CONTROL OF HAEMOLYMPH LIPID CONCENTRATION DURING LOCUST FLIGHT - AN ADIPOKINETIC HORMONE FROM CORPORA CARDIACA

Injection of extract of locust corpora cardiaca into adult Schistocerca gregaria produces an increase in the lipid concentration of the haemolymph. The haemolymph lipid level reaches a maximum 20 to 30 min after injection and returns to the initial value after about 2 hr. The major part of the lipid increase is accounted for by an increase in the diglyceride fraction. A change also occurs in the lipoproteins of the haemolymph which is similar to the change which occurs during flight. Extracts of corpora cardiaca also stimulate the release of diglyceride from fat body into haemolymph in vitro. Haemolymph from flown locusts contains significant amounts of active material whereas haemolymph from unflown locusts does not. The active factor of the corpora cardiaca extracts is stable to boiling but is inactivated by proteolytic enzymes. It is proposed that the control of the diglyceride concentration of locust haemolymph during flight is mediated, at least in part, by a peptide hormone released from the corpora cardiaca. This hormone ('adipokinetic hormone') is assumed to act by stimulating the release of diglyceride from the fat body. © 1969.