Department of Surgery, Division of Otolaryngology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
PLoS One. 2019 Aug 2;14(8):e0220734. doi: 10.1371/journal.pone.0220734. eCollection 2019.
The neural mechanisms underlying behavioral therapy for vocal acoustic deficits in patients with Parkinson disease is unknown. A primary hypothesis is that voice therapy may modulate mesolimbic brainstem regions, including the ventral tegmental area (VTA). The VTA is implicated in ultrasonic call peak frequency, involved in rewarding behaviors, and impacted by Parkinsonism. We tested the hypothesis that chronic (daily) behavioral vocal exercise of male Pink1-/- rats would alter ultrasonic vocalization acoustics and mesolimbic neurochemistry (catecholamines, GABA, mu-opioid receptor) compared to three different controls: sham-exercised Pink1-/-, unexercised Pink1-/-, and unexercised wildtype (WT) rats. A sub-hypothesis is that sham-exercise rats may exhibit changes to VTA neurochemistry as a result of a type or rewarding intervention. Results demonstrate that average bandwidth (frequency range) of ultrasonic vocalizations did not differ between WT, Pink1-/- no exercise vs. sham and vocal-exercise rats. However, average peak frequency is significantly reduced in vocal-exercised Pink1-/- rats compared to Pink1-/- no exercise, and WT groups. Unexpectedly, there were no significant acoustic differences between the vocal- and sham-exercised groups. There were no differences in catecholamine protein concentrations or tyrosine hydroxylase mRNA expression in the VTA between any of the groups. However, there was significant upregulation of all GABA-related genes in both vocal- and sham-exercised Pink1-/- rats (Gad1, Gad2, Gls, Glul); this finding was confirmed with follow up quantitative Western blotting for GAD. Additionally, there were differential results for mu-opioid receptor quantification in the VTA: vocal-exercised Pink1-/- rats showed increased mRNA expression for mu-opioid receptors whereas Western blotting indicated decreased protein levels in all Pink1-/- rats compared to WT controls suggesting the possible onset of pathology in this model. These data demonstrate modulatory effects of a rewarding behavioral paradigm on ultrasonic vocalization peak frequency. The results suggest that neuromodulators such as GABA and opioid activity, as well as the rewarding aspects of therapy may play a key role in shaping vocal treatments.
行为疗法治疗帕金森病患者发声缺陷的神经机制尚不清楚。一个主要假设是，语音治疗可能会调节中脑边缘脑区，包括腹侧被盖区（VTA）。VTA 与超声呼叫峰值频率有关，涉及奖励行为，并受帕金森病影响。我们测试了以下假设：与三种不同的对照组（假锻炼 Pink1-/-、不锻炼 Pink1-/-、不锻炼野生型（WT）大鼠）相比，慢性（每日）行为声乐锻炼雄性 Pink1-/-大鼠会改变超声发声的声学特性和中脑边缘神经化学（儿茶酚胺、GABA、μ-阿片受体）。一个子假设是，假锻炼大鼠可能会因为某种奖励干预而改变 VTA 神经化学。结果表明，WT、Pink1-/-不锻炼与假锻炼和声乐锻炼大鼠之间的超声发声平均带宽（频率范围）没有差异。然而，与 Pink1-/-不锻炼组和 WT 组相比，声乐锻炼的 Pink1-/-大鼠的平均峰值频率显著降低。出乎意料的是，声乐锻炼组和假锻炼组之间没有明显的声学差异。在 VTA 中，儿茶酚胺蛋白浓度或酪氨酸羟化酶 mRNA 表达在任何组之间均无差异。然而，在声乐和假锻炼的 Pink1-/-大鼠中，所有 GABA 相关基因都有显著的上调（Gad1、Gad2、Gls、Glul）；这一发现通过后续的 GABA 定量 Western blot 得到了证实。此外，VTA 中μ-阿片受体定量存在差异结果：声乐锻炼的 Pink1-/-大鼠的μ-阿片受体 mRNA 表达增加，而 Western blot 表明所有 Pink1-/-大鼠的蛋白水平均低于 WT 对照组，表明该模型中可能出现了病理。这些数据表明，奖励行为范式对超声发声峰值频率具有调节作用。研究结果表明，神经调质如 GABA 和阿片活性以及治疗的奖励方面可能在塑造声乐治疗方面发挥关键作用。
