Protective Effects of Dendrobium Alkaloids against Manganese-Induced Cytotoxicity in SH-SY5Y Cells

Excessive environmental exposure to manganese (Mn) is associated with neurotoxicity and can produce Parkinson’s disease (PD)like neurological disorders. Although the molecular mechanism is not fully described, Mn-induced neuronal cell death is central to Mn neurotoxicity. The present study was designed to determine the effects of Dendrobium alkaloids (DNLA), a Chinese medicinal herb extract, on Mn-induced cell toxicity, and to investigate whether modulation of the expression of apoptotic regulator proteins is involved in the mechanism of DNLA-mediated cell protection against Mn toxicity. The human neuroblastoma SH-SY5Y cell line was utilized as an in vitro model of Mn cell toxicity. It was found that the treatment of the SH-SY5Y cells with Mn for 48h resulted in a concentration-dependent cell death, whereas pretreatment of cells with DNLA significantly alleviated cell toxicity induced by Mn. Examination of apoptosis regulator proteins Bax and Bcl-2 revealed that Mn treatment caused a marked increase in the protein expression of Bax and a decrease in the expression of Bcl-2 protein. On the contrary, DNLA increased Bcl-2 expression, and concomitantly decreased Bax/Bcl-2 ratio. These results demonstrate that DNLA is able to suppress Mn induced cell toxicity, which may be mediated through modulating the expression of the apoptotic regulatory proteins Bax and Bcl-2.