EFFECTS OF THE ADIPOKINETIC HORMONE ON THE RELEASE AND TURNOVER OF HEMOLYMPH DIGLYCERIDES AND ON THE FORMATION OF THE DIGLYCERIDE-TRANSPORTING LIPOPROTEIN SYSTEM DURING LOCUST FLIGHT

When the release of the adipokinetic hormone in Locusta migratoria during flight is prevented by high concentrations of haemolymph trehalose or sucrose, neither the characteristic elevation of the haemolymph diglyceride concentration nor the formation of the flight specific diglyceride-carrying haemolymph lipoproteins is observed. Nevertheless, although the transport capacity is restricted to the lipoproteins present in the resting condition, the transport rate of diglycerides through the haemolymph is elevated considerably. Continuation of flying activity in such locusts injected with extracts of corpora cardiaca and flying under trehalose or sucrose loads, resulted in a rapid increase of both the content and the turnover of the haemolymph diglycerides. This was accompanied by the formation of the specific haemolymph lipoprotein system capable of accepting the elevated lipid. It is suggested that the primary effect of the increasing adipokinetic hormone titre at the onset of normal flight is to elicit the changes in association of haemolymph protein components already present in the resting locust to form the specific lipoproteins which allow both the enhanced concentration and transport of diglycerides required for optimum energy supply for the flight muscles. In addition, the hormone may have a moderatory function in controlling fat body lipolytic processes. © 1979.