Choline increases serum insulin in rat when injected intraperitoneally and augments basal and stimulated aceylcholine release from the rat minced pancreas in vitro.
Intraperitoneal injection of choline (30-90 mg.kg-1) produced a dose-dependent increase in serum insulin, glucose and choline levels in rats. The increase in serum insulin induced by choline (90 mg.kg-1) was blocked by pretreatment with the muscarinic acetylcholine receptor antagonists, atropine (2 mg.kg-1), pirenzepine (2 mg.kg-1) and 4-diphenylacetoxy-N-methylpiperidine (2 mg.kg-1) or the ganglionic nicotinic receptor antagonist, hexamethonium (15 mg.kg-1). The effect of choline on serum insulin and glucose was enhanced by oral glucose administration (3 g.kg-1). Choline administration was associated with a significant (P < 0.001) increase in the acetylcholine content of pancreatic tissue. Choline (10-130 microm) increased basal and stimulated acetylcholine release but failed to evoke insulin release from the minced pancreas at considerably higher concentrations (0.1-10 mm). Hemicholium-3, a choline uptake inhibitor, attenuated the increase in acetylcholine release induced by choline augmentation. Choline (1-32 mm) inhibited [3H]quinuclidinyl benzilate binding to the muscarinic receptors in the pancreatic homogenates. These data show that choline, a precursor of the neurotransmitter acetylcholine, increases serum insulin by indirectly stimulating peripheral acetylcholine receptors through the enhancement of acetylcholine synthesis and release.
Ilcol
Yesim Ozarda
YO
Department of Biochemistry, Uludag University Medical School, 16059 Gorukle Kampusu, Bursa, Turkey. yesim@uludag.edu.tr
Gurun
M Sibel
MS
Taga
Yavuz
Y
Ulus
Ismail H
IH
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D002794:Choline / Q000008:administration & dosage* / Q000097:blood; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology; D066298:In Vitro Techniques; D007274:Injections, Intraperitoneal; D007328:Insulin / Q000097:blood*; D008297:Male; D018727:Muscarinic Antagonists / Q000494:pharmacology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D010179:Pancreas / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D001786:Blood Glucose; D007328:Insulin; D018727:Muscarinic Antagonists; D018733:Nicotinic Antagonists; D005947:Glucose; D002794:Choline; D000109:Acetylcholine