Sigma receptor ligands and imidazoline secretagogues mediate their insulin secretory effects by activating distinct receptor systems in isolated islets.
The effects of two potent sigma receptor agonists (+)-3-PPP ((R)-3-(3-hydroxyphenyl)-N-(1-propyl)piperidine) and DTG (N,N'-di-(o-tolyl)guanidine) on the insulin secretory responses in rat islets of Langerhans were investigated. Both sigma receptor ligands were able to potentiate the insulin secretory response of islets incubated at 6 mM glucose, in a dose-dependent manner and were also able to reverse the effects of diazoxide on insulin release. When islets were treated with efaroxan, a well-characterised imidazoline insulin secretagogue, and either (+)-3-PPP or DTG together, there was an unexpected and profound absence of stimulation of insulin release as compared to when islets were incubated with each compound alone. Experiments performed with islets where there was desensitization of DTG/sigma receptor or efaroxan/imidazoline binding site mediated responses suggest that at least two distinct receptor systems appear to be involved. The complex interactions of these two classes of drug require further investigation.
Department of Biological Sciences, Keele University, Staffs, UK. s.l.f.chan@biol.keele.ac.uk
S L
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Chan
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Morgan
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001386:Azides / Q000494:pharmacology; D001572:Benzofurans / Q000494:pharmacology; D018491:Dopamine Agonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006146:Guanidines / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D054755:Imidazoline Receptors; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism*; D008024:Ligands; D008297:Male; D010880:Piperidines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011955:Receptors, Drug / Q000187:drug effects*; D017480:Receptors, sigma / Q000187:drug effects*
D000317:Adrenergic alpha-Antagonists; D001386:Azides; D001572:Benzofurans; D018491:Dopamine Agonists; D006146:Guanidines; D007093:Imidazoles; D054755:Imidazoline Receptors; D007328:Insulin; D008024:Ligands; D010880:Piperidines; D011955:Receptors, Drug; D017480:Receptors, sigma; C055550:1-(4-azido-2-methylphenyl)-3-(2-methylphenyl)guanidine; C026539:preclamol; C062597:efaroxan