ISOLATION AND CHARACTERIZATION OF AN ADIPOKINETIC HORMONE RELEASE-INDUCING FACTOR IN LOCUSTS - THE CRUSTACEAN CARDIOACTIVE PEPTIDE

A methanolic extract of 700 desert locust (Schistocerca gregaria) brai ns contains several factors that stimulate the in vitro release of adi pokinetic hormone (AKH) by glandular cells of locust (Locusta migrator ia and Schistocerca gregaria) corpora cardiaca. The most potent one ha s now been fully identified. Matrix-assisted laser desorption ionizati on mass spectrometry-time of flight analysis revealed a mass of 954.6 Da. The primary structure of the peptide, Pro-Phe-Cys-Asn-Ala-Phe-Thr- Gly-Cys-NH2, appeared identical to that of a previously identified cru stacean cardioactive peptide. This myotropin was first isolated from t he shore crab, Carcinus maenas, and later from several insect species, but was never reported in the context of AKH release. The present stu dy shows that synthetic crustacean cardioactive peptide induces the re lease of AKH from corpora cardiaca in a dose-dependent manner when tes ted in concentrations ranging from 10(-5)-10(-9) M. This is the first demonstration in invertebrates of a peptide neurohormone controlling t he release of a second peptide hormone.