Cepeda Carlos, Murphy Kerry P S, Parent Martin, Levine Michael S
Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
Huntington's Disease Research Forum, Department of Life, Health and Chemical Sciences, The Open University, Milton Keynes, Buckinghamshire, UK.
Prog Brain Res. 2014;211:235-54. doi: 10.1016/B978-0-444-63425-2.00010-6.
Alterations in dopamine (DA) neurotransmission in Parkinson's disease are well known and widely studied. Much less is known about DA changes that accompany and underlie some of the symptoms of Huntington's disease (HD), a dominant inherited neurodegenerative disorder characterized by chorea, cognitive deficits, and psychiatric disturbances. The cause is an expansion in CAG (glutamine) repeats in the HTT gene. The principal histopathology of HD is the loss of medium-sized spiny neurons (MSNs) and, to a lesser degree, neuronal loss in cerebral cortex, thalamus, hippocampus, and hypothalamus. Neurochemical, electrophysiological, and behavioral studies in HD patients and genetic mouse models suggest biphasic changes in DA neurotransmission. In the early stages, DA neurotransmission is increased leading to hyperkinetic movements that can be alleviated by depleting DA stores. In contrast, in the late stages, DA deficits produce hypokinesia that can be treated by increasing DA function. Alterations in DA neurotransmission affect glutamate receptor modulation and could contribute to excitotoxicity. The mechanisms of DA dysfunction, in particular the increased DA tone in the early stages of the disease, are presently unknown but may include initial upregulation of DA neuron activity caused by the genetic mutation, reduced inhibition resulting from striatal MSN loss, increased excitation from cortical inputs, and DA autoreceptor dysfunction. Targeting both DA and glutamate receptor dysfunction could be the best strategy to treat HD symptoms.
帕金森病中多巴胺（DA）神经传递的改变是众所周知且被广泛研究的。对于亨廷顿舞蹈病（HD）某些症状伴随并作为其基础的DA变化，人们了解得要少得多。HD是一种显性遗传性神经退行性疾病，其特征为舞蹈症、认知缺陷和精神障碍。病因是HTT基因中CAG（谷氨酰胺）重复序列的扩增。HD的主要组织病理学特征是中等大小棘状神经元（MSN）的丧失，以及在较小程度上大脑皮层、丘脑、海马体和下丘脑的神经元丧失。对HD患者和基因小鼠模型进行的神经化学、电生理和行为学研究表明，DA神经传递存在双相变化。在疾病早期，DA神经传递增加，导致运动机能亢进，通过耗尽DA储备可缓解这种情况。相反，在疾病晚期，DA缺乏会导致运动功能减退，可通过增强DA功能进行治疗。DA神经传递的改变会影响谷氨酸受体调节，并可能导致兴奋性毒性。目前尚不清楚DA功能障碍的机制，尤其是疾病早期DA水平升高的机制，但可能包括基因突变引起的DA神经元活动最初上调、纹状体MSN丧失导致的抑制作用减弱、皮质输入引起的兴奋增加以及DA自身受体功能障碍。针对DA和谷氨酸受体功能障碍可能是治疗HD症状的最佳策略。
