Tests of potential adipokinetic hormone precursor related peptide (APRP) functions: Lack of responses

The adipokinetic hormone (AKH) precursor related peptides (APRPs) are end p roducts of the synthesis of the web-conserved AKHs. The large amount of met abolic energy devoted to APRP synthesis suggests they have an important fun ction(s) in the insects. Several functions have been proposed, but currentl y none are known. We tested whether the APRPs stimulate hyperlipemia, hyper trehalosemia, fat body glycogen phosphorylase activation, Malpighian tubule secretion, and hindgut myotropia. Surprisingly none of these responses wer e stimulated by APRPs isolated from the lubber grasshopper, Romalea micropt era (= guttata). In addition, the APRPs delivered in concert with AKHs did not significantly increase hyperlipemia, hypertrehalosemia, or phosphorylas e activation over the AKHs alone. Our data discount several proposed functi ons for the APRPs. (C) 1999 Wiley-Liss, Inc.