Signaling Pathways of Bisphenol A–Induced Apoptosis in Hippocampal Neuronal Cells: Role of Calcium-Induced Reactive Oxygen Species, Mitogen-Activated Protein Kinases, and Nuclear Factor–jB Soyoung Lee, 1 Kyoungho Suk, 1 In Kyeom Kim, 1 Il-Sung Jang, 2 Jin-Woo Park, 3 Victor J. Johnson, 4 Taeg Kyu Kwon, 5 Byung-Ju Choi, 2 and Sang-Hyun Kim 1 * 1 CMRI, Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea 2 Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea 3 Department of Periodontology, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea 4 Toxicology and Molecular Biology Branch, Biostatistics Branch, Health Effects Laboratory Division, NIOSH, Morgantown, West Virginia 5 Department of Immunology, School of Medicine, Keimyung University, Daegu, Republic of Korea In the present study, we investigated the neurotoxicity of bisphenol A [BPA; 2,2-bis-(4 hydroxyphenyl) pro- pane] and the underlying mechanisms of action in mouse hippocampal HT-22 cells. BPA, known to be a xenoestrogen, is used in the production of water bot- tles, cans, and teeth suture materials. BPA-treated HT- 22 cells showed lower cell viability than did controls at concentrations of BPA over 100 lM. BPA induced apo- ptotic cell death as indicated by staining with Hoechst 33258, costaining with Annexin V/propidium iodide, and activation of caspase 3. BPA regulated the generation of reactive oxygen species (ROS) by increasing intra- cellular calcium. BPA activated phosphorylation of extracellular signal–regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), and nuclear translocation of nuclear factor (NF)-jB. Pretreatment with specific inhib- itors for calcium, ROS, ERK, and JNK decreased BPA- induced cell death; however, inhibitor for NF-jB increased BPA-induced cell death. The results suggest that calcium, ROS, ERK, and JNK are involved in BPA- induced apoptotic cell death in HT-22 cells. In contrast, an NF-jB cascade was activated for survival signaling after BPA treatment. V V C 2008 Wiley-Liss, Inc. Key words: bisphenol A; apoptosis; reactive oxygen species; nuclear factor-jB; mitogen-activated protein kinase Bisphenol A [BPA; 2,2-bis-(4 hydroxyphenyl) pro- pane], a monomer in polycarbonate plastics and a constit- uent of epoxy, has been used extensively in the food- packaging industry (Staples et al., 1998). Because of an increase in the use of products based on BPA, the possi- bility of environmental contamination by BPA has increased. Recent studies have shown that routes of human exposure to BPA were identified in water, air, and soil environment, and food contamination including can surfaces and plastic containers (Tsai, 2006). BPA released from polycarbonate flasks during autoclaving was also shown to have estrogenic effects (Staples et al., 1998). However, BPA has been reported to have not only estro- genic activity but also several other types of biological toxicity. BPA induces apoptosis in several types of cells, including primary germ and sertoli cells (Hughes et al., 2000; Oka et al., 2003). BPA has potent harmful effects on multipotent neural progenitor cells through altered mitogen-activated protein kinase (MAPK) signaling and reactive oxygen species (ROS) generation (Kim et al., 2007a). However, little is known about the specific mechanisms of BPA’s neurotoxic effects. Contract grant sponsor: Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MOST); Contract grant number: M10646020001-06N4602-00110; Contract grant sponsor: Basic Research Program; Contract grant number: R01-2005-000-10103-0. *Correspondence to: Sang-Hyun Kim, Department of Pharmacology, Kyungpook National University Medical School, 101 Dong-In, Joong-gu, Daegu, 700-422, Republic of Korea. E-mail: shkim72@knu.ac.kr Received 17 December 2007; Revised 26 February 2008; Accepted 29 February 2008 Published online 2 June 2008 in Wiley InterScience (www. interscience.wiley.com). DOI: 10.1002/jnr.21739 Journal of Neuroscience Research 86:2932–2942 (2008) ' 2008 Wiley-Liss, Inc.