NITRIC-OXIDE PROMOTES MEDIAL PREOPTIC DOPAMINE RELEASE DURING MALE-RAT COPULATION

DOPAMINE (DA) is released in the medial preoptic area (MPOA) of male r ats during copulation. DA agonists infused into the MPOA facilitate, a nd antagonists impair, copulatory behavior. Local administration of th e nitric oxide (NO) precursor L-arginine also increases DA release in the MPOA. The present experiment used microdialysis to test whether NO promotes DA release during copulation. Males received either an synth esis inhibitor, nitro-L-arginine methyl (L-NAME, 400 mu M), or its ina ctive isomer D-NAME (400 mu M) into the MPOA via a microdialysis probe for 3 h prior to the introduction of a female. Following D-NAME admin istration, DA increased during copulation, while L-NAME prevented this increase. NO may therefore promote DA release in the MPOA of male rat s, thereby facilitating copulation.