Prenatal stress diminishes neurogenesis in the dentate gyrus of juvenile Rhesus monkeys

Background Early life stress, including during fetal development, has been hypothesized to predispose individuals to several illnesses and psychiatric disorders later in adulthood. Methods To determine whether prenatal stress alters neural, hormonal, and behavioral processes in nonhuman primates, pregnant rhesus monkeys were acutely stressed on a daily basis for 25% of their 24-week gestation with an acoustical startle protocol. At 2 to 3 years of age, hippocampal volume, neurogenesis in the dentate gyrus, and cortisol levels were evaluated in the offspring generated from stressed and control pregnancies. Results Prenatal stress, both early and late in pregnancy, resulted in a reduced hippocampal volume and an inhibition of neurogenesis in the dentate gyrus. These changes were associated with increased pituitary–adrenal activity, as reflected by higher cortisol levels after a dexamethasone suppression test, and also with behavioral profiles indicative of greater emotionality. Conclusions These findings indicate that the prenatal environment can alter behavior, dysregulate neuroendocrine systems, and affect the hippocampal structure of primates in a persistent manner.