Melatonin Receptor 1-Positive (IMAGE) Neural Regeneration Research Caption 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. Credit <I>Neural Regeneration Research</I> Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.