Change of pulmonary angiotensin II type 1 receptor in diabetic rats and its effects on expression of transforming growth factor-β1

Objective In order to explore the change of pulmonary angiotensin Ⅱ type 1 receptor (AT1R) in diabetic rats and its effect on expression of transforming growth factor-β1(TGF-β1). Method Twenty diabetes mellitus (DM) model rats were established via chain of high sugar and high fat diet in combination with small dose of streptozotocin caudal vein injection. They were randomly divided into DM group (n=10), losartan (LST) group (n=10). Each rat of LST group was fed with 30 mg · kg-1·d-1, LST for 12 weeks by gavage.Ten normal rats were established as normal control (NC) group. Immunohistochemistry was used to assay the expression of AT1R in lung of each group rats. RT-PCR and western blotting was performed to compare the expression of AT1R and TGF-β1 between different group. One-way analysis of variance was applied to compare data among groups. LSD anaysis was used for comparision between two groups. Results Compared with NC group, the expression of pulmonary AT1R and TGF-β1 in DM group rats increased significantly (AT1R mRNA: 0.04±0.03 vs 0.29±0.15, t=5.252; AT1R protein: 0.62±0.05 vc 0.77±0.05, t=6.736 ;TGF-β1 mRNA :0.10±0.05 vs 0.73±0.16, t=12.377 ;TGF-β1 protein :0.47±0.05 vs 0.70±0.05, t=10.66; all aboveP< 0.05). The expression of pulmonary AT1R and TGF-β1 in LST group rats significantly decresed, compared with DM group (AT1R mRNA: 0.292±0.148 vs 0.068±0.024, t=4.741; AT1R protein: 0.77±0.05 vs 0.63±0.04, t=7.396;TGF-β1 mRNA: 0.74±0.16 vs 0.19±0.09, t=9.563;TGF-β1 protein: 0.702±0.047 vs 0.439±0.018,t=16.601; all aboveP<0.05). Conclusion Part of the reninangiotensin system may be activated in lung tissue of DM rats, it promoted the increase of TGF-β1 expression and involved in the change of lung extracellular matrix. Key words: Diabetes mellitus; Lung; Angiotensin Ⅱ type 1 receptor; Transforming growth factor -β1; Rat