dermatoglyphic asymmetry (r = −.56). Prenatal maternal stress during the period of fingerprint development results in greater dermatoglyphic asymmetry in their children, especially in the face of greater maternal distress.

Social influences on early developing biological and behavioral systems related to risk for affective disorder

Dramatic changes take place in the neural physiology and emotional behavior of the human infant during the first 2 years of life. Evidence suggests that certain variations in the infant's early social environment, such as disturbances in mother-infant interaction that are associated with maternal depression, influence the development of biological systems related to the expression and regulation of emotion, particularly those systems involved in frontal lobe, autonomic, and adrenocortical functioning. In this essay, we provide an overview of the links between maternal depression and disruptions in early social and emotional development, and we highlight parallels between disturbances in biological systems found in depressed adults and those found in infants of mothers experiencing depression. We then discuss the possibility of sensitive periods for the enduring influences of maternal depression on the emotional development of these children and for increased risk for affective disorder. Finally, we point to directions for further research on the nature of the intergenerational transmission of emotional disturbance.

The long-term behavioural consequences of prenatal stress

Maternal distress during pregnancy increases plasma levels of cortisol and corticotrophin releasing hormone in the mother and foetus. These may contribute to insulin resistance and behaviour disorders in their offspring that include attention and learning deficits, generalized anxiety and depression. The changes in behaviour, with or independent of alterations in the function of the hypothalamic pituitary adrenal (HPA) axis, can be induced by prenatal stress in laboratory rodents and non-human primates. The appearance of such changes depends on the timing of the maternal stress, its intensity and duration, gender of the offspring and is associated with structural changes in the hippocampus, frontal cortex, amygdala and nucleus accumbens. The dysregulation of the HPA axis and behaviour changes can be prevented by maternal adrenalectomy. However, only the increased anxiety and alterations in HPA axis are re-instated by maternal injection of corticosterone.

CONCLUSION

Excess circulating maternal stress hormones alter the programming of foetal neurons, and together with genetic factors, the postnatal environment and quality of maternal attention, determine the behaviour of the offspring.

Effects of maternal prenatal stress on infant outcomes: a synthesis of the literature

There is growing evidence that maternal prenatal stress may be hazardous to infant health. Changes in maternal hormonal and immune function as a result of stress may adversely affect the immune function and neurodevelopment of the fetus. Prenatal stress in the mother may produce lasting effects on the (1) infant's health status, (2) development and function of the infant's immune system, and (3) neurocognitive development of the infant. This article provides a synthesis of current human and animal literature on the effects of maternal prenatal stress on the developing fetus and the infant, with the resulting model evolving out of the framework of psychoneuroimmunology. The intent of the authors is an integrative review. The authors examined the following research question: What effect does maternal prenatal stress have on infants' immune development and neurodevelopment? All relevant studies were reviewed with no exclusion criteria. Major databases (CINAHL, MEDLINE, PsychINFO) were searched using a combination of the following key words: prenatal stress, cytokines, thymus, and infant neurodevelopment.

The effects of prenatal maternal stress on children's cognitive development: Project Ice Storm

There exists considerable research on the effects of prenatal maternal stress on offspring. Animal studies, using random assignment to experimental and control groups, demonstrate the noxious effects of prenatal maternal stress on physical, behavioural and cognitive development. The generalizability of these results to humans is problematic given that cognitive attributions moderate reactions to stressors. In humans, researchers have relied upon maternal anxiety or exposure to life events as proxies for the stressors used with animals. Yet, the associations between maternal anxiety or potentially non-independent life events and problems in infants are confounded by genetic transmission of temperament from mother to child. We summarize the literature on prenatal maternal stress and infant cognitive development, leading to the conclusion that the human literature lacks the ability to separate the effects of the objective exposure to a stressor and the mother's subjective reaction. We then describe our prospective Project Ice Storm in which we are following 150 children who were exposed in utero to a natural disaster. We demonstrate significant effects of the objective severity of exposure on cognitive and language development at age two years with important moderating effects of the timing during pregnancy. The implications of our findings are discussed.

The effects of prenatal stress on temperament and problem behavior of 27-month-old toddlers

AIM

To examine, in a prospective study, the influence of prenatal stress on infant temperament and problem behavior.

METHOD

Self-report data on stress and anxiety, and levels of cortisol in saliva were collected from nulli-parous women during pregnancy. Temperament of the child was measured at 27 months by parent report on the Infant Characteristics Questionnaire. Behavior of the child was assessed by direct observation during the administration of the Bayley Scales of Development 2-30, and by parent report on the Child Behavior Checklist 2-3.

RESULTS

Complete data were available for 103 healthy toddlers. Logistic regression analyses were performed and results were adjusted for possible prenatal, perinatal and postnatal confounders. Perceived stress during pregnancy was a predictor of lower levels of restless/disruptive temperament (OR=0.77), more total behavioral problems (OR=1.17), and more externalizing behavioral problems (OR=1.12) in 2-year-olds. Fear of bearing a handicapped child was a predictor of higher levels of restless/disruptive temperament (OR=1.39) and more attention regulation problems in toddlers (OR=1.46).

CONCLUSIONS

Increased levels of maternal prenatal stress appear to be associated with temperamental and behavioral problems in toddlers.

Stress during pregnancy affects general intellectual and language functioning in human toddlers

Prenatal maternal stress has been shown to impair functioning in nonhuman primate offspring. Little is known about the effects of prenatal stress on intellectual and language development in humans because it is difficult to identify sufficiently large samples of pregnant women who have been exposed to an independent stressor. We took advantage of a natural disaster (January 1998 ice storm in Québec, Canada) to determine the effect of the objective severity of pregnant women's stress exposure on general intellectual and language development of their children. Bayley Mental Development Index (MDI) scores and parent-reported language abilities of 58 toddlers of mothers who were exposed to varying levels of prenatal stress were obtained at 2 y of age. The hierarchical multiple regression analyses indicated that the toddlers' birth weight and age at testing accounted for 12.0% and 14.8% of the variance in the Bayley MDI scores and in productive language abilities, respectively. More importantly, the level of prenatal stress exposure accounted for an additional 11.4% and 12.1% of the variance in the toddlers' Bayley MDI and productive language abilities and uniquely accounted for 17.3% of the variance of their receptive language abilities. The more severe the level of prenatal stress exposure, the poorer the toddlers' abilities. The level of prenatal stress exposure accounted for a significant proportion of the variance in the three dependent variables above and beyond that already accounted for by non-ice storm-related factors. We suspect that high levels of prenatal stress exposure, particularly early in the pregnancy, may negatively affect the brain development of the fetus, reflected in the lower general intellectual and language abilities in the toddlers.

Moderate level alcohol during pregnancy, prenatal stress, or both and limbic-hypothalamic-pituitary-adrenocortical axis response to stress in rhesus monkeys

This study examined the relationship between moderate-level prenatal alcohol exposure, prenatal stress, and postnatal response to a challenging event in 6-month-old rhesus monkeys. Forty-one rhesus monkey (Macaca mulatta) infants were exposed prenatally to moderate level alcohol, maternal stress, or both. Offspring plasma cortisol and adrenocorticotrophic hormone (ACTH) were determined from blood samples before maternal separation and after separation. Behavioral observations were made repeatedly across separation. Moderate-level prenatal alcohol exposure was associated with significantly higher plasma ACTH response to maternal separation. Offspring exposed to prenatal alcohol, prenatal stress, and prenatal alcohol and stress showed reduced behavioral adaptation to stress compared with controls. Baseline, 2-hr, and 26-hr plasma ACTH levels were intercorrelated and predicted behavior during separation.

Prenatal stress and risk for psychopathology: specific effects or induction of general susceptibility?

This review focuses on prenatal stress as a risk factor for psychopathology. Evidence from animal studies is summarized, and the relevance of prenatal stress models in animals for human studies is discussed. In the offspring of prenatally stressed animals, overactivity and impaired negative feedback regulation of the hypothalamic-pituitary-adrenal axis are consistent findings and may reflect a pathophysiological mechanism involved in the development of psychopathology. Reduced activity of the opioid GABA/benzodiazepine, serotonin, and dopamine systems and increased activity of the sympathico-adrenal system have been found as well. These alterations have been linked to a diverse spectrum of psychopathology. Therefore, the evidence supports the view that exposure to prenatal stress may result in a general susceptibility to psychopathology, rather than exerting a direct effect on a specific form of psychopathology.

Prenatal stress and cognitive development and temperament in infants

Studies in rodents and nonhuman primates indicate that maternal stress during pregnancy can influence the developing fetus, resulting in delay of motor and cognitive development and impaired adaptation to stressful situations. These effects may be mediated by the hypothalamic-pituitary-adrenal (HPA) axis. We examined whether stress during pregnancy predicted developmental outcome of human infants in a prospective design. Self-report data about daily hassles and pregnancy-specific anxiety and salivary cortisol levels were collected in nulliparous pregnant women. Dependent measures were scores on the Bayley Scales of Infant Development and on temperamental questionnaires at 3 and 8 months. Pregnancy-specific anxiety in mid pregnancy predicted lower mental and motor developmental scores at 8 months. Early morning values of cortisol in late pregnancy were negatively related to both mental and motor development at 3 months and motor development at 8 months. Pregnancy-specific anxiety explained 7% of the variance of test-affectivity and goal-directedness at 8 months. Increased maternal stress during pregnancy seems to be one of the determinants of temperamental variation and delay of development of infants and may be a risk factor for developing psychopathology later in life.

Psychological measures of prenatal stress as predictors of infant temperament

OBJECTIVE

To examine, in a prospective study, whether maternal stress during pregnancy is related to infant temperament.

METHOD

Self-report data on various aspects of prenatal stress were collected from nulliparous women in early pregnancy. Infant temperament was measured at 3 and 8 months by direct observation and by parent report.

RESULTS

Complete data were available for 170 term-born infants. Pregnancy-specific anxiety explained 3.3% of the variance of attention regulation at 3 months. Perceived stress and pregnancy anxiety taken together explained 5% of the variance of attention regulation at 8 months. Perceived stress accounted for 8.2% of the variance of difficult behavior of the 3-month-old infant. All results were adjusted for covariates.

CONCLUSIONS

Increased maternal prenatal stress seems to be associated with temperamental variation of young infants and may be a risk factor for psychopathology later in life.

Fatty acid formula supplementation and neuromotor development in rhesus monkey neonates

Docosahexaenoic acid (DHA) is an omega-3 fatty acid that is highly concentrated in CNS tissues. Although breast milk contains the fatty acids DHA and arachidonic acid, infant formulas marketed in North America do not contain these nutrients. The potential deleterious effects of rearing infants with formulas devoid of these nutrients was assessed by comparing nursery-reared rhesus macaque infants (Macaca mulatta) fed standard formula with infants fed standard formula supplemented with physiologically relevant concentrations of DHA (1.0%) and arachidonic acid (1.0%). Neurobehavioral assessments were conducted on d 7, 14, 21, and 30 of life using blinded raters. The 30-min assessment consisted of 45 test items measuring orienting, temperament, reflex capabilities, and motor skills. Plasma concentrations of DHA in standard formula-fed infants were significantly lower than those fed supplemented formula or mother-raised (breast-fed) infants; however, infants fed the supplemented formula exhibited higher arachidonic acid levels than either mother-reared infants or infants fed standard formula. Infant monkeys fed the supplemented formula exhibited stronger orienting and motor skills than infants fed the standard formula, with the differences most pronounced during d 7 and 14. This pattern suggests an earlier maturation of specific visual and motor abilities in the supplemented infants. Supplementation did not affect measures of activity or state control, indicating no effect on temperament. These data support the assertion that preformed DHA and arachidonic acid in infant formulas are required for optimal development.

Socioeconomic differences in children's health: how and why do these relationships change with age?

The effects of socioeconomic status (SES) on health are well documented in adulthood, but far less is known about its effects in childhood. The authors reviewed the literature and found support for a childhood SES effect, whereby each decrease in SES was associated with an increased health risk. The authors explored how this relationship changed as children underwent normal developmental changes and proposed 3 models to describe the temporal patterns. The authors found that a model's capacity to explain SES-health relationships varied across health outcomes. Childhood injury showed stronger relationships with SES at younger ages, whereas smoking showed stronger relationships with SES in adolescence. Finally, the authors proposed a developmental approach to exploring mechanisms that link SES and child health.

The impact of prenatal stress, fetal alcohol exposure, or both on development: perspectives from a primate model

The question of whether psychosocial stress during pregnancy (alone or in combination with fetal alcohol exposure) has negative consequences for offspring has not been clearly established in human studies. In this article, we present an overview of three prospective longitudinal studies. Using rhesus monkeys as subjects, a noise or hormone stressor, alone or in combination with moderate level alcohol solution, was presented daily during different stages of pregnancy. Prenatal stress resulted in lighter birth weights in two of three studies, and males from the alcohol plus noise stress condition had reduced birth weights. There were no significant effects of any of the prenatal treatments on gestation duration. Both prenatal stress and moderate fetal alcohol exposure reduced attention span and neuromotor capabilities of offspring during the first month of life, while early gestation prenatal stress, during the period of neuronal migration, emerged as a period of enhanced vulnerability for these effects. Under conditions of challenge, prenatally stressed monkeys showed more disturbance behaviors and reduced locomotion and exploration as well as altered hypothalamic-pituitary-adrenal (HPA) axis reactivity to stress. Fetal alcohol exposed monkeys also showed increased HPA axis activity in response to stressful conditions. Finally, altered patterns of alcohol consumption during adolescence were associated with prenatal stress.

Prenatal stress alters early neurobehavior, stress reactivity and learning in non-human primates: a brief review

In this paper we review three prospective longitudinal studies from our laboratory examining the effects of prenatal stress on early neuro behavior, stress reactivity and learning performance in rhesus monkeys. Either a noise stressor or ACTH treatment was administered to pregnant monkeys during specific periods of pregnancy and offspring were examined repeatedly across development. In all three studies, the prenatally stressed monkeys showed reduced attention and impaired neuromotor functioning during the first month of life compared to controls from undisturbed pregnancies. When the monkeys were separated from their mothers or peers at 6-8 months of age, prenatally stressed monkeys exhibited more disturbance behavior and showed hypothalamic-pituitary-adrenal axis dysregulation. During adolescence, they exhibited impairments in learning, compared to controls.

Moderate Alcohol Consumption and Psychological Stress during Pregnancy Induce Attention and Neuromotor Impairments in Primate Infants

This study examined the effect of moderate alcohol and/or psychological stress during prenancy on off-spring growth and behavior in 33 rhesus monkey infants (Macaca mulatta). Infants were derived from 1 of 3 groups of female: (1) alcohol-consuming,0.6g/Kg, Daily throughou gestation (equivalet, to 1-2 drinks), beginning 5 day prior to breeding;(2) alcohol-consuming (as above) and exposed to mild psychological stress(removal from home cage and exposed to 3 random noise bursts); (3) sucrose-consuming, equivolemic, and equicaloric to the alcohol solution.Beginning on day 4 postpartum, intantrs underwent brief weekly separations from their mother for assessment of growth, behavior, and facial dimensions. Results indicated that moderate alcohol consumption throughout pregnancy was sufficient to affect attention and neuromotor functioning, even though the infants were normol in birthweight, gestational length, and facial dimensions, Moreover, alcohol-induced neuromotor impairments were exacerbated by maternal exposure to psychological stress, and males from the alcohol/stress condition had reduced birthweights. Finally, although all females consuming alcohol produced viable offspring, alcohol accompanie by stress during gestation resulted in 23% fetal losses (abortion and stillbirths).

Long-term effects of prenatal stress on HPA axis activity in juvenile rhesus monkeys

The effect of stress to the pregnant mother on hormonal responses of the offspring to stressful events was investigated in juvenile rhesus monkeys. Six pregnant monkeys were repeatedly removed from their home cages and exposed to unpredictable noise during mid- to late gestation (Days 90-145 postconception), while six undisturbed pregnant mothers served as controls. Blood samples were collected from the juvenile offspring under anesthesia on four occasions and assayed for ACTH and cortisol. In a second experiment, blood samples were collected from the awake offspring under a baseline and four progressively stressful conditions. Offspring of stressed mothers showed higher ACTH and cortisol levels than control offspring at all four anesthesia samples and at a nonanesthesized home cage baseline. Prenatally stressed offspring also showed higher ACTH values in all four stress conditions. Cortisol values were similar for the two groups under the stress conditions. The disparity between the two groups in the relationship between ACTH and cortisol was greatest in the most stressful condition, suggesting regulatory differences between the two groups. These results indicate that offspring of primate mothers stressed during pregnancy show enhanced HPA axis responsivity to stressors later in life, and concur with rodent findings indicating that prenatal stress may have long-term effects on HPA axis regulation.

Prenatal stress has long-term effects on behavioral responses to stress in juvenile rhesus monkeys

The effect of maternal psychological disturbance during pregnancy on postnatal responses of the offspring to stressful events was investigated in juvenile rhesus monkeys. Six pregnant monkeys were repeatedly removed from their home cages and briefly exposed to unpredictable noise during mid to late gestation (Days 90-145 postconception). Six undisturbed pregnant mothers served as controls. Behavioral data were later collected from the 18-month-old offspring under a baseline and four progressively stressful conditions. Social behaviors were considerably more affected by prenatal treatment than nonsocial behaviors. Prenatally stressed offspring showed more abnormal social behavior (mutual clinging) and less normal social behavior (proximity, contact) than controls. These results suggest that offspring of mothers stressed during pregnancy may show enhanced responsivity to stressors later in life, and concur with rodent findings indicating that prenatal stress may have long-term effects on behavioral reactivity.

Prenatal stress exposure alters postnatal behavioral expression under conditions of novelty challenge in rhesus monkey infants

This prospective study investigated whether mild maternal stress during pregnancy could alter the behavioral and affective responses in rhesus monkey infants in a complex, novel environment. Twenty-four rhesus monkey infants were tested on three occasions at 6 months of age in a novel environment. Twelve infants were derived from mothers exposed to a daily 10-min mild stressor from Day 90 to Day 145 postconception, while 12 were derived from mothers undisturbed during pregnancy. Prenatally stressed infants demonstrated more disturbance behavior, and lower levels of gross motor/exploratory behavior. Moreover, half of the prenatally stressed infants showed an abnormal response, falling asleep, while none of the control infants displayed this behavior. Males exhibited more clinging to surrogates, while females spent more time in gross motor/exploratory behaviors, with prenatally stressed males tending to spend the least time in gross motor/exploratory activity.

Endocrine activation mimics the adverse effects of prenatal stress on the neuromotor development of the infant primate

Pregnant female rhesus monkeys were exposed to a 2-week period of adrenocorticotropic hormone (ACTH) to determine whether it would affect the early neuromotor development of their fetuses in a manner similar to that observed after psychological stressors. During the first month after birth, infants were tested on two occasions with a modification of the Brazelton Newborn Behavioral Assessment Scale. Infants derived from ACTH-treated pregnancies showed early impairments in motor coordination and muscle tonicity and shorter attention spans as compared to controls. In addition, on a temperament rating scale, infants from the ACTH condition were more irritable and difficult to console. These findings indicate that a delimited period of endocrine activation during pregnancy can have an adverse effect on infant neurobehavioral development, like that of prenatal stress.