Vulnerability to stress in mouse offspring is ameliorated when pregnant dams are provided a chewing stick during prenatal stress

Abstract

ObjectiveTo investigate whether maternal chewing during prenatal stress alters the responsivity of young offspring to novel stress, we examined the expression of hippocampal glucocorticoid receptors and mineralocorticoid receptors, and the levels of hypothalamic corticotropin-releasing hormone in young adult mouse offspring of dams exposed to restraint stress during pregnancy. DesignTo induce stress, the dams were placed in a ventilated restraint tube for 45 min each day from day 12 of pregnancy through parturition. While restrained in the tube, one group of dams was provided a wooden stick for chewing. Hippocampal expression of glucocorticoid receptor and mineralocorticoid receptor messenger ribonucleic acid was assessed in 1-month-old pups. Hypothalamic expression of corticotropin-releasing hormone messenger ribonucleic acid was examined before and after exposing the offspring to a novel stressor. ResultsPrenatal stress significantly decreased hippocampal expression of both glucocorticoid receptor and mineralocorticoid receptor messenger ribonucleic acid in the offspring, and increased the expression of corticotropin-releasing hormone messenger ribonucleic acid in the hypothalamic paraventricular nucleus in the offspring after novel stress exposure. Maternal chewing during exposure to prenatal stress attenuated the decreased hippocampal expression of both glucocorticoid receptor and mineralocorticoid receptor messenger ribonucleic acid, and the increased corticotropin-releasing hormone messenger ribonucleic acid expression in the hypothalamic paraventricular nucleus in the offspring. ConclusionsDownregulation of hippocampal glucocorticoid receptor and mineralocorticoid receptor expression in offspring due to prenatal stress, which may be associated with increased susceptibility to novel stress in adulthood, are attenuated by allowing the dams to chew on a wooden stick.