Nicotinic activation of reticulospinal cells involved in the control of swimming in lampreys
Nicotinic activation of reticulospinal cells involved in the control of swimming in lampreys
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DOI：
10.1046/j.1460-9568.2003.02417.x
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发表时间：
2003-01-01
影响因子：
3.4
通讯作者：
Dubuc, R
中科院分区：
文献类型：
--
作者：
Le Ray, D;Brocard, F;Dubuc, R
与其他脊椎动物一样，七鳃鳗的脑干中心在运动的启动和控制中发挥着关键作用。一个这样的中心，中脑运动区(MLR)，在生理上被确定为中桥脑边界。来自MLR的下行输入由脑桥和延髓的网状脊髓神经元传递，但执行这一过程的机制尚不清楚。由于之前对高等脊椎动物和七鳃鳗的研究描述了MLR区域内的胆碱能细胞，我们调查了胆碱能激动剂在MLR控制的运动中的假定作用。局部应用乙酰胆碱或尼古丁对网状脊髓神经元产生直接的剂量依赖性兴奋，并诱导主动或假想的运动。它还加速了正在进行的虚构运动。胆碱乙酰转移酶免疫反应阳性细胞出现在七鳃鳗和烟碱拮抗剂抑制的MLR区域，而毒扁豆碱则增强电刺激该区域在网状脊髓神经元中诱发的复合EPSP。此外，从MLR到网状脊髓神经元的胆碱能输入被发现是单突触的。当脑干灌流d-Tubocurarine时，在半完整的准备中，MLR刺激的游泳诱导被抑制，但没有被阻止。综上所述，这些结果支持从MLR到网状脊髓细胞的胆碱能输入在运动的启动和控制中发挥重要作用的假说。
In lampreys as in other vertebrates, brainstem centres play a key role in the initiation and control of locomotion. One such centre, the mesencephalic locomotor region (MLR), was identified physiologically at the mesopontine border. Descending inputs from the MLR are relayed by reticulospinal neurons in the pons and medulla, but the mechanisms by which this is carried out remain unknown. Because previous studies in higher vertebrates and lampreys described cholinergic cells within the MLR region, we investigated the putative role of cholinergic agonists in the MLR-controlled locomotion. The local application of either acetylcholine or nicotine exerted a direct dose-dependent excitation on reticulospinal neurons as well as induced active or fictive locomotion. It also accelerated ongoing fictive locomotion. Choline acetyltransferase-immunoreactive cells were found in the region identified as the MLR of lampreys and nicotinic antagonists depressed, whereas physostigmine enhanced the compound EPSP evoked in reticulospinal neurons by electrical stimulation of this region. In addition, cholinergic inputs from the MLR to reticulospinal neurons were found to be monosynaptic. When the brainstem was perfused with d-tubocurarine, the induction of swimming by MLR stimulation was depressed, but not prevented, in a semi-intact preparation. Altogether, the results support the hypothesis that cholinergic inputs from the MLR to reticulospinal cells play a substantial role in the initiation and the control of locomotion.