中脑中央灰质在躯体神经抑制中枢性心肌缺血中的作用

THE ROLE OF MIDBRAIN PERIAQUEDUCTAL GREY IN THE INHIBITION OF CENTRAL CARDIAC ISCHEMIA BY SOMATIC NERVE AND ITS MECHANISM IN RABBITS

中脑中央灰质(导水管周围灰质,简称PAG)存在防御反应中枢,刺激PAG尾端背外侧亚核(CDL)能引起血压升高、心律失常、心肌缺血等反应。一些研究指出,刺激外周神经模拟针刺穴位能抑制CDL诱发的升压反应与心律失常。

Experiments were performed on vagotomized male rabbits weighing 1.8-2.2 kg. Urethane and chloralose were administered intravenously, and were paralyzed by flaxedil. After a caanula was inserted into femoral artery to measure blood pressure, the epicardial electrogram (EECG) was recorded. Then we inserted a bipolar electrode into caudal dorsolatera[ subdivision of periaqueductal grey (CDL), or dorsomedial hypothalamic nucleus (DMH). In some animals., a microinjecting lube was insetted into CDL for microinjection of enkephalin antibodies. In 12 animals, slimulation of CDL could elicit pressor response and elevation of EECG-ST segment. When stimulating deep peroncal nerve, these two responses were inhibited. In 14 animals, with brainslem transected in P5 level, the stimulation of DPN could not inhibit the presser response induced by CDL, but still inhibited the EECG-ST segment changes. After enkephalin antibodies were injected into CDL, DPN could not inhibited EECG-ST changes. In 4 animals, instead of enkephalin antibodies, rabbit serum had no effects. The unit discharges of 96 neurons in CDL were recorded by glass microelectrodes, among them, 15 neurons could be excited by DMH stimulation. We called these neurons the defence reaction related neurons. Stimulation of DPN or median nerve could inhibit the spontaneous discharge and DMH evoked discharge of these defence reaction related neurons. Conclusions: 1. DPN slimulation can inhibit the pressor response and cardiac ischemia induced bv defence reaction centre in CDL of PAG. The inhibitory effect on cardiac ischemia is still eminently remained after the brainstem is cut in P5 level to eliminate the influence of hypothalamic arcuate nucleus. Local enkephalin may be involved in this inhibitory process. 2. The inhibitory process is present in the defence reaction centre at CDL of PAG during the acupoint inhibition of cardiac ischemia induced by DMH stimulation, which means that midbrain defence reaction centre may be directlyinhibited by stimulating the acupoint zusanli or neiguan, in the inhibitory process of central cardiac ischemia.