Maternal endocrine activation during pregnancy alters neurobehavioral state in primate infants

Why are behavioral and immune traits linked?

Through behavior, animals interact with a world where parasites abound. It is easy to understand how behavioral traits can thus have a differential effect on pathogen exposure. Harder to understand is why we observe behavioral traits to be linked to immune defense traits. Is variation in immune traits a consequence of behavior-induced variation in immunological experiences? Or is variation in behavioral traits a function of immune capabilities? Is our immune system a much bigger driver of personality than anticipated? In this review, I provide examples of how behavioral and immune traits co-vary. I then explore the different routes linking behavioral and immune traits, emphasizing on the physiological/hormonal mechanisms that could lead to immune control of behavior. Finally, I discuss why we should aim at understanding more about the mechanisms connecting these phenotypic traits.

Behavioral epigenetics and the developmental origins of child mental health disorders

Advances in understanding the molecular basis of behavior through epigenetic mechanisms could help explain the developmental origins of child mental health disorders. However, the application of epigenetic principles to the study of human behavior is a relatively new endeavor. In this paper we discuss the 'Developmental Origins of Health and Disease' including the role of fetal programming. We then review epigenetic principles related to fetal programming and the recent application of epigenetics to behavior. We focus on the neuroendocrine system and develop a simple heuristic stress-related model to illustrate how epigenetic changes in placental genes could predispose the infant to neurobehavioral profiles that interact with postnatal environmental factors potentially leading to mental health disorders. We then discuss from an 'Evo-Devo' perspective how some of these behaviors could also be adaptive. We suggest how elucidation of these mechanisms can help to better define risk and protective factors and populations at risk.

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.

Stability of parental care across siblings from undisturbed and challenged pregnancies: intrinsic maternal dispositions of female rhesus monkeys

The concept of fetal programming is based on the idea that the developmental trajectory of infants is adjusted in response to in utero conditions. In species with extended parental care, these prenatally derived tendencies are further substantiated by behavioral attributes of the mother during the postnatal period. We investigated the stability of maternal behavioral interactions with infant monkeys and carefully varied prenatal conditions across siblings reared by the same mother. We hypothesized that effects of prenatal disturbance and the infant's susceptibility would be differentially affected by maternal attributes. Using hierarchical linear modeling, we analyzed observational data on 121 rhesus macaques reared by a total of 35 multiparous mothers. A portion of the variance in 5 dyadic behaviors was statistically driven by the infant (or was unique to a particular mother-infant pair), but stable maternal propensities and a consistent style of care across siblings also substantially influenced behavioral interactions. Moreover, the magnitude and direction of the prenatal effects were contingent on a female's intrinsic dispositions. When mothers typically exhibited high levels of a corresponding behavior, responsiveness to infants was enhanced as a consequence of prenatal disturbance. The opposite was true for less expressive females. Challenges to the well-being of pregnancy thus served to accentuate maternal predispositions and served to magnify the range of variation in mother-infant behavior across the whole population.

Children of addicted women

The purpose of this article was to review follow up studies of children with prenatal drug exposure from preschool through adolescence. Specifically, the authors focus on the effects of prenatal exposure to cocaine, methamphetamine, and opiates on behavior and development. The largest number of studies have examined cocaine-exposed children. The authors identified 42 studies that suggest that there are unique effects of prenatal cocaine exposure on 4- to 13-year-old children, particularly in the areas of behavior problems, attention, language, and cognition. In addition, studies make reasonable attempts to control for possible confounding factors. Systematic research on the long-term effects of prenatal methamphetamine exposure is just beginning but seems to be showing similar effects to that of cocaine. The literature on the on the long-term effects of children with prenatal opiate exposure is more substantial than the methamphetamine literature but it is still relatively sparse and surprising in that there is little recent work. Thus, there are no studies on the current concerns with opiates used for prescription mediation. There is a growing literature using neuroimaging techniques to study the effects of prenatal drug exposure that holds promise for understanding brain/behavior relationships. In addition to pharmacological and teratogenic effects, drugs can also be viewed from a prenatal stressor model. The author discuss this "fetal origins" approach that involves fetal programming and the neuroendocrine system and the potential implications for adolescent brain and behavioral development.

In utero cortisol and testosterone exposure and fear reactivity in infancy

Fetal programming is emerging as a major conceptual model for understanding developmental origins of health and disease, including behavioral outcomes. As part of a larger study of prenatal stress and child development, we examined the association between prenatal hormone exposure and fear reactivity, a temperament dimension that is a predictor of long-term behavioral adjustment. Amniotic fluid was collected from a sample of women undergoing clinically indicated amniocentesis for later analysis of cortisol and testosterone. Children with normal birth outcomes were recalled for follow-up assessment at 17 months, at which time we administered an observational assessment of temperament (lab-TAB; n=108). Information on pregnancy and obstetric outcome was included as covariates. Results indicated that there was a significant association between prenatal testosterone and observed fear reactivity in boys (r(53)=0.34, p=0.01); no significant effect was found in girls (r(54)=-0.07, ns); the effect remained when obstetric, psychosocial, and parental anxiety were controlled for. There was not a significant association between fetal cortisol exposure and fear reactivity. The prediction from in utero testosterone exposure to fear reactivity in boys extends prior research on prenatal testosterone and may represent an association with a general predisposition to greater arousal and reactivity.

Maternal antenatal anxiety and amniotic fluid cortisol and testosterone: possible implications for foetal programming

Both animal and human studies have shown that maternal stress or anxiety during pregnancy is associated with increased risk of disturbance in offspring neurodevelopment and behaviour. In animal models, increased foetal exposure to glucocorticoids has been found to be one mechanism for such foetal programming. Little is understood of the mediating mechanisms in humans, and one aim of our research programme is to investigate this further. This review presents a synopsis of some of our recent results. We aimed to test the hypothesis that maternal anxiety was associated with raised maternal cortisol, and that this in turn was related to increased foetal exposure to cortisol. We studied this by recruiting women at amniocentesis, obtained their Spielberger State Anxiety scores, and assessed maternal plasma cortisol and amniotic fluid cortisol. We also examined maternal plasma and amniotic fluid testosterone levels. Awaiting amniocentesis was in general anxiogenic, but with a wide range of anxiety scores. Maternal anxiety was significantly associated with plasma cortisol before 17 weeks, albeit of modest magnitude (r = 0.0.23), and not after 17 weeks of gestation. This is probably due to the known attenuation of the maternal hypothalamic-pituitary-adrenal axis with increasing gestation. We found a strong correlation between maternal plasma and amniotic fluid cortisol levels, which increased with gestation and became robust after 18 weeks. This correlation increased with maternal anxiety, suggesting a possible effect of maternal mood on placental function. There was a positive correlation between cortisol and testosterone in amniotic fluid, in both male and female foetuses independent of maternal anxiety, plasma testosterone, gestational age, and time of collection. Foetal stress may be associated with increased foetal exposure to testosterone. However, maternal anxiety did not predict amniotic fluid cortisol or testosterone level. Thus, the role of these hormones in mediating the effect of maternal mood on foetal development in humans remains to be demonstrated.

Contributions of non-human primates to neuroscience research

Non-human primates have a small but important role in basic and translational biomedical research, owing to similarities with human beings in physiology, cognitive capabilities, neuroanatomy, social complexity, reproduction, and development. Although non-human primates have contributed to many areas of biomedical research, we review here their unique contributions to work in neuroscience, and focus on four domains: Alzheimer's disease, neuroAIDS, Parkinson's disease, and stress. Our discussion includes, for example, the role of non-human primates in development of new treatments (eg, stem cells, gene transfer) before phase I clinical trials in patients; basic research on disease pathogenesis; and understanding neurobehavioural outcomes resulting from genotype-environment interactions.

Intrauterine exposure to dexamethasone impairs proliferation but not neuronal differentiation in the dentate gyrus of newborn common marmoset monkeys

Glucocorticoids applied prenatally alter birth weight and the maturation of the lungs. Moreover, glucocorticoids impair neuronal proliferation and differentiation in the hippocampal dentate gyrus. In the present study proliferation and neuronal differentiation in the dentate gyrus were studied in newborn common marmoset monkeys which were intrauterinely exposed to the synthetic glucocorticoid dexamethasone (DEX). Pregnant marmoset monkeys received DEX (5 mg/kg body weight) daily either during early (days 42-48) or late (days 90-96) pregnancy. In the hippocampi of newborn monkeys immunohistochemistry was performed with markers of proliferation (Ki-67), apoptosis (in situ tailing) as well as early and late neuronal differentiation (calretinin and calbindin). Both after early and late intrauterine exposure to DEX, proliferation of dentate gyrus cells was significantly decreased (P < 0.05). The density of apoptotic neurons was not altered by DEX treatment. Quantification of calretinin- and calbindin-immunoreactive neurons showed no significant differences between DEX-exposed and control animals. In conclusion, the proliferation of putative precursor cells but not the differentiation into mature cells was impaired in the dentate gyrus of newborn marmosets exposed intrauterinely to DEX.

Prenatal origins of individual variation in behavior and immunity

The in utero environment plays a critical role in initiating the normal ontogeny of many physiological systems. As a consequence, disturbances during prenatal life can affect the baby's maturational trajectory and sometimes cause chronic alterations that influence health postpartum. Our review summarizes a series of studies in rhesus monkeys supporting these conclusions. Psychological disturbance or pharmacological stimulation of the gravid female's pituitary-adrenal axis affected the infant's neurological development: monkeys evinced immature neuromotor reflexes at birth, greater emotionality during the first year of life, and a smaller hippocampus as juveniles. Immune responses of the infants were also affected: lymphocyte proliferation, natural killer activity and cytokine production were reduced. Several mediating pathways were implicated, including the placental transfer of hormones and nutrients, and a differential response of the infant monkey to the rearing environment. For example, the establishment of beneficial types of microflora in the gastrointestinal tract was significantly reduced, which was associated with a greater risk for enteric infection. These findings indicate that events during fetal life can persistently influence physiology after birth and tilt the balance away from health and toward illness.

Effects of prenatal stress on cellular and humoral immune responses in neonatal pigs

In the present study, we investigated the effects of a daily 5 min restraint stress of pregnant sows in the last five gestational weeks on the development and reactivity of the immune system of the offspring. Maternal stress resulted in significant decreased serum immunoglobulin G (IgG) concentrations in suckling piglets at 1 and 3 days of age. Furthermore, the stress treatment of the sows had an immunosuppressive effect on lymphocyte proliferation in response to the T-cell mitogen concanavalin A (ConA) at postnatal days 1 and 7. A suppressive effect was also found in response to the B-cell mitogens lipopolysaccharid (LPS) at days 1 and 35 and pokeweed mitogen (PWM) at day 1 of life, whereas natural killer (NK) cell cytotoxicity was not altered by prenatal stress. The relative thymus weights were significantly reduced in prenatally stressed piglets on the first and 35th day of life and the morbidity and mortality during the suckling period were significantly increased in prenatally stressed litters, as shown by a higher frequency of diseased and died piglets per litter. In addition, the ConA-, LPS- and PWM-stimulated lymphocyte proliferation at the age of 7, 21 and 35 days, and the NK cell cytotoxicity at the age of 21 and 35 days decreased in prenatally stressed and in control piglets 1h after a corticotropin (ACTH) injection. However, the cellular immunity was always higher in the control piglets which might be a result of the weaker stress hormone reactivity in prenatally stressed animals. In conclusion, the results provide first experimental evidence that prenatal maternal stress during late gestation is able to impair both humoral and cellular immune function in suckling piglets. The data also suggest that gestational stress in pigs may affect the ontogeny of the foetal immune system with consequences on the susceptibility to diseases and immune responsiveness to stressful stimuli of the offspring.

The role of estrogen in schizophrenia: implications for schizophrenia practice guidelines for women

OBJECTIVE

The objective of this paper is to integrate what is known about estrogen effects on symptoms and treatment response into a global understanding of schizophrenia. The aim is to expand Canadian schizophrenia guidelines to include the specific needs of women.

METHOD

We searched the Medline database; keywords included estrogen, estrogen replacement therapy, schizophrenia, psychosis, treatment, tardive dyskinesia (TD), and women. We examined reference lists from relevant articles to ensure that our review was complete. We review the evidence for the effects of estrogen in schizophrenia and we make recommendations for the next revision of official practice guidelines.

RESULTS

The epidemiologic evidence suggests that, relative to men, women show an initial delay in onset age of schizophrenia, with a second onset peak after age 44 years. This points to a protective effect of estrogen, confirming animal research that has documented both neurotrophic and neuromodulatory effects. Clinical research results indicate that symptoms in women frequently vary with the menstrual cycle, worsening during low estrogen phases. Pregnancy is often, though not always, a less symptomatic time for women, but relapses are frequent postpartum. Some work suggests that in the younger age groups women require lower antipsychotic dosages than men but that following menopause they require higher dosages. Estrogen has been used effectively as an adjunctive treatment in women with schizophrenia. Estrogen may also play a preventive role in TD.

CONCLUSIONS

Symptom evaluation and diagnosis in women needs to take hormonal status into account. Consideration should be given to cycle-modulated neuroleptic dosing and to careful titration during pregnancy, postpartum, and at menopause. We recommend that discretionary use of newer neuroleptic medication and adjuvant estrogen therapy be considered.

The importance of neurobiological research to the prevention of psychopathology

There is both a biological and environmental component to the neural substrates for various forms of psychopathology. Brain dysfunction itself not only constitutes a formidable liability to psychopathology, but also has an impact on environmental and social responses to the individual, compounding the risk for an adverse outcome. Environmental conditions, such as social and physical stimulus deprivation, poverty, traumatic stress, and prenatal drug exposure, can further compromise brain function in the context of existing liabilities. The relationship between genetic and environmental processes is interactive, fluid, and cumulative in their ability to influence an individual's developmental trajectory and alter subsequent behavioral outcomes. Given the codependent relationship between these processes, brain function is now believed to be malleable via manipulations of the environment in ways that may decrease liability for psychopathology. Research that explores these relationships and ways in which interventions can redirect this developmental track may substantially advance both the science and practice of prevention. Studies attempting to isolate the neurobiological effects of socioenvironmental factors are reviewed, implications for intervention strategies are discussed, and a future research agenda is proposed to provide greater insight into specific brain-environment relationships. Armed with this knowledge, prevention scientists may eventually design programs that directly target these effects to reverse or attenuate negative outcomes.