Cholera toxin induces pineal enzymes in culture.

Addition of choleragen to rat pineal organ cultures caused a long-lasting stimulation of adenylate cyclase activity, and this was followed by increases in seroton N-acetyltransferase and cyclic adenosine monophosphate phosphodiesterase activities. These effects of choleragen were not blocked by the beta-adrenoceptor antagonist propranolol, but the increases in cyclic adenosine monophosphate phosphodiesterase and serotonin N-acetyltransferase activities could be prevented by the protein synthesis inhibitor cycloheximide. The results indicate that cholera toxin can mimic the induction of pineal enzymes that normally follows beta-adrenoceptor activation and suggest that increased cyclic adenosine monophosphate is a necessary and sufficient signal for such changes in enzyme activity.