Comparison of proctolin and fmrfamide actions on the motility of male and female beetle reproductive tracts

Authors:

• Paweł Marciniak,
• Grzegorz Rosiński

Abstract

Two myotropic peptides, proctolin and FMRFamide, were tested for their action on the frequency of contractions of the the male ejaculatory duct and female oviduct of two beetle species: Tenebrio molitor and Zophobas atratus. The tested peptides caused changes in endogenous contraction frequencies of the reproductive tracts in both species. Proctolin exerted a strong stimulatory effect on spontaneous muscular contractions of the ejaculatory ducts and oviducts of T. molitor and Z. atratus. FMRFamide action, however, differed between species and organ tested. At high doses (10⁻⁷–10⁻⁵ M) it stimulated oviduct contractions in Z. atratus but inhibited the T. molitor oviduct contractility. In T. molitor, the peptide had a stimulatory effect on oviduct contractions at low doses (10⁻¹¹–10⁻⁹ M). In contrast to proctolin, FMRFamide is a weak inhibitor of the ejaculatory ducts of both beetles at high concentrations (10⁻⁶–10⁻⁵ M). Differentiated responses of the ejaculatory ducts and oviducts of T. molitor and Z. atratus suggest that these peptides are functional and specific regulators of both reproductive tracts. © 2010 Taylor & Francis Group, LLC.