ARECOLINE REVERSES DEXAMETHASONE SUPPRESSION OF CORTISOL IN NORMAL MALES - A PILOT-STUDY

Six normal controls participated in two or three individual, intraveno us challenges (each separated by 1 week) of saline or one of two doses of arecoline at 8 AM following ingestion of 1 mg dexamethasone at 12 midnight the previous evening. Individuals differed in their subjectiv e and neuroendocrine responses to arecoline. At 2.1 mu g/kg (n = 4) or 2.8 mu g/kg (n = 1), four of five subjects evidenced dexamethone supp ression test (DST) nonsuppression, which followed the rise in prolacti n. Cholinergic side effects and nausea were minimal. At a dose of 4.2 mu g/kg, four of five subjects evidenced cortisol escape from dexameth asone suppression, which was associated with a substantial vise in pro lactin, some subjective cholinergic symptoms, and little to modest nau sea, These data are consistent with the notion that cholinergic mechan isms are involved in the escape from dexamethasone suppression. Furthe r, arecoline may be preferable to physostigmine as a cholinergic agoni st, since it appears less likely to cause marked cholinergic side effe cts and significant nausea.