5-HT1A and 5-HT1C/1D receptor agonists produce reciprocal effects on male sexual behavior of rhesus monkeys.

Research has indicated that serotonin (5-HT) is involved in regulating male sexual behavior in rodent, as well as primate species. The present study was designed to further characterize 5-HT influences on male sexual behavior of rhesus monkeys. Experiment 1 examined the effects of 5-HT1A and 5-HT1C/1D receptor stimulation on penile erections and yawning behavior. Administration of the 5-HT1C/1D receptor agonist, m-chlorophenylpiperazine (m-CPP, 0.8 and 3.0 mg/kg), facilitated the occurrence of penile erection, and at doses greater than 0.2 mg/kg stimulated yawning. By contrast, the 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT, 0.01-0.2 mg/kg) did not significantly influence penile erections or yawning behavior. Experiment 2 evaluated the effects of m-CPP and 8-OH-DPAT on the behavior of male monkeys in the presence of a sexually receptive female monkey which the males could see, hear and smell, but not physically contact. Administration of m-CPP along with presentation of a receptive female stimulated penile erections to a greater extent than they were stimulated by either one of these manipulations alone. Administration of 8-OH-DPAT (0.1 and 0.2 mg/kg) produced a decrease in the percent of monkeys exhibiting penile erections in the presence of the female. In this experiment, yawning was affected in opposite directions, with m-CPP stimulating and 8-OH-DPAT decreasing the frequency of yawning. Experiment 3 assessed the effects of m-CPP on male copulatory behavior of rhesus monkeys. Administration of m-CPP (0.8-3.0 mg/kg) produced a dose-dependent decline in the percent of males initiating copulation and achieving ejaculation.(ABSTRACT TRUNCATED AT 250 WORDS)