Gelissen M, Cools A
Department of Pharmacology, University of Nijmegen, The Netherlands.
Behav Brain Res. 1987 Aug;25(2):83-96. doi: 10.1016/0166-4328(87)90001-5.
Recently it has been shown that the substantia nigra pars reticulata (SNR) is required for adjusting the body position. In this study the role of the SNR in the execution of movements was investigated. Therefore, the effects of bilateral SNR injections of picrotoxin (500 ng/0.5 microliter) and muscimol (200 ng/1 microliter) were investigated on movements of cats which were trained to cross a rotating cylinder. SNR injection of picrotoxin suppressed the movements that were executed by cats injected with distilled water (0.5 microliter), i.e. 'normal movements'. While crossing the rotating cylinder, picrotoxin-injected cats mainly executed movements that almost never occurred in distilled water treated cats. Picrotoxin-injected cats executed 'special movements', i.e. forward locomotion in which the hindlimbs were affected, and 'counter-movements'. While executing the latter movements no forward locomotion occurred at all; the cats solely executed lateral fore- and hindlimb movements opposite to the direction in which the cylinder rotated. SNR application of muscimol enhanced the execution of 'normal movements'. Since the SNR sends information to the deeper layers of the superior colliculus (dl-SC) via GABAergic fibers, it was also investigated whether pharmacological stimulation (muscimol) and inhibition (picrotoxin) of the GABAergic dl-SC activity affected these movements on the rotating cylinder: no changes were observed after injecting otherwise effective doses of muscimol (75 ng/1 microliter) and picrotoxin (100 ng/0.5 microliter). In order to compare the function of the SNR and dl-SC in programming a different type of movements, the effects of GABAergic agents in the dl-SC (picrotoxin 100 ng/0.5 microliter and muscimol 75 ng/1 microliter) and the SNR (picrotoxin 500 ng/0.5 microliter and muscimol 200 ng/1 microliter) were investigated on the feline ability to execute goal-directed movements in an experimental set-up that prevented the occurrence of targeting movements which were continuously guided by external, i.e. auditory, visual, tactile and olfactory stimuli. For that purpose cats were trained to step out of a startbox on a rotating cylinder, i.e. the target. Dl-SC injection of muscimol or SNR application of picrotoxin prevented the cats from stepping out of the startbox on the rotating cylinder. In contrast, cats injected with muscimol into the SNR or picrotoxin into the dl-SC stepped out of the startbox, although dl-SC application of picrotoxin elicited forelimb misplacements: frequently the cats placed their forelimbs alongside of, but not on the cylinder when trying to leave the startbox.(ABSTRACT TRUNCATED AT 400 WORDS)
最近研究表明，黑质网状部（SNR）对于调整身体姿势是必需的。在本研究中，对SNR在运动执行中的作用进行了调查。因此，研究了双侧SNR注射印防己毒素（500纳克/0.5微升）和蝇蕈醇（200纳克/1微升）对经训练穿过旋转圆柱体的猫的运动的影响。注射印防己毒素的SNR抑制了注射蒸馏水（0.5微升）的猫所执行的运动，即“正常运动”。在穿过旋转圆柱体时，注射印防己毒素的猫主要执行几乎从未在注射蒸馏水的猫身上出现过的运动。注射印防己毒素的猫执行“特殊运动”，即后肢受影响的向前运动和“反向运动”。在执行后一种运动时，根本没有向前运动；猫仅执行与圆柱体旋转方向相反的前肢和后肢侧向运动。应用蝇蕈醇增强了“正常运动”的执行。由于SNR通过γ-氨基丁酸能纤维向上丘深层（dl-SC）发送信息，还研究了γ-氨基丁酸能dl-SC活动的药理刺激（蝇蕈醇）和抑制（印防己毒素）是否会影响在旋转圆柱体上的这些运动：在注射其他有效剂量的蝇蕈醇（75纳克/1微升）和印防己毒素（100纳克/0.5微升）后未观察到变化。为了比较SNR和dl-SC在规划不同类型运动中的功能，研究了γ-氨基丁酸能药物在dl-SC（印防己毒素100纳克/0.5微升和蝇蕈醇75纳克/1微升）和SNR（印防己毒素500纳克/0.5微升和蝇蕈醇200纳克/1微升）中对猫在防止出现由外部即听觉、视觉、触觉和嗅觉刺激持续引导的靶向运动的实验装置中执行目标导向运动能力的影响。为此，训练猫从旋转圆柱体上的起始箱中走出，即目标。向dl-SC注射蝇蕈醇或向SNR应用印防己毒素可防止猫从旋转圆柱体上的起始箱中走出。相比之下，向SNR注射蝇蕈醇或向dl-SC注射印防己毒素的猫从起始箱中走出，尽管向dl-SC应用印防己毒素会引起前肢错位：猫在试图离开起始箱时经常将前肢放在圆柱体旁边但不是放在圆柱体上。（摘要截断于400字）
