Accumulating research indicates that melatonin has a major role in pain transmission and has an ultra-sensitizing effect. Dr. Fang Huang and colleagues from Sun Yat-sen University in China for the first time located the distribution of melatonin receptor 1 in the caudal spinal trigeminal nucleus. Their results, published in the Neural Regeneration Research (Vol. 8, No. 32, 2013), showed that when melatonin receptor 1 expression in the caudal spinal nucleus is significantly reduced, melatonin's regulatory effect on pain is attenuated. Further study is required to determine whether the decreased melatonin receptor 1 expression in the central caudal trigeminal spinal nucleus can attenuate the analgesic effect of the melatonin/melatonin receptor/nitric oxide pathway.
Article: " Orofacial inflammatory pain affects the expression of MT1 and NADPH-d in rat caudal spinal trigeminal nucleus and trigeminal ganglion," by Fang Huang, Hongwen He, Wenguo Fan, Yongliang Liu, Hongyu Zhou, Bin Cheng (Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, Guangdong Province, China)
Huang F, He HW, Fan WG, Liu YL, Zhou HY, Cheng B. Orofacial inflammatory pain affects the expression of MT1 and NADPH-d in rat caudal spinal trigeminal nucleus and trigeminal ganglion. Neural Regen Res. 2013;8(32):2991-3002.