Postmating Change in Physiology of Male Drosophila Mediated by Serotonin (5-HT)

Abstract:

Sex peptides transferred during mating from male to female fly profoundly influence the female's behavior and physiology, including an increase in the movement of eggs along the oviduct. In the male ejaculatory duct, the authors have identified peristaltic waves that travel distally with an average frequency of 0.6 Hz. The frequency of peristalsis is increased by 0.1 μM serotonin (5-HT) and completely blocked by 5-HT antagonists (IC₅₀< 1 μM). The authors also report that mating affects the male reproductive tract; peristaltic waves along the ejaculatory duct are significantly reduced postcopulation by 30%. Serotonergic neurons innervate the ejaculatory duct, but their genetic ablation does not prevent peristalsis. The authors propose that peristalsis may be modulated by serotonin circulating in the hemolymph. As serotonin is linked with attentiveness in both flies and mammals, this bioassay suggests reduced behavioral sensitivity of the male fly after mating.

Keywords::

• copulation
• ejaculation
• peristalsis
• serotonin

ACKNOWLEDGMENTS

We are grateful to Stephen Goodwin (University of Glasgow) for the gifts of fly stocks and for reading the manuscript in draft. We would like to thank MRC for their support (G0400580 to STS).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.