Liraglutide promotes the reduction of blood pressure and drives the water and salt through in renal medulla of type 2 diabetes rats / 天津医药

ABSTRACT

Objective To observe the effects of glucagon like peptide-1 (GLP-1) analogues liraglutide on expressions of nitric oxide synthase (NOS) and cyclo-oxygen-ase (COX)2 in renal medulla of type 2 diabetes rats, and the mechanism of its lowering blood pressure and promoting excretion of water and salt in kidney. Methods Type 2 diabetes model rats were generated by high-fat and high-sugar feeding for 8 weeks followed by intraperitoneal injection of streptozotocin (STZ). Subse?quently, eighteen type 2 diabetes rats were divided into two groups liraglutide treatment group (DMT) and diabetes group (DM). Twelve normal rats were divided into two groups liraglutide treatment wild type group (WTT) and wild type group (WT). DMT and WTT groups were given liraglutide (200μg/kg) by subcutaneous injection, DM and WT groups were given equivalent normal saline by the same way. The levels of blood glucose and blood pressure were detected at 0, 2, 4 and 6 weeks after treatment in groups of rats. Samples of urine were collected for detecting ion concentrations (K+, Na+and Cl-) af?ter treatment for six weeks. Rats were sacrificed and blood samples were collected for detecting ion concentrations (K+, Na+and Cl-). The expression levels of NOS and COX2 mRNA and protein in renal medulla were detected by real-time PCR and Western blot assay. Results After treating with liraglutide, the values of blood glucose (F=5.933, P sure (F=22.070, P<0.05) were gradually decreased in DMT group. After treatment with liraglutide for 6 weeks, the values of blood glucose (mmol/L12.78 ± 3.82 vs. 18.75 ± 1.68) and blood pressure (mmHg119.98 ± 4.43 vs. 136.42 ± 4.48) were signifi?cantly decreased (P<0.05) in DMT group than those of DM group (P<0.05). There were no significant differences in the concentrations of K+, Na+and Cl-between the two groups. There were higher levels of K+(mmol/L46.55 ± 6.43 vs. 33.13 ± 9.71), Na+(mmol/L56.33±8.83 vs. 41.20±7.25) and Cl-(mmol/L159.81±25.06 vs. 71.44±12.99) in urine in DMT group than those of DM group (P<0.05). The mRNA levels and protein expressions of NOS and COX2 in renal medulla were significant?ly increased in DMT group than those of DM group (P<0.05). Conclusion GLP-1 analogues liraglutide may enhance the expression of COX2 by increasing the expression of NOS to excrete water and salt, and decrease blood pressure.