Cadmium induces apoptotic cell death through p38 MAPK in brain microvessel endothelial cells Yi-Sook Jung a,b,1 , Euy-Myoung Jeong a,1 , Eun Kyung Park a , You-Mie Kim a,c , Seonghyang Sohn d , Soo Hwan Lee a,c , Eun Joo Baik a,c , Chang-Hyun Moon a,c, ⁎ a Department of Physiology, School of Medicine, Ajou University, Suwon 443-749, Republic of Korea b BK21 for Molecular Science and Technology, Ajou University, Suwon 443-749, Republic of Korea c BK21 Graduate Program for Medical Science, Ajou University, Suwon 443-749, Republic of Korea d Laboratory of Cell Biology, Ajou University Institute for Medical Science, Suwon 443-749, Republic of Korea Received 3 July 2007; received in revised form 23 August 2007; accepted 30 August 2007 Available online 20 September 2007 Abstract Cadmium (Cd), an ubiquitous heavy metal, is known to be accumulated outside of the blood–brain barrier. In this study, we investigated whether Cd has cytotoxicity in mouse brain microvascular endothelial cells (bEnd.3). Results from the cell viability assay showed that Cd caused a remarkable decrease in cell viability in a dose-dependent manner. The cell death induced by Cd appeared to involve apoptosis, based on our results from annexin V staining, electron microscopy and TUNEL staining. And the cell death induced by Cd was inhibited by caspase inhibitor ZVAD- fmk. To further investigate the mechanism of the Cd-induced cell death, we examined the effects of selective inhibitors for mitogen activated protein kinase (MAPK) pathways on the cell death. The Cd-induced cell death was significantly inhibited by p38 MAPK inhibitor SB202190, but not by either, c-Jun N-terminal kinase (JNK) inhibitor SP600125 or extracellular signal-regulated kinase (ERK) inhibitor U0126. Phosphorylations of p38 MAPK, JNK and ERK were stimulated by treatment with CdCl 2 . In summary, our results suggest that Cd can induce apoptotic cell death, at least in part, through the p38 MAPK pathway in brain microvascular endothelial cells. © 2007 Elsevier B.V. All rights reserved. Keywords: Cadmium; Brain microvascular endothelial cells; Apoptosis; p38 MAPK 1. Introduction The cerebrovascular endothelial cells, the cellular compo- nent of the blood–brain barrier, play an essential role in forming a barrier which limits access of potentially harmful blood-borne substances to the brain under physiological conditions (Rubin and Staddon, 1999; Demeuse et al., 2002). Nevertheless, in pathological situations such as stroke and multiple sclerosis, a disruption in blood–brain barrier integrity occurs, resulting in permeability increase, edema, and thereby exacerbation of brain damage (Petty and Lo, 2002). Mechanisms by which the disruption of blood–brain barrier occurs have been demon- strated to involve abnormal changes of the junctional complexes of the cerebrovascular endothelium (Krizbai et al., 2005; Fischer et al., 2005), and transmigrations of leukocytes across the cerebrovascular endothelium mediated through adhesion molecules such as integrin and intercellular adhesion molecule- 1 (ICAM-1) (Bolton et al., 1998; Bolton and Perry, 1998). Furthermore, a recent report suggested that apoptotic death of the cerebrovascular endothelial cells may be also an important cause of the disruption of the blood–brain barrier integrity (Zhang et al., 2000). Heavy metals, including lead and manganese, are well known to cause neurotoxicity (Bressler et al., 1999; Mergler et al., 1999). Cadmium (Cd), a highly ubiquitous heavy metal, has also been demonstrated to induce brain edema and hemorrhage, and blood–brain barrier disruption (Webster and Valois, 1981; Shukla et al., 1996). In support of these Cd-induced brain Available online at www.sciencedirect.com European Journal of Pharmacology 578 (2008) 11 – 18 www.elsevier.com/locate/ejphar ⁎ Corresponding author. Department of Physiology, School of Medicine, Ajou University, Suwon 443-749, Republic of Korea. Tel.: +82 31 219 5041; fax: +82 31 219 5049. E-mail address: yisjung@hanmail.net (C.-H. Moon). 1 These authors contributed equally. 0014-2999/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.ejphar.2007.08.049