title: Reactive oxygen species and mitogen-activated protein kinase induce apoptotic death of SH-SY5Y cells in response to fipronil.
abstract: There are multiple lines of evidence showing that environmental toxicants including pesticides may contribute to neuronal cell death. Fipronil (FPN) is a phenylpyrazole insecticide that acts on insect GABA receptors. Although the action of FPN is restricted to insect neuronal or muscular transmitter systems, a few studies have assessed the effects of this neurotoxicant on neuronal cell death distinct from an insect. To determine the mechanisms underlying FPN-induced neuronal cell death, we evaluated the ability of this chemical to induce oxidative stress and studied the involvement of mitogen activated protein kinases (MAPKs) in FPN-induced apoptosis stress in human neuroblastoma SH-SY5Y (SH-SY5Y) cells. Exposure of SH-SY5Y cells to FPN led to the production of reactive oxygen species (ROS) and apoptotic cell death via activation of caspase-9 and caspase-3. Interestingly, the antioxidant, N-acetyl-cysteine (NAC) attenuated apoptotic cell death and ROS production induced by FPN. These results indicated that oxidative stress plays a central role in FPN-induced cytotoxicity. Mitochondrial complex I activity was also inhibited by FPN treatment. These finding indicate that FPN triggers intrinsic apoptosis via the mitochondrial signaling pathway that is initiated by the generation of ROS. Furthermore, FPN treatment induced phosphorylation of MAPK members. Activation of these protein kinases by FPN was involved in the onset of apoptosis as inhibitors specific to these kinases protect against FPN-induced cell death as well as ROS generation. Our data indicate that FPN-induced apoptosis is mediated primarily by the generation of ROS and activation of MAPK members followed by activation of the intrinsic apoptotic pathway.
authors.affiliation: Department of Pharmacology, College of Medicine, Hanyang University, Sungdong-Gu, Heandang-Dong 17, 133-791 Seoul, Republic of Korea.
authors.forename: Yeo-Woon
authors.initials: YW
authors.lastname: Ki
authors.forename: Jeong Eun
authors.initials: JE
authors.lastname: Lee
authors.forename: Jae Hyeon
authors.initials: JH
authors.lastname: Park
authors.forename: In Chul
authors.initials: IC
authors.lastname: Shin
authors.forename: Hyun Chul
authors.initials: HC
authors.lastname: Koh
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D045744:Cell Line, Tumor; D006801:Humans; D007306:Insecticides / Q000494:pharmacology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009447:Neuroblastoma / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D011720:Pyrazoles / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D007306:Insecticides; D011720:Pyrazoles; D017382:Reactive Oxygen Species; D020928:Mitogen-Activated Protein Kinases; D053148:Caspase 3; D053453:Caspase 9; C082360:fipronil; D000111:Acetylcysteine