Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Cachexia Sarcopenia and Muscle  

BACKGROUND: Diabetes is associated with an increased risk of deleterious changes in muscle mass and function or sarcopenia, leading to physical inactivity and worsening glycaemic control. Given the negative energy balance during sodium-glucose cotransporter-2 (SGLT2) inhibition, whether SGLT2 inhibitors affect skeletal muscle mass and function is a matter of concern. However, how SGLT2 inhibition affects the skeletal muscle function in patients with diabetes remains insufficiently explored. We aimed to explore the effects of canagliflozin (CANA), an SGLT2 inhibitor, on skeletal muscles in genetically diabetic db/db mice focusing on the differential responses of oxidative and glycolytic muscles. METHODS: Db/db mice were treated with CANA for 4 weeks. We measured running distance and handgrip strength to assess skeletal muscle function during CANA treatment. At the end of the experiment, we performed a targeted metabolome analysis of the skeletal muscles. RESULTS: CANA treatment improved the reduced endurance capacity, as revealed by running distance in db/db mice (414.9 ± 52.8 vs. 88.7 ± 22.7 m, P < 0.05). Targeted metabolome analysis revealed that 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranosyl 5'-monophosphate (AICARP), a naturally occurring AMP-activated protein kinase (AMPK) activator, increased in the oxidative soleus muscle (P < 0.05), but not in the glycolytic extensor digitorum longus muscle (P = 0.4376), with increased levels of AMPK phosphorylation (P < 0.01). CONCLUSIONS: This study highlights the potential role of the AICARP/AMPK pathway in oxidative rather than glycolytic skeletal muscles during SGLT2 inhibition, providing novel insights into the mechanism by which SGLT2 inhibitors improve endurance capacity in patients with type 2 diabetes.

DOI： 10.1002/jcsm.13350

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Endocrinology United States  

Pancreatic islet inflammation plays a crucial role in the etiology of type 2 diabetes (T2D). Macrophages residing in pancreatic islets have emerged as key players in islet inflammation. Macrophages express a plethora of innate immune receptors that bind to environmental and metabolic cues and integrate these signals to trigger an inflammatory response that contributes to the development of islet inflammation. One such receptor, Dectin-2, has been identified within pancreatic islets; however, its role in glucose metabolism remains largely unknown. Here we have demonstrated that mice lacking Dectin-2 exhibit local inflammation within islets, along with impaired insulin secretion and β-cell dysfunction. Our findings indicate that these effects are mediated by proinflammatory cytokines, such as interleukin (IL)-1α and IL-6, which are secreted by macrophages that have acquired an inflammatory phenotype because of the loss of Dectin-2. This study provides novel insights into the mechanisms underlying the role of Dectin-2 in the development of islet inflammation.

DOI： 10.1210/endocr/bqad181

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Language：Japanese   Publisher：(株)ニュー・サイエンス社  

SGLT2阻害薬は尿糖排泄を促進する血糖降下薬として開発されたが,糖尿病を合併しない心不全や腎臓病においても有効性が報告されており,臓器保護効果があることが示唆されている。骨格筋は代謝特性の異なる遅筋線維と速筋線維から構成され,前者は酸化的リン酸化,後者は解糖系によるエネルギー産生を行い,それぞれ持久的運動と瞬発的運動で使用される。筆者らは,非糖尿病および肥満糖尿病マウスを用いて骨格筋に対するカナグリフロジン(CANA)の作用を検討した。非糖尿病マウスでは,摂餌制限下でのCANA投与は速筋機能(握力)を低下させた。一方,肥満糖尿病マウスでは,CANA投与は遅筋機能(走行距離)を改善させた。本稿では上記2つのモデルの結果を踏まえ,代謝特性の異なる2種類の骨格筋に対するSGLT2阻害薬の作用について,メタボローム解析の結果とともに紹介する。(著者抄録)

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Biochemical Journal  

There has been a concern that sodium-glucose cotransporter 2 (SGLT2) inhibitors could reduce skeletal muscle mass and function. Here, we examine the effect of canagliflozin (CANA), an SGLT2 inhibitor, on slow and fast muscles from nondiabetic C57BL/6J mice. In this study, mice were fed with or without CANA under ad libitum feeding, and then evaluated for metabolic valuables as well as slow and fast muscle mass and function. We also examined the effect of CANA on gene expressions and metabolites in slow and fast muscles. During SGLT2 inhibition, fast muscle function is increased, as accompanied by increased food intake, whereas slow muscle function is unaffected, although slow and fast muscle mass is maintained. When the amount of food in CANA-treated mice is adjusted to that in vehicle-treated mice, fast muscle mass and function are reduced, but slow muscle was unaffected during SGLT2 inhibition. In metabolome analysis, glycolytic metabolites and ATP are increased in fast muscle, whereas glycolytic metabolites are reduced but ATP is maintained in slow muscle during SGLT2 inhibition. Amino acids and free fatty acids are increased in slow muscle, but unchanged in fast muscle during SGLT2 inhibition. The metabolic effects on slow and fast muscles are exaggerated when food intake is restricted. This study demonstrates the differential effects of an SGLT2 inhibitor on slow and fast muscles independent of impaired glucose metabolism, thereby providing new insights into how they should be used in patients with diabetes, who are at a high risk of sarcopenia.

DOI： 10.1042/BCJ20210700

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PubMed

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