To study the effect of L-arginine (L-Arg) which was injected into cerebral ventricle of rats on electroacupuncture (EA) analgesia

the potassium iontophoresis was used to induce tail-flick for mea- suring the pain threshold during EA analgesia

the precursor of NO

L-arginine(L-Arg) and the inhibitor of nitric oxide synthase (NOS)

NG-nitro-L-arginine methyl ester(L-NAME) were injected into cerebral ventricle of rats. The effects of L-Arg and L-NAME on pain thresholds during EA analgesia were investigated. Results: L-Arg administration could significantly attenuate the pain threshold during EA and after EA 15 min. The effects of L-Arg 5mmol

10mmol

20mmol

40mmol on EA analgesia were in a dose-dependent manner. In addition

a remarkable enhanced role of EA analgesia was observed by microinjecting L-NAME into cerebral ventricle of rats. The results sugested that an increase of NO in central nervous system of rats could decrease the EA analgesia. And a decrease of NO level in brain might be increase the effects of EA analgesia in rats.