Yan Zhang1, Teng-Yue Diao2, Sa-Sa Gu2, Shu-Yan Wu3, Yoseph A Gebru2, Xi Chen4, Jing-Yu Wang5, Shu Ran3, Man-Sau Wong6. 1. Center for Systems Biomedical Sciences, University of Shanghai for Science and Technology, People's Republic of China Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, People's Republic of China School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, People's Republic of China bcmswong@polyu.edu.hk medicineyan@yahoo.com.cn. 2. Center for Systems Biomedical Sciences, University of Shanghai for Science and Technology, People's Republic of China School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, People's Republic of China. 3. Center for Systems Biomedical Sciences, University of Shanghai for Science and Technology, People's Republic of China. 4. School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, People's Republic of China. 5. Department of Radiology, The Norman Bethune First Hospital of Jilin University, People's Republic of China. 6. Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, People's Republic of China.
Abstract
INTRODUCTION: This study was performed to address the pathological roles of the skeletal renin-angiotensin system (RAS) in type 1 diabetes-induced osteoporosis and the effects of the angiotensin II type 1 receptor blocker losartan on bones in diabetic mice. MATERIALS AND METHODS: Bone histomorphology was detected by H&E staining, Safranin O staining and X-ray radiography. Micro-CT was performed for the analysis of bone parameters. Gene and protein expression were determined by RT-PCR and immunoblotting. RESULTS: Type 1 diabetic mice displayed osteopenia phenotype, and losartan treatment had no osteoprotective effects on diabetic mice as shown by the reduction of bone mineral density and microarchitectural parameters at the proximal metaphysis of the tibia. The mRNA expression of AGT, renin receptor and ACE, and protein expression of renin and AT1R were markedly up-regulated in the bones of vehicle-treated diabetic mice compared to those of non-diabetic mice. The treatment with losartan further significantly increased the expression of AGT, renin, angiotensin II and AT1R, and reduced the expression of AT2R receptor as compared to those of diabetic mice. CONCLUSION: Local bone RAS functionally played a role in the development of type 1 diabetic osteoporosis, and losartan had no bone-sparing function in diabetes mice because of enhance skeletal RAS activity.
INTRODUCTION: This study was performed to address the pathological roles of the skeletal renin-angiotensin system (RAS) in type 1 diabetes-induced osteoporosis and the effects of the angiotensin II type 1 receptor blocker losartan on bones in diabeticmice. MATERIALS AND METHODS: Bone histomorphology was detected by H&E staining, Safranin O staining and X-ray radiography. Micro-CT was performed for the analysis of bone parameters. Gene and protein expression were determined by RT-PCR and immunoblotting. RESULTS: Type 1 diabeticmice displayed osteopenia phenotype, and losartan treatment had no osteoprotective effects on diabeticmice as shown by the reduction of bone mineral density and microarchitectural parameters at the proximal metaphysis of the tibia. The mRNA expression of AGT, renin receptor and ACE, and protein expression of renin and AT1R were markedly up-regulated in the bones of vehicle-treated diabeticmice compared to those of non-diabeticmice. The treatment with losartan further significantly increased the expression of AGT, renin, angiotensin II and AT1R, and reduced the expression of AT2R receptor as compared to those of diabeticmice. CONCLUSION: Local bone RAS functionally played a role in the development of type 1 diabetic osteoporosis, and losartan had no bone-sparing function in diabetesmice because of enhance skeletal RAS activity.