Expression of GPR30 and GPR43 in oral tissues: deriving new hypotheses on the role of diet in animal physiology and the development of oral cancers.

Food components and salivary hormones modulate the function of various tissues in the oral cavity. However, the mechanisms underlying such interactions are poorly understood. This study aimed at the detection of GPR30 and GPR43 in oral epithelia. Although unknown yet, the expression of these receptors is hypothesized to be fundamental for the actions of salivary oestrogens, dietary isoflavones and short chain fatty acids (SCFA) in the oral environment. Either immunoblotting or RT-PCR techniques were used for receptor detection in bovine and primate oral tissues. Here we show for the first time that mRNA of the G-protein-coupled oestrogen receptor, GPR30, and the short chain fatty acid receptor, GPR43, are expressed in bovine parotid glands. Furthermore, GPR30 protein is expressed in bovine parotid gland and the tongue of the primate Theropithecus gelada. With GPR30 being a target for dietary isoflavones and GPR43 being a suggested target for short chain fatty acids, we propose new hypotheses concerning the receptors' roles in salivary gland physiology and pathology. Our findings may trigger more detailed studies on GPRs to unravel their role in regulatory mechanisms in the oral cavity as well as in cancer development in relation to diets or biologically active compounds like soy isoflavones.