Effects of coffee components on the response of GABA(A) receptors expressed in Xenopus oocytes.
The effects of both coffee components and coffee extract on the electrical responses of GABA(A) receptors expressed in Xenopus oocytes were studied by injecting cRNAs of the alpha(1) and beta(1) subunits of the bovine receptors. The aqueous extract of coffee dose-dependently inhibited the GABA-elicited responses, whereas the lipophilic extract of coffee by diethyl ether slightly potentiated it at low doses (0.1-0.4 microL/mL) but showed inhibition at high doses (0.5-0.8 microL/mL). Theophylline inhibited the response in a noncompetitive mechanism (K(i) = 0.55 mM), whereas theobromine and trigonelline hydrochloride inhibited it in a competitive manner, K(i) = 3.8 and 13 mM, respectively. Benzothiazole, catechol, 2,4-dimethylstyrene, guaiacol, 1-octen-3-ol, sotolone, and 2,3,5-trimethylphenol potentiated the responses significantly. Potentiation elicited by guaiacol and sotolone was independent of GABA concentrations, whereas that by 1-octen-3-ol was dependent. When 1-octen-3-ol (100 mg/kg) was orally administered to mice prior to intraperitoneal administration of pentobarbital, the sleeping time of mice induced by pentobarbital increased significantly.
Hossain
Sheikh Julfikar
SJ
Department of Physics, Biology and Informatics, Faculty of Science, Yamaguchi University, Yoshida, Yamaguchi 753-8512, Japan.
Aoshima
Hitoshi
H
Koda
Hirofumi
H
Kiso
Yoshinobu
Y
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D040503:Coffea / Q000737:chemistry*; D004357:Drug Synergism; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology; D015870:Gene Expression; D009865:Oocytes / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D011963:Receptors, GABA-A / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D013805:Theobromine / Q000494:pharmacology; D013806:Theophylline / Q000494:pharmacology; D014982:Xenopus laevis; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D000470:Alkaloids; D018756:GABA Antagonists; D010936:Plant Extracts; D011963:Receptors, GABA-A; C009560:trigonelline; D005680:gamma-Aminobutyric Acid; D013806:Theophylline; D013805:Theobromine