Oxabicycloheptene Sulfonate Protects Against β-Amyloid-induced Toxicity by Activation of PI3K/Akt and ERK Signaling Pathways Via GPER1 in C6 Cells

Oxabicycloheptene sulfonate (OBHS) is a novel bicyclic core selective estrogen receptor modulator (SERM) with estrogen receptor (ER) antagonistic-activity and anti-inflammatory activity. However, little is known about protective action of OBHS on neurodegenerative disorders. In the present study, OBHS demonstrated a remarkably protective effect against amyloid beta (A beta) induced cytotoxicity via G-protein-coupled estrogen receptor 1 (GPER1) in rat astroglial cell line (C6). The C6 cell death induced by A beta was decreased by OBHS (1 mu M) treatment for 45 min. This rapid protective action was blocked by GPER1 specific antagonist or siRNA knockdown. Inhibitors of phosphatidylinositol 3-kinase (PI3k)/Akt and extracellular signal-regulated kinase (ERK) activation also exhibited similar effects as GPER1 antagonist in blocking the protective effects of OBHS. Moreover, the expression of anti-apoptotic protein Bcl-2 was also increased by OBHS as a consequence of the activation of GPER1-PI3K/Akt and ERK pathways. Additionally, the phenyl sulfonate moiety of OBHS played a vital role in producing GPER1's agonist property according to the molecular docking analysis. These findings suggest that OBHS provide protection directed at enhancing glial cell survival through the activation of GPER1, which, in turn, offers a novel insight into the molecular mechanisms behind the potential application of OBHS in treating Alzheimer's disease (AD).