Corticosteroidogenesis and the Response to Stress in the Developing Fetal Rabbit

Abstract

Abstract

This study examined the in vitro synthesis and secretion of corticosteroids by the adrenal glands of fetal rabbits on Days 21, 24, 27, and 30 of gestation and in the neonate, as well as in Day 30 fetuses obtained from pregnant rabbits who had been either dehydrated or restrained. The results (ng steroid/mg protein/hr) demonstrate that the synthesis and secretion of aldosterone were low on Day 21 and gradually increased as development progressed, while comparable parameters of corticosterone were initially high and then decreased. Fetal cortisol production was quite low in relation to corticosterone and changed very little throughout gestation. The neonates' adrenal glands exhibited marked increases in aldosterone production but not in corticosterone or cortisol. These data suggest that those enzymes related to glucocorticoid production are present prior to those for aldosterone production. Moreover, since maternal dehydration or restraint caused increases or slight diminutions, respectively, in the fetal production of both aldosterone and corticosterone, these data indicate that the fetal adrenal gland is responsive to maternal stressors. Factors implicated in this fetal adrenal response include fetal ACTH and maternal glucocorticoids.