Fundamental aspects and potential roles of ecdysteroids in schistosomes an update overview.

The human digenic trematodeSchistosoma mansoni produces ecdysteroid hormones. Both ecdysone (22R)-2β,3β,14,22,25-pentahydroxy-cholest-7-en-6-one and 20-hydroxyecdysone (22R)-2β,3β, 14,20,22,25-hexahydroxycholest-7-en-6-one were detected during the critical development stages of this bisexual parasite: during the exponential growth phase to adult stage (day 11 postinfection) and during the sexual maturation of adult and egg laying (day 40 postinfection). The parasites released their ecdysteroid hormones in the biological fluids of the infected vertebrates as soon as six days postinfection. In addition, the time course of the ecdysteroid titer was correlated with the susceptibility or the innate resistance of the host to schistosome infection. Moreover, we demonstrated that after a schistomicide therapy, ecdysteroids from urine of infected children decreased markedly four days after drug administration. We also have demonstrated that immunization of rodents with an ecdysone-BSA complex led to the reduction of the worm burden. By in vitro studies, we have shown that the ecdysterone antibodies were able to kill the juvenile worms within 24 hr. In addition, we have demonstrated that the enzymes Superoxide dismutase (SOD, EC 1.15.1.1) were present in schistosomes and that the total Superoxide dismutase activities in both males and females could be correlated with the 20-hydroxyecdysone within parasites.