针刺可以影响海马的自发电活动

也可以影响海马的诱发电活动。外周的伤害性刺激信号和针刺信号都可以到达海马

并且发生会聚和阻塞

提示海马可能参与针刺镇痛。针刺抑制内脏伤害性刺激反应(简称“内脏痛反应”)的作用已在多种动物模型上观察到

也为一些临Experiments were performed on 68 rabbits.Stainless steel stimulation electrode or microinjection cannula was stereotaxically implanted in the dorsal hippocampus.Silver stimulation electrode was also chronically placed on the splanchnic nerve.As short pulse train of current pulse(0.2ms

50Hz

0.5sec) was deliverede at splanchnic nerve with 0.1mA step increase every 5 seconds

the behavioral withdraw reflex(WR)and visceral somatic reflex(VSR)eli- cited was measured and taken as visceral nociceptive responses.The minimal intensity required to elicit the response was recorded as pain threshold. It was observed that hippocampal stimulation(n=13)significantly eleva- ted WR threshold from 0.53±0.04mA(M±SE)to 0.73±0.09mA.NO obvi- ous change was seen in the control experiment.Electroacupuncture on bihu- atuojiaji points(T_(10)-L_4

160Hz

6-10mA

15min.)resulted in marked enha- ncement of both WR threshold and VSR threshold(n=10)with after-effect lasting.15min.and 5min.respectively.WR threshold rose more steeply in the hippocampal stimulation+acupuncture experiment(n=8)than that of acupuncture experiment(n=8).The difference was statistically significant. NO significant difference in changes of VSR threshold was found between the two experiments.However the after-effect in the former experiment was 10min.10nger than that og the latter

Naloxone(2μg/2μl saline)microinje- cted into the dorsal hippocampus could reverse the effect of electroacupu- ncture on WR threshold but showed no such result on VSR threshold

NO reversal change was seen in the control experiment administrated with saline (2μ1).There was no any corresponding change found in another control experiment administrated with naloxone alone. The above data thus suggest that the dorsal hippocampus with endogenous opioid peptides may participate in acupuncture analgesia on visceral nocice- ption.