Forrest Taylor J, Desmond Timothy J, Issa Mohamad, Scott Peter J H, Basura Gregory J
1 Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute University of Michigan, Ann Arbor, MI, USA.
2 Kresge Hearing Research Institute University of Michigan, Ann Arbor, MI, USA.
Mol Imaging. 2019 Jan-Dec;18:1536012119848927. doi: 10.1177/1536012119848927.
Noise-induced hearing loss leads to anatomic and physiologic changes in primary auditory cortex (A1) and the adjacent dorsal rostral belt (RB). Since acetylcholine is known to modulate plasticity in other cortical areas, changes in A1 and RB following noise damage may be due to changes in cholinergic receptor expression. We used [H]scopolamine and [F]flubatine binding to measure muscarinic acetylcholine receptor (mAChR) and nicotinic acetylcholine receptor (nAChR) expression, respectively, in guinea pig A1 and RB 3 weeks following unilateral, left ear noise exposure, and a temporary threshold shift in hearing. [H]Scopolamine binding decreased in right A1 and RB (contralateral to noise) compared to sham controls across all cortical layers. [F]Flubatine binding showed a nonsignificant upward trend in right A1 following noise but only significantly increased in right RB and 2 layers of left RB (ipsilateral to noise). This selective response may ultimately influence cortical plasticity and function. The mechanism(s) by which cholinergic receptors are altered following noise exposure remain unknown. However, these data demonstrate noise exposure may differentially influence mAChRs that typically populate interneurons in A1 and RB more than nAChRs that are traditionally located on thalamocortical projections and provide motivation for cholinergic imaging in clinical patient populations of temporary or permanent hearing loss.
噪声性听力损失会导致初级听觉皮层（A1）和相邻的背侧嘴侧带（RB）发生解剖学和生理学变化。由于已知乙酰胆碱可调节其他皮层区域的可塑性，噪声损伤后A1和RB的变化可能是由于胆碱能受体表达的改变。我们使用[H]东莨菪碱和[F]氟巴汀结合分别测量豚鼠在左耳单侧噪声暴露及听力出现暂时阈移3周后A1和RB中M型乙酰胆碱受体（mAChR）和烟碱型乙酰胆碱受体（nAChR）的表达。与假手术对照组相比，右侧A1和RB（与噪声相对侧）所有皮层层中的[H]东莨菪碱结合均减少。噪声暴露后，右侧A1中的[F]氟巴汀结合呈不显著的上升趋势，但仅在右侧RB和左侧RB的2层（与噪声同侧）中显著增加。这种选择性反应最终可能会影响皮层可塑性和功能。噪声暴露后胆碱能受体发生改变的机制尚不清楚。然而，这些数据表明，噪声暴露对通常存在于A1和RB中间神经元中的mAChRs的影响可能大于传统上位于丘脑皮质投射上的nAChRs，并为在暂时性或永久性听力损失的临床患者群体中进行胆碱能成像提供了动力。
