Finn M, Mayorga A J, Conlan A, Salamone J D
Department of Psychology, University of Connecticut, Storrs 06269-1020, USA.
Neuroscience. 1997 Sep;80(2):535-44. doi: 10.1016/s0306-4522(97)00087-0.
Four experiments were conducted to investigate the role of pallidal and nigral GABA in the generation of tremulous jaw movements in rats. In these experiments, tremulous jaw movements were induced by i.p. injections of the anticholinesterase tacrine (5.0 mg/kg). Previous work has shown that the tremulous jaw movements induced by cholinomimetics and dopamine depletion are dependent upon striatal mechanisms. Thus, the present study investigated potential striatal output pathways that could be involved in the generation of these movements. Because there are GABAergic projections from neostriatum to entopeduncular nucleus (medial globus pallidus) and substantia nigra pars reticulata, the GABA agonist muscimol was injected directly into these structures to study the effects of GABA stimulation on tacrine-induced jaw movements. Injections of muscimol into the entopeduncular nucleus (25-100 ng) failed to have any significant effects on tacrine-induced vacuous jaw movements. However, injections of muscimol (12.5-50 ng) into the substantia nigra pars reticulata blocked the jaw movements induced by tacrine. In the third experiment, it was again demonstrated that 25.0 ng of muscimol injected directly into the substantia nigra pars reticulata blocked the jaw movements induced by tacrine; in addition, it was shown that injections of this dose 2.0 mm dorsal to the substantia nigra pars reticulata failed to affect tacrine-induced tremulous jaw movements. It was shown in the fourth experiment that injections of muscimol into a more medial portion of the substantia nigra pars reticulata also reduced tacrine-induced tremulous jaw movements. These results indicate that stimulation of GABA(A) receptors in substantia nigra pars reticulata can block tacrine-induced tremulous jaw movements. This finding is consistent with the notion that striatonigral GABA projections are involved in the generation of tremulous jaw movements. It is also possible that striatonigral GABA mechanisms are involved in human clinical phenomena such as parkinsonian tremor.
进行了四项实验来研究苍白球和黑质γ-氨基丁酸（GABA）在大鼠震颤性下颌运动产生中的作用。在这些实验中，通过腹腔注射抗胆碱酯酶他克林（5.0毫克/千克）诱导震颤性下颌运动。先前的研究表明，拟胆碱药和多巴胺耗竭诱导的震颤性下颌运动依赖于纹状体机制。因此，本研究调查了可能参与这些运动产生的潜在纹状体输出通路。由于从新纹状体到内苍白球（内侧苍白球）和黑质网状部存在GABA能投射，将GABA激动剂蝇蕈醇直接注射到这些结构中，以研究GABA刺激对他克林诱导的下颌运动的影响。向内苍白球注射蝇蕈醇（25 - 100纳克）对他克林诱导的空嚼性下颌运动没有任何显著影响。然而，向黑质网状部注射蝇蕈醇（12.5 - 50纳克）可阻断他克林诱导的下颌运动。在第三个实验中，再次证明直接向黑质网状部注射25.0纳克蝇蕈醇可阻断他克林诱导的下颌运动；此外，还表明在黑质网状部背侧2.0毫米处注射该剂量对他克林诱导的震颤性下颌运动没有影响。第四个实验表明，向黑质网状部更内侧部分注射蝇蕈醇也可减少他克林诱导的震颤性下颌运动。这些结果表明，刺激黑质网状部的GABA(A)受体可阻断他克林诱导的震颤性下颌运动。这一发现与纹状体黑质GABA投射参与震颤性下颌运动产生的观点一致。纹状体黑质GABA机制也可能参与人类临床现象，如帕金森震颤。
