Regulation of ecdysteroid biosynthesis in crayfish Y-organs: I. Role of cyclic nucleotides

✍ Scribed by Sedlmeier, Dietrich ;Fenrich, Renate

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 625 KB
• Volume: 265
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402650415

✦ Synopsis

Abstract

Ecdysteroidogenesis in crustacean Y‐organs is negatively regulated by the so‐called molt‐inhibiting hormone (MIH), which is thought to inhibit the ecdysteroid pathway either directly through phosphorylation of the key enzyme(s) and/or through action on the synthesis of these enzymes. In the present study the role of cyclic nucleotides in the mode of action of MIH in the astacuran Orconectes limosus was investigated. Orconectes Y‐organs were incubated in vitro with sinus gland conditioned medium (SGCM) and cyclic AMP (cAMP) and cyclic GMP (cGMP) levels were measured. A striking increase of cGMP values (4 to 43 pmoles/mg protein) was observed after 2 hours, whereas cAMP levels were unchanged. Using the established in vitro bioassay for the measurement of inhibitory action on ecdysteroid release from Y‐organs (Soumoff and O'Connor, '82) the potential of dBcAMP, dBcGMP, forskolin, and IBMX to diminish this release was demonstrated, suggesting a possible role of both cyclic nucleotides in the mode of action of MIH. The present findings are discussed in view of the effect of MIH‐material on cyclic nucleotide levels in crab Y‐organs (Mattson, '86). © 1993 Wiley‐Liss, Inc.