RESUMEN
The aim of this study was to investigate the effect of isolated soy protein on prevention of rheumatoid arthritis in collagen-induced rats. A total of 24 female Sprague-Dawley rats [body weights: 180-200g] were randomly divided into four equal groups including normal; control of rheumatoid arthritis; rheumatoid arthritis + isolated soy protein [7g/kg]; rheumatoid arthritis + dexamethasone [1mg/kg]. Experimentally rheumatoid arthritis in rats was induced by subcutaneous injection of collagen II emolsified in Incomplete Frund s Adjuvant in days 1 and 7. Treatments were gavaged to animals for 30 days, once a day. The severity of rheumatoid arthritis symptoms in paws were daily measured in double blind format by standard method. The statistical comparison between the experimental groups was performed by Independent -samples t- test and One-Way ANOVA using SPSS software. The clinical symptoms of rheumatoid arthritis started from day 17.4 +/- 2.4, 20 +/- 4 and 14.1 +/- 1.9 in isolated soy protein, dexamethasone and control groups, respectively [P<0.05]. The severity of clinical symptoms of rheumatoid arthritis on day 30 was 3.84 +/- 2.04, 2 +/- 1.78 and 6.5 +/- 1.76 in isolated soy protein, dexa methasone and control groups, respectively [p<0.05]. At the end of the study, the incidence rates of rheumatoid arthritis in isolated soy protein and control groups was 83.33% and 100%, respectively. Isolated soy protein decreased the severity of clinical symptoms of rheumatoid arthritis. Therefore, it could be a key factor in prevention and even treatment of rheumatoid arthritis