The adrenal androgen dehydroepiandrosterone (DHEA) is produced in the inner zone of the adrenal cortex which is in direct contact to adrenal medullary cells. Due to their close anatomical proximity and tightly intermingled cell borders a direct interaction of adrenal cortex and medulla has been postulated. In humans congenital adrenal hyperplasia due to 21-hydroxylase (OH) deficiency results in androgen excess accompanied by severe adrenomedullary dysplasia and chromaffin cell dysfunction. Therefore, in order to define the mechanisms of DHEA action on chromaffin cell function, we investigated its effect on cell survival and differentiation processes on a molecular level in the chromaffin cell line PC12.

DHEA lessened the positive effect of NGF on cell survival and neuronal differentiation. NGF-mediated induction of a neuronal phenotype was inhibited by DHEA as indicated by reduced neurite outgrowth and decreased expression of neuronal marker proteins such as SNAP-25 and VAMP-2. We examined whether DHEA may stimulate the cells towards a neuroendocrine phenotype. DHEA significantly elevated catecholamine release from unstimulated PC12 cells in the presence, but not in the absence of NGF. Accordingly, DHEA enhanced the expression of the neuroendocrine marker protein chromogranin A. Next, we explored the possible molecular mechanisms of DHEA and NGF interaction. We demonstrate that NGF-induced ERK1/2 phosphorylation was reduced by DHEA.

In summary, our data show that DHEA influences cell survival and differentiation processes in PC12 cells, possibly by interacting with the ERK1/2 MAPK pathway. DHEA drives NGF-stimulated cells towards a neuroendocrine phenotype, suggesting that the interaction of intraadrenal steroids and growth factors is required for the maintenance of an intact adrenal medulla.