Manipulation of the induction of adjuvant arthritis in Sprague-Dawley rats

Abstract.

Objective

To investigate the roles of various variables in the induction of adjuvant-induced arthritis (AIA) in the outbred Sprague-Dawley (SD) rats, and further characterize its arthritic features by comprehensive examinations.

Methods

The roles of different preparative techniques, inoculation routes and doses of Mycobacterium tuberculosis (MT) suspension as well as the sex preference in the induction of AIA were comparatively studied using clinical assessment. The hind paws of animals were analyzed by radiological and histological examinations. The serum levels of cytokines interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α were determined by ELISA.

Results

The particle size and dose of MT played a dominant role in the induction and severity of AIA. Male rats manifested markedly more severe arthritic signs than female rats. After subcutaneously inoculated with 500 μg MT, male rats developed pronounced arthritis with 100% incidence and low variable clinical signs. Even using only 62.5 μg MT, AIA was efficiently induced in male rats and characterized by upregulated expression profiles of IL-1β, IL-6 and TNF-α.

Conclusions

Since outbred SD rats are much cheaper and more readily available than Lewis rats, this well-developed SD rat AIA model is an efficient and cost-effective arthritis model available for screening novel anti-arthritic agents.