title: Thioredoxin-1 overexpression in transgenic mice attenuates streptozotocin-induced diabetic osteopenia: a novel role of oxidative stress and therapeutic implications.
abstract: Diabetes mellitus is associated with increased risk of osteopenia and bone fracture. However, the mechanisms accounting for diabetic bone disorder are unclear. We have previously reported that streptozotocin-induced diabetic mice develop low turnover osteopenia associated with increased oxidative stress in the diabetic condition. To determine the role of oxidative stress in the development of diabetic osteopenia, we presently investigated the effect of overexpression of thioredoxin-1 (TRX), a major intracellular antioxidant, on the development of diabetic osteopenia, using TRX transgenic mice (TRX-Tg). TRX-Tg are C57BL/6 mice that carry the human TRX transgene under the control of beta-actin promoter. Eight-week-old male TRX-Tg mice and wild type (WT) littermates were intraperitoneally injected with either streptozotocin or vehicle. Mice were grouped as 1) non-diabetic WT, 2) non-diabetic TRX-Tg, 3) diabetic WT, and 4) diabetic TRX-Tg. After 12 weeks of streptozotocin treatment, oxidative stress on the whole body and bone was evaluated, and the physical properties of the femora, and histomorphometry parameters of the tibiae were assessed. TRX overexpression did not affect either body weight or hemoglobin A1c levels. There were no significant differences in renal function and in serum levels of calcium, phosphate, and intact parathyroid hormone among the four groups. On the other hand, urinary excretion of 8-hydroxydeoxyguanosine (8-OHdG), a marker of oxidative DNA damage, was significantly elevated in diabetic WT and attenuated in diabetic TRX-Tg. Immunohistochemical staining for 8-OHdG revealed marked intensity in the bone tissue of diabetic WT compared with non-diabetic WT, while staining was attenuated in diabetic TRX-Tg. TRX overexpression partially restored reduced bone mineral density and prevented the suppression of bone formation observed in diabetic WT. Increased oxidative stress in diabetic condition contributes to the development of diabetic osteopenia. Suppression of increased oxidative stress by TRX induction could be a potential therapeutic approach for diabetic osteopenia.
authors.affiliation: Division of Nephrology and Kidney Center, Kobe University School of Medicine, Kobe, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Hamada
authors.forename: Hideki
authors.initials: H
authors.lastname: Fujii
authors.forename: Riko
authors.initials: R
authors.lastname: Kitazawa
authors.forename: Junji
authors.initials: J
authors.lastname: Yodoi
authors.forename: Sohei
authors.initials: S
authors.lastname: Kitazawa
authors.forename: Masafumi
authors.initials: M
authors.lastname: Fukagawa
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D001835:Body Weight / Q000235:genetics; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000209:etiology* / Q000378:metabolism / Q000473:pathology*; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000652:urine; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000150:complications; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology*; D011859:Radiography; D017382:Reactive Oxygen Species / Q000378:metabolism; D013879:Thioredoxins / Q000378:metabolism / Q000502:physiology*
chemical_list: D000080242:8-Hydroxy-2'-Deoxyguanosine; D003849:Deoxyguanosine; D006442:Glycated Hemoglobin; D017382:Reactive Oxygen Species; D013879:Thioredoxins