RESUMO
BACKGROUND: Adjuvant arthritic animals show immunologic and inflammatory features which are also observed in patients with rheumatoid arthritis. This study investigated whether high dose vitamin E (alpha-tocopherol) has any additional anti-inflammatory or analgesic effects, or both, in Complete Freund's adjuvant (CFA) induced arthritic rat model. METHODS: Male Sprague-Dawley rats (300-350 g, n = 3) underwent testing up to 26 days after induction of the model. Vitamin E (100 mg/kg) or vehicle was given daily intraperitoneally (IP) for 10 or 20 days following induction. Thus, groups were as follows: group 1, untreated, n = 3; group 2, CFA + vehicle, n = 10; group 3, CFA + vitamin E for 10 days, n = 10; group 4, CFA + vitamin E for 20 days, n = 10. Parameters compared between groups included ankle circumference, range of articulation of the arthritic joint, extravasation of plasma proteins in the tissues around the arthritic joint and sensory withdrawal threshold to von Frey filament mechanical stimulation. RESULTS: Compared to CFA rats administered drug vehicle, those given vitamin E for 20 days exhibited a reduction in all symptoms of monoarthritis, including less ipsilateral ankle swelling, reduced loss of the range of joint articulation, low plasma extravasation and reversal of the decrease in sensory withdrawal threshold. But, vitamin E for 10 days has only analgesic effect until 10 days. CONCLUSIONS: This study showed relatively long duration of high-dose vitamin E treatment have anti-inflammatory and early onset analgesic effects. The findings raise the possibility of high dose vitamin E, or potentially other antioxidants, as adjuvant therapy for alleviation of symptoms of rheumatoid arthritis.