Obesity is commonly accompanied by chronic tissue inflammation and leads to insulin resistance. Aerobic exercise is an essential treatment for insulin resistance and has anti-inflammatory effects. However, the molecular mechanisms of exercise on obesity-associated inflammation and insulin resistance remain largely unknown. Here, we evaluated the effects of aerobic exercise on inflammation and insulin resistance in skeletal muscles of high-fat diet (HFD) mice. Male C57BL/6J mice were fed a high-fat diet or a normal diet for 12 weeks, and then aerobic training was performed on a treadmill for 8 weeks. Body weight, fasting blood glucose, food intake levels, and glucose and insulin tolerance were evaluated. The levels of cytokines, skeletal muscle insulin resistance, and inflammation were also analyzed. Eight weeks of aerobic exercise attenuated HFD-induced weight gain and glucose intolerance, and improved insulin sensitivity. This was accompanied by enhanced insulin signaling. Exercise directly resulted in a significant reduction of lipid content, inflammation, and macrophage infiltration in skeletal muscles. Moreover, exercise alleviated HFD-mediated inflammation by suppressing the activation of the NF-κB pathway within skeletal muscles. These results revealed that aerobic exercise could lead to an anti-inflammatory phenotype with protection from skeletal muscle insulin resistance in HFD-induced mice.

Background/Objectives: This study aimed to assess the effect of aerobic exercise on capillary density and vascular smooth muscle cell (VSMC) phenotype in the visceral and subcutaneous adipose tissue of high-fat-diet (HFD) mice in order to understand the mechanisms underlying improvements in insulin resistance (IR) and chronic inflammation in adipose tissue (AT). Methods: Male C57BL/6J mice were divided into HFD and normal diet groups for 12 weeks and then further split into sedentary and aerobic exercise subgroups for an additional 8 weeks. Various parameters including body weight, fat weight, blood glucose, lipid profile, insulin levels, glucose tolerance, and inflammatory cytokines were evaluated. Results: Aerobic exercise reduced HFD-induced weight gain, IR, and improved lipid profiles. HFD had a minimal effect on inflammatory cytokines except in visceral adipose tissue (VAT). IR was associated with capillary density in subcutaneous adipose tissue (SAT) and VSMC phenotype in VAT. Aerobic exercise promoted anti-inflammatory responses in VAT, correlating with VSMC phenotype in this tissue. Conclusions: Aerobic exercise can alleviate HFD-induced IR and inflammation through the modulation of VSMC phenotype in AT.

Osteoporosis is highly prevalent in postmenopausal women, causing chronic pain, fractures, and limited mobility that burden individuals and society. While resistance exercise benefits bone health, its role in osteoporotic bone injury healing and underlying mechanisms remain unclear. This study aimed to explore the effects of 10-week weight-bearing ladder climbing exercise on ovariectomy (OVX)-induced osteoporosis and subsequent bone injury healing, and to investigate whether these effects are associated with the myostatin (MSTN) and Wnt/β-catenin pathways. Fifty-four 12-week-old female SD rats were randomized into Sham, OVX, and OVX + EX groups. Rats in the OVX and OVX + EX groups underwent ovariectomy to induce postmenopausal osteoporosis, and those in the OVX + EX group received 10-week weight-bearing ladder climbing. After the exercise intervention, 6 rats in each group were sacrificed; the remaining rats underwent femoral midshaft drilling to establish bone injury. The improvement in osteoporosis was evaluated via Micro-CT, biomechanical tests, RT-qPCR for mRNA detection, and Western blot for measuring protein levels of MSTN and Wnt/β-catenin pathway-related molecules at post-exercise and 21 days post-injury. Bone healing was reflected by the bone volume fraction at the bone injury site detected via Micro-CT at 10 and 21 days post-injury. This exercise significantly enhanced muscle strength and improved femoral bone mineral density (BMD), trabecular microstructure, and biomechanical properties in OVX rats. Meanwhile, the level of MSTN in the OVX + EX group was decreased, the expression of its downstream signaling pathways was inhibited, and the mRNA and protein expressions of Wnt/β-catenin were upregulated. Moreover, 21 days after exercise intervention, the biomechanical properties and bone microstructure of the OVX + EX group were still significantly superior to those of the OVX group, and the aforementioned molecular regulatory effect remained. In addition, pre-conducted exercise was able to promote increases in bone volume fraction at the bone injury site 10 and 21 days after drilling, which was conducive to bone injury healing. Ten-week weight-bearing ladder climbing ameliorates OVX-induced bone loss and promotes osteoporotic bone repair via regulating the MSTN/ActRIIB/Smad3 and Wnt/β-catenin pathways, providing evidence for exercise as a safe non-pharmacological intervention.

Objective: Insulin resistance (IR) is a complex and multifactorial disorder that contributes to type 2 diabetes and cardiovascular disease. MicroRNAs (miRNAs) play important roles in diverse developmental and disease processes. However, the molecular mechanisms of IR are unclear. This paper aims to explore the role of miRNA in regulating IR and to elucidate the mechanisms responsible for these effects. Methods: IR models were created by feeding a high-fat diet (HFD) to mice or stimulating 3T3-L1 cells with palmitate. Twelve weeks of HFD trigger weight gain, leading to lipid accumulation and insulin resistance in mice. The expression profiles of miRNAs in adipose tissues (AT) from the HFD-induced mouse models were analyzed. The relationship between miR-221-3p and SOCS1 was determined using dual luciferase reporter gene assays. Metabolic alterations in AT were investigated by real-time PCR and Western blot. Results: miR-221-3p was significantly increased in AT. HFD-induced disturbances in glucose homeostasis were aggravated by miR-221-3p upregulation. The inhibition of miR-221-3p promoted insulin sensitivity including reduced lipid accumulation and the disruption of glucose metabolism. Of note, the 3′-UTR of SOCS1 was found to be a direct target of miR-221-3p. The SOCS1 inhibitor attenuated miR-221-3p-induced increases in IRS-1 phosphorylation, AKT phosphorylation, and GLUT4. miR-221-3p was considered to be involved in the PI3K/AKT signaling pathway, thus leading to increased insulin sensitivity and decreased IR in HFD-fed mice and 3T3-L1 adipocytes. Conclusions: The miR-221-3p/SOCS1 axis in AT plays a pivotal role in the regulation of glucose metabolism, providing a novel target for treating IR and diabetes.