NEURONS IN THE CAUDAL VENTROLATERAL MEDULLA MEDIATE THE ARTERIAL BARORECEPTOR REFLEX BY INHIBITING BAROSENSITIVE RETICULOSPINAL NEURONS IN THE ROSTRAL VENTROLATERAL MEDULLA IN RABBITS
NEURONS IN THE CAUDAL VENTROLATERAL MEDULLA MEDIATE THE ARTERIAL BARORECEPTOR REFLEX BY INHIBITING BAROSENSITIVE RETICULOSPINAL NEURONS IN THE ROSTRAL VENTROLATERAL MEDULLA IN RABBITS
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DOI：
10.1016/0165-1838(91)90077-g
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发表时间：
1991-06-01
期刊：
影响因子：
--
通讯作者：
KUMADA, M
中科院分区：
文献类型：
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作者：
MASUDA, N;TERUI, N;KUMADA, M
在麻醉、切断双侧主动脉神经的家兔中，观察了延髓尾侧腹外侧区参与动脉压力感受性反射的情况。尾侧腹外侧髓质的范围被映射的肾交感神经活动和动脉压的减少后，局部微量注射的神经兴奋性氨基酸，谷氨酸钠（0.075-1.5 nmol）。它延伸到水平之间的1.3毫米吻和3.0毫米尾奥贝斯。向延髓尾侧腹外侧区注射谷氨酸钠也减少了延髓头侧腹外侧区压力敏感性网状脊髓神经元的自发活动。在“劈髓制备”中，沿正中矢状面沿着劈髓以破坏与两侧相关的纤维连接，将神经毒性剂红藻氨酸单侧注射到延髓头端腹外侧。这种治疗显着衰减的反应，肾交感神经活动和动脉压引起的谷氨酸钠注射到同侧尾侧腹外侧延髓，而反应到对侧尾侧腹外侧延髓注射完全保存。在四个独立的实验中，单侧注射三到五次红藻氨酸，以覆盖尾部腹外侧髓质的整个范围。刺激同侧主动脉神经引起的交感神经抑制和降压反应完全消失。同时，与心脏周期相关的肾交感神经活动的节律性波动，这代表了颈动脉窦压力感受性反射的活动，被衰减到噪声水平。这些结果，连同我们以前的电生理演示的压力敏感性尾侧延髓腹外侧区神经元的轴突投射到头侧延髓腹外侧区，强烈支持的假设，即在尾侧延髓腹外侧区的神经元介导的动脉压力感受器血管反射通过抑制压力敏感性网状脊髓神经元在头侧延髓腹外侧区。
Participation of the caudal ventrolateral medulla in the arterial baroreceptor reflex was examined in urethane-anesthetized, vagotomized and immobilized rabbits whose aortic nerve was cut bilaterally. The extent of the caudal ventrolateral medulla was mapped by decreases in the renal sympathetic nerve activity and arterial pressure following a local microinjection of a neuroexcitatory amino acid, sodium glutamate (0.075-1.5 nmol). It extended between the levels 1.3 mm rostral and 3.0 mm caudal to the obex. An injection of sodium glutamate into the caudal ventrolateral medulla also diminished spontaneous activity of barosensitive reticulospinal neurons in the rostral ventrolateral medulla. In the 'split medulla preparation' in which the medulla was split along the midsagittal plane to disrupt fiber connections associating both sides, a neurotoxic agent, kainic acid, was injected unilaterally into the rostral ventrolateral medulla. This treatment markedly attenuated responses of renal sympathetic nerve activity and arterial pressure induced by a sodium glutamate injection into the ipsilateral caudal ventrolateral medulla, whereas responses to an injection into the contralateral caudal ventrolateral medulla were totally preserved. In four separate experiments, three to five injections of kainic acid were made unilaterally to cover the whole extent of the caudal ventrolateral medulla. The sympathoinhibitory and depressor responses to stimulation of the ipsilateral aortic nerve were then totally abolished. Simultaneously, the cardiac cycle-related rhythmic fluctuation of renal sympathetic nerve activity, which represented activity of the carotid sinus baroreceptor reflex, was attenuated to the noise level. These results, together with our previous electrophysiological demonstration of barosensitive caudal ventrolateral medulla neurons with axonal projections to the rostral ventrolateral medulla, strongly support the hypothesis that neurons in the caudal ventrolateral medulla mediate the arterial baroreceptor-vasomotor reflex through inhibition of barosensitive reticulospinal neurons in the rostral ventrolateral medulla.