Role of allatostatins in the regulation of juvenile hormone synthesis

Abstract

The identification of neuropeptides that inhibit juvenile hormone (JH) synthesis by the corpora allata (CA) has verified the existence of these allatostatins, which, from much experimental evidence, have long been postulated to occur. It also makes possible new approaches for studying the role of allatostatins in the regulation of JH synthesis. Allatostatins, localized immunocytochemically, occur in lateral neurosecretory cells of the brain that innervate the CA. Presumably their effect on the CA results from the release of allatostatins at these nerve endings. Allatostatins also occur in the hemolymph in cockroaches and have been shown to act on the CA through this pathway. The ability of allatostatins to inhibit CA depends not only on the concentration of the peptides but also on the sensitivity of the CA to them. Male Diploptera punctata were treated with JH analog following denervation of CA and implanted with a previtellogenic or vitellogenic ovary or injected with saline. Animals implanted with a vitellogenic ovary, compared to the previtellogenic ovary or saline, showed significantly increased JH synthesis by their CA and a reduced amount of allatostatin in the hemolymph. The denervated CA from these JH analog treated animals, following implantation with a previtellogenic and vitellogenic ovary, showed a tendency toward increased and decreased sensitivity, respectively, to a given dose of allatostatin in vitro compared to those from saline injected controls. Experiments such as these suggest that changes in release of allatostatins and in sensitivity of CA to them could be postulated to be major factors regulating JH synthesis in the cockroach. © 1996 Wiley‐Liss, Inc.

Immunological evidence for FGLamide‐ and W2W9‐allatostatins in the ovary of Gryllus bimaculatus (Ensifera, Gryllidae)

“…In addition to the brain, the ovary is an important stimulatory and inhibiting regulator of CA activity (Stay et al . 1994b, 1996; Bylemans et al . 1998; Unnithan et al .…”

Mass spectrometric characterization and physiological actions of VPNDWAHFRGSWamide, a novel B type allatostatin in the crab, Cancer borealis

“…The allatostatins (ASTs) belong to a part of a major neuropeptide family that is widely distributed in decapod crustaceans. ASTs were first identified in insects for their ability to inhibit the synthesis of juvenile hormone in the corpora allata (Pratt et al 1989;Woodhead et al 1989;Stay et al 1992Stay et al , 1996Lorenz et al 1995a;Bendena et al 1999;Stay 2000;Nichols et al 2002). There are three types of ASTs identified: cockroach-or A-type ASTs (with conserved C-terminus F/YXFGLamide) (Pratt et al 1989;Woodhead et al 1989), cricket-or B-type ASTs (with conserved C-terminus WXXXXXXWamide) (Schoofs et al 1991;Blackburn et al 1995;Lorenz et al 1995aLorenz et al , 2000Hua et al 1999;Predel et al 2001;Williamson et al 2001a;Wang et al 2004), and C-type ASTs (conserved C-terminus pEVRXRQCYFNPISCF) (Kramer et al 1991;Jansons et al 1996;Williamson et al 2001b) based on their distinct structural differences.…”

In vivo effects of allatostatins in crickets,Gryllus bimaculatus (Ensifera: Gryllidae)

“…The influence of the ovary on JH biosynthesis is well known in D. punctata Stay, 1983, 1985a,b;Stay and Rankin, 1986), P. americana (Weaver, 1981), B. germanica (Gadot et al, 1991), Teleogryllus commodus (Loher et al, 1987), and G. bimaculatus (Wennauer et al, 1989); more recent results indicate that the reactions of the regulatory system on JH analogue treatment are also ovary dependent (Fairbairn and Stay, 1995;Stay et al, 1996). The major release products of the ovaries are ecdysteroids, which in turn could influence JH biosynthesis.…”