By using a kinetic cadmium-reduction method for determination of inorganic nitrite and using immunohitochemistry method for observation of NOS immunoactivity in rat brain

we surveyed changes of inorganic nitrite and NOS immunoactivity in middle cerebral artery occlusion (MCAo) group and MCAo+ electroacupuncture (EA) group. The results showed that: ① content of inorganic nitrite in the region of infarction in MCAo group was higher than that of control side (P < 0. 05)

rising degree was 95 %; ② iNOS immunoactive neurons were only distributed in cerebral cortex on the ischemic side but not on the control side in MCAo group; ③ after treating with acupuncture

changes differing from MCAo group emerged as below: the content of inorganic nitrite on the ischemia side was remarkably lower than MCAo group (P < 0. 05 ). In comparing with control side

the content of inorganic nitrite on the ischemic side was slightly increased

rising degree was 33. 3 %

no difference was discovered. Above results demonstrate that rise of NO level in rats brain was related to iNOS immunoactive enhancing after MCAo following reperfusion. One of the mechanism of protecting neurons against damage after cerebral ischemia with acupuncture was inhibiting iNOS activity.