Discipline: Veterinary Medicine
In this study, expression of androgen receptor (AR) in ruptured canine anterior cruciate ligament (ACL) was immunohistochemically investigated. The samples used in the study were ACLs obtained from 16 dogs (six males and ten females) with ruptured ACL and nine healthy beagles (five males and four females). Blood samples were collected and serum testosterone level was determined. Ligament tissue at the proximal femur was sampled from the site of rupture in each dog and subjected to immunohistochemistry and immunofluorescent antibody test. The intensity of AR expression in the samples from dogs with ruptured ACL, particularly castrated males and spayed females, was lower in comparison with that in samples from the healthy dogs, suggesting its relationship with serum testosterone level. It was also revealed that androgen acted on ligament fibroblasts, activated cell proliferation and stimulated type I procollagen synthesis. The results of this study suggest that the intensity of AR expression in the canine ACL is greatly associated with the incidence of ruptured ACL.