Direct inhibitory effects of leptin on the neonatal adrenal and potential consequences for brain glucocorticoid feedback.

Leptin is most studied for its primary role in the CNS control of energy balance and food intake in humans and rodents, yet it has functions on multiple target sites including the adrenal gland. In adult rodents, leptin has been shown to inhibit adrenal steroidogenesis and we have recently demonstrated that some of the mechanisms responsible for leptin-induced inhibition of adrenal glucocorticoid production, namely a reduction of StAR protein expression are already present in the neonatal adrenal gland. The effect of leptin on the neonatal adrenal gland integrates well with the previously demonstrated effect of this protein to inhibit stress responses, enhance glucocorticoid receptor expression in the CNS and sensitivity to glucocorticoid inhibitory feedback in neonates.

Inhibition of steroidogenic response to adrenocorticotropin by leptin: implications for the adrenal response to maternal separation in neonatal rats.

Previous studies have shown that leptin can regulate the adrenocortical axis. Neonatal rodents exhibit a period of adrenal hyporesponsiveness to stress in the first 2 wk of life, and we determined the role of leptin as a mediator of this process. We examined the direct effects of leptin on neonatal adrenal steroidogenic responses to ACTH under basal conditions and after 24-h maternal separation.