in vivo and in vitro studies on the uptake of[³H]-Cholesterol by different tissues of the gram pod borer, Helicoverpa armigera (Hubner) in the presence of sterol metabolism inhibitors-The azasteroids
Rita Rath, Versha Goel
Certain compounds such as azasteroids are known to disrupt growth and development in insects. 25-azacholestane and 25-azacoprostane, the two azasteroids tested in the present study, caused a decrease in cholesterol incorporation in the sixth instar larvae of Helicoverpa armigera which were fed [³H]-cholesterol 24 hours before sacrificing indicating that cholesterol formation as well as cholesterol incorporation is responsible for their inhibitive effect on the growth in H. armigera. In the adult females, these azasteroids caused a decrease in the cholesterol incorporation in fat body (7.2% in controls to 0.8% at 50 ppm azacholestane treatment) and ovaries (9.6% in controls to 6.9% at 50 ppm azacholestane treatment) as well as reduction in their weights. The azasteroids might in some way be affecting the ecdysteroid biosynthesis by the ovaries which in turn affects vitellogenin synthesis by the fat body and their subsequent release and uptake by the ovaries. Due to azacholestane treatment, in the in vitro studies, decrease in cholesterol incorporation by ovaries was observed but no such effect was seen in the fat body. The studies on the binding of cholesterol to the lipoproteins of hemolymph showed that maximum cholesterol binding occurred in LP-I out of six bands obtained. In the presence of azasteroid an increase in binding of cholesterol to LP-I was seen, which was reversed when additional cholesterol was given along with the azasteroid. In adult males, cholesterol incorporation decreased in fat body (4.8% in controls to 1.4% at 50 ppm azacholestane) with concomitant increase in the weight when treated with 25- azacholestane though not with 25-azacoprostane. Testes, however showed an increase in cholesterol incorporation in presence of the azasteroids both in vivo and in vitro.
Rita Rath, Versha Goel. in vivo and in vitro studies on the uptake of [³H]-Cholesterol by different tissues of the gram pod borer, Helicoverpa armigera (Hubner) in the presence of sterol metabolism inhibitors-The azasteroids. International Journal of Entomology Research, Volume 7, Issue 2, 2022, Pages 193-202