Parkinson’s disease (PD) is a common neurodegenerative disease worldwide. While the typical motor symptoms of PD are well known, the lesser known non-motor symptoms can also greatly impact the patient’s quality of life. These symptoms often appear before motor impairment, therefore identifying biomarkers that may predict PD risk or pathology has been a major and challenging endeavour. Given that the loss of dopamine, and its rate-limiting enzyme tyrosine hydroxylase (TH) occurs in PD, the expression and accompanying post-translational changes in TH during PD progression could yield insight into the disruption of cellular signalling occurring in the CNS, and also in peripheral tissues wherein catecholamine function plays a role. Furthermore, changes in expression and phosphorylation of TH in the brain and periphery can potentially reveal how TH stability and function are compromised in PD. As such, these changes can reveal how catecholamine synthesis capacity is gradually compromised and how changes in cellular signalling may govern the functional status of remaining catecholaminergic neurons. This review summarises the findings of clinical PD and neurotoxin models of PD that assessed TH expression or phosphorylation in catecholaminergic pathways in the brain and relevant peripheral tissues. We propose that establishing similar changes in TH expression and function in the CNS and periphery of established neurotoxin models can be a potential reference for comparison to changes in TH in human peripheral tissues. These changes in TH expression and phosphorylation may have predictive validity to estimate risk of PD progression before motor impairment is evident.

帕金森氏病（PD）是全世界常见的神经退行性疾病。虽然PD的典型运动症状是众所周知的，但鲜为人知的非运动症状也会极大地影响患者的生活质量。这些症状通常出现在运动功能障碍之前，因此，鉴定可预测PD风险或病理的生物标记物是一项主要且具有挑战性的工作。鉴于多巴胺的丢失及其限速酶酪氨酸羟化酶（TH）在PD中发生，因此在PD进展过程中TH的表达及其伴随的翻译后变化可以深入了解中枢神经系统中发生的细胞信号转导，以及在儿茶酚胺功能起作用的外周组织中也有作用。此外，脑和外周血中TH的表达和磷酸化的变化可能揭示TH在PD中如何损害其稳定性和功能。这样，这些变化可以揭示儿茶酚胺的合成能力是如何逐渐受到损害的，以及细胞信号传导的变化如何可以控制剩余的儿茶酚胺能神经元的功能状态。这篇综述总结了PD的临床PD和神经毒素模型的发现，这些模型评估了大脑和相关外围组织中儿茶酚胺能途径中TH的表达或磷酸化。我们建议，在中枢神经系统和已建立的神经毒素模型的外周中建立类似的TH表达和功能变化，可以作为与人周围组织中TH变化进行比较的潜在参考。