Abstract: To investigate the effects of capsaicin on calcium concentration (［Ca²⁺］_i) and mitochondiral membrane potential (MMP) of dissociated cultured dorsal root ganglion (DRG) neurons of 15day embryonic Wistar rats. MethodsDissociated DRG cells were treated with capsaicin at various concentrations (0.001, 0.01, 0.1, 1, 10μmol/L). 1min after capsaicin exposure to the DRG cultures, ［［Ca²⁺］_i was determined by confocal laser scanning microscopy (CLSM), and 10min after removing capsaicin, ［Ca²⁺］_i was determined by CLSM in the ［Ca²⁺］_i increased group with 1min stimulation of capsaicin and MMP was monitored by flow cytometry. ResultsAfter stimulation with 0.001μmol/L or 0.01μmol/L capsaicin, ［Ca²⁺］_i had no change, but after 1 min incubation of capsaicin at 0.1, 1, and 10μmol/L concentrations, ［［Ca²⁺］_i increased. 10min after removing the capsaicin, ［［Ca²⁺］_i returned to the basal level at 0.1 and 1μmol/L capsaicin incubation, however, it remained at the same level induced by 10μmol/L capsaicin. ［Ca²⁺］_i was not changed by capsaicin in Ca²⁺free extracellular solution. MMP was decreased after 1?min incubation of capsaicin at 10μmol/L concentration, while it was not changed by 0.1 and 1μmol/L capsaicin. Conclusion ［Ca²⁺］_i increases and MMP decreases after exposure to capsaicin at the given concentrations. After removing capsaicin for 10 min, ［Ca²⁺］_i may return to the basal level in low concentrations but not in high concentrations. The increase of ［Ca²⁺］_i induced by capsaicin may exclusively originate from Ca²⁺ influx.

Key words: Capsaicin, Ganglion, spinal, Neurons, Calcium concentration, Mitochondiral membrane potential