IMMUNOCYTOCHEMICAL LOCALIZATION OF AN FMRFAMIDE-LIKE PEPTIDE IN THE FILARIAL NEMATODES DIROFILARIA-IMMITIS AND BRUGIA-PAHANGI

Immunocytochemical techniques were used to detect FMRFamide-like immun oreactivity in adults of the filarial nematodes Dirofilaria immitis an d Brugia pahangi. An FMRFamide-like peptide was also located in third- and fourth-stage larvae of D. immitis. Positive immunoreactivity was observed in all parasites examined, irrespective of developmental stag e. The major areas of positive immunoreactivity were located in the an terior nerve ring, lateral/dorso-ventral nerves, cephalic papillary ga nglia and lateral ganglia. No staining was seen in the intestine or go nads of any parasite. These results indicate that filarial worms posse ss a peptidergic component in their nervous system. The possible role of an FMRFamide-like peptide in the control of certain physiological e vents is discussed.