title: Canavanine induces insulin release via activation of imidazoline I3 receptors.
abstract: The aim of the present study was to identify the effect of canavanine on the imidazoline receptor because canavanine is a guanidinium derivative that has a similar structure to imidazoline receptor ligands. Transfected Chinese hamster ovary-K1 cells expressing imidazoline receptors (nischarin (NISCH)-CHO-K1 cells) were used to elucidate the direct effects of canavanine on imidazoline receptors. In addition, the imidazoline I3 receptor has been implicated in stimulation of insulin secretion from pancreatic β-cells. Wistar rats were used to investigate the effects of canavanine (0.1, 1 and 2.5 mg/kg, i.v.) on insulin secretion. In addition the a specific I3 receptor antagonist KU14R (4 or 8 mg/kg, i.v.) was used to block I3 receptors. Canavanine decreased blood glucose by increasing plasma insulin in rats. In addition, canavanine increased calcium influx into NISCH-CHO-K1 cells in a manner similar to agmatine, the endogenous ligand of imidazoline receptors. Moreover, KU12R dose-dependently attenuated canavanine-induced insulin secretion in HIT-T15 pancreatic β-cells and in the plasma of rats. The data suggest that canavanine is an agonist of I3 receptors both in vivo and in vitro. Thus, canavanine would be a useful tool in imidazoline receptor research.
authors.affiliation: The School of Chinese Medicine for Post-Baccalaureate, I-Shou University, Yanchao, Kaohsiung City, Taiwan.
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Yang
authors.forename: Ho-Shan
authors.initials: HS
authors.lastname: Niu
authors.forename: Li-Jen
authors.initials: LJ
authors.lastname: Chen
authors.forename: Po-Ming
authors.initials: PM
authors.lastname: Ku
authors.forename: Kao-Chang
authors.initials: KC
authors.lastname: Lin
authors.forename: Juei-Tang
authors.initials: JT
authors.lastname: Cheng
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002172:Canavanine / Q000494:pharmacology*; D006224:Cricetinae; D003412:Cricetulus; D054755:Imidazoline Receptors / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D008297:Male; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001786:Blood Glucose; D054755:Imidazoline Receptors; D007328:Insulin; D002172:Canavanine; D002118:Calcium
keywords: Chinese hamster ovary-K1 cells; canavanine; imidazoline I3 receptor; insulin secretion; nischarin (NISCH)