title: Effects of muscarinic blockade on insulin secretion and on glucose-induced thermogenesis in lean and obese human subjects.
abstract: To determine whether hyperinsulinaemia of human obesity is dependent on the activity of the parasympathetic nervous system, and whether activation of the parasympathetic nervous system plays a role in glucose-induced thermogenesis, the metabolic effect of a continuous intravenous glucose infusion [44.4 mumol kg-1 body weight (bw) min-1] with or without atropine infusion was assessed in 11 obese patients and 10 lean controls. Compared with lean controls, obese patients had increased basal and glucose-stimulated plasma insulin and C-peptide concentrations and increased plasma glucose concentrations during glucose infusion. Glucose oxidation during i.v. glucose was lower in obese patients than in lean controls. Glucose-induced thermogenesis was similar in obese patients and in lean controls. Atropine infusion did not affect basal plasma glucose, insulin or free fatty acid concentrations nor glucose-stimulated plasma glucose, insulin, C-peptide, glucagon or free fatty acid concentrations in both groups of subjects. Glucose and lipid oxidation rates and glucose-induced thermogenesis were also unaffected by atropine administration. It is concluded that (1) glucose-stimulated hyperinsulinaemia in human obesity is not dependent on a hyperactivity of the parasympathetic nervous system, which indicates that human obesity is different from most animal models of obesity; (2) glucose-induced thermogenesis is similar in obese and lean subjects when a similar load of glucose is administered; (3) inhibition of the parasympathetic nervous system does not affect the thermic effect of i.v. glucose.
authors.affiliation: Institute of Physiology, Lausanne, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Schneeberger
authors.forename: L
authors.initials: L
authors.lastname: Tappy
authors.forename: E
authors.initials: E
authors.lastname: Temler
authors.forename: E
authors.initials: E
authors.lastname: Jequier
mesh_terms: D000328:Adult; D001285:Atropine / Q000494:pharmacology; D001786:Blood Glucose / Q000378:metabolism; D001833:Body Temperature Regulation / Q000187:drug effects / Q000502:physiology; D002096:C-Peptide / Q000097:blood; D005260:Female; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D006946:Hyperinsulinism / Q000209:etiology; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D007333:Insulin Resistance; D000078790:Insulin Secretion; D008297:Male; D009765:Obesity / Q000150:complications / Q000503:physiopathology*; D010275:Parasympathetic Nervous System / Q000187:drug effects / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D001285:Atropine; D005947:Glucose