ABSTRACT
<p><b>BACKGROUND</b>The decreased degradation of extra-cellular matrix proteins plays an important role in the onset of diabetic nephropathy. Matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1), which are members of the matrix metalloproteinase family, are associated with this process. Angiotensin II (AII) plays an important role in the development of diabetic nephropathy also. This research aimed to investigate the effect of angiotensin II receptor blocker on glucose-induced mRNA expressions of MMP-9 and TIMP-1 in rat mesangial cells.</p><p><b>METHODS</b>Rat mesangial cells were cultured and divided into 5 groups: normal glucose (group NG), high glucose (group HG), group NG + AII, NG + AII + saralasin (group NG + AII + S, saralasin is the AII receptor blocker) and HG + saralasin (group HG + S). After the cells were incubated for 24 hours, AII concentrations in the supernatant were measured by radioimmunoassay and the expression of MMP-9 and TIMP-1 mRNA was assayed by reverse transcription-polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>AII concentrations were higher in group HG ((56.90 +/- 13.54) pg/ml) and group HG + S ((51.30 +/- 5.96) pg/ml) than in group NG ((37.89 +/- 8.62) pg/ml, P < 0.05), whereas there was no significant difference between group HG and group HG + S. The expression of MMP-9 mRNA and MMP-9/TIMP-1 mRNA ratio in group NG + AII (MMP-9, 0.33 +/- 0.04; MMP-9/TIMP-1, 0.40 +/- 0.06) and group HG (MMP-9, 0.36 +/- 0.02; MMP-9/TIMP-1, 0.45 +/- 0.03) were decreased more significantly than those in group NG (MMP-9, 0.72 +/- 0.02; MMP-9/TIMP-1, 1.21 +/- 0.07). These values in group NG + AII + S (MMP-9, 0.71 +/- 0.02; MMP-9/TIMP-1, 1.18 +/- 0.05) were higher than those in group NG + AII, and the values in group HG + S (MMP-9, 0.71 +/- 0.02; MMP-9/TIMP-1, 1.16 +/- 0.05) were higher than those in group HG (all were P < 0.05). TIMP-1 mRNA expression was increased more significantly in group NG + AII (0.81 +/- 0.03) and group HG (0.80 +/- 0.03) than in group NG (0.59 +/- 0.02), but it was lower in group NG + AII + S (0.60 +/- 0.01) than in group NG + AII and also lower in group HG + S (0.61 +/- 0.01) than in group HG (all were P < 0.05).</p><p><b>CONCLUSIONS</b>High glucose stimulates AII production. Both high glucose and AII induce a decrease in MMP-9 mRNA expression and MMP-9/TIMP-1 mRNA ratio as well as an increase in TIMP-1 mRNA expression, which can be reversed by saralasin, suggesting that high glucose can aggravate impaired matrix degradation by altering gene expression of MMP-9 and TIMP-1 and that the effect of high glucose may be mediated by AII.</p>
Subject(s)
Animals , Rats , Angiotensin II Type 1 Receptor Blockers , Pharmacology , Angiotensin Receptor Antagonists , Cells, Cultured , Gene Expression , Glucose , Pharmacology , Matrix Metalloproteinase 9 , Genetics , Mesangial Cells , Cell Biology , Metabolism , RNA, Messenger , Genetics , Metabolism , Reverse Transcriptase Polymerase Chain Reaction , Saralasin , Pharmacology , Tissue Inhibitor of Metalloproteinase-1 , GeneticsABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of losartan, an angiotensin II type-1 receptor (AT1R) antagonist, on the levels of angiotensin II (Ang II) and AT1R in diabetic rat kidney.</p><p><b>METHODS</b>Male Wistar rats were divided into 3 groups, group A (n=11) served as the control group, group B (n=11) included the diabetic rats (induced by intraperitoneal injection of streptozotocin) without any therapy, and group C (n=9) diabetic rats treated with losartan. After 18 weeks of treatment, the kidneys were taken from all the rats to measure the expression of AT1R mRNA by RT-PCR and detect the Ang II level. Blood was also drawn from the heart to measure Ang II level, and 24-hour urine was collected to measure albumin level (urine albumin excretion, UAE) with rat albumin enzyme immunoassay kit.</p><p><b>RESULTS</b>The blood and renal Ang II levels showed no significant difference between the 3 groups. The expression of renal AT1R mRNA in group B (0.62-/+0.17) was significantly lower than that in group A (1.13-/+0.82, P<0.01) and group C (1.13-/+0.62,P<0.01). UAE in group B (2.18-/+1.98 mg) was significantly higher than that in group A (0.41-/+0.47 mg/d, P<0.01) and C (0.65 -/+0.89 mg/d, P<0.01).</p><p><b>CONCLUSION</b>Losartan can increase the expression of AT1R mRNA in diabetic rat kidneys without altering the blood and renal Ang II levels.</p>
Subject(s)
Animals , Male , Rats , Angiotensin II , Blood , Metabolism , Angiotensin II Type 1 Receptor Blockers , Therapeutic Uses , Diabetes Mellitus, Experimental , Blood , Drug Therapy , Genetics , Immunoassay , Methods , Kidney , Metabolism , Pathology , Losartan , Therapeutic Uses , RNA, Messenger , Genetics , Rats, Wistar , Receptor, Angiotensin, Type 1 , Genetics , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
High glucose stimulated angiotensinⅡ(ATⅡ) production in mesangial cells of rat.Both high glucose and ATⅡdecreased expressions of matrix metalloprotein-9 (MMP-9) mRNA and MMP-9/tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNA ratio and increased TIMP-1 mRNA expression in mesangial cells of rat,which could be reversed by an ATⅡreceptor blocker,Saralasin.