Capsaicin Blocks the Hyperpolarization-Activated Inward Currents via TRPV1 in the Rat Dorsal Root Ganglion Neurons
Experimental Neurobiology
;
: 75-82, 2012.
Article
in English
| WPRIM
| ID: wpr-57565
ABSTRACT
Capsaicin, the pungent ingredient in hot pepper, activates nociceptors to produce pain and inflammation. However, prolonged exposures of capsaicin will cause desensitization to nociceptive stimuli. Hyperpolarization-activated cation currents (Ih) contribute to the maintenance of the resting membrane potential and excitability of neurons. In the cultured dorsal root ganglion (DRG) neurons, we investigated mechanisms underlying capsaicin-mediated modulation of Ih using patch clamp recordings. Capsaicin (1 microM) inhibited Ih only in the capsaicin-sensitive neurons. The capsaicin-induced inhibition of Ih was prevented by preexposing the TRPV1 antagonist, capsazepine (CPZ). Capsaicin-induced inhibition of Ih was dose dependent (IC50= 0.68 microM) and partially abolished by intracellular BAPTA and cyclosporin A, specific calcineurin inhibitor. In summary, the inhibitory effects of capsaicin on Ih are mediated by activation of TRPV1 and Ca(2+)-triggered cellular responses. Analgesic effects of capsaicin have been thought to be related to desensitization of nociceptive neurons due to depletion of pain-related substances. In addition, capsaicin-induced inhibition of Ih is likely to be important in understanding the analgesic mechanism of capsaicin.
Full text:
Available
Index:
WPRIM (Western Pacific)
Main subject:
Spinal Nerve Roots
/
Nociceptors
/
Capsaicin
/
Cyclosporine
/
Egtazic Acid
/
Calcineurin
/
Ganglia, Spinal
/
Inflammation
/
Membrane Potentials
/
Neurons
Limits:
Animals
Language:
English
Journal:
Experimental Neurobiology
Year:
2012
Type:
Article
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