Effect of running exercise on titanium dioxide (TiO2)-induced chronic arthritis and sarcopenia in mice. A titanium prosthesis loosening injury model study.

AIMS: This study aimed to investigate if titanium dioxide (TiO2) joint administration is a useful pre-clinical model to study sarcopenia-related chronic arthritis, and if exercise is a useful therapeutic approach against the pathogenesis of TiO2-induced arthritis and sarcopenia in mice. MAIN METHODS: Two experiments were conducted. Firstly, 36 female Swiss mice were randomly divided into a control group (n = 12) and two groups who received intra-articular TiO2 injections of 0.3-mg (n = 12) and 3-mg (n = 12), respectively. Mice were euthanized 4 and 8 weeks after TiO2 injections. Based on data of the first experiment, mice were exposed to four groups: control (C, n = 10), exercised (Ex, n = 10), injected with 3-mg of TiO2 (TiO2, n = 10), and injected with 3-mg of TiO2 and exercised (TiO2 + Ex, n = 10) for a total of 8-weeks. KEY FINDINGS: Eight-week of 3 mg of TiO2 joint administration promoted characteristics of chronic inflammation such as elevated histopathological score, inflammation, edema and pain. Hallmarks of sarcopenia were also observed such as muscle atrophy and loss of strength. Furthermore, voluntary exercise running reduced TiO2-induced chronic inflammation and pain, attenuating chronic arthritis-related muscle atrophy, strength loss and impairment of locomotion capacity. In addition, exercise was also able to prevent TiO2-induced collagen degradation, an important marker of functional and structural integrity loss of cartilage and chronic arthritis disease progression. SIGNIFICANCE: TiO2 joint administration mimed titanium prosthesis release-induced joint chronic arthritis and sarcopenia-related chronic arthritis, disturbances that were attenuated by voluntary exercise.

Creatine supplementation in Walker-256 tumor-bearing rats prevents skeletal muscle atrophy by attenuating systemic inflammation and protein degradation signaling.

PURPOSE: The aim of this study was to investigate the effects of creatine supplementation on muscle wasting in Walker-256 tumor-bearing rats. METHODS: Wistar rats were randomly assigned into three groups (n = 10/group): control (C), tumor bearing (T), and tumor bearing supplemented with creatine (TCr). Creatine was provided in drinking water for a total of 21 days. After 11 days of supplementation, tumor cells were implanted subcutaneously into T and TCr groups. The animals' weight, food and water intake were evaluated along the experimental protocol. After 10 days of tumor implantation (21 total), animals were euthanized for inflammatory state and skeletal muscle cross-sectional area measurements. Skeletal muscle components of ubiquitin-proteasome pathways were also evaluated using real-time PCR and immunoblotting. RESULTS: The results showed that creatine supplementation protected tumor-bearing rats against body weight loss and skeletal muscle atrophy. Creatine intake promoted lower levels of plasma TNF-α and IL-6 and smaller spleen morphology changes such as reduced size of white pulp and lymphoid follicle compared to tumor-bearing rats. In addition, creatine prevented increased levels of skeletal muscle Atrogin-1 and MuRF-1, key regulators of muscle atrophy. CONCLUSION: Creatine supplementation prevents skeletal muscle atrophy by attenuating tumor-induced pro-inflammatory environment, a condition that minimizes Atrogin-1 and MuRF-1-dependent proteolysis.