Levels of ecdysteroid-like material in adults of Nippostrongylus brasiliensis during the intestinal phase

Abstract

Total ecdysteroid-like immunoreactive material was assayed and quantified in adults of the parasitic nematode N. brasiliensis during the intestinal phase in the rat in order to detect possible physiological fluctuations in titre. Worms of the same sex isolated from one rat were pooled in order to quantify ecdysteroids using enzyme immunoassay (EIA). The concentration of ecdysteroids fluctuated during adult life according to the sex and the age of the parasite. Important differences of levels of ecdysteroid-like compounds between the two sexes of parasites 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 time of egg-laying. Following HPLC-EIA analysis, the presence of ecdysone, 20-hydroxyecdysone and apolar ecdysteroid-like material was ascertained during this peak. The physiological role and the possible origin of ecdysteroids in this nematode are discussed.

Molting, Ecdysis, and Reproduction of Trichinella spiralis Are Supported In Vitro by Intestinal Epithelial Cells

“…20-Hydroxyecdysone is the main molting hormone in insects. Nematodes synthesize ecdysteroid hormones (11,17,30), and the concentrations are high in the reproductive systems of Dirofilaria immitis and Ascaris suum (11). Experiments designed to test the influence of exogenous ecdysteroid hormones on the development and reproduction of nematodes have revealed a variety of effects.…”

Intestinal Damage in Strongyloidiasis: The Imbalance Between Cell Death and Proliferation

“…Transforming growth factor β (TGFβ), which inhibits epithelial cell proliferation and induces apoptosis, should also be considered in the mechanism, because of its high levels in different intestinal pathologies, namely, ulcerative colitis, Crohn's disease, pouchitis (40), and Bacteroides fragilis colitis (41). The direct effect of S. stercoralis on the small bowel mucosa can be related to the secreted ecdysteroids as discussed by Genta (42) and identified in other parasitic helminths (43). This hormone is structurally similar to some metabolites of human steroids (44) from which corticosteroids are known to induce apoptosis concomitant with inhibition of cell proliferation (45,46).…”