| Objective:1.To study the effect of TSF on the improvement of renal lipid deposition in DN,and to explore the correlation between its mechanism and PGC-1α,FXR,SREBP-1c,SCD-1,FAS and ACC-2 in db/db mice(spontaneous type 2 diabetic mellitus model).2.To investigate the mechanism of TSF to improve the renal lipid deposition in DN by regulating FXR and its downstream genes in mouse renal tubular epithelial cells(m RTECs)stimulated by sodium palmitate(PA).Methods:Eight-week-old male db/db mice were used as the model of spontaneous type 2 diabetes mellitus and randomly divided into two groups(db/db and db/db + TSF).Eight-week-old male db/m mice were the normal control group.The general state of mice was observed.Blood glucose,serum creatinine(Scr),blood urea nitrogen(BUN),serum lipids,24 h urinary albumin and urinary creatinine were detected.The pathological changes of kidney were observed by HE staining,PAS staining and Masson staining.The lipid deposition in the kidney and PAstimulated m RTECs was observed by Oil red O staining and Filipin staining.The contents of triglyceride(TG)and total cholesterol(TC)in kidney and PA-stimulated m RTECs were determined by colorimetric method.The expression levels of lipid synthesis related molecules PGC-1α,FXR,SREBP-1C,SCD-1,Fas and ACC-2 in kidney were detected by Western Blot and real-time PCR.The expression of PGC-1α/FXR/SREBP-1c signal pathway were detected by Western Blot and real-time PCR in m RTECs stimulated by PA.We also used small interfering RNA(si RNA)technology to investigate the molecular mechanism of TSF activating FXR to inhibit lipid synthesis.Results:1.The body weight of db/db mice was significantly higher than that of the db/m mice,while the body weight of db/db mice treated with TSF decreased.The treatment with TSF decreased serum levels of TG,TC,low density lipoprotein cholesterol(LDL-C),serum creatinine,and urine albumin-to-creatinine ratio(UACR)in db/db mice.HE staining,PAS staining and Masson staining results showed that TSF alleviated tubulointerstitial injury,the thickening of glomerular basement membrane,and mesangial matrix deposition in db/db mice.2.Oil red O and Filipin results staining showed that TSF attenuated lipid deposition in the kidney of db/db mice.The treatment with TSF could decrease the contents of TG and TC in the kidney of db/db mice by colorimetric method.In addition,Real-time PCR and Western Blot results showed that the protein and m RNA expression levels of PGC-1α and FXR in the kidney of db/db mice were significantly upregulated by TSF treatment,and the protein and m RNA expression levels of SREBP-1c,FAS,SCD-1 and ACC-2 were significantly downregulated by TSF treatment,thus inhibiting the lipogenesis in kidney.3.Oil red O and Filipin staining results showed that TSF treatment could significantly reduce the lipid deposition in m RTECs stimulated by PA.The treatment with TSF could decrease the contents of TG and TC in PA-stimulated m RTECs PA by colorimetric method.Real-time PCR and Western Blot results showed the protein and m RNA expression levels of PGC-1α and FXR in PA-stimulated m RTECs were significantly upregulated by TSF treatment,and the protein and m RNA expression levels of SREBP-1c,FAS,SCD-1 and ACC-2 in PAstimulated m RTECs were significantly downregulated by TSF treatment.Of note,Silencing FXR significantly abolished inhibition of TSF on the expressions of SREBP-1c,FAS,SCD-1and ACC-2 in PA-stimulated m RTECs.Conclusions:TSF can effectively improve the lipid deposition in the kidney of db/db mice(spontaneous type 2 diabetic mellitus model),so as to alleviating kidney injury.The mechanism may be related to PGC-1α/FXR/SREBP-1c signaling pathway.TSF can inhibit the expression of downstream genes related to lipid synthesis by activating FXR,thus attenuating lipid deposition in the kidney.These data inspire us to re-recognize the mechanism by which TSF is involved in inhibiting lipogenesis and the potential application of TSF in the treatment of DN. |
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