Hormonal control of fat-body glycogen mobilization for locust flight

Fat-body phosphorylase in locusts injected with adipokinetic hormone (AKH I) is highly activated, as revealed by the relative proportions of the three forms present. Activation of phosphorylase during flight is strongly reduced when locusts are ligated at the neck, indicating that this activation is due to a factor from the head, which upon flight is released into the hemolymph. Flight-induced activation of phosphorylase is prevented when the release of AKH from the corpus cardiacum is blocked by the presence of high trehalose levels in the hemolymph, and also when the production of AKH is made impossible by prior removal of the corpus cardiacum glandular lobe. These results are discussed in relation to the possible involvement of AKH in the control of fat-body phosphorylase activity during flight.