微电泳导入脑啡肽和吗啡对中缝大核神经元放电的影响

<正> 近年来研究表明,发源于中脑导水管周围灰质(PAG)的脑干下行抑制系统,在吗啡镇痛、脑刺激镇痛中具有十分重要的作用。延脑中缝大核(NRM)是该系统换元传递的枢纽。国外一些学者设想,下行抑制系统中PAG到NRM的下行通路可能是由吗啡类物质调制的。这一观点在我们以往的工作中得到了初步证实。我们观察到,电针对NRM神经元的激活效应可被局部导入吗啡拮抗纳洛酮所阻断。那么,在NRM直接微电泳导入脑啡肽和吗啡,是

THE EFFECT OF ELECTRO--ACUPUNCTURE AND IONTOPHORETIC ENKEPHALIN ON THE NEURONAL ACTIVITIES IN NUCLEUS RAPHE MAGNUS

In our Previous work, the activation of neuronal activities of nucleus raphe magnus (NRN) by acupunture could be blocked by iontophoretic nal- oxone, suggesting that the endogenous opiate-like substance (OLS) may play an important role in activating NRN neurons by acupuncture, In pre- sent study, The effect of acupuncture was compared with that of iontoph- oretic leucine-enkephalin, so as to further investigate the enkephalinergic mechanism of the activation of NRN neurons by acupuncture. The experiments were carried out on adult male rats under slight uret- han anaesthesia. Unit activities were extracellularly recorded with central tube of the multi-pippetes filled with 4 M Nacl and neuronal responses to acupuncture and iontophoretic enkephalin were observed. Among 11 neurons, the firing rate of 8 neurons (73%) was increased by acupuncture applied on "Zusanli" Points, only that of one neuron was dec- reased and the remaining 2 neurons showed no change. When leucine-enk- ephalin was iontophoretically ejected near the cell body of the NRN neu- rons, the firing rate was increased in most neurons (14 of 21 neurons,67%), decreased only in one neuron, and the remainder had no Change. The effect of iontophoretic enkephalin was quite similar to that of acupuncture, only that the occurene of the exciting effect of acupuncture required a longer period of time. Bcth of their exciting effects could be blocked by iontoph- oretic naloxone. In addition, the effect of iontophoretic morphine was observed. Only in 50% neurons the firing rate was increased and the magnitude of the ac- tion was less than that of acupuncture and iontophoretic enkephalin. These results further support that the OLS released by acupuncture may mediate the activation of NRN neurons and it may play an important role in acupuncture analgesia.