Effects of a potent dopamine receptor agonist, RDS-127, on penile reflexes and seminal emission in intact and spinally transected rats.
Administration of RDS-127 (3.0 mg/kg) induced seminal emission within three minutes of IP injection and suppressed the display of penile reflexes in intact and spinally transected rats. In Experiment 1, RDS-127 was administered to intact, sexually experienced rats in a protocol previously demonstrated to selectively lower the ejaculatory threshold of copulating animals. The incidence of seminal emission was significantly elevated by RDS-127 but penile reflexes were present in only 8% of the drug-treated rats, compared to 59% of controls. In Experiment 2, seminal emission was induced 2.3 +/- 0.4 (S.E.) minutes from injection of RDS-127. Animals which responded to RDS-127 with multiple emissions had significantly lower ejaculation latencies during copulatory tests conducted prior to drug treatment than animals which had no or only single seminal emissions following RDS-127 injection. Spontaneous seminal emission in the 3 day period initiated 2 hours after RDS-127 injection was unaffected by the drug. Spontaneously produced plugs were approximately twice the weight of those induced by RDS-127. In Experiment 3, seminal emission was induced in spinally transected rats 1.7 +/- 0.4 minutes following RDS-127 administration, whereas drug treatment attenuated the enhancement of penile reflexes observed following midthoracic spinal transection. These experiments suggest that a spinally-mediated dopaminergic mechanism is capable of stimulating seminal emission acutely in the rat and inhibiting the display of penile reflexes by the supine animal.
D000818:Animals; D004542:Ejaculation / Q000187:drug effects*; D007189:Indans / Q000494:pharmacology*; D007192:Indenes / Q000494:pharmacology*; D008297:Male; D009115:Muridae; D010413:Penis / Q000294:innervation*; D011930:Reaction Time / Q000187:drug effects; D011954:Receptors, Dopamine / Q000187:drug effects*; D012018:Reflex / Q000187:drug effects*; D012726:Sexual Behavior, Animal / Q000187:drug effects; D013116:Spinal Cord / Q000502:physiology*
D007189:Indans; D007192:Indenes; D011954:Receptors, Dopamine; C035604:2-N,N-di-n-propylamino-4,7-dimethoxyindan