In vitro effects of hypothalamic-pituitary-adrenal axis (HPA) hormones on Schistosoma mansoni

The effects of in vitro treatment of cercariae, schistosomula, and adult wo rms of Schistosoma mansoni with 4 hypothalamic-pituitary-adrenal (HPA) axis hormones are described. Dehydroepiandrosterone (DHEA) had the strongest ef fect on viability. Cercariae were more susceptible to this hormone than sch istosomula and adults. Mechanically transformed schistosomula showed 100% m ortality (determined microscopically by progressive internal disorganizatio n, development of lucent areas in the cytoplasm, and progressive loss of mo tility) after 48 hr, whereas physiologically induced schistosomula were mor e resistant, maintaining viability for up to 5 days of exposure. Males were considerably less sensitive than females to the lethal action of DHEA. Whe n adult worms were paired, DHEA lethality was markedly reduced, with viabil ity beginning to decrease only after 4 days in culture. Cortisol reduced th e viability of each of the stages tested about equally. Corticotropin-relea sing hormone (CRH) and adrenocorticotropin (ACTH) did not affect the viabil ity of any stage. DHEA and cortisol significantly inhibited in vitro ovipos ition, whereas CRH and ACTH did not. DHEA and cortisol exerted their effect s on schistosome viability and oviposition in a concentration-dependent man ner. These results suggest possible new avenues for the control of schistos omiasis.