Distribution and colocalization of melatonin 1a-receptor and NADPH-d in the trigeminal system of rat

PeerJ. 2019 May 1:7:e6877. doi: 10.7717/peerj.6877. eCollection 2019.

Authors

Yifan He^{1

2}, Wenguo Fan^{1

2}, Yue Xu^{1

2}, Yong Liang Liu¹, Hongwen He^{1

2}, Fang Huang^{1

2}

Affiliations

¹ Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China.
² Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-Sen University, Guangzhou, China.

Abstract

Melatonin and nitric oxide (NO) are involved in orofacial signal processing in the trigeminal sensory system. The aim of the present study was to examine the distribution of melatonin 1a-receptor (MT1) and its colocalization with nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) in the spinal trigeminal nucleus (STN), the trigeminal ganglion (TG), and the mesencephalic trigeminal nucleus (MTN) in the rat, using histochemistry and immunohistochemistry. Our results show that MT1-positive neurons are widely distributed in the TG and the subnucleus caudalis of the STN. Furthermore, we found that MT1 colocalizes with NADPH-d throughout the TG and MTN, most extensively in the TG. The distribution pattern of MT1 and its colocalization with NADPH-d indicate that melatonin might play an important role in the trigeminal sensory system, which could be responsible for the regulation of NO levels.

Keywords: Melatonin 1a-receptor; Mesencephalic trieminal nucleus; NADPH-diaphorase; Spinal trigeminal nucleus; Trigeminal ganglion.

Grants and funding

This work was supported by the National Natural Science Foundation of China (NO: 81870737 and 81771098). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.