Atividades antirreabsortiva e anti-inflamatória do ranelato de estrôncio na periodontite induzida em ratos

Abstract

Periodontitis is a disease which involves the presence of bacteria and it is characterized by inflammatory events that lead to loss of periodontal tissues such as root cementum periodontal ligament and alveolar bone Strontium Ranelate (RS) is a recent developed drug used for osteoporosis treatment that different from other anti-osteoporotic drugs it possess a dual effect on bone metabolism: it decreases bone resorption by the time it stimulates bone formation The aim of this study was to evaluate the RS anti-resorptive effect in experimental periodontitis considering local and systemic aspects and the inflammatory response through classical inflammation experimental models in animals Periodontitis was induced by placing a suture (nylon 3.0) around the left 2nd upper left molars of rats (± 200g) using their contralateral hemimaxillae for control. The animals were divided into 4 groups (n = 6/each) which received RS (70, 210 and 630 mg/kg) or saline 0.9% (SAL) orally during 11 days Two more groups were added (RS and SAL) for histological analysis Alveolar bone loss (ABL) was evaluated by macroscopic mm2) histologic and immunohistochemistry analysis and by serum bone alkaline phosphatase (BALP) levels In order to evaluate possible systemic repercussions body weight variation (g) leukocyte count and serum levels of: transaminases (AST and ALT) urea and creatinine were assessed In order to investigate inflammatory response peritonitis model and paw edema we used both of them induced by carrageenan (Cg 700 g) a potent anti-inflammatory agent by intraperitoneal and in rat hind paw, respectively Animals were divided in groups (± 200 g; n = 6/each) which received 0.9% saline-vo (SAL); Dexamethasone 1 m/kg-sc (DEX) and RS 630 mg/kg-vo before Cg injection. On peritonitis model a group of non-handled (Normal) animals was added After the 4th hour of peritonitis animals were sacrificed in order to collect peritoneal fluid and to evaluate neutrophil migration On paw edema model the dislocated liquid volume by rats paw (edema) was measured by a hydropletismometer before (0h) and 1 2 3 and 4 h after Cg injection It was observed that RS (70, 210 and 630 mg/kg) prevented ABL (p<0.05) by 16.9% 39.4% and 37.5% respectively On immunohistochemical and histologic analysis RS reduced TNF-a but not reduced IL-1b expression and additionally promoted important (p<0.05) decrease on leukocyte infiltrate and osteoclast number as well as alveolar bone periodontal ligament and root cementum preservation [RS 630 = 1.5 (1-3); SAL=2.5 (2-3)] These analyses were corroborated by the increase (p<0.05) of BALP serum levels (RS70= 94±4.6; RS210= 90.9±6; RS630= 107.5±14.2; SAL= 57.9±6.9 U/l) Initially animals presented loss of weight followed by a normal tendency but as well as in leukogram or in the other serum biochemical dosage it was not observed any significant alteration (p>0.05) between groups About inflammatory response RS 630 mg/kg was able to reduce neutrophil migration induced by Cg [RS=5.7±0.6; Sal=8.3±0.6 (x103/mm3); p<0.05] besides paw edema decreased on the 3rd and 4th hour after Cg administration In summary RS was able to prevent ABL confirming its anti-resorptive potential and also exhibit anti-inflammatory activity which can be an important tool as adjuvant to periodontitis treatment.