Abstract
Paired Y‐organs secrete ecdysteroid hormones that control cycles of growth and molting in crustaceans. Y‐Organs are regulated, at least in part, by molt‐inhibiting hormone (MIH), a polypeptide produced and released by the X‐organ/sinus gland complex of the eyestalks. In the present studies, crab (Callinectes sapidus) Y‐organs were incubated in vitro in the presence of [^35^S]methionine, and cyclic nucleotide analogs or experimental agents that influence the cAMP signaling pathway. In 4‐hr incubations, 8‐Br‐cAMP and db‐cAMP (but not 8‐Br‐cGMP) suppressed incorporation of [^35^S]methionine into Y‐organ proteins; the effect of 8‐Br‐cAMP was concentration‐dependent. Autoradiograms of radiolabeled Y‐organ proteins separated on SDS‐PAGE gels indicated the effect of 8‐Br‐cAMP was general (as opposed to selective) suppression of protein synthesis. Addition of both forskolin (an adenylyl cyclase activator) and 3‐isobutyl‐1‐methylxanthine (a phosphodiesterase inhibitor) likewise suppressed incorporation of [^35^S]methionine into Y‐organ proteins. Cycloheximide (a protein synthesis inhibitor) suppressed incorporation of [^35^S]methionine into Y‐organ proteins and secretion of ecdysteroids. The combined results suggest that cAMP is involved in regulation of protein synthesis in C. sapidus Y‐organs. We are currently investigating the link of protein synthesis to ecdysteroid production, and the possibility of cross‐talk between cAMP and other cellular signaling pathways in Y‐organs. J. Exp. Zool. 305A:328–334, 2006. © 2006 Wiley‐Liss, Inc.