Effects of cyclosporin A on the mandibular condylar cartilage in rats

Twenty, 5-week-old, male, Sprague–Dawley rats were divided into a control and a cyclosporin A (CSA) group for evaluating effects of the drug on condylar cartilage. Animals in the treatment group daily received CSA (15 mg/kg body wt) in mineral oil by gastric feeding over a 4-week observation interval. Control animals received mineral oil only. Five animals from each group were killed at weeks 2 and 4 of study. After histological processing, five tissue sections from the mid-region of the condyle were selected and examined. Three compositional zones (articular fibrous, proliferative, and hypertrophic) of the superior, posteriosuperior and posterior regions of the condylar cartilage were evaluated by light microscopy. At week 2, total condylar cartilage thickness was similar in the CSA and control groups, but the thickness of each zone was altered in CSA-treated animals, including a decrease of the fibrous and proliferative zones and an increase in hypertrophic zone compared to control (P<0.05). At week 4, CSA-treated animals exhibited overall decreased cartilage thickness, including decreased thickness of each zone compared to control (P<0.05). The results suggest that CSA has an inhibitory effect on the maturation of the mandibular condyle in rats.