Comparison of platelet serotonin transporter activity in subjects with severe sleep bruxism and control

Purpose: The aim of this study was to evaluate the correlation between sleep bruxism (SB) frequency and serotonin transporter (SERT)-driven serotonin (5-HT)-uptake in platelets. Methods: Subjects were dental trainee residents and faculty members of Okayama University Hospital who were aware of having severe or no SB. SB frequency was assessed for 3-consecutive nights by a self-contained electromyographic detector/analyzer, which indicated individual SB levels as one of four grades (score 0, 1, 2 and 3). Subjects were classified as normal control (NC) when SB scores indicated only 0 or 1 during the 3 nights, or as severe SB for scores 2 or 3. Those subjects whose scores fluctuated from 0 to 3 during the 3 nights were omitted from further analysis. Fasting peripheral venous blood samples were collected in the morning following the final SB assessment. Amounts of SERTs proteins collected from peripheral platelets were quantified using ELISA, and SERTs transport activity was assessed by uptake assay using [³H]-5-HT. Results: Thirteen severe SB subjects and 7 NC subjects were eligible. Gender distribution, mean age, 5-HT concentration and total amounts of SERT protein in platelets showed no significant differences between NC and severe SB (p=0.85: Chi-squared test; p=0.64, 0.26, 0.46: t-test). However, [³H]-5-HT uptake by platelets was significantly greater in NC compared to severe SB subjects (12.79±1.97, 8.27±1.91fmol/10⁵ platelets/min, p<0.001, t-test). Conclusion: The results of this pilot study suggest a possible correlation between peripheral platelet serotonin transporter uptake ability and SB severity.