Trail immunolocalization in the rat periodontal ligament during experimental tooth movement. A preliminary study

The aim of this study was to evaluate immunohistochemically TRAIL (TNF-Related Apoptosis Inducing Ligand) ex- pression in the periodontal ligament of rats’ molars considering its distribution pattern in the tension and compressive regions of ligament during orthodontic movement. Sixteen Sprague-Dawley rats, weighing between 120 and 200 g were used in the present study. Tooth movement was induced by placing elastic bands between the maxillary first and second molars. The elastic bands were left in place for 12 (time T1) and 24 (time T2) hours. After rats’ euthanasia, maxillae were dissected free and the sections were exposed to a primary rabbit polyclonal anti-TRAIL anti-body. The staining status was identified as either negative or positive by using 3,3’-diaminobenzidine (DAB) to develop the immunoreac- tion. Data were analyzed using ANOVA test and a post-hoc Dunn’s Multiple Comparison test. P-values of less than 0.05 were considered statistically significant. The staining for TRAIL in the tension side appeared darker (intensity of staining = 2) than in the compressive side (intensity of staining = 1) 12 h after the tooth movement. The stainings of both sides of PDL were observed to be up-regulated 24 h after the application of the force (tension side = 3, compres- sion side = 2; P < 0.05). TRAIL is expressed in the periodontal ligament of rats’ molars during experimental tooth movement both in the compression and in the tension sides. The latter showed the highest amount of TRAIL immu- nolabeling.