Co-operative effect between gamma-aminobutyric acid A receptors and central-type benzodiazepine receptors on amylase release in rat parotid acinar cells.
We investigated the inhibitory role of gamma-aminobutyric acid A (GABA(A)) receptors on amylase release and the evidence for functional coupling with central-type benzodiazepine receptors in rat parotid acinar cells. Muscimol and GABA decreased isoprenaline-induced amylase release. This effect was blocked by bicuculline, a GABA(A)-receptor antagonist, and enhanced by clonazepam, a central-type benzodiazepine-receptor agonist, and diazepam, a central- and peripheral-type benzodiazepine-receptor agonist. Although bicuculline completely blocked the combination effect of GABA(A)-receptor agonist and clonazepam, it did not completely block the combination effect with diazepam. These results suggest that protein secretion is suppressively regulated by GABA(A) receptors coupled with central-type benzodiazepine receptors.
Okubo
Migiwa
M
Department of Pharmacology, Tokyo Dental College, Mihama-ku, Chiba 261-8502, Japan. okubo@tdc.ac.jp
Kawaguchi
Mitsuru
M
D000681:Amylases / Q000378:metabolism*; D000818:Animals; D001640:Bicuculline / Q000378:metabolism; D002998:Clonazepam / Q000494:pharmacology; D003975:Diazepam / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D010306:Parotid Gland / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000187:drug effects / Q000378:metabolism*
D011963:Receptors, GABA-A; D009118:Muscimol; D002998:Clonazepam; D000681:Amylases; D007545:Isoproterenol; D003975:Diazepam; D001640:Bicuculline