大鼠中缝隐核增强dPAG诱导的vPAG的c－Fos表达及对vPAG神经元放电的影响

THE EFFECTS OF STIMULATION OF NUCLEUS RAPHE OBSCURUS ON FOS-EXPRESSION EVOKED BY ACTIVITING DORSAL PERIAQUEDUCTAL GRAY AND UNIT DISCHARGE IN VENTRAL PERIAQUEDUCTAL GRAY IN RAT

本实验通过Ｐｏｓ免疫细胞化学、电生理及微量注射法对中缝隐核（ＮＲＯ）的交感抑制作用的相关途径进行探讨。实验在成巴比妥钠或α－氯醛糖和氨基甲酸乙脂麻醉的Ｓｐｒａｇｕｅ－Ｄａｗｌｅｙ（ＳＤ）大鼠上进行。同时予以ＮＲＯ，中脑导水管周围灰质背侧部（ｄＰＡＧ）方波脉冲串刺激，诱导中脑和延髓的ｃ－Ｆｏｓ表达。刺激ＮＲＯ过程中，基础血压升高（Ｐ＜０．０５），刺激ｄＰＡＧ引起的防御性升压反应则减少（Ｐ＜０．０１）；中脑导水管周围灰质腹侧部（ｖＰＡＧ）、巨细胞旁外侧核（ＰＧＬ）的Ｆｏｓ样免疫阳性反应（ＦＬＩ）细胞计数分别为６６．５±８．３和１０．８±１．５（刺激ＮＲＯ＋ｄＰＡＧ组），较单独刺激ｄＰＡＧ组明显增加，Ｐ值分别小于０．０１和０．００１；单或双脉冲刺激中缝隐核在ｖＰＡＧ可以记录到相关单位，其中８４％为兴奋单位，抑制单位占１６％。双侧ｖＰＡＧ内微量注射利多卡因（每侧２μｇ／０．１μｌ），基础血压无明显变化，而刺激ＮＲＯ引起的降压反应幅度减小（Ｐ＜０．０１），提示，延髓腹外侧区（ＶＬＭ）、ＮＲＯ存在不同功能分化的神经元；ＮＲＯ可能有向ｖＰＡＧ的兴奋性投射，此投射可加强ＮＲＯ的交感抑制效应。

Experiments were carried out on rats anaesthetized with sodium Pentobarbital or urethane and alpha-chloralose. Nucleus raphe obscurus (NRO) and dorsal periaqueductal grey (dPAG) were stimulated singly or simultaneously by square-wave pulses to induce the Fos-expression in midbrain and medulla oblongata. During the period of NRO stimulation, the hasal blood pressure was increased (P<0.05), the defensive pressor respouse to stimulation of dPAG was attenuated (P<0.01). When both NRO and dPAG were stimulated, Fos-like immunoreactive (FLI) cells in the ventral periaqueductal grey (vPAG) and paragigantocellularis lateralis (PGL) were increased as compared with cases in which the stimulation was only delivered to dPAG, i. e., reaching a FLI cell count value of 66.5±8.3 and 10.8±1.5 respectively. Stimulation of the NRO with single or paired stimulus evoked both excitatory (84% ) and inhibitory (16% ) respouses of the units in vPAG. Bilateral microinjection of lidocaine (2 μg in 0.1 μl/side) into vPAG attenuated the depressor responses induced by stimulation of NRO, but little change in hasal blood pressure (P>0.01). It is suggested that there exist different types of neurons possessing different functions in the ventral lateral medulla (VLM) and NRO and that an excitatory projection from the NRO to vPAG may mediate the sympathoinhibitory effect of the nucleus.