Assessment of the role of cyclic nucleotides in allatostatin-induced inhibition of juvenile hormone biosynthesis in Diploptera punctata

Abstract

In an effort to identify the signal transduction mechanism associated with the inhibition of juvenile hormone (JH) biosynthesis by the neuropeptides allatostatins, levels of the cyclic nucleotides cAMP and cGMP were measured in corpora allata (CA) of virgin and mated Diploptera punctata females using radioimmunoassays. Treatment of isolated CA with varying concentrations of synthetic allatostatins 1, 2, 3 or 4 did not elicit significant changes in the levels of either cAMP or cGMP in any of the test glands, suggesting that these compounds do not act as second messengers for the four allatostatins tested. Simultaneous treatment of CA with allatostatin 4 and the adenylate cyclase activator forskolin did not increase the degree of inhibition of juvenile hormone biosynthesis relative to that obtained with forskolin (5 or 50 μM) alone. We interpret these results as lending further support to the suggestion that cyclic nucleotides do not play a role in the signal transduction of allatostatins 1–4 in cockroach CA.