Department of Experimental Medicine, Section of Physiology and Biochemistry, University of Perugia, via Gambuli, 1, 06132 Perugia, Italy; Santa Lucia Foundation IRCCS, via del Fosso di Fiorano, 64, 00143 Rome, Italy.
Neurological Clinic, Department of Medicine, University of Perugia, Santa Maria della Misericordia Hospital, via Gambuli, 1, 06132 Perugia, Italy.
Neurobiol Dis. 2018 Oct;118:1-8. doi: 10.1016/j.nbd.2018.06.008. Epub 2018 Jun 13.
Among genetic abnormalities identified in Parkinson's disease (PD), mutations of the leucine-rich repeat kinase2 (LRRK2) gene, such as the G2019S missense mutation linked to enhanced kinase activity, are the most common. While the complex role of LRRK2 has not been fully elucidated, evidence that mutated kinase activity affects synaptic transmission has been reported. Thus, our aim was to explore possible early alterations of neurotransmission produced by the G2019S LRRK2 mutation in PD. We performed electrophysiological patch-clamp recordings of striatal spiny projection neurons (SPNs) in the G2019S-Lrrk2 knock-in (KI) mouse model of PD, in D1994S kinase-dead (KD), Lrrk2 knock-out (KO) and wild-type (WT) mice. In G2019S Lrrk2 KI mice, basal spontaneous glutamatergic transmission, synaptic facilitation, and NMDA/AMPA ratios were unchanged, whereas the stimulation of dopamine (DA) D2 receptor by quinpirole reduced the spontaneous and evoked excitatory postsynaptic currents (EPSC). Quinpirole reduced the EPSC amplitude of SPNs in KI but not in KD, KO and WT mice, suggesting that the enhanced LRRK2 kinase activity induced by the G2019S mutation is associated with the observed functional alteration of SPNs synaptic transmission. The effect of quinpirole was mediated by a phospholipase C (PLC)-dependent release of endocannabinoid, with subsequent activation of presynaptic cannabinoid receptor 1 and reduced release of glutamate. The key role of DA D2 receptor in reducing glutamatergic output in our LRRK2 genetic model of PD further supports the use of DA agonists in the treatment of early PD patients with LRRK2 mutations to counteract the disease progression.
在帕金森病（PD）中鉴定出的遗传异常中，富亮氨酸重复激酶 2（LRRK2）基因突变，例如与增强激酶活性相关的 G2019S 错义突变，是最常见的。虽然 LRRK2 的复杂作用尚未完全阐明，但有证据表明突变激酶活性会影响突触传递。因此，我们的目的是探索 G2019S LRRK2 突变在 PD 中产生的神经传递的可能早期改变。我们对帕金森病 G2019S-Lrrk2 敲入（KI）小鼠模型中的纹状体棘突投射神经元（SPNs）进行了电生理学膜片钳记录，包括 D1994S 激酶失活（KD）、Lrrk2 敲除（KO）和野生型（WT）小鼠。在 G2019S Lrrk2 KI 小鼠中，基础自发性谷氨酸能传递、突触易化和 NMDA/AMPA 比值没有变化，而通过 quinpirole 刺激多巴胺（DA）D2 受体则减少了自发性和诱发的兴奋性突触后电流（EPSC）。在 KI 小鼠中，quinpirole 减少了 SPNs 的 EPSC 幅度，但在 KD、KO 和 WT 小鼠中没有减少，这表明 G2019S 突变诱导的增强的 LRRK2 激酶活性与观察到的 SPNs 突触传递功能改变有关。quinpirole 的作用是通过 PLC 依赖性内源性大麻素的释放来介导的，随后激活了突触前大麻素受体 1，并减少了谷氨酸的释放。DA D2 受体在我们的 LRRK2 遗传 PD 模型中减少谷氨酸能输出的关键作用进一步支持在早期 PD 患者中使用 DA 激动剂来治疗 LRRK2 突变，以对抗疾病进展。
