Hindawi Publishing Corporation Journal of Toxicology Volume 2013, Article ID 347312, 10 pages http://dx.doi.org/10.1155/2013/347312 Research Article Differential Effects of Methyl-4-Phenylpyridinium Ion, Rotenone, and Paraquat on Differentiated SH-SY5Y Cells João Barbosa Martins, 1 Maria de Lourdes Bastos, 1 Félix Carvalho, 1 and João Paulo Capela 1,2 1 REQUIMTE (Rede de Qu´ ımica e Tecnologia), Laborat´ orio de Toxicologia, Departamento de Ciˆ encias Biol´ ogicas, Faculdade de Farm´ acia, Universidade do Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal 2 Faculty of Health Sciences, University Fernando Pessoa, Rua Carlos da Maia 296, 4200-150 Porto, Portugal Correspondence should be addressed to Jo˜ ao Barbosa Martins; joao b martins@hotmail.com and Jo˜ ao Paulo Capela; joaocapela@f.up.pt Received 15 November 2012; Revised 28 January 2013; Accepted 28 January 2013 Academic Editor: Lucio Guido Costa Copyright © 2013 Jo˜ ao Barbosa Martins et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Paraquat (PQ), a cationic nonselective bipyridyl herbicide, has been used as neurotoxicant to modulate Parkinson’s disease in laboratory settings. Other compounds like rotenone (ROT), a pesticide, and 1-methyl-4-phenylpyridinium ion (MPP + ) have been widely used as neurotoxicants. We compared the toxicity of these three neurotoxicants using diferentiated dopaminergic SH- SY5Y human cells, aiming to elucidate their diferential efects. PQ-induced neurotoxicity was shown to be concentration and time dependent, being mitochondrial dysfunction followed by neuronal death. On the other hand, cells exposure to MPP + induced mitochondrial dysfunction, but not cellular lyses. Meanwhile, ROT promoted both mitochondrial dysfunction and neuronal death, revealing a biphasic pattern. To further elucidate PQ neurotoxic mechanism, several protective agents were used. SH-SY5Y cells pretreatment with tiron (TIR) and 2-hydroxybenzoic acid sodium salt (NaSAL), both antioxidants, and N  -nitro-L-arginine methyl ester hydrochloride (L-NAME), a nitric oxide synthase inhibitor, partially protected against PQ-induced cell injury. Additionally, 1-(2-[bis(4-fuorophenyl)methoxy]ethyl)-4-(3-phenyl-propyl)piperazine (GBR 12909), a dopamine transporter inhibitor, and cycloheximide (CHX), a protein synthesis inhibitor, also partially protected against PQ-induced cell injury. In conclusion, we demonstrated that PQ, MPP + , and ROT exerted diferential toxic efects on dopaminergic cells. PQ neurotoxicity occurred through exacerbated oxidative stress, with involvement of uptake through the dopamine transporter and protein synthesis. 1. Introduction Parkinson’s disease (PD) is considered the second most common neurodegenerative disorder worldwide, afecting 0.5 to 1% of the population aged between 65 and 69 years and 1 to 3% of the population over 80 years [1]. PD develops from a loss of nigrostriatal neuromelanin-con- taining dopaminergic neurons, whose cell bodies lay in the substantia nigra pars compacta (SNpc) [2]. Tis nigrostri- atal pathway is essential for a normal motor function and movement control. PD is thought to have a multifactorial etiology, frequently including genetic and environmental factors [2, 3]. Several neurotoxic chemicals to dopaminergic neurons leading to PD-like symptoms have been used to study this disease. Te synthetic compounds 1-methyl-4- phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4- phenyl-4-propionoxy-piperidine (MPPP) were the frst to be associated with PD symptoms, as described by Langston and Ballard [4]. MPTP enters the blood-brain barrier and is metabolized in glial cells by monoamine oxidases to 1- methyl-4-phenyl-2,3-dihydropyridium (MPDP + ), which is subsequently oxidized to MPP + [5]. Next, MPP + enters the dopaminergic cell via dopamine transporter (DAT) [5], accu- mulates inside the mitochondria, and interferes with complex I of mitochondrial transport chain, inhibiting its activity [6]. Tis reduces ATP cellular stores, promoting reactive oxygen species (ROS) formation and consequentially leading to neuronal death [5]. Another substance known to promote