An Experimental Study On MRNA Expression Of The P2Y₂ Receptor In Dorsal Root Ganglions Of Chronic Neuropathic Rats

Objective Use RT-PCR method to investigate the changes of P2Y₂ receptor mRNA expression in lumbar dorsal root ganglion neurons of chronic constriction injury(CCI) models,for the purpose of approaching the P2Y₂ receptor's function in the chronic neuropathic pain.Method Chronic neuropathic pain model was set up by loose ligature left sciatic nerve of rat by chromic gut.Twenty-four SD rats were randomly divided into four groups,six in each group.Group A--ligature left sciatic nerve,observing seven days after operation.Group B—sham operation,observing seven days after sham operation. Group C—ligature left sciatic nerve,observing fourteen days after operation.Group D—sham operation,observing fourteen days after sham operation.Mechanical and thermal threshold of rats'two hindlimbs were measured on one day before operation and the first,fourth,seventh,tenth,fourteenth day after operation.Pain threshold after CCI was compared with that in contralateral side,then rejected the rats whose pain threshold was invariant.Bilateral L4-L6 dorsal root ganglions were removed and crushed and total RNA was extracted on the seventh and fourteenth day after operation,the changes of P2Y₂ receptor mRNA expression were determined by semi-reverse transcriptase-PCR.Results Thermal allodynia and tactile allodynia were detectable four days after operation,and achieved peaks at the fourteenth day. The results of RT-PCR semiquantitative showed that P2Y₂ mRNAs expressed in homolateral lumber DRGs of chronic neuropathic pain rats were downregulated as compared with that in contralateral DRGs of the same group(p<0.05),and even greater in group C than in group A.In contrast, bilateral lumber DRGs of the control group and the contralateral DRGs of the CCI group had no difference in P2Y₂ mRNA expression(p>0.05).Conclusions Gene expressions of P2Y₂ receptor in DRGs of chronic neuropathic pain rats were down regulated as compared with those in normal rats.The P2Y₂ receptor may be involved in the regulation of chronic neuropathic pain.