The Effect of Cholera Enterotoxin on Steroidogenesis in Cultured Adrenal Tumor Cells

Purified cholera enterotoxin was as effective as adrenocorticotropin (ACTH) in stimulating steroidogenesis in adrenal tumor cells in tissue culture. In contrast to the rapid response to ACTH, there was a 60-min lag before increased steroidogenesis could be detected. Ten minutes of exposure to cholera toxin followed by removal of toxin resulted in maximal stimulation of steroidogenesis after incubation for 2 hr. Equine antiserum to choleragenoid or mixed gangliosides effectively blocked cholera toxin-induced steroidogenesis. Further studies suggested that cholera enterotoxin induced steroidogenesis in adrenal tumor cells by interacting with a membrane receptor distinctive from the ACTH receptor. Half maximal doses of cholera enterotoxin and ACTH produced an additive effect on steroidogenesis. There was no calcium requirement for cholera enterotoxin-induced steroidogenesis as opposed to stimulation by ACTH. A mutant cell line unresponsive to ACTH was stimulated by cholera enterotoxin.