Neonatal Hypoxia Induces Behavioral Deficit Associated with Impaired Glucocorticoid and Serotoninergic Systems in Adult Rats.

We investigated plasma concentrations of adrenocorticotropic hormone (ACTH), corticosterone and serotonin in juvenile and adult rats, as well as raphe serotonin levels and behavioral responses in the open field and elevated plus maze tests in adult rats, exposed to three sessions of neonatal hypobaric hypoxia (360 mm Hg, 2 h each, once a day) within days 8–10 postpartum. This noninvasive rat model of neonatal hypoxia (NH) simulates mild perinatal hypoxic injury in human fetuses and premature infants. At 3 months of age, NH-exposed rats exhibited reduced exploratory behavior and increased anxiety in both behavioral tests, accompanied by decreased serotonin levels in the raphe nuclei. In adult NH-exposed rats, plasma corticosterone and serotonin levels remained unaltered, while ACTH levels showed a significant decrease. Our findings suggest that early postnatal hypoxic stress disrupts the serotoninergic system and modifies the hypothalamic–pituitary–adrenocortical axis, leading to long-lasting behavioral deficits in adult rats. [ABSTRACT FROM AUTHOR]