Hormonal regulation of proline synthesis and glucose release in the fat body of the Colorado potato beetle, Leptinotarsa decemlineata

Abstract In the adult males of the Colorado potato beetle, Leptinotarsa decemlineata , corpora cardiaca extract injected in vivo gives rise to an increase in glucose and a decrease in alanine concentration of the haemolymph. The regulation of proline synthesis and glucose release in the fat body of the Colorado potato beetle was investigated further in vitro . Proline regulates its own synthesis by a feedback inhibition. Moreover, a factor present in extracts from the corpora cardiaca stimulates synthesis in the fat body in vitro . This effect was demonstrated with corpora cardiaca extracts from beetles, locusts and cokroaches. Also, synthetic adipokinetic hormone stimulates proline synthesis in the fat body of the Colorado beetle. In addition, a release of glucose from the fat body of the beetle could be evoked by the addition of locust and beetle corpora cardiaca extracts or synthetic adipokinetic hormone. The physiological significance of both effects is discussed.