To induce PD, rats were first anesthetized with an intramuscular injection of ketamine (90 mg/kg) and xylazine (10 mg/kg). A cotton ligature was placed in a subgingival position around the cervix of both sides of mandibular first molars in each animal.16 (link) In order to immobilize the ligature, two knots were made at the mesial aspect of the first molars.
After the ligature placement, animals were randomly assigned to three experimental groups (n=10 animals/group): 1) Control rats (without ligature); 2) rats with ligature + placebo (saline); 3) rats with ligature + fluoxetine (20 mg/kg/day11 (link) in saline). Fluoxetine hydrochloride# was dissolved in saline solution (vehicle). All treatments (saline or fluoxetine) were given orally (gavages) 1 hour before the attachment of ligature and daily during experimental periods.
Rats were euthanized under general anesthesia at 3 or 15 days after the attachment of the ligature, respectively, according to the protocols established by Rodini et al.17 (link) and Holzhausen et al.5 (link) At Day 3, gingival tissue samples of the same size were collected from the mandibular first molars regions, immediately frozen, and kept at −80°C until processing for reverse transcriptase- polymerase chain reaction (RT-PCR) analysis and protein assays. Mandibular alveolar bone specimens of rats collected at Day 15 were submitted to histological analysis.