The Effects Of All-trans Retinoic Acid On Rats With Adriamycin-induced Nephropathy

Objective: To constrct the model of adriamycin-induced nephropathy(AIN) To assess the renal prorective effects of all-trans retinoic acid (ATRA) in AIN and to explore the possible mechanism by investigating the expression of inflammation factors, nephrin and podocin mRNA in each group.Methods: 1. AIN model construction: 60 male SD rats were divided into four groups randomly: normal control group, AIN group, high dose of ATRA group and moderate dose of ATRA group (n=15 per group). SD rats were injected adriamycin at 4.0mg/Kg firstly and 3.5 mg/Kg one week later secondly through tail intravenous. The normal control group was only injected isotonic Na chloride.2. ATRA was administrated the day after the second adriamycin injection at 20mg/ Kg/d for the high dose group and 10mg/Kg/d for the moderate dose group respectively. The normal control and AIN groups were fed water. The treatment lasted four weeks.3. The amount of proteinuria was performed on every week during the treatment. All rats were sacrificed after four weeks, the renal histology was observed by light microscope and electronic microscope. 4. The expression level of nephrin and podocin mRNA in each group were detected by reverse transcriptase-polymerase chain reaction (RT-PCR) tech nique.5. Immunohistochemical staining was used to decet MCP-1 and TGF-β1 in the renal tissue.Results:1. Compared to normal control group, AIN group showed high levels of proteinuria half a month later after adriamycin injection (P＜0.05), While on week 3 and 4, the difference was much greater (P＜0.01). The high dose of ATRA groups had less amount of proteinuria since week 2, compared with AIN group(P＜0.05). The moderate dose of ATRA group showed low level of proteinuria since week 3(P＜0.05). Furthermore, the high dose ATRA had better inhibition for proteinuria than the moderate dose ATRA.2. Histology change: (1) Light microscope:AIN group showed tubular viscera epithelial cellular swelling, a lot of protein casts in renal tubule, soakage of lymphocytes in tubulointerstitial. But in the high and moderate dose of ATRA groups, the changes of tubulointerstitial ameliorated, less protein casts in renal tubule; (2) Electronic microscope: there was a wide fusion of foot process on AIN group. Both the high and moderate dose of ATRA groups only exhibited focal fusion.3. Compared to the normal control group, there was an obvious downregulation of nephrin and podocin mRNA in AIN group. The expression of nephrin and podocin mRNA in the high and moderate dose of ATRA groups showed higher level than the AIN group. And the high dose ATRA showed higher level than the moderate group. 4. In comparison with normal control group, the expression of MCP-1 and TGF-β1 in the kidney tissue of the AIN group were increased,maily in tubular epithelial cell and glomerulus(P＜0.01). The high dose group showed a lower level expression of MCP-1 and TGF-β1,compared to the AIN group (P＜0.05). The moderate dose group only showed difference in TGF-β1(P＜0.05). Furthermore, there was a great difference between the high and moderate groups in TGF-β1 expression(P＜0.05).Conclusion 1. Construct AIN model successfully. 2. ATRA has the effect of reducing proteinuria,the high dose showed better effects than the moderate group. 3.The ATRA could postpone the renal diseases progression by increasing the nephrin and podocin mRNA expression and inhibiting the expression of TGF-β1 and MCP-1.