Neurobiology of increased vulnerability to social stressors during adolescence

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DESCRIPTION (provided by applicant): Postnatal stressors, producing a dysregulation of the limbic-hypothalamic pituitary adrenal (LHPA) axis, can have a deleterious effect on a child's pubertal and psychosocial development. Importantly, the gonadal release of estradiol (E2) occurring during the pubertal transition likely contributes to the continued maturation of cortico-limbic circuits that regulate emotional behavior but stress-induced delayed puberty could compromise this development. Puberty may, thus, be a time when children, particularly girls, show an increased vulnerability to the emergence of psychosocial problems as a result of incomplete cortico-limbic development resulting from psychosocial stress exposure. In addition, some individuals are genetically predisposed to respond differentially to stress, as individuals with a specific polymorphism in the gene encoding the serotonin (5HT) reuptake transporter (SERT) are more susceptible to stressors. We propose that psychosocial stress interacts with genetic vulnerability to induce dysregulation of the LHPA axis to disrupt puberty and delay exposure to increases in E2, thus placing these females at risk for neurobiological defects and mood disorders. This project will study the behavioral, physiological, and neurobiological consequences of psychosocial stress, imposed by social subordination, during adolescence in female rhesus monkeys. Specific Aim 1 will test the hypothesis that social subordination, exacerbated by the presence of the short allele in the SERT gene, produces LHPA dysregulation and delays puberty. Aim 2 will test the hypothesis that exposure to psychosocial stressors during adolescence increases emotional reactivity by prolonging the pubertal transition and reducing exposure to E2, particularly in females with the short allele in the SERT gene. Aim 3 will use neuroimaging to test the hypothesis that development of cortico-limbic circuits and 5HT systems regulating emotional behavior are adversely affected by exposure to psychosocial stressors and reduced levels of E2. Aim 4 will test the hypothesis that SSRI therapy to subordinate females may normalize LHPA activity but not growth or puberty, delaying exposure to increasing levels of E2, and attenuating maturation of cortico-limbic circuits and 5HT systems. These studies will elucidate the complex interplay between behavior, genetics, and reproductive maturation, providing a comprehensive understanding of the role of adolescence as a critical period for the emergence of mood disorders in girls. PUBLIC HEALTH RELEVANCE: Using a rhesus monkey model, this project is designed to provide a better understanding of how psychosocial stress, imposed by social subordination, affects brain maturations and emotional development in females and whether this is influenced by polymorphisms in the gene that encodes the serotonin re-uptake transporter (SERT), a protein essential for normal serotonin neurotransmission and emotionality. These studies will elucidate the complex interplay between behavior, genetics, and reproductive maturation, providing a comprehensive understanding of how adolescence represents a critical period for the emergence of psychiatric disorders.