刺激大鼠 PVN 影响痛感受下行途径的研究

THE STUDIES OF THE EFFECT OF STIMULATING PVN OF THE RAT ON THE PAIN SENSIBILITY DESCENDING INHIBITORY PATHWAY

在大鼠腰脊髓背角泳入辣根过氧化酶（ＨＲＰ），下丘脑室旁核（ＰＶＮ）找到逆行标记细胞；在ＰＶＮ泳入ＨＲＰ，脊髓内均有顺行标记纤维和终末分布于脊髓背角第Ⅰ、Ⅱ、和Ⅳ、Ⅴ板层。可见大鼠ＰＶＮ－脊髓背角间存在直接纤维联系。用行为测痛法观察到电刺激ＰＶＮ或注射谷氨酸钠、盐酸吗啡，痛阈均显著升高。纳络酮可翻转盐酸吗啡的作用。电刺激ＰＶＮ的同时，电针双侧“足三里”痛阈升高更显著，说明刺激ＰＶＮ可使痛阈升高，电针“足三里”有协同作用。用微电极记录脊髓背角神经元伤害单位活动，其反应可被电刺激ＰＶＮ所抑制。分别电解中脑导水管周围灰质（ＰＡＧ）和中缝大核（ＮＲＭ）后，ＰＶＮ对脊髓背角神经元伤害反应的抑制仍存在。实验结果表明，ＰＶＮ参与了痛觉下行的调制过程。

Analgesic effect was examined in rat anesthetized with urathane(1g/kg)or chloral hydrate(0.4g/kg).Our results demonstrated as follows:①Identified cells in paraventricular neucleus (PVN)paracellular division were antidromically traced by electrophoring horseradis peroxidase(HRP)in rat lumbar spinal cord dorsal horn.Otherwise,identified fibers and terminals could also be orthodromically found by electrophoring HRP in PVN.These fibers and terminals distributed in laminae I ,ll and Vll,X in the dorsal horn.So that there were direct fiber connections between PVN and dorsal horn in the rat.②With behavioral measure pain method(Tail flick),it is investigated that pain threshold was markedly enhanced by electrostimulation of PVN or injection of monosodium glutamate(MSG)and hydrochloric acid morphine.Naloxone could reverse the analgesic effect of hydrochloric acid morphine.Pain threshold was more markedly increased by electrically stimulating PVN electro acupuncturing bilateral Zusanli point.The result showed that pain threshold could strenthened by stimulating PVN and there was synergism by electro acupuncture of both Zusanli point and PVN.③Noxious response was inhibited by electro stimulation of PVN .After electrolysising the midbrain periqueductal gray(PAG)and neucleus raphe magnus(NRM)respectively,the inhibition effect of stimulation of PVN on the discharge of noxious units was still existed.It demonstrated that stimulation in PVN could suppress the noxious responses of dorsal horn neurons.Our results indicated that PVN involved in the pain modulation.