THE ALPHA(2)-ADRENOCEPTOR ANTAGONIST, (-EFAROXAN, ENHANCES ACETYLCHOLINE-RELEASE IN THE RAT CORTEX IN-VIVO())

Noradrenergic modulation of the cortical cholinergic system in vivo wa s studied by examining the effect of the selective alpha(2)-adrenocept or antagonist (+)-efaroxan on cortical acetylcholine outflow in the co nscious rat, using the microdialysis technique. (+)-Efaroxan produced a dose-dependent increase in acetylcholine outflow (up to 300% at 0.63 mg/kg) which persisted for up to 3 h and which was stereospecific. Th e results demonstrate that rat cortical acetylcholine release can be a ugmented by (+)-efaroxan and that alpha(2)-adrenoceptors may be involv ed. (+)-Efaroxan may have therapeutic potential in disorders in which cortical acetylcholine release is deficient.