Hyperglycemia induced by intracerebroventricular choline: involvement of the sympatho-adrenal system.
Intracerebroventricular (i.c.v.) injection of choline (75-300 microg) produced a dose-dependent increase in blood glucose levels. Pre-treatment with the nicotinic acetylcholine receptor antagonist, mecamylamine (50 microg, i.c.v.) blocked the hyperglycemia induced by choline (150 microg, i.c.v.), but the response was not affected by pre-treatment with the muscarinic acetylcholine receptor antagonist, atropine (10 microg, i.c.v.). Pre-treatment with the neuronal choline uptake inhibitor, hemicholinium-3 (20 microg, i.c.v.), attenuated the hyperglycemia induced by choline. The hyperglycemic response to choline was associated increased plasma levels of adrenaline and noradrenaline. The hyperglycemia elicited by choline was greatly attenuated by bilateral adrenalectomy, and entirely blocked by either surgical transection of the splanchnic nerves or by pre-treatment with the alpha-adrenoceptor antagonist, phentolamine. These data show that choline, a precursor of acetylcholine, increases blood glucose and this effect is mediated by central nicotinic acetylcholine receptor activation. An increase in sympatho-adrenal activity appears to be involved in the hyperglycemic effect of choline.
Gürün
M Sibel
MS
Department of Pharmacology and Clinical Pharmacology, Uludag University Medical School, Bursa, Turkey.
Ilçöl
Yeşim Ozarda
YO
Taga
Yavuz
Y
Ulus
Ismail H
IH
D000311:Adrenal Glands / Q000187:drug effects / Q000502:physiology; D000315:Adrenalectomy; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001786:Blood Glucose / Q000187:drug effects* / Q000378:metabolism; D002794:Choline / Q000494:pharmacology*; D018678:Cholinergic Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000097:blood; D006426:Hemicholinium 3 / Q000494:pharmacology; D006943:Hyperglycemia / Q000139:chemically induced*; D007276:Injections, Intraventricular; D008297:Male; D008464:Mecamylamine / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D009638:Norepinephrine / Q000097:blood; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology; D013997:Time Factors
D001786:Blood Glucose; D018678:Cholinergic Agents; D018733:Nicotinic Antagonists; D006426:Hemicholinium 3; D008464:Mecamylamine; D001285:Atropine; D011433:Propranolol; D002794:Choline; D009638:Norepinephrine; D004837:Epinephrine; D010646:Phentolamine