Akeyson E W, Knuepfer M M, Schramm L P
Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Brain Res. 1990 Dec 17;536(1-2):30-40. doi: 10.1016/0006-8993(90)90005-v.
The urinary responses of 62 T8-T11 spinal neurons were recorded extracellularly following electrical stimulation of the greater splanchnic nerve (GSN) in chloralose-anesthetized rats. Recorded neurons were found in both the dorsal and ventral horns. Fifty-seven neurons increased their firing rate in response to GSN stimulation; 8 of these exhibited biphasic responses consisting of excitations followed by inhibitions. Excitatory responses to GSN stimulation consisted of either one or two bursts with latencies consistent with activation by either A delta or C fibers. GSN stimulation inhibited 5 neurons. The effects of reversible spinalization on spontaneous activity and on both synchronous and non-synchronous (afterdischarge) GSN-evoked responses were investigated using a cooling probe on the spinal cord between C1 and C2. Of 19 neurons tested in this way, 9 exhibited opposite directional changes in their spontaneous activities and their GSN-evoked responses upon spinalization. Differential effects of cold-block on first and second bursts, or on A delta- and C-fiber mediated responses, were not usually observed. However, differential effects of cold-block on synchronous and non-synchronous portions of the overall GSN-evoked response were often observed in that their magnitudes often changed independently of one another. Supraspinal pathways contributed to GSN-evoked responses of several neurons because their responses were diminished during cooling while spontaneous activity was increased or unchanged. These decreases in the magnitude of the GSN-evoked response were not always accounted for by decreases in the synchronous portions of the responses. However, most neurons did exhibit decreases in the number of non-synchronous responses, or afterdischarges, during spinal cooling, exhibiting in some cases biphasic responses. This study provides evidence for strong supraspinal regulation of splanchnic afferent input to the spinal cord of the rat. Further, this regulation exhibits some specificity toward different portions of splanchnic-evoked responses in spinal neurons.
在水合氯醛麻醉的大鼠中，对62个T8 - T11脊髓神经元进行细胞外记录，记录其在电刺激内脏大神经（GSN）后的泌尿反应。在背角和腹角均发现了记录的神经元。57个神经元对GSN刺激的放电频率增加；其中8个表现出双相反应，先是兴奋随后是抑制。对GSN刺激的兴奋性反应由一或两个爆发组成，其潜伏期与Aδ纤维或C纤维激活一致。GSN刺激抑制了5个神经元。使用C1和C2之间脊髓上的冷却探针，研究了可逆性脊髓横断对自发活动以及对同步和非同步（后放电）GSN诱发反应的影响。以这种方式测试的19个神经元中，9个在脊髓横断后其自发活动和GSN诱发反应呈现相反方向的变化。通常未观察到冷阻断对第一和第二个爆发，或对Aδ纤维和C纤维介导反应的差异效应。然而，经常观察到冷阻断对整体GSN诱发反应的同步和非同步部分的差异效应，因为它们的幅度常常彼此独立变化。上位脊髓通路对几个神经元的GSN诱发反应有贡献因为在冷却期间它们的反应减弱，而自发活动增加或不变。GSN诱发反应幅度的这些降低并不总是由反应同步部分的降低所解释。然而，大多数神经元在脊髓冷却期间确实表现出非同步反应或后放电数量减少，并在某些情况下表现出双相反应。本研究为大鼠脊髓内脏传入输入的上位脊髓强力调节提供了证据。此外，这种调节对脊髓神经元内脏诱发反应的不同部分表现出一定的特异性。
