Characterization of molecular mechanisms of extracellular acidification-induced intracellular Ca increase in LβT2 cells.

Extracellular acidification regulates endocrine cell functions. Ovarian cancer G protein-coupled receptor 1 (OGR1), also known as GPR68, is a proton-sensing G protein-coupled receptor and is activated by extracellular acidification, resulting in the activation of multiple intracellular signaling pathways. In the present study, we found that OGR1 was expressed in some gonadotropic cells in rat anterior pituitary and in LβΤ2 cells, which are used as a model of gonadotropic cells. When we reduced extracellular pH, a transient intracellular Ca increase was detected in LβT2 cells. The Ca increase was inhibited by a G inhibitor and Cu, which is known as an OGR1 antagonist. We also found that extracellular acidification enhanced GnRH-induced Gaussia luciferase secretion from LβT2 cells. These results suggest that OGR1 may play a role in the regulation of gonadotropic cell function such as its hormone secretion.