PEPTIDES WITH HYPERGLYCEMIC ACTIVITY FROM THE CEPHALIC NEUROENDOCRINE SYSTEM OF APIS MELLIFERA: BIOCHEMICAL CHARACTERIZATION AND COMPARISON WITH PRAWN RED PIGMENT-CONCENTRATING HORMONE AND LOCUST ADIPOKINETIC HORMONE (INSECT NEUROPEPTIDES, HONEYBEE).

摘要

Shrimp red pigment concentrating hormone (RPCH) and locust adipokinetic hormone I (AKH I) are known to elicit hyperlipidemia in locusts, concentrate shrimp erythrophores and elevate hemolymph carbohydrate in cockroaches. Data reported here show AKH II is also hyperglycemic in cockroaches. Peptides with comparable activity have not previously been found in the Hymenoptera. These data show that a peptide is extractable from the honeybee Apis mellifera brain-CC-CA complex sharing the hyperglycemic and chromatophorotropic activities of RPCH/AKH peptides and a similar elution profile on Sephadex G-25 columns. The hyperglycemic activity of Apis hyperglycemic peptide (AHP) is heat stable, resistant to oxidation and is destroyed by proteolytic enzymes. Paper electrophoresis of partially purified AHP suggests a net negative charge at neutral and basic pH while gel filtration suggests a molecular weight between 1400 and 3000 daltons.; Purification of two peptides, AHP I and AHP II, was accomplished after water extraction of 584g of lyophilized Apis heads by preparative Sephadex G-25 chromatography, butanol extraction and C-8 and C-18 reverse phase HPLC. Both purified peptides remained contaminated with non-peptide material as evidenced by UV spectral analysis and by a single peptide contaminant on thin layer plates. Amino acid analysis of AHP I and AHP II suggest them to be similar peptides of approximately 2760 daltons. Attempts to elicit hyperglycemia or hyperlipidemia in honeybees in vivo using partially purified AHP were unsuccessful. The question of the similarity or dissimilarity of AHP peptides with RPCH/AKH peptides and with mammalian glucagon is discussed.; The bioassay of hyperglycemia-inducing peptides in the cockroach Periplaneta americana is also examined quantitatively for adherence to a linear regression model. Per cent change in total hemolymph carbohydrate when regressed on log-dose was found to adequately describe the response to RPCH, AKH I and partially purified AHP with sufficient accuracy for quantitation of AHP during purification. Standard methods for the cockroach bioassay are described.