Antirheumatic and Memory-enhancing Effect of Memantine on Complete Freund’s Adjuvant-induced Rheumatoid Arthritis Compared to Methotrexate in Wistar Rats

To evaluate the anti-inflammatory and memory-enhancing effects of memantine (MEM) in complete Freund’s adjuvant (CFA)-induced rheumatoid arthritis (RA) in Wistar rats. The effect of MEM on cognition in CFA-induced RA was also evaluated. The rats were randomly assigned to one of five groups: sham control (SC), disease control (DC)—CFA 0.1 mg, positive control (PC)—methotrexate (MTX) 1 mg/kg, low dose MEM—20 mg/kg, and high dose MEM (HD-M)—50 mg/kg. All groups received a subcutaneous injection of CFA in the left paw on day 0, except for the SC group, which received a distilled water (DW) injection. The study drugs, MEM and MTX, were administered orally from days 15 to 28. The SC group received DW orally from days 15 to 28. Variables for physical (paw volume, paw surface temperature, and ankle joint diameter) and behavior (open field test, grip strength test, and water corn test) were performed on days 1, 0, 7, 14, 21, and 28. On day 28, blood was collected for serum inflammatory markers, tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-6. Ex vivo radiological changes in the ankle joint were recorded using a digitalized X-ray machine. Histopathology of the ankle joint was performed. When compared to the DC group, the HD-M group showed a significant improvement in all physical and behavioral characteristics ( p < 0.001). When compared to the DC group, TNF-α, IL-6 levels, and histopathological scores were significantly lower in the HD-M group ( p < 0.01). MEM reduces inflammation and improves memory in Wistar rats with CFA-induced RA. MEM can be used as an anti-inflammatory drug in elderly patients at risk of dementia.