Early events in peptide-stimulated ecdysteroid secretion by the prothoracic glands of Manduca sexta.

The prothoracic glands of the tobacco hornworm, Manduca sexta, have been an advantageous model for investigating the cellular mechanisms underlying hormone-stimulated ecdysteroid secretion in insects. The cerebral neuropeptide prothoracicotropic hormone (PTTH) is currently thought to activate the prothoracic glands via a calcium-dependent increase in cAMP synthesis, activation of cAMP-dependent protein kinase, and protein phosphorylation (Gilbert et al.: Bioessays, 8:153-158, '88). The present paper discusses current research regarding early changes in cell function elicited by PTTH, with emphasis on the regulation of cAMP synthesis and degradation and the involvement of translational events in PTTH action.