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.
Melatonin receptor 1-positive neurons of varying sizes (arrows) were observed in orofacial pain rats. The medium and small neurons, which are related to pain, were more numerous than large neurons.
(Photo Credit: Neural Regeneration Research)
Source: Neural Regeneration Research