Effects of some vertebrate hormones on lipid mobilization in the insect fat body

Abstract

Several vertebrate adipokinetic hormones were studied for their effects on the release of lipids from the insect fat body, using short term in vitro procedures. ACTH was found to be without effect. Insulin inhibited the release of diglycerides and free fatty acids from the pupal fat body of H. cecropia, an effect analogous to that which it exerts on vertebrate adipose tissue. Growth hormone, gonadotropin (HCG), and thyroxine exerted a stimulatory effect on the release of diglycerides and free fatty acids; that is, they had adipokinetic effects. Epinephrine greatly stimulated the release of free fatty acids from the fat body of four species of cockroaches. In the case of fat body from pupal or adult H. cecropia, epinephrine also stimulated the rate of free fatty acid release, but had a dual effect in that it inhibited the release of diglycerides. Preliminary evidence suggests that increased lipolysis in the cockroach fat body in the presence of epinephrine may be mediated by cyclic 3′,5′-AMP.