Geraniol (GER) is
a plant-derived acyclic isoprenoid monoterpene
that has displayed anti-inflammatory effects in numerous in
vivo and in vitro models. This study was
therefore designed to evaluate the antiarthritic potential of GER
in complete Freund’s adjuvant (CFA)-induced inflammatory arthritis
(IA) model in rats. IA was induced by intraplantar injection of CFA
(0.1 mL), and a week after CFA administration, rats were treated with
various doses of methotrexate (MTX; 1 mg/kg) or GER (25, 50, and 100
mg/kg). Treatments were given on every alternate day, and animals
were sacrificed on the 35th day. Paw volume, histopathological, hematological,
radiographic, and qPCR analyses were performed to analyze the severity
of the disease. GER significantly reduced paw edema after 35 days
of treatment, and these results were comparable to the MTX-treated
group. GER-treated animals displayed a perfect joint structure with
minimal inflammation and no signs of cartilage or bone damage. Moreover,
GER restored red blood cell and hemoglobin levels, normalized erythrocyte
sedimentation rate, platelet, and c-reactive protein values, and also
attenuated the levels of rheumatoid factor. RT-qPCR analysis demonstrated
that GER decreased mRNA expression of pro-inflammatory cytokines like
tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta.
GER also down-regulated the transcript levels of cyclooxygenase-2
(COX-2), microsomal prostaglandin E synthase-1, prostaglandin D2 synthase,
and interstitial collagenase (MMP-1). Molecular docking of GER with
COX-2, TNF-α, and MMP-1 also revealed that the antiarthritic
effects of GER could be due to its direct interactions with these
mediators. Based on our findings, it is conceivable that the antiarthritic
effects of GER could be attributed to downregulation of pro-inflammatory
mediators and protease like MMP-1.