Potentiation of Adenosine A_1 Receptor Agonist CPA-Induced Antinociception by Paeoniflorin in Mice(Pharmacology)

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The effect of paeoniflorin (PF), a major constituent isolated from Paeony radix, on N^6-Cyclopentyladenosine (CPA), a selective adenosine A_1 receptor (A_1 receptor) agonist, induced antinociception was examined in mice. In the tail-pressure test, CPA (0.05, 0.1, 0.2mg/kg, s.c.) could induce antinociception in a dose-dependent manner. PF (5, 10, 20mg/kg, s.c.) alone failed to exhibit any antinociceptive effect in mice; however, pretreatment of PF (20mg/kg, s.c.) could significantly enhance CPA-induced antinociception. Additionally, pretreatment of 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX, 0.25mg/kg, s.c.), a selective A_1 receptor antagonist, could antagonize the antinociceptive effect of combining CPA with PF. Furthermore, in the competitive binding experiments, PF did not displace the binding of [^3H]-8-Cyclopentyl-1,3-dipropylxanthine ([^3H]-DPCPX) but displaced that of [^3H]-2-Chloro-N^6-cyclopentyladenosine ([^3H]-CCPA, a selective A_1 receptor agonist) to the membrane preparation of rat cerebral cortex. These results suggested that PF might selectively increase the binding and antinociceptive effect of CPA by binding with A_1 receptor.
公益社団法人日本薬学会の論文
2006-08-01