Gender differences and protective effects of testosterone in collagen induced arthritis in rats.

To understand the gender differences noticed in autoimmune disorders, particularly rheumatoid arthritis, we used a rat model of collagen induced arthritis (CIA). This study was carried out in two parts. In the first study, severity of inflammation was compared between male and female rats with respect to radiology, histology, activities of lysosomal enzymes, lipid peroxidation, immune response to type II collagen and the level of prostaglandin, a major inflammatory mediator. Since female rats developed severe inflammation, this study was extended to confirm if testosterone at physiological concentration had protective effect against CIA. Hence, studies were carried out on the effect of testosterone application on castrated arthritic rats. Female arthritic rats were also treated with testosterone to find out the effectiveness of the androgen in the presence of female hormones. Results of this study conclusively showed that testosterone possessed significant anti-inflammatory effects at physiological concentration and exerted its action in a gender nonspecific manner.