Antimony-induced astrocyte activation via mitogen-activated protein kinase activation-dependent CREB phosphorylation

Abstract

Recent studies suggest that the chemical element antimony (Sb) is neurotoxic; however, the molecular mechanisms behind Sb-related neuronal damage are currently unknown. In this study, we found that Sb exposure promoted astrocyte proliferation and increased the expression of inducible nitric oxide synthase (iNOS) and glial fibrillary acidic protein (GFAP), two key protein markers of reactive astrogliosis, at both the gene and protein level, suggesting that Sb induced astrocyte activation. Moreover, the p38 mitogen-activated protein kinase (p38 MAPK) and extracellular signal-related kinase (ERK) pathways were activated following Sb exposure. Inhibition of p38 MAPK reduced Sb-induced iNOS and GFAP upregulation, while inhibiting ERK reduced GFAP expression only, in Sb-exposed C6 cells. Sb treatment also induced the phosphorylation of cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB), and the inhibition of CREB caused a reduction in Sb-induced GFAP and iNOS expression. Furthermore, inhibiting both p38 MAPK and ERK effectively alleviated CREB phosphorylation in Sb-exposed C6 cells. Taken together, our results suggest that p38 MAPK and ERK activation mediate Sb-induced astrocyte activation through CREB phosphorylation. These results help to clarify the molecular mechanisms underlying Sb-associated neurotoxicity.

Keywords: Antimony; Astrocyte activation; CREB; ERK; p38 MAPK.