INHIBITION OF FLIGHT IN PERIPLANETA-AMERICANA (LINN) BY A TREHALASE INHIBITOR, VALIDOXYLAMINE-A

Male adults of Periplaneta americana were graded into three groups acc ording to their flight activity; very active (continuous flight longer than 5 min), active (1-5 min) and inactive (shorter than 1 min). H-1- NMR analysis showed that approx. 30 mM trehalose was present in the ha emolymph of each of the above categories of untreated cockroaches. Aft er exhaustive flight, the haemolymph trehalose concentration in very a ctive individuals decreased to <10 mM. When validoxylamine A, which is reported to be a potent and specific inhibitor of trehalase in variou s organisms, was injected into the cockroaches, they were unable to co ntinue flying for >2.5 min. The trehalase activity of the flight muscl e was inhibited about 70% and the haemolymph trehalose concentration i ncreased to about 3 times the normal level without change in the other haemolymph components. Trehalose also accumulated in the tissues of t he cockroaches injected with validoxylamine A. These observations sugg est that validoxylamine A inhibits the muscle trehalase and prevents t he use of trehalose as a source of energy for flight.