1 Institute for Biomedical Sciences of Pain, Capital Medical University, Beijing 100069, China
2 Institute for Biomedical Sciences of Pain and Institute for Functional Brain Disorders, Tangdu Hospital, the Fourth Military Medical University, Xi抋n 710038, China

Abstract 

Objective
Melittin (MEL) is a major component of bee venom and can produce both persistent spontaneous nociception and pain hypersensitivity when injected subcutaneously in the periphery. The present study aimed to examine the roles of transient receptor potential canonical (TRPC) channels in mediation of MEL-induced activation of primary nociceptive cells.
Methods
Whole-cell patch-clamp and laser scanning confocal calcium detection were used to evaluate the effects of SKF-96365, a TRPC inhibitor, applied on the acutely isolated dorsal root ganglion (DRG) cells of rat, on MEL-induced increase in intracellular calcium concentration ([Ca2+]i) and inward current.
Results
Under voltage-clamp mode, 43.9% (40/91) DRG cells were evoked to give rise to the inward current by 2 ?mol/L MEL, which could be significantly suppressed by 3 doses of SKF-96365 (1, 5 and 10 μmol/L) in a dose-dependent manner. Of the other 210 cells, 67.6% responded to MEL with an intracellular Ca2+ rise, as revealed by confocal calcium imaging. Of these MEL-sensitive cells, 46.5% (66/142) were suppressed by the highest dose of SKF-96365.
Conclusion
MEL-induced activation of small to medium-sized DRG cells can be suppressed by SKF-96365, suggesting the involvement of TRPC channels in the mediation of MEL-induced activation of primary nociceptive cells.

Keywords

melittin; transient receptor potential canonical channel; dorsal root ganglion; patch-clamp technique; calcium imaging

[SpringerLink]