Expression Of Voltage Gated Sodium Channel Nav1.8in Human Dental Pulp

Objective Tetrodotoxin-resistant voltage gated sodium channel Nav1.8expressed specifically in peripheral nervous system, underlies pain associated with tissue injury and inflammation. The nerve fibers in pulp tissue is nociceptor. The normal pulp seems insensitive to exteroceptive stimulate, however, in pathological states, electrical, thermal, mechanical and chemical stimulate all produce a nocieptive response. The study aimed to investigate the relationship between dental pain and Nav1.8expression level.Methods23normal permanent molar teeth and24painful permanent molar teeth about to be extracted were tested the pathology condition. Immunohistochemistry, reverse transcription polymerase chain reaction(RT-PCR) and Western blotting were used to detect the expression of Nav1.8in normal human dental pulp and inflamed dental pulp.Results Nav1.8expressed in dental pulps and the expression level of Nav1.8increased significantly in painful dental pulps comparison with normal pulp tissues. The Immunohistochemistry results revealed that Nav1.8in painful pulp tissue generated an average of0.547±0.049in relative intensity, whereas Nav1.8in normal pulp showed the average value of0.356±0.058. And Western blot showed similar results that0.234±0.030vs0.108±0.012in relative intensities. RT-PCR results also demonstrated that Navl.8mRNA up-regulation7-fold in painful group compare with normal group. Conclusions The results showed that the expression level of Navl.8increased significantly in painful dental pulp tissue, suggesting that Navl.8may play a possible role in the development and transmission of dental pain. Further studies suggest that the high expression of Navl.8in inflamed painful pulp may be responsible for the lowered efficacy of unselective sodium channel blockers.