| Summary: | 碩士 === 國立陽明大學 === 口腔生物研究所 === 93 === Areca quid (AQ) chewers have a higher prevalence of periodontal diseases than non-chewers. There are two major metabolic pathways of arachidonic acid, the cyclooxygenase-2 (COX-2) pathway and the 5-lipoxygenase (5-LO) pathway. The amounts of leukotriene B4 (LTB4) and prostaglandin E2 (PGE2) in gingival crevicular fluid (GCF) were higher in the periodontal disease sites than the healthy sites from healthy control. Neutrophils are the major source of LTB4. LTB4 is synthesized via the 5-LO pathway. Activation of 5-LO pathway is regulated by intracellular calcium and phosphorylation of p38 mitogen-activated protein kinase (MAPK). PGE2 is a product of the COX-2 pathway. The propose of the study was to investigate the effects of areca nut extract (ANE), the main component of AQ, on arachidonic acid metabolic cascade in neutrophils. Neutrophils were treated with various concentrations of ANE for different incubation times. The amounts of LTB4 and PGE2 in culture supernatants were measured using enzyme immunoassay (EIA). The effects of ANE on intracellular calcium concentration were measured using fluorescent dye, Fura-2. The effects of ANE on phosphorylation of p38 MAPK and expression of COX-2 protein were examined using Western blotting technique. The results showed that ANE induced the generation of LTB4 in a dose-dependent manner. Time-dependent decrease in generation of LTB4 was observed following the treatment of ANE. ANE also induced secretion of PGE2 in a dose-and time-dependent manner. ANE caused a rapid elevation of cytosolic calcium concentration in neutrophils. The phosphorylation of p38 MAPK was induced in neutrophils after ANE treatment for 0.5 hour. After treating neutrophils with ANE for 20 hours, the expression of COX-2 was increased. In conclusion, the results indicated that ANE regulated the activation of arachidonic acid metabolic cascade in neutrophils. These data may help to explain the association of AQ chewing and periodontal diseases.
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