Effect of cycloheximide on eclosion hormone sensitivity and the developmental appearance of the eclosion hormone and cGMP regulated phosphoproteins in the CNS of the tobacco hornworm, manduca sexta

The neuropeptide, eclosion hormone (EH), triggers ecdysis behavior at the end of each molt in Manduca sexta. Previous studies have shown that the action of EH is mediated by an increase in cGMP and is associated with the phosphorylation of two proteins, named the EGPs. The ability of insects to respond to EH is developmentally regulated with sensitivity being first seen at about 8 hr prior to the normal time of ecdysis. The EGPs are also first detectable in the CNS at 8 hr prior to ecdysis, suggesting that it is their synthesis which determines EH sensitivity. The protein synthesis inhibitor, cycloheximide was used to study the development of the events leading to pupal ecdysis in Manduca. The results of these experiments suggest that protein synthesis is necessary about 10 hr before ecdysis for both the development of EH sensitivity and for the appearance of the EGPs.