Title: Corazonin: a role in stress physiology?
Authors: Boerjan, Bart
Cardoen, Dries
De Loof, Arnold
Huybrechts, Jurgen
Schoofs, Liliane #
Issue Date: 2009
Conference: INC conference location:India date:january 2009
Abstract: Corazonin was originally isolated by Veenstra (1989) from an extract of corpora cardiaca of the American cockroach as a potent in vitro cardiostimulant. It is active at concentrations as low as 0.2 nM. It shows sequence similarities with some members of the AKH/RPCH family of peptides, and with α-MSH (Tawfik et al., 1999). A few more isoforms have been discovered since. Corazonin has been identified in all insect orders, except in the Coleoptera, in a tick and in some crustaceans.

This almost ubiquitous distribution suggests a well-conserved role in arthropod physiology. In addition to its selective myotropic effects, some other functions have been reported, but usually in selected species only. It reduces the spinning rate in Bombyx, it acts as dark pigmentotropin in locusts, it promotes tegumentary pigment migration in the crayfish Procambarus clarkii, it is part of the circadian clock (output signal), it plays a role in ecdysis initiation in Manduca, in controlling behavior of locusts (towards gregarization), in changing morphometrics, and it increases the number of antennal sensillae in Schistocerca. Whether some of its degradation products ([Dopa(5),His(7)]-corazonin) serve as a source of a putative maternal egg foam gregarization factor of locusts remains to be verified.

An albino mutant of Locusta (the Okinawa strain of S. Tanaka), which is deficient in intact corazonin, develops quite normally. This suggests that none of the documented roles of corazonin is indispensable for survival, at least not in locusts. Thus, a non-vital function may be envisaged.

An accidental observation gave a hint in the direction of a possible role in stress physiology. A relatively large number of last stadium nymphs of Schistocerca had been caged in high density in a small box for over a week. These animals turned much more black than regular crowd-reared (gregarious) animals, and evidently than isolated-reared ones This raised the idea that, perhaps, corazonin plays a role in population-density stress.

A number of experiments were carried out, ranging from monitoring cuticular darkening at increasing crowding densities and at higher and lower ambient temperatures, to monitoring the effects of injections of corazonin on the duration of the last nymphal instar, on the volume prothoracic glands (which are better developed in isolated-reared locusts), and on female reproduction.
Publication status: accepted
KU Leuven publication type: IMa
Appears in Collections:Animal Physiology and Neurobiology Section - miscellaneous
Department of Biology - miscellaneous
# (joint) last author

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