ABSTRACT
This study investigated the effects of telmisartan on insulin resistance in high-fat diet-treated rats and the possible mechanism.A total of 40 male Sprague-Dawley rats enrolled in the study were divided into 4 groups at random:ND group (n=10) and HD group (n=10),in which the rats were given a normal chow diet or a high-fat diet for 20 weeks following a one-week adaptation; ND+telmisartan (n=10) group and HD+telmisartan group (n=10),in which the rats were initially administered in the same way as the ND or HD group,and then they were orally gavaged with telmisartan (5 mg/kg daily)additionally for 5 weeks.Related inflammatory factors were measured by ELISA.Monocyte chemotactic protein 1 (MCP-1),phosphorylated JNK and Iκ B-α expressions in both adipose and liver were detected by Western blotting.CRP and angiotensin Ⅱ receptor 1 (AT1) mRNA expressions in both adipose and liver were determined by RT-PCR.The results showed that telmisartan administration in vivo reversed insulin resistance as evidenced by a decrease in plasma fasting glucose levels,plasma fasting insulin levels and homeostasis model of assessment-insulin resistance (HOMA-IR).Furthermore,telmisartan administration significantly reduced serum CRP,TNF-α and IL-1β levels,and elevated serum IL-10 levels.It was also found to hamper the high-fat diet-induced increase in CRP mRNA,AT1 mRNA and MCP-1,and decrease in Iκ B-α in both adipose and liver.It was concluded that telmisartan administration in vivo may improve insulin resistance through attenuated inflammatory response pathways.
ABSTRACT
Tubulointerstitial fibrosis(TIF)is a common pathological feature of end-stage kidney disease.Previous studies showed that upregulation of TGFβ1 notably contributed to the chronic renal injury and irbesartan halted the development of TIF in rats with 5/6 renal mass reduction.This study was to investigate the effects of irbesartan on chronic TIF and the mechanism involved TGFβ1 in the rodent model of chronic renal failure involving 5/6 nephrectomy.The results showed that irbesartan significantly attenuated the rise in blood pressure and tubulointerstitial injury observed in this model.Masson staining of the renal tissue revealed that there appeared severe renal tubule atrophy and fibrosis in operation group,but the lesion was attenuated mostly in irbesartan-treated group.Immunohistochemistry showed that irbesartan treatment apparently decreased the protein expression of TGFβ1 which was up-regulated in operation groups.Western blot showed that irbesartan treatment down-regulated the expression of TGFβ1,phosphorylated smad2(p-smad2),AT1R and phosphorylated p38(p-p38)MAPK,but significantly up-regulated the protein expression of smad6 as compared with operation group.These findings suggest that irbesartan attenuates hypertension and reduces the development of TIF in rats with 5/6 renal mass reduction via changes in the expression of these proteins at least including smad6,TGF-β1,p-smad2,AT1 and p-p38 MAPK.
ABSTRACT
. These results suggest that simvastatin could stimulate the activity of eNOS via its phosphorylation by Akt and AMPK, which provides a new mechanism, other than lipid-lowering effect, for the cardiovascular protection of statins.