Analysis of Gender-specific Differences in Oral Melatonin Receptor Expression

Objectives: Melatonin is a natural circadian-regulated hormone that is involved in the regulation of the sleep-wake cycle. Melatonin is also available as a dietary supplement and has recently been tested for efficacy in a randomized, double-blind, placebo-controlled crossover trial involving sleep disruption. Because melatonin disruption may also be associated with oral cancer, and major differences are found in oral cancer risk between females and the primary objective goal of this study was to evaluate gender-specific difference in the expression of melatonin receptors among dental clinic patients.
Methods: Following IRB approval, patients in the dental clinic waiting area were randomly asked to participate in the study over several weeks, which involved the collection of saliva and non-identifiable demographic information. DNA and RNA were subsequently extracted from the saliva samples and screened for melatonin receptor expression.
Results: : From 122 samples collected, 75 had sufficient RNA and demographic information available to for analysis. Samples were nearly equally female (n=37/75 or 49.3%) and male (n=38 or 50.7%). Average RNA recovery was approximately 771 ng/uL, which was not significantly different between females and males (p >0.05). However, the preliminary RT-PCR screening of melatonin receptors may suggest there are some differences in expression between males and females – although this may not be statistically significant.
Conclusions: Although some studies have evaluated gender expression differences in melatonin, these focused on insomnia and other sleep-related disorders. This study may be among the first to examine the role of gender in healthy oral tissues from adults specifically for expression of the three primary melatonin receptors. As oral cancer risk is greatly increased for males compared with females, and the likelihood of dietary supplementation is also greatly influenced by gender, understanding the natural distribution of melatonin receptor function between males and females would increase our understanding for the importance of potential responsiveness and the relationship with oral health.