ORIGINAL RESEARCH—BASIC SCIENCE
A Role for Peripheral 5-HT2 Receptors in Serotonin-Induced Facilitation of the Expulsion Phase of Ejaculation in Male Rats
Article first published online: 12 SEP 2013
© 2013 International Society for Sexual Medicine
The Journal of Sexual Medicine
Volume 10, Issue 11, pages 2688–2702, November 2013
How to Cite
Ishigami, T., Yoshioka, K., Karicheti, V. and Marson, L. (2013), A Role for Peripheral 5-HT2 Receptors in Serotonin-Induced Facilitation of the Expulsion Phase of Ejaculation in Male Rats. Journal of Sexual Medicine, 10: 2688–2702. doi: 10.1111/jsm.12306
- Issue published online: 4 NOV 2013
- Article first published online: 12 SEP 2013
- Urethrogenital Reflex;
The urethrogenital reflex (UGR) is used as a physiological animal model of the autonomic and somatic activity that accompanies ejaculatory-like reflexes (ELRs). Serotonin (5-HT) plays an important role in regulating ejaculation.
To examine the effects of intraurethral 5-HT on ELRs and to examine the effects of various 5-HT receptor subtypes on the 5-HT-induced changes in the ELRs.
The effects of intraurethral infusion of 5-HT on ELRs were examined by monitoring the urethrogenital reflex in male rats. The effects of various 5-HT receptor-specific antagonists on the 5-HT-induced responses were examined.
Main Outcome Measures
Main outcome measures were urethral pressure threshold required to elicit the UGR and bulbospongiosus activity or ELRs.
Intraurethral infusion of 5-HT (10–1,000 μM) produced a dose-dependent facilitation of the UGR, i.e., decrease in threshold urethral perfusion pressure and an increase in number of ELRs. The 5-HT3 receptor antagonists tropisetron (1 and 3 mg/kg, i.v.) and ramosetron (0.1 and 1 mg/kg, i.v.), the 5-HT7 receptor antagonist SB269970 (3 mg/kg, i.v.), and the 5-HT1A receptor antagonist WAY-100635 (1 mg/kg, i.v.) all failed to inhibit 5-HT-induced facilitation of the UGR. However, ritanserin (1 mg/kg, i.v.), a nonselective 5-HT2 receptor antagonist, and xylamidine (0.01–1 mg/kg, i.v.), a peripherally restricted nonselective 5-HT2 receptor antagonist, significantly inhibited both the decrease in urethral pressure threshold and the increase in number of ELRs induced by intraurethral infusion of 5-HT.
These results suggest that in the male rat urethra, peripheral 5-HT2 receptors are involved in the 5-HT-induced facilitation of the expulsion phase of ejaculation. Ishigami T, Yoshioka K, Karicheti V, and Marson L. A role for peripheral 5-HT2 receptors in serotonin-induced facilitation of the expulsion phase of ejaculation in male rats. J Sex Med 2013;10:2688–2702.