Hypolipemia, hypoglycemia, and inactivation of glycogen phosphorylase in Locusta migratoria

Abstract

AbstractFeeding starved adult migratory locusts, Locusta migratoria, caused decreases of hemolymph lipid concentrations and of the percentage of active fat body glycogen phosphorylase which suggested that a molecule(s) from the neurosecretory system or the midgut may have been released to regulate metabolism. Fat body phosphorylase was also inactivated after insects were transferred from 0 to 25 ° C. In adults with elevated hemolymph lipid levels after the injection of small doses of corpus cardiacum extract (CC), feeding did not induce a decrease in hemolymph lipid concentrations. It appears that the processes initiated by feeding could not override the effects of the continued presence of adipokinetic hormone(s) (AKHs) in the hemolymph or their long‐term effects.Aqueous, methanolic, or ethanolic extracts of brains or storage lobes (SL) of fed locust CC did not lead to decreases of hemolymph lipid concentrations. Bovine insulin was equally inactive when tested at doses which were previously reported to reduce lipid levels. Fractions of ethanolic brain extracts from 3‐day‐starved males collected after high‐performance size‐exclusion chromatography, however, produced hypoglycemic effects in fed males. Two biologically active fractions were found, one with high (≥ 10 kDa) and one with low molecular weight (approximately 1 kDa). © 1995 Wiley‐Liss, Inc.