Pattern generation in caudal-lumbar and sacrococcygeal segments of the neonatal rat spinal cord
Pattern generation in caudal-lumbar and sacrococcygeal segments of the neonatal rat spinal cord
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DOI：
10.1152/jn.2002.88.2.732
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发表时间：
2002-08-01
影响因子：
2.5
通讯作者：
Lev-Tov, A
中科院分区：
文献类型：
--
作者：
Gabbay, H;Delvolvé, I;Lev-Tov, A
研究了新生大鼠离体脊髓和尾脊髓制剂中脊髓尾神经支配节段（L4-Co3）的节律性。在腰椎中段脊髓横断后，浴用血清素/ n -甲基- d -天冬氨酸（NMDA）不能产生强健的骶尾骨节律性。相比之下，骶尾椎段在腰中段脊髓横断前后应用去甲肾上腺素（NA）或NA和NMDA可诱导有规律的左右交替节律。这种节律随着NMDA浓度的增加而加速，并被α 1或α 2肾上腺素能受体拮抗剂阻断。NA/NMDA诱导的传出脉冲伴随着左右尾肌交替激活和尾侧屈肌、伸肌和外展肌共同激活所产生的有节奏的尾部运动。这种共激活意味着相互抑制途径在节律期间未被激活。损伤实验显示，节律性电路分布在骶尾骨的全部或大部分节段。NA/ nmda诱导的节律持续存在于离体骶尾骨（S1-Co3）、骶部（S1-S4）、尾骨（Co1-Co3）和较小的骶尾骨脊髓离体区域。在纵向分裂的骶尾骨半索中，屈肌、伸肌和外展运动神经元共同激活，这种节律也可以维持。这一发现表明，骶尾索节律发生并不需要左/右或屈肌/伸肌抑制相互作用。NA/NMDA在尾神经支配的离体L4-Co3制剂后腰椎节段诱导出缺乏左右交替模式的缓慢节律。这种节律独立于并发的骶尾骨节律和尾部肌肉组织的活动模式，在这些条件下，它似乎并不有助于有节奏的尾部运动。对孤立的腰尾部、骶尾椎束和腰尾部胸-吻侧节段产生的节律的比较研究显示，S1-Co3节律比L4-L6节律快，比T6-L3节律慢。这表明脊髓的腰尾部和骶尾椎段通常是由更快的吻侧腰椎中枢模式发生器驱动的。本文讨论了上述发现与哺乳动物脊髓模式生成的相关性。
The rhythmogenic capacity of the tail-innervating segments (L4-Co3) of the spinal cord was studied in isolated spinal cord and tail-spinal cord preparations of neonatal rats. Bath-applied serotonin/N-methyl-D-aspartate (NMDA) failed to produce a robust sacrococcygeal rhythmicity following midlumbar transection of the spinal cord. By contrast, a regular alternating left-right rhythm could be induced in the sacrococcygeal segments by application of noradrenaline (NA) or NA and NMDA before and after midlumbar transection of the cord. This rhythm was accelerated with the concentration of NMDA and was blocked by alpha1 or alpha2 adrenoceptor antagonists. The efferent bursts induced by NA/NMDA were accompanied by rhythmic tail movements produced by alternating activation of the left and right tail muscles and by coactivation of flexors, extensors, and abductors on a given side of the tail. This coactivation implies that reciprocal inhibitory pathways were not activated during the rhythm. Lesion experiments revealed that the rhythmogenic circuitry is distributed along all or most of the sacrococcygeal segments. The NA/NMDA-induced rhythm persisted in the isolated sacrococcygeal (S1-Co3), sacral (S1-S4), coccygeal (Co1-Co3), and smaller isolated regions of the sacrococcygeal cord. The rhythm also could be maintained in longitudinally split sacrococcygeal hemicords in which flexor, extensor, and abductor motoneurons are coactivated. This finding indicates that neither left/right nor flexor/extensor inhibitory interactions are required for rhythmogenesis in the sacrococcygeal cord. A slow rhythm lacking the alternating left-right pattern was induced by NA/NMDA in tail-innervating caudal lumbar segments of isolated L4-Co3 preparations. This rhythm was independent of the concurrent sacrococcygeal rhythm and the activity pattern of the tail musculature and it does not seem to contribute to rhythmic tail movements under these conditions. Comparative studies of the rhythm produced in the isolated caudal lumbar, sacrococcygeal cord, and caudal thoracic-rostral lumbar segments revealed that the S1-Co3 rhythm was faster than the L4-L6 pattern and slower than the T6-L3 rhythm. It is suggested that the caudal lumbar and sacrococcygeal segments of the cord are normally driven by the faster rostral lumbar central pattern generators. The relevance of the findings described above to pattern generation in the mammalian spinal cord is discussed.