Effect of a Trehalase Inhibitor, Validoxylamine A, on Oocyte Development and Ootheca Formation in Periplaneta americana (Blattodea, Blattidae)

Abstract

Injection of a specific trehalase inhibitor, validoxylamine A(VAA), suppressed oocyte development in the American cockroach, Periplaneta americana. Ootheca formation was also affected by the same treatment. Inhibition of trehalases of ovaries and thoracic muscles in P. americana in vitro by VAA was very strong; I50 values were 5.0×10-9 M and 1.4×10-8 M, respectively. When the inhibition of trehalase activity was measured after injection of VAA(5 and 50 μg/insect) into cockroaches, more than 90% of the activity in the ovaries was inhibited. The high level of inhibition lasted 2 weeks at the higher dosage, but recovery activity was observed in the second week following the injection of the lower dosage. VAA injection also inhibited the muscular trehalase but to a lesser degree than the ovarian trehalase. Enhancement of haemolymph trehalose concentration and the maintenance of its higher level after the injection of VAA suggested strong inhibition of trehalase in various tissues of the cockroach. It is speculated that the uptake of materials required for oocyte development as well as the energy supply was prevented through the inhibition of trehalase.