Localization of melatonin and its receptors (melatonin 1a and 1b receptors) in the mouse inner ear

Abstract

Background: In the inner ear, evidence has been gathered indicating that melatonin plays important roles in inner ear physiology and pathophysiology. However, no attempt has been made previously to investigate the localization or expression of melatonin and its receptors in the whole inner ear.

Aims/objectives: To analyze the presence of melatonin and its receptors in the normal mouse inner ear.

Material and methods: C57BL6/J mice were used in this study. The localizations of melatonin, MT1a and MT1b in the inner ear, i.e. cochlea, vestibular end organs, vestibular ganglion and endolymphatic sac (ES), were studied by immunohistochemistry.

Results: The organ of Corti, spiral ganglion, vestibular ganglion, vestibular sensory cells, vestibular dark and transitional cells, and ES epithelial cells showed an immunofluorescence reaction to melatonin, MT1a and MT1b.

Conclusion and significance: The present findings show that melatonin and its receptors (MT1a and MT1b) are present in the inner ear, thus supporting the hypothesis that melatonin plays a physiological role in the inner ear.

Chinese abstract

背景：有证据表明褪黑素在内耳生理和病理生理方面起着重要作用。然而, 以前没有人试图研究褪黑素在整个内耳的定位或表达以及它的受体。

目的：对正常小鼠内耳中褪黑素的存在及其受体进行分析。

材料与方法：采用C57BL6/J小鼠。用免疫组织化学方法研究褪黑素、MT1a和MT1b在内耳、耳蜗、前庭末端器官、前庭神经节和内淋巴囊中的定位。

结果：皮质醇、螺旋神经节、前庭神经节、前庭感觉细胞、前庭暗细胞和过渡细胞、ES上皮细胞对褪黑素、MT1a和MT1b有免疫荧光反应。

结论与意义：本研究结果表明, 褪黑素及其受体（MT1a和MT1b）存在于内耳, 支持了褪黑素在内耳中发挥生理作用的假说。

Keywords:

• Melatonin
• melatonin receptor
• inner ear
• mouse
• immunohistochemistry

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Additional information

Funding

This study was supported by a Grant-in-Aid for Scientific Research (18K09320) provided by the Japan Society for the promotion of science and also by the Swedish Medical Research Council [grant no. 17X-7305].