Glycerol dynamics and metabolism during flight of the locust, Locusta migratoria

• Published in: Insect biochemistry Vol. 13; no. 1; pp. 45 - 55
• Main Authors: Van der Horst, D.J., Abbink, J.H.M., Van Doorn, J.M., Van Marrewijk, W.J.A., Beenakkers, A.M.Th
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1983
• Subjects: flight; energy supply; lipid metabolism; adipokinetic hormone; Locusta migratoria; trehalose; turnover; glycerol
• ISSN: 0020-1790
• DOI: 10.1016/0020-1790(83)90063-X

On the initiation of flight activity in Locusta migratoria, the concentration of glycerol in the flight muscles is rapidly elevated to six times the basal level, while in the fat body the glycerol concentration is increased nearly 50-fold. In the haemolymph, a steady state concentration of glycerol is maintained at the resting level during the initial 20 min of flight. A second steady state is attained after a further 40 min of flight when the concentration increases to six times that of the resting value. Minimal turnover rates of the haemolymph glycerol pool at both steady state levels during flight are 6.3 and 18.7 μ-mole glycerol/ml haemolymph per hr, respectively, corresponding with a 2.5- and 7-fold acceleration of the glycerol turnover in unflown insects. In the haemolymph, the main products of injected [U- 14C]-glycerol are diacylglycerol and trehalose, both during flight and at rest, as well as after injection of adipokinetic hormone, though the quantitative incorporation of radioactivity differs. In the fat body, a considerable proportion of the radiolabel is recovered in triacylglycerol as well. It is suggested that during prolonged flight, when diacylglycerol is the major fuel, the glycerol liberated by lipolysis in the flight muscles and re-esterified with free fatty acids in the fat body accounts for the balance between triacylglycerol mobilization and diacylglycerol oxidation. Conversion of glycerol to trehalose is only of limited quantitative importance for flight muscle energy supply.