ABSTRACT
In the adrenal tumor cell system ganglioside Gm1 inhibited cholera enterotoxin (CT)-induced steroidogenesis if it was preincubated with the toxin or added to adrenal cells 10 min before CT. In the preincubation studies a molar ratio of Gm1 to toxin of 3:1 was necessary for half-maximal inhibition of steroidogenesis. On the other hand, horse serum anticholeragenoid neutralized the steroidogenic response to cell-bound CT by 50% if it was added to adrenal monolayer cultures 15 min after the toxin. Specific antiserum was able to neutralized 20% of the toxin-induced activity even if it was added to adrenal cultures 2 h after CT. Phase contrast microscopy demonstrated that partial neutralization of the biochemical effect of CT by horse serum anticholeragenoid was accompanied by partial prevention of toxin-induced rounding of adrenal cells. Further studies showed that pretreatment of cultured adrenal cells with a maximal dose of CT increased cyclic adenosine 3'-5'-monophosphate formation in response to a maximal stimulating dose of adrenocorticotropin. This result suggested potentiation of hormonal activation of adenylate cyclase in intact adrenal tumor cells in response to CT.
