Effect of sodium ferulate on the hyperalgesia mediated by P2X(3) receptor in the neuropathic pain rats.

Brain Res. 2009 Dec 4;

Authors: Zhang A, Gao Y, Zhong X, Xu C, Li G, Liu S, Lin J, Li X, Zhang Y, Liu H, Linag S

Neuropathic pain usually is persistent and no effective treatment. Activation of P2X(3) receptor subtype in primary sensory neurons is involved in neuropathic pain. Sodium ferulate (SF) is an active principle from Chinese herbal medicine and has anti-inflammatory activities. This study observed the effects of SF on the hyperalgesia mediated by P2X(3) receptor of rats after chronic constriction injury (CCI). Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured and the expression of P2X(3) receptor immunoreactivity and protein in dorsal root ganglion (DRG) neurons was analyzed by immunohistochemistry and western blotting. CCI rats treated with SF, the MWT and TWL were increased compared with CCI rats treated with normal saline. The expression of P2X(3) receptor in DRG neurons was increased after CCI. In CCI rats treated with SF, the up-regulated expression of P2X(3) receptor in DRG neurons was reduced. SF may reduce the thermal and mechanical hyperalgesia in CCI rat model by decreasing the pain transmitting of primary afferant neurons mediated by P2X(3) receptor during the chronic neuropathic pain injury.

Dr.Steve’s BOTTOM LINE: Neuropathic pain is experienced by up to 10% of people with 5% being reported as severe. Examples are pain suffered by diabetics, those afflicted with Herpes Zoster (or Simplex in some cases), and in some cancer and HIV patients. The P2X(3) receptor is one which is increased in number with this kind of pain. In this laboratory rat model, the receptor was “stimulated” to increase in number artificially (upregulation) and then blocked effectively with sodium ferulate, reducing the mechanism for pain transmission. This is very promising work and may help explain how certain Chinese anti-inflammatory and anti-pain herbs work at the molecular level. Human studies are needed but this means there is a plausible scientific explanation for how some Chinese herbs work to reduce pain and inflammation.