The presence of proctolin in the reproductive system of Rhodnius prolixus

Abstract

The distribution of proctolin throughout the reproductive system of female Rhodnius prolixus has been studied using reversed-phase high-performance liquid chromatography (RP-HPLC) together with a sensitive bioassay for proctolin. The spermathecae contained the largest amount of proctolin per mg protein, followed by the common oviduct, the bursa and lateral oviducts, with the ovaries containing the lowest amount. Immunohistochemistry of the reproductive structures revealed proctolin-like immunoreactivity in terminal aborisations extending from the lateral oviducts across the common oviduct, spermathecae and along to the bursa. No immunostaining was evident on the ovaries or cement gland. The oviducts of Rhodnius are sensitive to proctolin, with exposure to proctolin producing a dose-dependent increase in muscle tonus as well as an increase in amplitude and frequency of phasic contractions. Proctolin also produces an increase in the frequency of the rhythmical contractions of the spermathecae. The results indicate that proctolin is probably involved in the regulation of events associated with reproduction in this hemipteran.