Effects Of Gabapentin On Expressions Of P2X3 Receptors In The Chronically Compressed Dorsal Root Ganglion

As the first level of neurons in the Afferent pain, dorsal root ganglion (DRG) plays a very important role in the peripheral mechanism of pain. P2X3 is the major P2X receptors on dorsal root ganglion neurons and expressed in 95% small cell. P2X receptors on dorsal root ganglion neurons have been strongly implicated in pathological nociception after peripheral nerve injuries or inflammation. In neuropathic pain produced by a chronic compression of DRG (CCD)-an injury that may accompany an intraforaminal stenosis, a laterally herniated disc or other disorders of the spine leading to radicular pain. Gabapentin (GBP) is a new antiepileptic drug and recommended for the treatment of a variety of neuropathic pain in first-line drugs.ObjectiveTo study the expression of P2X3 receptor in DRG after CCD operation and clear the function of P2X3 receptor. To evaluate the efficacy of gabapentin to chronic neuropathic pain induced by compressed dorsal root ganglia and investigated the role of gabapentin to P2X3 receptor.Methods1. To establish chronic compression dorsal root ganglia model and to observate CCD changes in behavior.2. P2X3 receptor expression increased in chronic compressed DRG of rats. On 7 days after surgery, using Western Blot Technology and immunofluorescence staining, we detected the expression level of P2X3 receptor in DRG in CCD group and sham operated group.3. Chronic compression of dorsal root ganglion (CCD) of rats with neuropathic pain, to 100 mg/kg intraperitoneal injection of gabapentin,1 time/day for 7 days. Observe the effect of gabapentin to mechanical pain behavior of CCD rats.4. Chronic compression of dorsal root ganglion (CCD) of rats with neuropathic pain, to 100 mg/kg intraperitoneal injection of gabapentin,1 time/day for 7 days. Using Western Blot Technology and immunofluorescence staining, we detected the express level of P2X3 receptor in DRG in rats and the effect of gabapentin to the expression of P2X3 receptor in DRG.Results 1. Second day after CCD operation, animals produced mechanical hyperalgesia. The threshold of pain had Started lowering (p<0.05) lasting three weeks.2. On 7 days after surgery, DRG on operated side in CCD group significantly increased the expression, compared with the sham operated group (p<0.01). The number positive neurons of P2X3 receptor in CCD group was more than the sham operated group.3. An hour after intraperitoneal injection of gabapentin, CCD rats appeared temporary increase of the threshold of pain. The changes were significant differences (P< 0.05, vs. NS group); After continuous intraperitoneal inj ection of gabapentin, the threshold of pain of CCD rats were significantly higher (p<0.05, vs. NS group) and presented the trend to continue to rise.4. After the treatment of gabapentin for 7 days, DRG on operated side significantly descended the expression and the number positive neurons of P2X3 receptor was less than the sham operated group.ConclusionP2X3 receptor may produce a marked effect on the analgesia course of gabapentin to CCD rats.