Objective: To observe the effect of electroacupuncture (EA) of Neiguan (PC 6) Jianshi (PC 5) on acute myocardial ischemia (AMI) induced c-fos expression in the spinal cord and to analyze the functional connection between the Pericardium Meridian and the heart.

Methods: 30 Wistar rats (weighting from 200 to 300g) anesthetized with a mixture solution of urethane and chloralose were randomly divided into control group and EA group. AMI was produced by occlusion of the anterior descending branch of the left coronary heart artery for 1.5 hr. Four acupuncture needles were respectively inserted into bilateral Neiguan (PC 6) and Jianshi (PC 5) and then stimulated for 30min with an EA therapeutic apparatus by setting the stimulating parameters being 3V (load voltage) in strength, 40Hz in frequency and intermittent wave type. At the end of each electrophysiological experiment, the animal was perfused transhearted1y with cold paraformaldehyde 4% in 0.lM phosphate buffer (pH: 7.4). The spina[ cord (from C4-8 to T2) was dissected, taken out and cut into sections (20um in thickness) by using a cryostate. The tissue sections were stained using immunohistochemical method for detecting c-fos gene expression state in control group and EA group.

Results: Immunochemical stain displayed that, after AMI fos-like immunoactivity (FLI) grains appeared in dorsal horn neurons of the rat spinal cord from C5-8 to T3, gradually increased in the grain number and widely distributed from the cervica1 end to the thoracic segment. FLI grains were heaviest in I - III laminae of Rexed layer of the dorsal horn, partially in II- III laminae of C8 - T2 segments of the spinal cord. In EA group, FLI grains were significantly fewer (especially in Tl-2 segments) in number in comparison with those of the control group (P <0.05). It indicates that EA can effectively inhibit AMI-induced c-fos expression in rat spinal cord, suggesting that EA is capable of lightening harmful AMI information induced hyperactivity of spinal neurons, favoring alleviation of myocardiac ischemia.

Conclusion: EA of Neiguan (PC 6) -Jianshi (PC 5) can effectively inhibit AMI-induced c-fos expression in rat spinal cord to lighten AMI-induced hyperactivity of thc spinal neurons.

　　Luo Mingfu, Gao Yonghui; Wang Zhiying
　　Institute of Acupuncture and Moxibustion, China Academy of TCM, Beijing 100700, China.