Department of Otorhinolaryngology, University Hospital Zurich, (USZ), University of Zurich (UZH), Zurich, Switzerland.
Faculty of Medicine, University of Zurich (UZH), Zurich, Switzerland.
Sci Rep. 2022 Mar 8;12(1):4068. doi: 10.1038/s41598-022-07835-8.
We performed magnetic resonance spectroscopy (MRS) on healthy individuals with tinnitus and no hearing loss (n = 16) vs. a matched control group (n = 17) to further elucidate the role of excitatory and inhibitory neurotransmitters in tinnitus. Two-dimensional J-resolved spectroscopy (2D-JPRESS) was applied to disentangle Glutamate (Glu) from Glutamine and to estimate GABA levels in two bilateral voxels in the primary auditory cortex. Results indicated a lower Glu concentration (large effect) in right auditory cortex and lower GABA concentration (medium effect) in the left auditory cortex of the tinnitus group. Within the tinnitus group, Glu levels positively correlated with tinnitus loudness measures. While the GABA difference between groups is in line with former findings and theories about a dysfunctional auditory inhibition system in tinnitus, the novel finding of reduced Glu levels came as a surprise and is discussed in the context of a putative framework of inhibitory mechanisms related to Glu throughout the auditory pathway. Longitudinal or interventional studies could shed more light on interactions and causality of Glu and GABA in tinnitus neurochemistry.
我们对耳鸣且无听力损失的健康个体（n = 16）与匹配对照组（n = 17）进行了磁共振波谱（MRS）分析，以进一步阐明兴奋性和抑制性神经递质在耳鸣中的作用。应用二维 J 分辨波谱（2D-JPRESS）将谷氨酸（Glu）与谷氨酰胺区分开，并估计初级听觉皮层两个双侧体素中的 GABA 水平。结果表明，耳鸣组右听觉皮层的 Glu 浓度较低（大效应），左听觉皮层的 GABA 浓度较低（中效应）。在耳鸣组内，Glu 水平与耳鸣响度测量呈正相关。虽然组间 GABA 差异与以前关于耳鸣中听觉抑制系统功能障碍的发现和理论一致，但 Glu 水平降低的新发现令人惊讶，并在与听觉通路上与 Glu 相关的抑制机制的假设框架中进行了讨论。纵向或干预性研究可以更深入地了解 Glu 和 GABA 在耳鸣神经化学中的相互作用和因果关系。
