LEVELS OF ECDYSTEROID-LIKE MATERIAL IN ADULTS OF NIPPOSTRONGYLUS-BRASILIENSIS DURING THE INTESTINAL PHASE

Total ecdysteroid-like immunoreactive material was assayed and quantif ied in adults of the parasitic nematode N. brasiliensis during the int estinal phase in the rat in order to detect possible physiological flu ctuations in titre. Worms of the same sex isolated from one rat were p ooled in order to quantify ecdysteroids using enzyme immunoassay (EIA) . The concentration of ecdysteroids fluctuated during adult life accor ding to the sex and the age of the parasite. Important differences of levels of ecdysteroid-like compounds between the two sexes of parasite s were noted particularly at 128 and 168 h post-infection. The peak at 128 h, present in female, but not in male worms, corresponds to the t ime of egg-laying. Following HPLC-EIA analysis, the presence of ecdyso ne, 20-hydroxyecdysone and apolar ecdysteroid-like material was ascert ained during this peak. The physiological role and the possible origin of ecdysteroids in this nematode are discussed.