HYPOLIPEMIA, HYPOGLYCEMIA, AND INACTIVATION OF GLYCOGEN-PHOSPHORYLASEIN LOCUSTA-MIGRATORIA

Feeding starved adult migratory locusts, Locusta migratoria, caused de creases of hemolymph lipid concentrations and of the percentage of act ive fat body glycogen phosphorylase which suggested that a molecule(s) from the neurosecretory system or the midgut may have been released t o regulate metabolism. Fat body phosphorylase was also inactivated aft er insects were transferred from 0 to 25 degrees C. In adults with ele vated hemolymph lipid levels after the injection of small doses of cor pus cardiacum extract (CC), feeding did not induce a decrease in hemol ymph lipid concentrations. It appears that the processes initiated by feeding could not override the effects of the continued presence of ad ipokinetic hormone(s) (AKHs) in the hemolymph or their long-term effec ts. Aqueous, methanolic, or ethanolic extracts of brains or storage lo bes (SL) of fed locust CC did not lead to decreases of hemolymph lipid concentrations. Bovine insulin was equally inactive when tested at do ses which were previously reported to reduce lipid levels. Fractions o f ethanolic brain extracts from 3-day-starved males collected after hi gh-performance size-exclusion chromatography, however, produced hypogl ycemic effects in fed males. Two biologically active fractions were fo und, one with high (greater than or equal to 10 kDa) and one with low molecular weight (approximately 1 kDa). (C) 1995 Wiley-Liss, Inc.