Stress, sex, and neural adaptation to a changing environment: mechanisms of neuronal remodeling

546

496

Stress-related variation in the intrauterine milieu may impact brain development and emergent function, with long-term implications in terms of susceptibility for affective disorders. Studies in animals suggest limbic regions in the developing brain are particularly sensitive to exposure to the stress hormone cortisol. However, the nature, magnitude, and time course of these effects have not yet been adequately characterized in humans. A prospective, longitudinal study was conducted in 65 normal, healthy mother-child dyads to examine the association of maternal cortisol in early, mid-, and late gestation with subsequent measures at approximately 7 y age of child amygdala and hippocampus volume and affective problems. After accounting for the effects of potential confounding pre-and postnatal factors, higher maternal cortisol levels in earlier but not later gestation was associated with a larger right amygdala volume in girls (a 1 SD increase in cortisol was associated with a 6.4% increase in right amygdala volume), but not in boys. Moreover, higher maternal cortisol levels in early gestation was associated with more affective problems in girls, and this association was mediated, in part, by amygdala volume. No association between maternal cortisol in pregnancy and child hippocampus volume was observed in either sex. The current findings represent, to the best of our knowledge, the first report linking maternal stress hormone levels in human pregnancy with subsequent child amygdala volume and affect. The results underscore the importance of the intrauterine environment and suggest the origins of neuropsychiatric disorders may have their foundations early in life.developmental programming | fetal origins | hypothalamus-pituitaryadrenal axis | depression | emotion regulation

“…These findings are consistent with extensive evidence of chronic stress being associated with larger adult amygdala volumes as a result of hypertrophy of nerve cells in the amygdala (71).…”

Section: Discussionsupporting

confidence: 79%

Maternal cortisol over the course of pregnancy and subsequent child amygdala and hippocampus volumes and affective problems

Buß

Davis²,

Shahbaba³

et al. 2012

546

496

“…A meta-analysis of volumetric brain studies of PTSD revealed that exposure to trauma had a relatively greater effect on hippocampal volume in males than in females (48). Consistent with this finding, animal studies have shown that chronic stress impairs neurogenesis and causes dendritic retraction in the hippocampus, along with spatial memory deficits, to a much greater degree in adult male than in female rats (49). These sex differences in sensitivity to the effects of chronic stress may reflect, in part, the effects of estrogen, which exhibits Fig.…”

Section: Discussionsupporting

confidence: 57%

“…The full model with moderation by sex is shown in Fig. 3. a number of neuroprotective effects in the hippocampus (49,50). However, in our sample, maltreatment during childhood showed similar associations with hippocampal rs-FC in both males and females.…”

Section: Discussionmentioning

confidence: 37%

“…Even less is known about sex differences in the impact of stress on the amygdala and PFC. Chronic stress increases dendritic arborization of the amygdala and decreases arborization of the PFC in male rats, but there are few such studies in female rats (49,51). In humans, structural connectivity between the vmPFC and amygdala/hippocampus is reduced in children who have suffered early neglect/maltreatment (52,53), but whether there are sex differences in the effects of stress on these white matter tracts remains unclear.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Childhood maltreatment is associated with altered fear circuitry and increased internalizing symptoms by late adolescence

Herringa

Birn

Ruttle

et al. 2013

364

314

Maltreatment during childhood is a major risk factor for anxiety and depression, which are major public health problems. However, the underlying brain mechanism linking maltreatment and internalizing disorders remains poorly understood. Maltreatment may alter the activation of fear circuitry, but little is known about its impact on the connectivity of this circuitry in adolescence and whether such brain changes actually lead to internalizing symptoms. We examined the associations between experiences of maltreatment during childhood, resting-state functional brain connectivity (rs-FC) of the amygdala and hippocampus, and internalizing symptoms in 64 adolescents participating in a longitudinal community study. Childhood experiences of maltreatment were associated with lower hippocampus-subgenual cingulate rs-FC in both adolescent females and males and lower amygdalasubgenual cingulate rs-FC in females only. Furthermore, rs-FC mediated the association of maltreatment during childhood with adolescent internalizing symptoms. Thus, maltreatment in childhood, even at the lower severity levels found in a community sample, may alter the regulatory capacity of the brain's fear circuit, leading to increased internalizing symptoms by late adolescence. These findings highlight the importance of fronto-hippocampal connectivity for both sexes in internalizing symptoms following maltreatment in childhood. Furthermore, the impact of maltreatment during childhood on both fronto-amygdala and -hippocampal connectivity in females may help explain their higher risk for internalizing disorders such as anxiety and depression.child maltreatment | sex differences | ventromedial prefrontal cortex I n both clinical and community samples, maltreatment during childhood represents one of the strongest risk factors for developing depression and anxiety (1-3). Childhood maltreatment and other adversities account for up to a third of the risk for mood and anxiety disorders (4). Further, depression and anxiety disorders are major public health problems, affecting 15 and 32% of youth, respectively, by the age of 18 y (5). The burden of these disorders is significant, representing the second and fifth leading causes, respectively, of years lived with disability in the United States (6). Some evidence suggests that maltreatment may impart greater risk for the development of internalizing symptoms in females than in males (e.g., refs. 7-9). This differential risk could account, in part, for the higher incidence of internalizing problems in females than in males (10, 11). However, the neurobiological pathways from maltreatment during childhood to the expression of internalizing problems, including potential differences for females and males, remain poorly understood. Such information is crucial for improving the treatment of depression and anxiety disorders and for mitigating the effects of maltreatment during childhood.Both maltreatment during childhood (12) and internalizing disorders (13, 14) have been associated with altered activity in specific b...

“…The hippocampus is a brain region noted for its plasticity in response to stress and sensitivity to adrenal steroid hormones (6). Acute stress enhances synaptic plasticity that is associated with improved cognition and other adaptive functions whereas chronic stress produces opposite effects mediating, in the hippocampus, spine synapse turnover, dendritic shrinkage, impaired long-term potentiation (LTP), and suppression of adult neurogenesis in the dentate gyrus (DG) (1,7). Importantly, neuroanatomical changes in response to repeated stress recover in young adult animals, based upon the restoration of dendritic length and branching and spine density (8).…”

mentioning

confidence: 99%

Stress dynamically regulates behavior and glutamatergic gene expression in hippocampus by opening a window of epigenetic plasticity

Nasca

Zelli

Bigio

et al. 2015

Self Cite

130

Excitatory amino acids play a key role in both adaptive and deleterious effects of stressors on the brain, and dysregulated glutamate homeostasis has been associated with psychiatric and neurological disorders. Here, we elucidate mechanisms of epigenetic plasticity in the hippocampus in the interactions between a history of chronic stress and familiar and novel acute stressors that alter expression of anxiety-and depressive-like behaviors. We demonstrate that acute restraint and acute forced swim stressors induce differential effects on these behaviors in naive mice and in mice with a history of chronic-restraint stress (CRS). They reveal a key role for epigenetic up-and down-regulation of the putative presynaptic type 2 metabotropic glutamate (mGlu2) receptors and the postsynaptic NR1/NMDA receptors in the hippocampus and particularly in the dentate gyrus (DG), a region of active neurogenesis and a target of antidepressant treatment. We show changes in DG long-term potentiation (LTP) that parallel behavioral responses, with habituation to the same acute restraint stressor and sensitization to a novel forced-swim stressor. In WT mice after CRS and in unstressed mice with a BDNF loss-of-function allele (BDNF Val66Met), we show that the epigenetic activator of histone acetylation, P300, plays a pivotal role in the dynamic up-and down-regulation of mGlu2 in hippocampus via histone-3-lysine-27-acetylation (H3K27Ac) when acute stressors are applied. These hippocampal responses reveal a window of epigenetic plasticity that may be useful for treatment of disorders in which glutamatergic transmission is dysregulated.S tress effects on higher brain regions, such as hippocampus, are known to involve actions of excitatory amino acids to induce structural and functional changes depending upon the type, intensity, and duration of the stressor (1). These differential responses, including determining susceptibility versus resilience to stress, contribute to the pathophysiology of debilitating stress-related disorders (2-5). The hippocampus is a brain region noted for its plasticity in response to stress and sensitivity to adrenal steroid hormones (6). Acute stress enhances synaptic plasticity that is associated with improved cognition and other adaptive functions whereas chronic stress produces opposite effects mediating, in the hippocampus, spine synapse turnover, dendritic shrinkage, impaired long-term potentiation (LTP), and suppression of adult neurogenesis in the dentate gyrus (DG) (1, 7). Importantly, neuroanatomical changes in response to repeated stress recover in young adult animals, based upon the restoration of dendritic length and branching and spine density (8). However, there are underlying changes that can be seen at the level of gene expression and epigenetic regulation that indicate that the brain is continually changing (9, 10). Epigenetic modifications, such as acetylation of histones, have also been involved in the consolidation of contextual memories that allow the brain to respond and adapt to changes in ...