Effects of steroids and steroid synthesis inhibitors on fecundity ofSchistosoma mansoni in vitro.

In vitro egg production bySchistosoma mansoni was examined following a 72-hr incubation period in the presence of various steroids, steroid precursors, or steroid synthesis inhibitors. Mevinolin, an inhibitor of cholesterol biosynthesis, significantly decreased egg production at 10(-6) M. However, neither cholesterol (at 10(-5) M) nor any of its hydroxylated derivatives (at 10(-4) M) affectedS. mansoni fecundity. Dianisidine, an inhibitor of cholesterol metabolism to hormonal products, was also ineffective in influencing egg production. The steroid hormones progesterone, 17α-hydroxyprogesterone and medroxyprogesterone acetate, all significantly decreased egg production; however, parasite muscle tension was also significantly reduced by the concentrations of these steroids needed to produce an effect on egg laying. Various androgenic hormones (androsterone, androstenedione, testosterone) and estrogenic hormones (17β-estradiol and estrone) demonstrated no effect on in vitro egg production. Significant elevation in the rate of parasite oviposition was seen in the presence of the corticosteroid prednisolone (at 10(-5) M), but not by dexamethasone, a corticosteroid analog.