REFLEX RESPONSES EVOKED IN THE ADRENAL SYMPATHETIC NERVE TO ELECTRICAL STIMULATION OF SOMATIC AFFERENT NERVES IN THE RAT
REFLEX RESPONSES EVOKED IN THE ADRENAL SYMPATHETIC NERVE TO ELECTRICAL STIMULATION OF SOMATIC AFFERENT NERVES IN THE RAT
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DOI：
10.1016/0168-0102(85)90026-4
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发表时间：
1985-01-01
影响因子：
2.9
通讯作者：
SWENSON R S
中科院分区：
文献类型：
--
作者：
ISA T;KUROSAWA M;SWENSON R S
本研究旨在探讨A(有髓)和C(无髓)传入纤维在中枢神经系统(CNS)完整麻醉大鼠反复机械挤压和刷洗皮肤时肾上腺交感神经活动增减反应中的作用。因此，在乌拉坦/氯醛糖麻醉的大鼠上，观察了重复和单次电击刺激各种脊髓传入神经，特别是第13胸(T13)脊神经和腓肠神经所引起的肾上腺交感神经活动的变化。重复电刺激T13脊神经或腓肠神经的A传入纤维可降低肾上腺神经的活动，与刷刺下胸或后肢皮肤的作用相似，而重复刺激这些神经的A+C传入纤维可增加肾上腺神经的活动，就像挤压刺激这些皮肤一样。单次刺激脊髓传入神经可引起肾上腺神经的各种反射成分：(1)自发活动的初始抑制(早期抑制)；(2)A传入纤维激活后的反射放电(A反射)；(3)C传入纤维激活后的反射放电(C反射)；以及(4)兴奋性后抑制。这些反射似乎主要是通过脊髓上通路来调节的，因为它们被在C1-2节段的脊髓横断所消除。虽然脊髓上的A和C反射可由多种脊髓节段传入水平所引起，但当更接近肾上腺神经流出水平的脊髓节段传入被兴奋时，早期的抑制更为明显。结果表明，重复电刺激A传入神经纤维引起的肾上腺神经反应降低是由于单次电击刺激引起的早期抑制和兴奋后抑制的叠加，而重复刺激A+C传入纤维时肾上腺神经反应的增加是由于单次电击刺激后C反射的叠加。在棘化大鼠，重复刺激Th13总是增加肾上腺神经活动，无论是单独刺激A纤维还是刺激A+C纤维，就像刷牙和捏胸下皮肤总是增加肾上腺神经活动一样。脊髓动物的反应增强似乎与以下事实有关：单一的Th13电刺激产生了起源于脊髓的A和C反射，而没有明显的抑郁。
The present study was initiated to determine the role of somatic A (myelinated) and C (unmyelinated) afferent fibers in both responses of increases and decreases in adrenal sympathetic nerve activities during repetitive mechanical pinching and brushing stimulations of the skin in anesthesized rats with central nervous system (CNS) intact. Accordingly, changes in adrenal sympathetic nerve activity resulting from repetitive and single shock electrical stimulation of various spinal afferent nerves, especially the 13th thoracic (Th13) spinal nerve and the sural nerve, were examined in urethane/chloralose-anesthetized rats. Repetitive electrical stimulation of A afferent fibers in Th13 spinal or sural nerve decreased the adrenal nerve activity similarly as brushing stimulation of skin of the lower chest or hindlimb did, while repetitive stimulation of A plus C afferent fibres of those nerves increased the adrenal nerve activity as pinching stimulation of those skins did. Single shock stimulation of spinal afferent nerves evoked various reflex components in the adrenal nerve: (1) an initial depression of spontaneous activity (the early depression); (2) the following reflex discharge due to activation of A afferent fibers (the A-reflex); (3) a subsequent reflex discharge due to activation of C afferent fibers (the C-reflex); and (4) following postexcitatory depressions. These reflexes seem to be mediated mainly via supraspinal pathways since they were abolished by spinal transection at the C1-2 level. Although the supraspinal A- and C-reflexes could be elicited from stimulation of a wide variety of spinal segmental afferent levels, the early depression was more prominent when afferents at spinal segments closer to the level of adrenal nerve outflow were excited. It is suggested that the decreased responses of the adrenal nerve during repetitive electrical stimulation of A afferent nerve fibers are attributable to summation of both the early depression and postexcitatory depression evoked by single shock stimulation, while the increased responses during repetitive stimulation of A plus C afferent fibers are attributable to summation of the C-reflex after single shock stimulation. In spinalized rats, repetitive stimulation of Th13 always increased the adrenal nerve activities regardless of whether A fibers alone or A plus C fibers were stimulated, just as brushing and pinching of the lower chest skin always increased them. The increased responses in spinal animals seem to be related to the fact that single electrical stimuli of Th13 produced A- and C-reflexes of spinal origin without clear depressions.