Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCB212

Poster Communications

Involvement of endocannabinoid and vanilloid pathways in periodontal disease in rats

C. Á. Ossola1,2, N. B. Balcarcel1, J. I. Astrauskas1, J. A. Rodas1, J. C. Elverdin1, J. Fernández-Solari1,2

1. Physiology, School of Dentistry, University of Buenos Aires, Buenos Aires, Argentina. 2. National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina.

Periodontal disease (PD) is an infectious illness characterized by alveolar bone loss (ABL) due, to a large extent, to an inflammatory response in the tissues surrounding teeth. Endogenous ligands and receptors of the endocannabinoid system have been associated with both bone metabolism and inflammation. Likewise, transient receptor potential vanilloid 1 (TRPV1) has been extensively linked to pain and inflammation. The aim of this study was to evaluate the effects of, on the one hand, the blockage of TRPV1 and, on the other hand, the increase of the bioavailability of anandamide (AEA), a CB1r and CB2r endogenous agonist, on the experimental PD in rats. Methods: male Wistar rats (300g) were used (n=6 per group). The groups performed were: 1) control (C); 2) injected with 20ul of Escherichia coli lipopolisaccharide (LPS) (1mg/ml) in upper and lower first molar gum, three days a week (days 1, 3 and 5 of each week) during six weeks; 3) injected with LPS as described for group 2) and treated daily with a topical solution of capsazepine (Cap) (2ug/ml saline), a TRPV1 antagonist, in the injection sites; 4) injected with LPS as described for group 2) and treated daily with topical solution of URB 597 (20ug/ml saline), an inhibitor of AEA degradation, in the injection sites. Anesthesia was induced by isofluorane inhalation for injections and topical applications procedures. After the rats' decapitation euthanasia, ABL of the upper and lower first molar was measured through morphometric and histomorphometric techniques. The content of prostaglandin E2 (PGE2), an inflammatory and bone resorption mediator, was evaluated by radioimmunoassay in gums of the first molar. Statistical analysis: two-way ANOVA. In the interradicular bone examination of the first lower molar, the increase in the periodontal space height caused by LPS-induced PD (270.7um±33.5) with respect to C (217.1um±20.4) resulted significantly attenuated in animals that underwent Cap treatment (216.4 um±19.9) (ρ<0.05 vs. LPS). On the other hand, animals treated with URB 597 evidenced lesser periodontal space height (233.7um±18.5) than those only submitted to LPS (281.7um±18.5), which showed an increase in this value with respect to C (204.5um±30.3) (ρ<0.05 vs. LPS). Concordant results were obtained from the ABL analysis of first upper molar. PGE2 content in gingival tissue, increased by LPS-induced PD (54.55pg±16.86) with regard to C (32.93pg±15.83), also resulted attenuated in animals treated with URB 597 (27.72pg±10.77) (ρ<0.05 vs. LPS). These results indicate that both the TRPV1 blockage and the rise in the bioavailability of AEA are effective mechanisms to prevent local damage associated with inflammation and bone resorption, suggesting that vanilloid as well as cannabinoid pathways could integrate a homeostatic mechanism that plays a critical role in the pathophysiology of the periodontal disease.

Where applicable, experiments conform with Society ethical requirements