Expression of thermosensitive trp channels in human dental pulp

Objectives: Transient receptor potential (TRP) channels are „cellular sensors” that play a central role in the detection of various (mechanical, osmotic, pain and thermal) stimuli. In recent years, in part due to the work of our laboratory, it has become apparent that the thermosensitive members of the family are widely expressed in non-neuronal tissues. Since the expression and function of thermosensors can have important effects on the thermal sensitivity of the tooth in physiological and pathological conditions, our goal was to determine the expression of thermosensitive TRP channels in healthy and inflamed human dental pulp. Methods: On healthy human dental pulp we identified the expression of the warm-sensitive TRPV1, TRPV3 and TRPV4 using quantitative real-time PCR. We were able to support these findings on the protein level, since the expression of TRPV1, TRPV3 and TRPV4 was also found by immunohistochemistry. Results: Interestingly the expression of the “cold-sensitive” TRPA1 and TRPM8 was not detected on either the gene, or the protein level. We also found that the expression of TRPV1 and TRPV4 in pulpitic samples decreased to approximately half that found in the healthy samples. The expression of TRPV3 on the other hand drastically increased in these samples (the expression of TRPA1 and TRPM8 was not found in the pulpitis samples). We are currently in the process of elucidating the functionality of these receptors. Conclusions: Our data suggests that human dental pulp expresses numerous receptors that are capable of detecting warm stimuli; on the other hand, structures other than TRP channels are responsible for the detection of cold stimuli. Our data also suggest to the possibility that the change in the expressional pattern of TRP channels might be responsible for the thermal hyperalgesia that develops on patients with pulpitis.