Objective To explore the efficacy of ginkgo diterpene lactone on renal lesions and explore its mechanism based upon signal pathway of toll-like receptor 4/nuclear factor-κB （TLR4/NF-κB） in diabetic mellitus （DM） rats.
Methods DM rat model was established by a daily intraperitoneal injection of 30 mg/kg streptozotocin after a 4-week diet of high sugar and high fat. The animals were assigned into model, ginkgo diterpene lactone, resatorvid （TLR4 inhibitor） and ginkgo diterpene lactone plus resatorvid and normal. After 14-day injection, the levels of fasting blood glucose（FBG）, serum creatinine（Scr）, urea nitrogen（BUN） and 24 h urinary totalprotein（24 h UTP） were measured. Renal pathological changes were observed after hematoxylin eosin （HE） and Masson staining. And ultrastructural changes of glomerular podocytes were examined by transmission electron microscopy. Apoptosis was observed after TdT-mediated dUTP nick-end labeling（TUNEL） staining. The contents of interleukin-1β（IL-1β）, interleukin-6（IL-6）, interleukin-8（IL-8） and tumor necrosis factor-α（TNF-α） were detected by enzyme-linked immunosorbent assay（ELISA）. And the expressions of TLR4, NF-κB p65, p-NF-κB p65, NF-κB inhibitor α（IκBα）, p-IκBα, B-cell lymphoma-2 （Bcl-2） and Bcl-2 associated X protein（Bax） were detected by Western blot.
Results As compared with model group, the levels of FBG（9.51 ± 1.13） mmol/L,（12.17 ± 1.42） mmol/L, （8.09 ± 1.05） mmol/L vs （21.08 ± 3.49） mmol/L, Scr （45.69 ± 5.78） μmol/L, （51.02 ± 6.91） μmol/L, （38.57 ± 4.28） μmol/L vs （91.44 ± 12.50） μmol/L, BUN （9.28 ± 1.54） mmol/L , （10.96 ± 1.80） mmol/L, （7.01 ± 0.78） mmol/L vs （16.13 ± 1.72） mmol/L and 24h UTP （17.69 ± 2.03） mg, （19.75 ± 2.16） mg, （13.54 ± 1.39） mg vs （45.28 ± 4.71） mg declined markedly（all P＜0.05）. There were marked improvements of glomerular atrophy, mesangial expansion, collagen deposition, inflammatory infiltration and podocyte shrinkage. And foot process fusion of podocytes widening, basement membrane thickening, mitochondrial swelling and crista rupturing lessened greatly. Apoptotic index dropped markedly（16.75 ± 2.06）% , （20.19 ± 2.50）%, （8.07 ± 1.14）% vs （38.45 ± 4.61）%（P＜0.05）. The contents of IL-1β （37.42 ± 4.81） ng/L , （40.95 ± 5.27） ng/L, （32.17 ± 4.30） ng/L vs （54.16 ± 7.03） ng/L, IL-6（49.37 ± 6.02） ng/L, （54.83 ± 6.53） ng/L, （43.26 ± 5.51） ng/L vs （74.22 ± 9.48） ng/L, IL-8 （28.04 ± 3.53） ng/L, （32.11 ± 3.98） ng/L, （20.47 ± 2.45） ng/L vs （41.86 ± 5.12） ng/L and TNF-α （461.57 ± 62.85） ng/L, （510.83 ± 69.21） ng/L, （351.29 ± 43.08） ng/L vs （772.63 ± 120.92） ng/L decreased markedly （all P＜0.05）. The expressions of TLR4（0.19 ± 0.04） vs （0.28 ± 0.05）, （0.13 ± 0.03） vs （0.43 ± 0.06）, p-NF-κB p65（0.22 ± 0.04） vs （0.56 ± 0.11）, （0.14 ± 0.03） vs （0.94 ± 0.17）, p-IκBα（0.17 ± 0.04） vs （0.26 ± 0.05）, （0.12 ± 0.03） vs （0.45 ± 0.07）, Bax（0.18 ± 0.04） vs （0.32 ± 0.07）, （0.14 ± 0.03） vs （1.14 ± 0.19） and ratio of p-NF-κB p65/NF-κB p65（0.27 ± 0.06） vs （0.69 ± 0.14）, （0.17 ± 0.04） vs （1.22 ± 0.24）, p-IκBα/IκBα（0.81 ± 0.17） vs （1.36 ± 0.22）, （0.54 ± 0.10） vs （2.25 ± 0.41） and Bax/Bcl-2（0.82 ± 0.17） vs （1.59 ± 0.24）, （0.29 ± 0.06） vs （22.78 ± 3.64） dropped markedly. The expression of Bcl-2 was up-regulated （0.22 ± 0.05） vs （0.20 ± 0.04）, （0.48 ± 0.10） vs （0.05 ± 0.01）（all P＜0.05）. The efficacies of ginkgo diterpene lactone plus resatovi group on the above parameters were significantly better than those of ginkgo diterpene lactone and resatovi groups （all P＜0.05）.
Conclusion Ginkgo diterpene lactone may alleviate podocyte ultrastructural lesions and improve renal function in DM rats. Its mechanism may be correlated with an inhibition of TLR4/NF-κB and lessening of inflammatory response and apoptosis.
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