VENTRAL MEDULLARY RELAY NEURONS IN THE PATHWAY FROM THE DEFENSE AREAS OF THE CAT AND THEIR EFFECT ON BLOOD-PRESSURE
VENTRAL MEDULLARY RELAY NEURONS IN THE PATHWAY FROM THE DEFENSE AREAS OF THE CAT AND THEIR EFFECT ON BLOOD-PRESSURE
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DOI：
10.1113/jphysiol.1983.sp014971
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发表时间：
1983-01-01
影响因子：
5.5
通讯作者：
TIMMS, RJ
中科院分区：
文献类型：
--
作者：
HILTON, SM;MARSHALL, JM;TIMMS, RJ
在用Althesin麻醉的猫中，通过确定电刺激诱发内脏警戒（防御）反应特征模式的部位，追踪脑干防御区的传出下行通路。这种反应包括由心率和心输出量增加以及肾床和内脏床血管收缩引起的动脉血压升高，伴有骨骼肌主动血管舒张。传出通路作为窄条延伸，距中线3 mm，位于上级橄榄核和斜方体核的腹侧，向尾侧延伸至位于面核腹侧的下橄榄核的吻侧部分。它非常接近腹侧延髓表面，就在吻侧，并且在双侧局部应用甘氨酸导致动脉血压大幅下降和呼吸停止的区域内。在双侧应用甘氨酸的腹侧延髓的敏感区域，内脏警觉反应引起的刺激在防御领域的杏仁核-下丘脑复合体，或中脑中央灰质或被盖，衰减与动脉压的下降平行，血管收缩反应被最强烈地减少。一旦动脉血压降到最低水平，内脏的警觉反应实际上就消失了。在腹侧延髓传出通路中，在甘氨酸敏感区的吻侧部分中进行的小的射频损伤具有与单侧应用甘氨酸产生的效果相同的效果：它本身导致很少的呼吸或心血管效应，但是将甘氨酸应用于对侧区域然后产生全部效果，否则仅在双侧应用甘氨酸时观察到。甘氨酸的作用是由于阻断了从防御区到节前交感神经元的传出通路中靠近延髓腹侧表面的突触中继。接受来自警戒（防御）区的输入的神经元通常为交感神经输出和可能的呼吸提供基本的紧张性兴奋驱动。在这种驱动力突然消失后，血管紧张度和动脉血压的正常水平无法维持。
In cats anesthetized with Althesin, the efferent descending pathway from the brain-stem defense areas was traced through the medulla by identifying sites at which electrical stimulation evoked the characteristic pattern of the visceral alerting (defense) response. This response includes an increase in arterial blood pressure resulting from increased heart rate and cardiac output and vasoconstriction in renal and splanchnic beds, accompanied by active vasodilatation in skeletal muscle. The efferent pathway runs as a narrow strip, .apprx. 3 mm from the mid line, ventral to the superior olive and the nucleus of the trapezoid body, extending caudally to the rostral portion of the inferior olive where it lies ventral to the facial nucleus. It lies very close to the ventral medullary surface just rostral to and within the area at which bilateral topical application of glycine results in a profound fall in arterial blood pressure and cessation of respiration. On bilaterial application of glycine to the sensitive area of the ventral medulla, the visceral alerting response evoked by stimulation in the defense areas of the amygdalo-hypothalamic complex, or the mid-brain central grey or tegmentum, was attenuated in parallel with the fall in arterial pressure, the vasoconstrictor responses being most strongly reduced. As soon as arterial blood pressure had fallen to its lowest level the visceral alerting response was virtually abolished. A small radio-frequency lesion made in the ventral medullary efferent pathway, in the rostral part of the glycine-sensitive area, had the same effect as that produced by unilateral application of glycine: it resulted in little respiratory or cardiovascular effect itself, but application of glycine to the contralateral area then produced the full effect otherwise seen only on bilateral application of glycine. The effects of glycine result from blockade of a synaptic relay, close to the ventral surface of the medulla, in the efferent pathway from the defense areas to the preganglionic sympathetic neurons. The neurons which receive an input from the alerting (defense) areas normally provide an essential, tonic excitatory drive to the sympathetic output and probably to respiration also. After sudden withdrawal of this drive, vasomotor tone and the normal level of arterial blood pressure are not maintained.