Dissociation of the Prothoracic Glands of Manduca Sexta into Hormone-Responsive Cells

Prothoracicotropic hormone (PTTH) is a cerebral neuropeptide which stimulates the synthesis of the steroid prohormone, ecdysone, by the insect prothoracic glands. In the tobacco hornworm, Manduca sexta, both calcium and cAMP have been found to play important roles in the steroidogenic action of PTTH (see Smith and Gilbert, 1986). These second messengers appear to act sequentially, with PTTH stimulating a calcium-dependent increase in cAMP formation, and the cyclic nucleotide in turn activating cAMP-dependent protein kinase and protein phosphorylation in a calcium-independent manner.