Effect of bitter compounds on amylase secretion in murine submandibular glands: Signaling pathways mechanisms

DASSO M ; PAGOTTO RM; PIGNATARO OP; DIEZ RA; SALES ME

BIOCHIMICA ET BIOPHYSICA ACTA-GENERAL SUBJECTS

ELSEVIER SCIENCE BV

Lugar: Amsterdam, The Netherlands; Año: 2011 vol. 1810 p. 1212 - 1219

0304-4165

Background: Amylase is synthesized in submandibular glands (SMG) and released into the oral cavity to degrade carbohydrates in the mouth. Bitter taste receptors (T2R) belong to the G-protein coupled receptor (GPCR) family and are expressed in the taste cells and also in the digestive tract. Methods: The activity of amylase secreted by murine SMG was measured, detecting maltose by Bernfeld´s method. Amylase and T2R6 were detected by imunohistochemistry and Western blot. The expression of Ggustducin, Gi, and phospholipase Câ2 was also studied by Western blot. cAMP levels were measured by radioimmunoassay and inositol monophosphate production was quantified by ELISA. Results: Theophylline, denatonium and cycloheximide exerted a dose-dependent inhibition on amylase secretion. This effect was reverted by preincubating SMG with an anti-Gái antibody. cAMP production was increased by the same compounds, an effect that was also abrogated by an anti-Gái antibody. Bitter compounds reduced inositol monophosphate formation in SMG and H-89, a protein kinase A inhibitor, reverted this action, revealing that this protein kinase down regulates phospholipase C activity. General significance: We demonstrated that theophylline, denatonium and cycloheximide inhibit salivary amylase secretion, activating an intracellular signaling pathway that involves cAMP and phospholipase C, that cross talks via protein kinase A.