Jankowska E, Läckberg Z S, Dyrehag L E
Department of Physiology, University of Göteborg, Sweden.
Eur J Neurosci. 1994 Jun 1;6(6):1058-61. doi: 10.1111/j.1460-9568.1994.tb00601.x.
The effects of one 5-HT1A serotonin agonist (8-OH-DPAT) and of two alpha 2 noradrenaline agonists (tizanidine and B-HT 933) were tested on the transmission between group II muscle afferents and spinal neurons in the sacral segments of the spinal cord in the cat. These agonists have previously been found to depress transmission from group II muscle afferents either in the dorsal horn or in the intermediate zone of midlumbar segments, and this study addressed the question of whether their actions in the sacral segments are similarly selective. The drugs were applied ionophoretically and their effects were tested on field potentials evoked from group II muscle afferents. As judged by changes in the amplitude of the early components of these field potentials, the transmission is effectively depressed by the serotonin agonist (to 56 +/- 26% after 2 min of ionophoresis of 8-OH-DPAT) but not by the noradrenaline agonists (to 97 +/- 12% after 6 min of ionophoresis of B-HT 933 and to 95 +/- 17% after 6 min of ionophoresis of tizanidine). These data suggest that transmission from group II muscle spindle afferents in the sacral segments is under control of serotonin releasing neurons, as in the dorsal horn of midlumbar segments, but leave open the question of the similarities or differences in the mechanisms (pre- and/or postsynaptic) of this control.
在猫脊髓骶段，测试了一种5-羟色胺1A（5-HT1A）血清素激动剂（8-羟基二丙胺四乙酸，8-OH-DPAT）以及两种α2去甲肾上腺素能激动剂（替扎尼定和B-HT 933）对II类肌传入神经与脊髓神经元之间神经传递的影响。此前已发现这些激动剂可抑制腰段脊髓背角或中间带中II类肌传入神经的神经传递，本研究探讨了它们在骶段的作用是否具有类似的选择性这一问题。通过离子电泳法施加药物，并测试其对II类肌传入神经诱发的场电位的影响。根据这些场电位早期成分的幅度变化判断，血清素激动剂可有效抑制神经传递（8-OH-DPAT离子电泳2分钟后降至56±26%），而去甲肾上腺素能激动剂则无此作用（B-HT 933离子电泳6分钟后为97±12%，替扎尼定离子电泳6分钟后为95±17%）。这些数据表明，与腰段脊髓背角一样，骶段II类肌梭传入神经的神经传递受血清素释放神经元的控制，但该控制机制（突触前和/或突触后）的异同问题仍未解决。
