Central modulatory neurons control fuel selection in flight muscle of migratory locust.
Insect flight is one of the most intense and energy-demanding physiological activities. High carbohydrate oxidation rates are necessary for take-off, but, to spare the limited carbohydrate reserves, long-distance flyers, such as locusts, soon switch to lipid as the main fuel. We demonstrate that before a flight, locust muscles are metabolically poised for take-off by the release of octopamine from central modulatory dorsal unpaired median (DUM) neurons, which increases the levels of the potent glycolytic activator fructose 2,6-bisphosphate in flight muscle. Because DUM neurons innervating the flight muscles are active during rest but selectively inhibited during flight, they stimulate carbohydrate catabolism during take-off but tend to decrease muscle glycolysis during prolonged flight. cAMP-dependent protein kinase A is necessary but not sufficient for signal transduction, suggesting parallel control via a calcium-dependent pathway. Locust flight is the first reported instance of a direct and specific involvement of neuronal activity in the control of muscle glycolysis in working muscle during exercise.
Mentel
Tim
T
Institute of Biology/Neurobiology, Free University Berlin, 14195 Berlin, Germany.
Duch
Carsten
C
Stypa
Heike
H
Wegener
Gerhard
G
Müller
Uli
U
Pflüger
Hans-Joachim
HJ
D000818:Animals; D002490:Central Nervous System / Q000166:cytology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D005260:Female; D005426:Flight, Animal; D005635:Fructosediphosphates / Q000096:biosynthesis; D006019:Glycolysis; D006110:Grasshoppers / Q000378:metabolism* / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000294:innervation* / Q000378:metabolism; D009474:Neurons / Q000502:physiology*; D009655:Octopamine / Q000494:pharmacology; D015398:Signal Transduction
D005635:Fructosediphosphates; D009655:Octopamine; C027652:fructose 2,6-diphosphate; D017868:Cyclic AMP-Dependent Protein Kinases