Crustacean cardioactive peptide in the Chagas’ disease vector, Rhodnius prolixus: Presence, distribution and physiological effects

Crustacean cardioactive peptide (CCAP), a cyclic nonapeptide (PFCNAFTGCamide), has multifunctional roles in insects including stimulating visceral and cardiac muscle contraction, and regulating ecdysis. Previously, we have sequenced the cDNA for CCAP from Rhodnius prolixus central nervous system (CNS) and shown expression of the CCAP transcript in neurons of the CNS. In the present study, we have biochemically identified and sequenced CCAP from 5th instar R. prolixus CNS using matrix-assisted laser desorption ionization-time of flight-tandem mass spectrometry, and mapped CCAP-like immunoreactivity in the CNS and peripheral tissues of 5th instar R. prolixus. Physiologically, the hindgut of R. prolixus was found to be sensitive to CCAP, showing dose-dependent increases in contractions with threshold at 5 × 10−9 M and maximum response at 10−7 M CCAP. Also, CCAP was found to increase the frequency of the heartbeat in a reversible, dose-dependent manner, with threshold close to 10−11 M and maximum response at 10−10 M CCAP.

► Sequence of CCAP in the CNS of Rhodnius prolixus, confirmed by mass spectrometry.
► CCAP has been localized in central and peripheral nervous systems.
► CCAP increases hindgut contraction and heart rate in a dose-dependent manner.