ISOQUERCITRIN INCREASES BRAIN cGMP LEVEL AND POTENTIATES ELECTROACUPUNCTURE (EA) ANALGESIA

In a previous study we have reported that icy injection of aminophylline or imidazole serving as inhibitor or activator of phosphodiesterase for cAMP respectively, was capable of increasing or decreasing the brain level of endogenous cAMP. EA analgesia was found to be markedly antagonized by aminophylline and significaantly augmented by imidazole. In the present study we have found that icy injection of isoquercitrin, an inhibitor of cGMP phosphodiestrase, resulted in an increase of cGMP level in the diencephalon and lower brain stem, as well as a generalized decrease of cAMP level in the telencephalon, dieneephalon and brain stem in the rat. Icy injection of isoquercitrin (20, 40. 80 μg) produced a dose-dependent antinociceptive effect. The effect of EA analgesia was significantly potentiated by the icy injection of 20μg of isoquercitrin which, by itself, exhibited only very weak analgesic effect. Moreover, a positive correlation was found between the isoquercitrin analgesia and EA analgesia in the same group of 30 rats. The results seem to support the conclusion that central cGMP plays an important role in mediating EA analgesia.