Enhancement of carbachol-induced amylase secretion in parotid glands from rats with experimental periodontitis

ObjectiveIn a previous study we observed that parotid glands from rats with experimental periodontitis showed an increase in basal amylase release as a result of an increase in cAMP accumulation induced by PGE2 production. The aim of this work was to study whether this change in amylase release influences the secretory effect of carbachol.DesignExperimental periodontitis was induced through placing a black thread around the cervix of the two lower first molars. Experiments were done 22 days after ligature induced periodontitis. Amylase release was evaluated in vitro and determined using a colorimetric method which uses starch as substrate.ResultsThe effect of carbachol was increased in parotid glands from periodontitis rats. The effect of 10−6 M carbachol was inhibited by 4-DAMP (10−6 M), U-73122 (5 × 10−6 M) and trifluoperazine (5 × 10−6 M) in both groups. No changes were observed in the binding sites and affinity in parotid membranes from rats with experimental periodontitis. The inhibition of the adenylyl cyclase and the cyclooxygenase induced a right shift of the carbachol concentration-response curve in periodontitis group whilst the opposite effect was observed in control group in the presence of db-cAMP and PGE2.ConclusionsParotid glands from rats with experimental periodontitis release more amylase in response to carbachol suggesting an interaction between Ca2+ and cAMP in the fusion/exocytosis step of secretory vesicles.