title: Activation of muscarinic M-1 cholinoceptors by curcumin to increase glucose uptake into skeletal muscle isolated from Wistar rats.
abstract: Curcumin, an active principle contained in rhizome of Curcuma longa, has been mentioned to show merit for diabetes through its anti-oxidative and anti-inflammatory properties. In the present study, we found that curcumin caused a concentration-dependent increase of glucose uptake into skeletal muscle isolated from Wistar rats. This action was inhibited by pirenzepine at concentration enough to block muscarinic M-1 cholinoceptor (M(1)-mAChR). In radioligand binding assay, the binding of [(3)H]-pirenzepine was also displaced by curcumin in a concentration-dependent manner. In the presence of inhibitors for PLC-PI3K pathway, either U73122 (phospholipase C inhibitor) or LY294002 (phosphoinositide 3-kinase inhibitor), curcumin-stimulated glucose uptake into skeletal muscle was markedly reduced. In Western blotting analysis, the membrane protein level of glucose transporter 4 (GLUT4) increased by curcumin was also reversed by blockade of M(1)-mAChR or PLC-PI3K pathway in a same manner. In conclusion, the obtained results suggest that curcumin can activate M(1)-mAChR at concentrations lower than to scavenge free radicals for increase of glucose uptake into skeletal muscle through PLC-PI3-kinase pathway.
authors.affiliation: Department of Urology, Chi-Mei Medical Center, Yong Kang, Taiwan, ROC.
authors.forename: Tse-Chou
authors.initials: TC
authors.lastname: Cheng
authors.forename: Chian-Shiung
authors.initials: CS
authors.lastname: Lin
authors.forename: Chih-Chieh
authors.initials: CC
authors.lastname: Hsu
authors.forename: Li-Jen
authors.initials: LJ
authors.lastname: Chen
authors.forename: Kai-Chun
authors.initials: KC
authors.lastname: Cheng
authors.forename: Juei-Tang
authors.initials: JT
authors.lastname: Cheng
mesh_terms: D000818:Animals; D003474:Curcumin / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000493:pharmacokinetics*; D066298:In Vitro Techniques; D008297:Male; D008657:Metabolic Clearance Rate / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D043643:Receptor, Muscarinic M1 / Q000819:agonists* / Q000378:metabolism*
chemical_list: D043643:Receptor, Muscarinic M1; D003474:Curcumin; D005947:Glucose