DOPAMINERGIC CONTROL OF SPINAL CORD AND RESTLESS LEGS

描述(申请人提供)：不宁腿综合症(RLS)是一种中枢神经系统疾病，涉及异常肌肉感觉，在运动活动中减少，在休息时恶化，并有明显的昼夜节律模式。主要的治疗包括提供增加中枢神经系统多巴胺能活性的药物，特别是激活D2-1ike受体。 下丘脑控制自主神经功能和昼夜节律。背部-后部(A11)区域包含唯一的多巴胺(DA)能投射到脊髓。DA纤维主要终止于节前交感神经元所在的中间外侧柱(IML)和与肌肉传入加工有关的背角区。我们假设：(I)下丘脑-脊髓DA活性的缺陷导致肌肉传入的异常激活；直接地，通过减少对传入输入的紧张性抑制，以及间接地，通过去抑制诱导对骨骼肌传入的交感驱动的增加。(Ii)低阈值传入活动(例如，在运动过程中)在突触前抑制高阈值肌肉传入。(3)DA去抑制作用应在夜间达到高峰，这是下丘脑多巴胺昼夜节律释放的最低点。 由于A11区提供唯一的DA输入，所有的脊髓调节作用都可以归因于它的功能。因此，对体外脊髓中DA调节作用的研究将表征下丘脑-脊髓多巴胺功能的复杂细胞和网络作用。首先，我们计划使用免疫染色和原位杂交技术来表征多巴胺受体在脊髓中的分布。然后，我们将研究5-羟色胺和多巴胺对IML神经元兴奋性的调节，以及交感神经驱动的增加是否促进肌肉传入活动和向脊髓神经元的输入。最后，我们将使用A11神经化学损伤和D3受体基因敲除小鼠来检查它们对脊髓功能变化的影响，并将这些变化与伴随EEG、颈部和肢体肌电和EKG记录的几个运动相关行为参数的变化联系起来。 我们建议的独特之处在于发展了关于引起RLS的脊髓机制的新的和可检验的假说。它涉及第一个关于DA对脊髓功能的调节的详细研究，它是在行为、网络和细胞水平上进行的，包括试图建立RLS的动物模型。

DESCRIPTION (provided by applicant): Restless legs syndrome (RLS) is a CNS disorder involving abnormal muscle sensations that are reduced during motor activity, worsen at rest, and have a marked circadian pattern. Primary treatment involves providing drugs that increase CNS dopaminergic activity, particularly activation of D2-1ike receptors. The hypothalamus controls autonomic function and circadian rhythmicity. The dorso-posterior (A11) region contains the only dopaminergic (DA) projections to spinal cord. DA fibers terminate largely in the intermediolateral column (IML) housing preganglionic sympathetic neurons and in dorsal horn regions related to muscle afferent processing. We hypothesize: (i) That a deficit in hypothalamo-spinal DA activity results in an aberrant activation of muscle afferents; directly, by reducing tonic inhibition of afferent input, and; indirectly, via a disinhibition-induced increase in sympathetic drive to skeletal muscle afferents. (ii) That low-threshold afferent activity (e.g. during movement) presynaptically depresses high-threshold muscle afferents. (iii) That DA disinhibitory actions should peak at night, the nadir of hypothalamic circadian dopamine release. As the A11 region provides the only DA input, all spinal modulatory actions can be ascribed to its function. Hence, studies of DA modulatory actions in the in vitro spinal cord will characterize the complex cellular and network actions of hypothalamo-spinal dopamine function. First, we plan to characterize the dopamine receptor distribution in spinal cord using immunostaining and in situ hybridization techniques. We will then study 5-HT and dopamine modulation of IML neuronal excitability and whether increases in sympathetic drive facilitate muscle afferent activity and input to spinal neurons. Lastly, we will use A11 neurochemical lesioning and D3 receptor knockout mice to examine their effects on alterations in spinal cord function and relate these changes to changes in several movement-related behavioral parameters concomitant with recordings of EEG, neck & limb EMG, and EKG. The uniqueness of our proposal is the development of novel and testable hypotheses on putative spinal mechanisms causing RLS. It involves the first detailed study of DA modulation of spinal cord function and it is undertaken at behavioral, network, and cellular levels, including an attempt to develop an animal model of RLS.