Evidence for an inhibitory role of cyclic AMP in the control of juvenile hormone biosynthesis by cockroach corpora allata.

High levels of cyclic AMP were found in the corpora allata of adult female Diploptera punctata. The adenylate cyclase activator forskolin caused a rapid, reversible and dose-dependent accumulation of cAMP in the corpora allata in vitro. The sensitivity of the corpora allata to forskolin was low when juvenile hormone (JH) synthetic activity was high, and vice versa. Incubation of corpora allata with compounds which cause or mimic elevated intracellular cAMP levels (forskolin, 3-isobutyl-1-methylxanthine, 8-bromo-cAMP) led to a rapid and dose-dependent inhibition of juvenile hormone synthesis. Glands from day 5 virgin females were more sensitive to forskolin than glands from mated females of the same age. The results suggest that a cAMP second messenger system may be responsible for the intracellular transduction of inhibitory signals to the corpora allata of D. punctata.