RT Journal Article
SR Electronic
T1 D2/D1 ratio in the medial preoptic area affects copulation of male rats.
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 422
OP 427
VO 251
IS 2
A1 E M Hull
A1 R K Warner
A1 T J Bazzett
A1 R C Eaton
A1 J T Thompson
A1 L L Scaletta
YR 1989
UL http://jpet.aspetjournals.org/content/251/2/422.abstract
AB The D1/D2 dopamine agonist apomorphine, microinjected into the medial preoptic area (MPOA), facilitates male rat sexual behavior and the D1/D2 antagonist cis-flupenthixol in the MPOA impairs it. The present study investigated the roles of D1 and D2 receptors in the regulation of copulation by microinjecting drugs selective for these receptors into the MPOA. The D2 agonist LY-163502 delayed the onset and slowed the rate of copulation and also reduced the number of vaginal intromissions required to trigger ejaculation (reduced ejaculatory threshold). The D1 agonist SKF-82526 had no effect, either alone or together with LY-163502. The D1 antagonist SCH-23390 delayed the onset of copulation and decreased ejaculatory threshold, as had the D2 agonist. A low dose of the D2 agonist alone and together with the D1 antagonist delayed the onset of copulation and reduced ejaculatory threshold; the combination of drugs was more effective than LY-163502 alone. Only the combination of drugs slowed the rate of copulation and delayed the resumption of copulation after an ejaculation. Thus, increasing the D2/D1 ratio in the MPOA, by selective stimulation of D2 and/or antagonism of D1 receptors, delays the onset of copulation and reduces ejaculatory threshold, possibly by altering autonomic control of penile reflexes.