帕立骨化醇对糖尿病肾病大鼠肾保护机制的研究

Renoprotective effect of paricalcitol in rats with diabetic nephropathy

目的探讨帕立骨化醇对糖尿病肾病(DN)大鼠的肾保护作用及其可能机制。方法采用腹腔内注射链脲佐菌素(STZ)构建DN大鼠模型。将造模成功的大鼠随机分为帕立骨化醇组(P组)、DN组(D组),并设置健康对照组(N组)。P组大鼠每周腹腔注射帕立骨化醇3次,剂量为0.4μg/kg,给药12周后检测24h尿蛋白定量及血生化指标,以实时PCR检测肾组织肾素及环氧化酶-2(COX-2)mRNA表达,免疫组化检测肾组织COX-2蛋白的表达,并以ELISA法检测尿前列腺素E_2(PG_2)水平。结果与N组相比,D组与P组24h尿蛋白定量、血肌酐(SCr)、空腹血糖及甲状旁腺激素(PTH)均显著升高(均P<0.05),肾组织肾素和COX-2mRNA及蛋白表达,以及尿PGE_2水平均显著升高(均P<0.05),且D组显著高于P组(P<0.05)。肾素水平与尿PGE_2水平及COX-2 mRNA表达均呈正相关(r=0.798、0.722,均P<0.01)。结论帕立骨化醇可显著减少DN大鼠早期蛋白尿,其机制可能与通过抑制肾组织COX-2表达,下调尿PGE_2水平,从而抑制肾组织肾素表达有关。

Objective To investigate the renoprotective effect of paricalcitol in rats with diabetic nephropathy （DN） and its mechanism. Methods Diabetic nephropathy was induced by intraperitoneal injection of streptozotocin in rats. The DN rats were randomly divided into DN group （group D） and paricalcitol group （group P）, rats in group P were intraperitonealy injected with 0.4μg/kg paricalcitol t.i.w. Healthy non- DN rats served as control group （group N）. After 12 weeks, 24h urinary protein and serum biochemical indicators were examined. Real- time PCR were used to detect expression of renin mRNA and cyclooxygenase- 2 （COX- 2） in renal tissue. Immunohistochemistry was used to detect the protein expression of COX- 2. ELISA method was used to detect the urine levels of prostaglandin E2 （PGE2）. Results Compared to group N, 24- h urinary protein, serum creatinine（SCr）, fasting blood glucose（FBG） and parathyroid hormone（PTH） levels and urinary PGE2 levels were significantly increased （P〈0.05） in groups D and P;the expression of renin mRNA, COX- 2 mRNA and protein in renal tissue of groups D and P were also signifi-cantly increased （P〈0.05）. The above indexes of group D were markedly higher than those of group P （P〈0.05）. The renin level was positively correlated with urinary PGE2 （r=0.798, P〈0.01） and COX- 2 mRNA expression （r=0.722, P〈0.01）. Conclusion Paricalcitol can significantly reduce the proteinuria in rats with diabetic nephropathy, which may be associated with down- regu-lation of COX- 2, PGE2 and renin expression.