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Background and objectives: Pyruvate dehydrogenase kinase 4 (PDK4) is an enzyme involved in the regulation of glucose and fatty acid metabolism and homeostasis. The purpose of this study was to investigate effects of continuous exercise and resveratrol supplementation on insulin resistance and expression of PDK4 in the soleus muscle of elderly rats with type 2 diabetes.
Methods: After inducing diabetes in 42 old male rats (mean weigh: 250-300 g, aged about two years), the rats were randomly divided into six groups: healthy control, diabetic control, continuous exercise, supplementation, continuous exercise + supplementation and sham. The continuous exercise group was subjected to eight weeks of running, five sessions a week. Daily 20 mg/Kg body weight resveratrol supplementation was administered to the supplementation and supplementation + exercise groups. To evaluate insulin resistance, the HOMA-IR insulin resistance index was calculated as the product of insulin (μIU/mL) and glucose (mmol/L) divided by 22.5. Expression of the PDK4 gene in the soleus muscle was analyzed by RT-PCR. Data were analyzed with IBM SPSS Statistics 23 using one-way ANOVA and Tukey's post hoc test at a significance level of 0.05.
Results: Resveratrol alone or combined with continuous exercise significantly increased PDK4 expression and slightly decreased insulin resistance in the subjects.
Conclusion: Our results show that diabetes is associated with reduced PDK4 expression and increased insulin resistance. These effects can be effectively reversed in the soleus muscle of elderly diabetic rats by resveratrol supplementation alone or combined with continuous exercise.
 

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Background and objectives: Osteoarthritis is the result of a defect in synovial membrane-covered joint tissues. The purpose of this study was to investigate effects of glucosamine sulfate alone and combined with moderate intensity exercise on serum levels of CS 846 epitope and cartilage oligomeric matrix protein (COMP) in a rat model of osteoarthritis.
Methods: In this study, after inducing osteoarthritis in 42 male Wistar rats (weighting 250±300 g, aged 8 to 12 weeks), the rats were randomly divided into five groups: control-healthy, control-patient, patient-exercise, patient-glucosamine and patient-glucosamine-exercise. The training program consisted of 30 minutes of running on a non-slip treadmill at speed of 16 m/min in the first week with progressive overload principle reaching 50 minutes by the eighth week. The glucosamine groups received oral glucosamine sulfate (250 mg/kg/day) once a day for eight consecutive weeks. The serum levels of CS 846 epitope and COMP were measured using commercial ELISA kits. Data were analyzed using one-way ANOVA and Tukey's post hoc test. All statistical analyses were performed in GraghPad prism 8 and at significance level of 0.05.
Results: Combined exercise and glucosamine supplementation caused a significant decrease in the COMP and CS846 levels. This decrease was more profound compared to that of glucosamine and exercise alone.
Conclusion: Overall, the findings of the present study showed that osteoarthritis increases serum COMP and CS 846 levels. In addition, glucosamine supplementation combined with exercise can significantly improve knee osteoarthritis in rats.