4.7. Measurement of IL-1β Concentration in Synovial Fluid

Measurements were conducted in groups treated with saline, APHC3 0.1 mg/kg, and meloxicam after OA induction and in the control group. On days 8 and 15 after knee joint injection, rats were sacrificed, and samples of the synovial fluid were collected via lavage with 100 µL of phosphate-buffered saline with 4 mM EDTA from the injected knee joints and stored at −80 °C until use. The concentration of IL-1β in the synovial fluid was detected using IL-1β Rat ELISA Kit (Invitrogen, Thermo Fisher Scientific, Waltham, MA, USA) according to the manufacturer’s protocol.