RESUMO
Objective To delineate the expressions of ubiquitin-specific proteinase 49 (USP49)and FK506 binding protein 51 (FKBP51) in the spinal dorsal horns and their roles in rats with diabetic neuropathic pain (DNP).Methods Male SD rats were fed with high glucose and high fat diet with an intraperitoneal injection of 1％ streptozocin to establish DNP rat models.DNP rats were allocated into DNP group,control shRNA group (KC group) and knockdown USP49 group (KD group,n=10);saline,Ad-scrambled shRNA (3×108 PFU/mL) and Ad-USP49-shRNA (3×108 PFU/mL) were intrathecally injected into the rats of the three groups.Another 10 normal rats were chosen as control group (C group).Thermal withdrawal latency (TWL) and mechanical withdrawal threshold (MWT) were measured one d before model establishment,one and 7 d after model establishment,one,three and 7 d after intrathecal injection.The mRNA and protein expressions of USP49,FKBP51 and glucocorticoid receptor α (GRα)in dorsal horn neurons were detected by real time-PCR and Western blotting.Results (1) TWL showed no significant difference among the four groups one d before model establishment (P＞0.05);three and 7 d after intrathecal injection,TWL in KD group was significantly prolonged as compared with that in the DNP group,and significantly shortened as compared with that in C group (P＜0.05).(2) MWT showed no significant difference among the four groups one d before model establishment (P＞0.05);three and 7 d after intrathecal injection,MWT in KD group was significantly higher as compared with that in the DNP group,and significantly lower as compared with that in C group (P＜0.05).(3) As compared with DNP group,KD group had significantly decreased mRNA expressions of USP49 and FKBP51,and statistically increased mRNA GRα expression (P＜0.05).(4) As compared with DNP group,KD group had significantly decreased protein expressions of USP49 and FKBP51,and statistically increased protein GRα expression (P＜0.05).Conclusion Specific knockdown of USP49 expression is associated with improvement of heat hyperalgesia and mechanical hyperalgesia in DNP rats,which may be attributed to the de-ubiquitination ofFKBP51 by USP49.