近年来不少研究表明

尾状核头部(Cd)具有镇痛机能

并与针刺镇痛机理有密切关系。我们已报道:伤害性刺激、电针穴位和刺激丘脑束旁核等

均可改变Cd神经元的自发放电活动

证明尾状核单位有异感觉会聚和异体区会聚的性质。在此基础上我们试图进一步探讨针刺镇痛过程中Cd不同区域细胞的神经联系和生理机能特点。首先拟了解Cd神经元在针刺镇痛中的作用

因此选择了内脏-躯体反射(VSR)作为内脏伤害性反射的指标

初步观察Experiments were conducted on 20 cats unanesthetized but curaro-imobi- lized to investigate the effects of electrical stimulation of both the head of caudate nucleus(Cd)and the acupuncture site "Zusanli" on the reflex dis- charge of intercostal nerve(T_9-T_(11))elicited by single rectangular pulse sti- mulation of the central end of greater splanchnic nerve-viscerosomatic reflex (VSR). Taking account of the facts that the intensity used to stiu- mulate the greater splanchnic nerve is strong enough to excite Aδ afferent fiber in the nerve and that the VSR can be depressed by morphine (4 mg/ kg i.v.)

the VSR is considered as a visceral noxious response. 49 points in Cd were stimulated in 17 cats by a total of 228 times. All of these points stimulated were histologically identified in Cd and their stereotaxic coordinates were A 14-17.5

L3-6.7

H+1.5-6.7. Dur- ing the stimulation of Cd with 5Hz or 100Hz square pulses

1mSec in dura- tion and 10-90V in intensity

for 10-30Sec

in 115 of 228 times(50.9%) the VSR was inhibited

whereas in 31 times(13.6%)it was enhanced and the rest remained nearly unchanged. Train of 100Hz stimulation of Cd was found to be more effective in inhibiting VSR than 5Hz stimulation(P< 0.005). The result shows that the Cd may play a role in modulation of VSR and usually the inhibitory effect occurs more often. The effective inhibitory points in Cd were damaged by electrolytic le- sion in 8 cats. After the damage the inhibitory effect of Cd stimulation on VSR could no longer be induced in 7 cats. From this result it may be de- duced that the inhibitory effect of Cd stimulation on VSR is not due to the spread of stimulation current to the adjacent brain structures but ra- ther an effect of Cd itself. 47 trials of electroacupuncture of "Zusanli" by model G6805 stimulator with continuous diphasic pulses of 360 pulses/min

0.6-12V

for 10-30Sec were carried out in 12 cats. In most cases(35/47) "Zusanli" could inhibit the VSR and only in a few cases(4/47)it was enhanced. Observation was also made on the probable cooperation of the inhibi- tory effects of both the Cd stimulation and "Zusanli" electroacupuncture on VSR in 8 cats. It was found that

in certain conditions

when they were applied simultaneously

they could induce a more effective inhibition than that induced by either of them given alone.