Beyond the 5-HT3 receptors

Accumulation of reactive oxygen species, such as hydrogen peroxide (H2 O2 ), generated by inflammatory cells or other pathological conditions, leads to oxidative stress, which may contribute to the neuronal degeneration observed in a wide variety of neurodegenerative disorders such as Alzheimer's disease. Recent investigations have described effective properties of tropisetron, such as antiphlogistic action or protection against β-amyloid induced-neuroinflammation in rats. Our data revealed that H2 O2 -induced cell death in rat pheochromocytoma cell line (PC12) can be inhibited by tropisetron, as defined by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide assay, caspase 3 and caspase 12 levels. We further showed that tropisetron exerts its protective effects by upregulation of heme oxygenase-1, glutathione, catalase activity, and nuclear factor-erythroid 2 p45-related factor 2 level. Moreover, tropisetron was recently found to be a partial agonist of [alpha]7 nicotinic acetylcholine receptor ([alpha]7nAChR). The activation of [alpha]7nAChR could inhibit inflammatory and apoptotic signaling pathways in the oxidative stress conditions. In this study, selective [alpha]7nAChR antagonists (methyllycaconitine) reversed the effects of tropisetron on caspase 3 level. Our findings indicated that tropisetron can protect PC12 cells against H2 O2 -induced neurotoxicity through [alpha]7nAChR in vitro .