Difference in perception of heat and the thermal grill illusion (TGI) in relation to the expression of the serotonin transporter and the effect of cutaneous capsaicin sensitization on the TGI

Aims The aims of this study are to investigate the differences in (1) heat pain threshold, (2) pain and temperature perception of the TGI and (3) the sensation of capsaicin between subjects with high and low expression of the serotonin transporter (5-HTT). In addition the effects of capsaicin sensitization on the thermal grill illusion are studied. Methods A total of 80 healthy subjects are selected on the basis of their tri-allelic 5-HTTLPR genotype. Threshold for heat pain is examined and pain and unpleasantness of cutaneous capsaicin application are rated on visual analog scales (VAS). The sensory dimensions of the TGI (before and after capsaicin) is determined i.e. description of temperature (burning hot, hot, neutral, cold or freezing cold) and potential pain and intensity of cold and warmth are rated on respective VAS-scales. Results The study is ongoing. We expect that the low expression group has a higher heat pain threshold and rates the TGI and capsaicin less painful. The capsaicin sensitization lowers the heat pain threshold and increases the cold pain threshold. Therefore we hypothesize a lower rating of the TGI, determined as a lower heat VAS-score. Conclusions No conclusions yet. Preliminary results from the study will be presented at the SASP14.