Impacts of Diabetes and an SGLT2 Inhibitor on the Glomerular Number and Volume in db/db Mice, as Estimated by Synchrotron Radiation Micro-CT at SPring-8Research in context
Yumi Takiyama,
Toshihiro Sera,
Masanori Nakamura,
Kanaki Ishizeki,
Yasuaki Saijo,
Tsuyoshi Yanagimachi,
Manami Maeda,
Ryoichi Bessho,
Takao Takiyama,
Hiroya Kitsunai,
Hidemitsu Sakagami,
Daisuke Fujishiro,
Yukihiro Fujita,
Yuichi Makino,
Atsuko Abiko,
Masato Hoshino,
Kentaro Uesugi,
Naoto Yagi,
Tsuguhito Ota,
Masakazu Haneda
Affiliations
Yumi Takiyama
Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, Japan; Corresponding author at: Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, 2-1-1-1 Midorigaoka Higashi, Asahikawa 078-8510, Japan.
Toshihiro Sera
Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Japan
Masanori Nakamura
Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Japan
Kanaki Ishizeki
Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, Japan
Yasuaki Saijo
Department of Health Science, Asahikawa Medical University, Japan
Tsuyoshi Yanagimachi
Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, Japan
Manami Maeda
Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, Japan
Ryoichi Bessho
Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, Japan
Takao Takiyama
Department of Neurosurgery, Asahikawa Medical University, Japan
Hiroya Kitsunai
Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, Japan
Hidemitsu Sakagami
Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, Japan
Daisuke Fujishiro
Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, Japan
Yukihiro Fujita
Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, Japan
Yuichi Makino
Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, Japan
Atsuko Abiko
Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, Japan
Masato Hoshino
Research & Utilization Division, Japan Synchrotron Radiation Research Institute, Japan
Kentaro Uesugi
Research & Utilization Division, Japan Synchrotron Radiation Research Institute, Japan
Naoto Yagi
Research & Utilization Division, Japan Synchrotron Radiation Research Institute, Japan
Tsuguhito Ota
Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, Japan
Masakazu Haneda
Division of Metabolism and Biosystemic Science, Department of Medicine, Asahikawa Medical University, Japan
Background: Recent large-scale clinical studies demonstrate that sodium-glucose cotransporter 2 (SGLT2) inhibitors protect the diabetic kidney. However, clinical and animal studies have not shown the changes of the total glomeruli in the whole kidney treated with SGLT2 inhibitors. Methods: We performed computed tomography (CT) imaging on mice using synchrotron radiation to investigate the impact of luseogliflozin, a SGLT2 inhibitor, on the number and volume of glomeruli in the whole kidney. Findings: We did not observe a significant difference in the total glomerular number (Nglom) among mice. Luseogliflozin redistributed the number of glomeruli in different regions, accompanied by the normalization of diabetes-augmented renal volume (Vkidney). Diabetic db/db mice had a larger glomerular volume in the mid-cortex than did control db/m mice, and luseogliflozin increased the glomerular volume in all renal cortical zones of the whole kidney in db/db mice. According to the multivariate regression analysis, hemoglobin A1c level was the most relevant determinant of Vkidney, not Nglom or mean glomerular volume (Vglom), indicating that hyperglycemia induced renal (tubular) hypertrophy, but not glomerular enlargement. Luseogliflozin increased hypoxia in the juxtamedullary region, sustained upregulated renal renin expression and plasma renin activity, and failed to decrease albuminuria by downregulating megalin in db/db mice. Interpretation: Based on our findings, SGLT2 inhibitors may alter glomerular distribution and size in addition to their glucose-lowering effects, presumably by affecting oxygen metabolism and humoral factors. Fund: Funding for this research was provided by The Japan Society for the Promotion of Science, the Japan Diabetes Foundation, and Asahikawa Medical University. Keywords: Sodium glucose cotransporter-2 inhibitor, Diabetic nephropathy, Glomerular number, Glomerular volume, Megalin, Hypoxia
