Garcia-Rill E, Skinner R D, Fitzgerald J A
Brain Res. 1985 Mar 18;330(1):43-54. doi: 10.1016/0006-8993(85)90006-x.
Electrical stimulation of the mesencephalic locomotor region (MLR) in the precollicular-postmammillary transected cat is known to induce controlled locomotion on a treadmill. We have been able to induce and block locomotion in this preparation by using localized infusions of transmitters and their agonists and antagonists. Infusions of the GABA antagonists bicuculline and picrotoxin into the MLR elicit locomotion at low concentration (5 mM). Applications of muscimol (5 mM) or GABA (0.5 M) were found to block chemically-induced locomotion, as well as electrically-elicited and spontaneous walking. Priming infusions of Diazepam amplified the blockage of locomotion by GABA. On the other hand, applications of strychnine (10 mM) were ineffective in inducing stepping, as were infusions of the excitatory agents glutamic acid, acetylcholine and norepinephrine. These findings suggest that the MLR is under inhibitory GABAergic input. The substantia nigra is the only known afferent to the MLR located posterior to the brainstem transection, and is a likely source for this input. A model is proposed to account for our results, as well as those of others, and it provides a working hypothesis for the neurochemical events occurring in brainstem centers which modulate locomotor events.
已知在中脑前丘 - 乳头体后横断的猫中，电刺激中脑运动区（MLR）可在跑步机上诱发可控运动。我们已经能够通过局部注入递质及其激动剂和拮抗剂在该制备物中诱导和阻断运动。向MLR中注入GABA拮抗剂荷包牡丹碱和印防己毒素在低浓度（5 mM）时可引发运动。发现应用蝇蕈醇（5 mM）或GABA（0.5 M）可阻断化学诱导的运动以及电诱发和自发行走。预先注入地西泮可增强GABA对运动的阻断作用。另一方面，应用士的宁（10 mM）诱导踏步无效，注入兴奋性递质谷氨酸、乙酰胆碱和去甲肾上腺素也无效。这些发现表明MLR受到抑制性GABA能输入的调控。黑质是已知在脑干横断后方投射至MLR的唯一传入神经，并且可能是这种输入的来源。本文提出了一个模型来解释我们以及其他研究人员的结果，并为在调节运动事件的脑干中枢中发生的神经化学事件提供了一个可行的假设。
