摘要Background : The neuropsychiatric disorders due to post- streptococcal autoimmune complications such as Sydenham' s chorea (SC) are associated with acute rheumatic fever and rheumatic heart disease (ARF/RHD). An animal model that exhibits char-acteristics of both cardiac and neurobehavioral defects in ARF/RHD would be an important adjunct for future studies. Since age, gender, strain differences, and geno-types impact on the development of autoimmunity, we investigated the behavior of male and female Wistar and Lewis rat strains in two age cohorts ( <6 weeks and> 12 weeks) under normal husbandry conditions and following exposure to group A streptococcus (GAS). Methods : Standard behavioral assessments were performed to determine the impair-ments in fine motor control (food manipulation test), gait and balance (beam walk-ing test), and obsessive- compulsive behavior (grooming and marble burying tests). Furthermore, electrocardiography, histology, and behavioral assessments were per-formed on male and female Lewis rats injected with GAS antigens. Results : For control Lewis rats there were no significant age and gender dependent differences in marble burying, food manipulation, beam walking and grooming be-haviors. In contrast significant age- dependent differences were observed in Wistar rats in all the behavioral tests except for food manipulation. Therefore, Lewis rats were selected for further experiments to determine the effect of GAS. After ex-posure to GAS, Lewis rats demonstrated neurobehavioral abnormalities and cardiac pathology akin to SC and ARF/RHD, respectively. Conclusion : We have characterised a new model that provides longitudinal stability of age- dependent behavior, to simultaneously investigate both neurobehavioral and cardiac abnormalities associated with post- streptococcal complications.