Opposite effects of 5-methoxy-N,N-di-methyl-tryptamine and 5-hydroxytryptophan on male rat sexual behavior.

A dose of 5-MeODMT, a serotonin receptor agonist, reduced the number of intromissions before ejaculation and shortened ejaculation latency in male rats, indicating facilitated sexual behavior. This effect was blocked by pindolol, a 5-HT1 receptor antagonist, but not by pirenperone or metergoline, which block 5-HT2 receptors. In contrast, 5-HTP, a serotonin precursor, increased mounts and intromissions and lengthened ejaculation latency, an effect that was additive with pindolol. Betaxolol had no effect alone or with 5-HTP. The findings suggest that stimulating 5-HT1 receptors facilitates male rat sexual behavior, while stimulating 5-HT2 receptors inhibits it.

Study at a glance

Abstract

The administration of 5-methoxy-N,N-di-methyl-tryptamine (5-MeODMT), O-2.0 mg.kg-1 SC -15 min, produced a dose-dependent facilitation of the male rat sexual behavior, as evidenced by a decrease in the number of intromissions to ejaculation and in the ejaculation latency. The effects produced by 5-MeODMT (1 mg.kg-1) were antagonized by pindolol (4 mg.kg-1 SC -30 min), but not pirenperone (0.25 mg.kg-1 SC -30 min) or metergoline (1 mg.kg-1 SC -30 min), administration. As expected, 5-HTP (25 mg.kg-1 SC -60 min) produced an increased number of mounts and intromissions to ejaculation and an increase in the ejaculation latency in benserazide (25 mg.kg-1 SC -90 min) pretreated animals. Pindolol (4 mg.kg-1) by itself produced the same effects as seen after 5-HTP administration, and the combination of these compounds produced additive effects. Betaxolol (8 mg.kg-1 SC -30 min) had no effects of its own and did not interact with 5-HTP. The results suggest that stimulation of brain 5-HT1 or 5-HT2 receptors produces facilitation and inhibition, respectively, of the male rat sexual behavior.