MicroRNAs are resistant to RNases and are highly specific for various pathological conditions, particularly inflammation, allowing them to be considered inflammation biomarkers. They were detected in all body fluids, and miR146a plays a key role in the pathogenesis of inflammation. A total of 180 male white Wistar rats were selected for the study. All animals were 8–10 weeks old and weighed 200–250 grams. The animals were divided into five groups of 36 each. The first received saline solution intramuscularly, while the others underwent experimental modeling of obesity and knee arthrosis. The second group received 1.0 ml of saline solution intramuscularly, while the third, fourth, and fifth groups received dexamethasone at doses of 1 ng/ml, 10 ng/ml, and 100 ng/ml, respectively. Blood samples for the study were collected on days 3, 5, and 10. The obtained parameters were analyzed at the statistical significance level (p < 0.05). Increased miR146a levels were observed in animals in the second group compared to the others, due to the development of inflammation associated with obesity and concomitant gonarthrosis. In the third group, expression levels decreased slightly, remaining high. In the fourth group, with the use of 10 ng/ml dexamethasone, miR146a expression levels decreased most significantly on days 3 and 5. In the fifth group, virtually no changes were observed, with the parameter decreasing only slightly. The 10 ng/ml dexamethasone dose demonstrated the greatest efficacy during the experiment, possessing the greatest anti-inflammatory activity compared to the other doses.