ER stress and ER stress-mediated apoptosis are involved in manganese-induced neurotoxicity in the rat striatum in vivo

•Mn could cause rat striatal neurocytes injury in a dose-dependent manner.•Mn could induce ER stress in rat striatal neurocytes.•ER stress-mediated apoptosis in rat striatal neurocytes is involved in Mn-induced neurotoxicity.

Manganese (Mn) is an essential trace element found in many enzymes, however, excessive Mn-exposure can result in manganism which is similar to Parkinson's movement disorder. The mechanisms of manganism are not well-known. The present in vivo study was carried out to determine whether endoplasmic reticulum stress (ER stress) and ER stress-mediated apoptosis are involved in manganese-induced neurotoxicity. Sixty-four SD rats were randomly divided into four groups and were administered intraperitoneally with normal saline (NS, as control) or MnCl2 (7.5, 15 and 30 mg/kg body weight, respectively) for 4 weeks. We found that MnCl2 dose-dependently accumulate in striatal. HE staining and TUNEL assay results indicated that MnCl2 induced striatal neurocytes apoptosis in both male and female rats. The alterations of ultrastructures showed that MnCl2 resulted in chromatin condensation, mitochondria and ER tumefaction in rat striatal neurocytes. Furthermore, MnCl2 increased the expressions of p-IRE-1, ATF-6α, PERK, GRP78, Sigma-1R, CHOP, Bim, Bax, caspase-12 and caspase-3, and decreased the expression of Bcl-2 in rat striatal neurocytes. In conclusion, MnCl2 could induce ER stress and ER stress-mediated apoptosis in rat striatal neurocytes, which might be one of the important mechanisms of Mn-induced neurotoxicity.