RESUMO
A functional endocannabinoid system is present in several mammalian organs and tissues. The endogenous cannabinoid anandamide (AEA) is a bioactive lipid neurotransmitter that is present in a variety of tissues and has multiple functions. Recently, this cannabinoid system was reported to play important roles in osteoblastic and osteoclastic cells. Human periodontal ligament (hPDL) cells modulate alveolar bone remodeling by producing cytokines when stimulated by many factors. The aim of this study was to investigate the AEA level in periodontal regions and the osteogenic effect of AEA on hPDL cells. The levels of AEA in the gingival crevicular fluid (GCF) of periodontitis patients were measured using liquid chromatography/mass spectrometry (LC/MS). Expressions of cannabinoid receptor mRNA were detected by RT-PCR in hPDL cells and expression of the transient receptor potential cation channel subfamily V member 1 (TRPV1) was observed by confocal laser scanning microscope (CLSM). IL-11 production from hPDL cells was measured using an ELISA, with or without AEA in the presence or absence of capsazepine, a selective TRPV1 antagonist AEA secreted into GCF was detected, but there was no correlation between the probing pocket depth (PPD) and AEA level. TRPV1 mRNA was detected in hPDL cells and the TRPV1 expression was observed by CLSM. IL-11 production from hPDL cells was significantly enhanced by AEA stimulation and this IL-11 production was suppressed by capsazepine. Our findings indicate that this endogenous cannabinoid system has a possible role in bone metabolism in periodontitis through TRPV1.