Effects of cyclosporin A on the mandibular condylar cartilage in rats

Twenty, 5-week-old, male, Sprague-Dawley rats were divided into a control a nd a cyclosporin A (CSA) group for evaluating effects of the drug on condyl ar cartilage. Animals in the treatment group daily received CSA (15 mg/kg b ody wt) in mineral oil by gastric feeding over a 4-week observation interva l. 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 examin ed. Three compositional zones (articular fibrous, proliferative, and hypert rophic) of the superior, posteriosuperior and posterior regions of the cond ylar cartilage were evaluated by light microscopy. At week 2, total condyla r cartilage thickness was similar in the CSA and control groups, but the th ickness of each zone was altered in CSA-treated animals, including a decrea se of the fibrous and proliferative zones and an increase in hypertrophic z one compared to control (P < 0.05). At week 4, CSA-treated animals exhibite d overall decreased cartilage thickness, including decreased thickness of e ach zone compared to control (P < 0.05). The results suggest that CSA has a n inhibitory effect on the maturation of the mandibular condyle in rats. (C ) 1999 Elsevier Science Ltd. All rights reserved.