D2 receptors in the paraventricular nucleus regulate genital responses and copulation in male rats.
The D2 dopamine receptor agonist quinelorane (LY-163502), microinjected into the paraventricular nucleus (PVN), affected genital response of restrained supine male rats in a biphasic dose-dependent fashion. A moderate dose (1 microgram) facilitated penile responses (intense erections and penile movements), and decreased the latency to the first response. A high dose of quinelorane (10 micrograms) facilitated seminal emission while inhibiting penile responses. The addition of the D1 antagonist SCH-23390 to the 1 microgram dose of quinelorane potentiated quinelorane's increase in seminal emission. We suggest that D1 receptors in the PVN may be antagonistic to D2 receptor-mediated seminal emission, and possibly also penile responses. In copulation tests 1 microgram quinelorane decreased mount latency, whereas 10 micrograms quinelorane increased mount and intromission latencies and slowed copulatory rate. Both 1 and 10 micrograms quinelorane, and also 1 and 10 micrograms of the mixed D1 and D2 agonist apomorphine, decreased the number of intromissions preceding ejaculation.
Eaton
R C
RC
Department of Psychology, State University of New York at Buffalo, Amherst 14260.
Markowski
V P
VP
Lumley
L A
LA
Thompson
J T
JT
Moses
J
J
Hull
E M
EM
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001552:Benzazepines / Q000494:pharmacology; D003307:Copulation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D005837:Genitalia, Male / Q000187:drug effects*; D008297:Male; D008845:Microinjections; D010052:Ovariectomy; D010286:Paraventricular Hypothalamic Nucleus / Q000502:physiology*; D010410:Penile Erection / Q000187:drug effects; D011804:Quinolines / Q000494:pharmacology*; D051381:Rats; D011954:Receptors, Dopamine / Q000187:drug effects*; D017448:Receptors, Dopamine D2
D001552:Benzazepines; D011804:Quinolines; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D004958:Estradiol; D001058:Apomorphine; C047726:quinelorane