M3-subtype muscarinic receptor activation stimulates intracellular calcium oscillations and aldosterone production in human adrenocortical HAC15 cells

Abstract A previous body of work in bovine and rodent models shows that cholinergic agonists modulate the secretion of steroid hormones from the adrenal cortex. In this study we used live-cell Ca 2+ imaging to investigate cholinergic activity in the HAC15 human adrenocortical carcinoma cell line. The cholinergic agonists carbachol and acetylcholine triggered heterogeneous Ca 2+ oscillations that were strongly inhibited by antagonists with high affinity for the M 3 muscarinic receptor subtype, while preferential block of M 1 or M 2 receptors was less effective. Acute exposure to carbachol and acetylcholine modestly elevated aldosterone secretion in HAC15 cells, and this effect was also diminished by M 3 inhibition. HAC15 cells expressed relatively high levels of mRNA for M 3 and M 2 receptors, while M 1 and M 5 mRNA were much lower. In conclusion, our data extend previous findings in non-human systems to implicate the M 3 receptor as the dominant muscarinic receptor in the human adrenal cortex.