Serotonergic influences on male sexual behavior of rhesus monkeys: effects of serotonin agonists.
Although numerous studies in rats have demonstrated an influence of serotonin (5-HT) on male copulation, no studies have yet to demonstrate whether such a relationship exists in primate species. The present study sought to characterize 5-HT influences on male copulatory behavior of rhesus monkeys by using three different 5-HT agonists: a full 5-HT1A agonist, 8-hydroxy-2-(din-propylamino) tetralin (8-OH-DPAT); a partial 5-HT1A agonist, ipsapirone; and a 5-HT 1C/ID agonist, m-chlorophenylpiperazine (m-CPP). 8-OH-DPAT had a biphasic effect upon ejaculation latency, with low doses (5-10 micrograms/kg) producing a shortening of ejaculation latency (time from initiation of copulation to ejaculation), and the highest dose (100 micrograms/kg) producing a lengthening of ejaculation latency. Intromission frequency (number of intromissions preceding ejaculation) was affected only at 10 micrograms/kg 8-OH-DPAT with monkeys requiring fewer intromissions to ejaculation at this dose. Ipsapirone administration led to a shortening of ejaculation latency at all doses tested (50-800 micrograms/kg), and a reduction in intromission frequency at 200-800 micrograms/kg ipsapirone. Administration of the 5-HT 1C/1D agonist, m-CPP, resulted in an increase in ejaculation latency at 200-400 micrograms/kg m-CPP and mount latency at 400 micrograms/kg m-CPP, but did not affect intromission frequency. In summary, stimulation of 5-HT1A receptors lowered the ejaculatory threshold of the monkeys, while stimulation of 5-HT 1C/1D receptors interfered with copulatory behavior and raised the ejaculatory threshold.(ABSTRACT TRUNCATED AT 250 WORDS)
Pomerantz
S M
SM
Department of Physiology, University of Pittsburgh School of Medicine, PA 15261.
Hepner
B C
BC
Wertz
J M
JM
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D003307:Copulation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004542:Ejaculation / Q000187:drug effects; D008253:Macaca mulatta; D008297:Male; D010879:Piperazines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D012701:Serotonin / Q000502:physiology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D012726:Sexual Behavior, Animal / Q000187:drug effects*
D010879:Piperazines; D011743:Pyrimidines; D017366:Serotonin Receptor Agonists; D012701:Serotonin; C043077:ipsapirone; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; C015068:1-(3-chlorophenyl)piperazine