Stress on a postpartum mother inhibits the secretion of growth hormone in the offspring and causes persistent growth impairment.

Children exposed to environmental stress in the early neonatal period often develop psychiatric or somatic diseases in adulthood. In the present study in mice, we examined how postpartum stress on the mother influences their pups and thus tried to provide new insight into the management of idiopathic short stature. The dams were exposed to daily 3-h immobilization stress (IS) only for 3 weeks from the day after delivery. When compared to the pups of nonstressed dams (control pups), those of the IS dams (IS pups) showed lower body weight and height which persisted even into adulthood. Their nutritional status was normal. The IS pups also showed low serum concentrations of insulin-like growth factor I (IGF-I) and poor responses to growth hormone-releasing hormone (GHRH) stimulation on day 22 and were behaviorally hyperactive at 8 weeks. Immunohistochemical analysis demonstrated that the number of pituitary GH-positive cells in response to treatment with GHRH was markedly decreased in the IS pups compared to the control pups. The IS dams did not show apparent behavioral abnormalities except downregulation of glucocorticoid receptor (GR) gene expression in the hippocampus. These results suggest that the perturbation of GH secretion in the pituitary glands is involved in the lifelong growth impairment of the IS pups.