兔孤束核腹外侧区微量注射谷氨酸钠及甘氨酸对弓状核诱发电位的影响

EFFECT OF MICROINJECTION OF SODIUM GIUTAMATE AND GLYCINE INTO VENTROLATERAL NUCLEUS OF TRACTUS SOLITARIUS ON THE EVOKED POTENTIALS OF ARCUATUS NUCLEUS IN RABBITS

实验在６６只麻醉、制动，断双侧颈迷走神经和人工通气的家兔上进行。通过微量注射神经元胞体兴奋剂谷氨酸钠和神经元胞体抑制剂甘氨酸，改变孤束核腹外侧区神经元兴奋活动，探讨对下丘脑弓状核诱发电位的影响及其可能的机制和意义。实验结果如下：（１）孤束核腹外侧区微量注射谷氨酸钠，可使膈神经放电显著增加和使弓状核诱发电位Ｐ２及Ｎ２波幅显著降低；而微量注射甘氨酸则使膈神经放电显著减少和使弓状核诱发电位Ｐ２及Ｎ２波幅显著增大。（２）静脉注射纳洛酮对谷氨酸钠引起的膈神经放电兴奋效应无明显影响，但能翻转谷氨酸钠对弓状核诱发电位Ｐ２及Ｎ２波幅的抑制效应。提示：孤束核腹外侧区呼吸神经元的兴奋活动可扩散至弓状核，并对弓状核诱发电位产生影响，此影响可能是由内源性阿片系统参与而实现的。

Experiments were performed on 66 anaesthetized, vagotomized, paralyzed and artificially ventilated rabbits. The effects of microinjection sodium glutamate and glycine into ventrolateral nucleus of tractus solitarius (VLNTS) on hypothalamic arcuatus nucleus evoked potentials were observed. The main results obtained were as follows: (1)Phrenic nerve discharges were increased and the amplitude of P2 and N2 waves of arenatus nucleus evoked potentials were decreased by microinjection of sodium glutamate into VLNTS. Phrenic nerve discharges were decreased and the amplitude of P2 and N2 waves of arcuatus nucleus evoked potentials were increased by microinjection of glycine into VLNTS. (2) After intravenous injection of naloxone, the phrenic nerve discharges could still be excited by microinjection of sodium glutamate as before, but the effects on the amplitude of P2 and N2 waves of arcuatus nucleus evoked potentials, unlike that of sodium glutumate, were reversed. The results suggest that the excitutory action of respiratory neurons in the VILTS may affect on the sensory function of arcuatus nuleus.The mechanism involved was discussed.