The Sequence of Acheta Adipokinetic Hormone and the Variation in Corpus cardiacum Content and Hyperlipaemic Response with Age

Abstract

The principle neuropeptide separated by reversed-phase liquid chromatography RP -HPLC from extracts of the corpora cardica of Acheta domesticus showed strong adipokinetic activity when injected into Acheta. The N -terminal pyroglutamate of the peptide was removed by enzymatic digestion, and the remaining peptide sequenced. The structure is identical to the peptide Grb -AKH previously described from the corpus cardiacum (CC) of Gryllus bimaculatus ( pGlu - Val - Asn - Phe - Ser - Thr - Gly - Trp - NH2). The ED50 was (0.8 pmol) and saturation was achieved with injection of 2 pmol of synthetic Grb-AKH . The time to maximum hyperlipaemic response was 90 -120 min. The response of the fat body to injected synthetic Grb- AKH doubled in 4 days during the last stadium , but was never greater than half the maximum response of the adult stage. The adult adipokinetic response doubled from the first to the fourth day then gradually declined through day 16. The increased AKH response was timecorrelated to fat storage in the larvae and to lipid diposits in the oocytes in the adult. Synthetic Grb -AKH activated glycogen phosphorylase in the fat body of Acheta. The amount of Grb- AKH present in the CC changed very little throughout the last larval stadium and through the first 9 days of the adult stage, averaging about 15 pmol/gland pair. A second peptide (a hexadecapeptide) was isolated from the CC of Acheta and sequenced. Its structure is identical to a putative diuretic hormone previously described in Acheta.