Recovery process of arthritis induced by 6-Sulfanilamidoindazole (6SAI) in rats

Abstract

6-Sulfanilamidoindazole (6SAI) is known to induce not only an acute arthritis but also serositis and arteritis which resemble those induced by some vasodilators in rats. In this study, the recovery process of ankle lesions was examined histopathologically for up to 12 weeks of recovery period in rats bearing arthritis induced by administration of 6SAI (500mg/kg) for 2 weeks. At 2 weeks of 6SAI-treatment, e x u d a t ive s y n ovitis and ex u d a t ive/edematous periarthritis with m a r ked formation of granulation tissues and periosteal reactive bone formation were noted in the ankles, but no remarkable neutrophil infiltration was detected in those lesions. The ankle swelling induced by 6SAI diminished by 4 weeks of recovery period, and the elevated plasma fibrinogen levels were normalized by 2 weeks of r e c overy period. Although fibrosis and new l y - f o r m e d periosteal bone were still observed after 2 weeks of recovery period, no inflammatory lesion was detected at that point. At 4 or 12 weeks of recovery periods, the ankles showed an almost normal appearance. These results indicate that 6SAI-induced arthritis is reve r s i b l e in nature and does not develop into chronic phase.