THE PULSATILE APPEARANCE OF FMRFAMIDE-RELATED PEPTIDES IN THE HEMOLYMPH AND LOSS OF FMRFAMIDE-LIKE IMMUNOREACTIVITY FROM NEUROHEMAL AREAS OF RHODNIUS-PROLIXUS FOLLOWING A BLOOD MEAL

The release of FMRFamide-related peptides (FaRPs) from nervous tissue and corpus cardiacum/dorsal vessel and their appearance in the haemolymph of Rhodnius prolixus after a blood meal was investigated using immunohistochemistry, RIA and HPLC. Release of FaRPs was indicated by a decrease in the intensity of FMRFamide-like immunoreactive staining of neurohaemal areas associated with the retrocerebral complex and abdominal nerves, and confirmed, using RIA, by the tissue-specific decreases and appearance of FaRPs in the haemolymph. Titres of FaRPs in the haemolymph rose and fell in a pulse-like manner at fairly fixed times during the first 12 h after feeding (period of observation). Titres in the haemolymph rose from 0.88 nM to post-feeding pulse titres which ranged from 2.4 to 19.6 nM. The highest titres found in the haemolymph occurred at about 3, 6 and 10 h after feeding. Results from HPLC and RIA indicate that FaRPs may be synthesized in the nervous system and then released into the haemolymph, possibly as a mixture, which might subsequently affect various physiological processes involved in digestion and development.