Cholinergic muscarinic stimulation of steroidogenesis in bovine adrenal cortex fasciculata cell suspensions.

Acetylcholine was found to acutely stimulate cortisol production by bovine fasciculata adrenocortical cell suspensions. This effect was maximal at 10(-4) M acetylcholine concentration, resulted in a 5-fold increase in cortisol production over the control after 1 h incubation, and represented about one fifth of the ACTH maximal stimulation under the same conditions. Acetylcholine-stimulated steroidogenesis was concentration-dependent (10(-8)-10(-5) M), proportional to the cell number (5 X 10(5)-1 X 10(6)) and reached a plateau after 30 min incubation. Use of various cholinergic specific agonists and antagonists showed that the steroidogenic action of acetylcholine was a typical muscarinic effect. This character is in agreement with the previously demonstrated presence of muscarinic receptors in bovine adrenocortical tissue. The steroidogenic effect of acetylcholine required the presence of extracellular calcium in the medium and was impaired upon addition of tetracaine and procaine. No change in cyclic AMP nor cyclic GMP levels could be detected in the system under acetylcholine stimulation. Acetylcholine appeared to exhibit a synergistic effect in combination with ACTH, and exogenous cyclic AMP; these observations suggest a different mechanism of action for acetylcholine and ACTH and point to a possible cholinergic participation in the regulation of adrenocortical differentiated functions in vivo.