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

The adipokinetic hormone (AKH) precursor related peptides (APRPs) are end products of the synthesis of the well-conserved AKHs. The large amount of metabolic energy devoted to APRP synthesis suggests they have an important function(s) in the insects. Several functions have been proposed, but currently none are known. We tested whether the APRPs stimulate hyperlipemia, hypertrehalosemia, fat body glycogen phosphorylase activation, Malpighian tubule secretion, and hindgut myotropia. Surprisingly, none of these responses were stimulated by APRPs isolated from the lubber grasshopper, Romalea microptera (= guttata). In addition, the APRPs delivered in concert with AKHs did not significantly increase hyperlipemia, hypertrehalosemia, or phosphorylase activation over the AKHs alone. Our data discount several proposed functions for the APRPs. Arch.