| dc.description.abstract | Arsenic (As) is a natural compound widely distributed in air, water, and soil. Drinking ground water is the major source of As exposure. As exposure causes many health issues, including nausea, vomiting, pain, diarrhea, cancer and neurotoxicity [1]. Alcohol drinks may also contain As because grapes and rice which are used in making wine and beer, take up As from soil, water, and fungicides containing As. Emerged evidence showed that ethanol (EtOH) also impairs neurological functions [2]. However, the combined toxic effects of As and EtOH on the brain is still unclear. Our long-term goal is to understand the effects of As combined with EtOH on the blood brain barrier (BBB). The BBB controls molecule exchange between peripheral and cerebral compartments [3]. Alterations of the BBB are a critical risk factor of pathology and progression of different neurological diseases [4]. Many studies have shown that As as well as EtOH induced BBB abnormalities [5, 6]. Since brain endothelial cells play a crucial role in the BBB, we used Rat Brain Endothelia (RBE4) cells to investigate the combined toxic effects of As and EtOH on the BBB. Overproduction of reactive oxygen species (ROS) results in destruction of cellular structures, lipid, and proteins [7]. Previously, our lab showed that As increased endothelial cell permeability through a ROS-vascular endothelial growth factor pathway in mouse brain vascular endothelial cells (bEnd 3 cells) [8]. Others have shown that EtOH also impairs the barrier function and junctional organization of human brain microvascular endothelial cell monolayer [9]. In neurons, EtOH-induced ROS mainly come from damaged mitochondria [10]. Since mitochondria are major source of ROS generation, we proposed that As-EtOH-combined treatment impairs the BBB through ROS released by damaged mitochondria. Mitochondrial oxidative stress affected microglia-associated neurodegenerative diseases through their role as pro-inflammatory molecules and modulators of pro-inflammatory processes [11]. BBB disruption is mediated by neuroinflammation which is associated with increase in pro-inflammatory cytokines [12]. Research showed that inflammatory mediators control BBB permeability through regulating the structural components [13]. As induced cytotoxicity in brains via regulation of oxidative stress and TNF-a associated inflammatory pathways [14]. Alcohol consumption enhanced oxidative and inflammatory stress, resulting in cognitive deficit [15]. Since microglial cells are the main effectors in the inflammatory process of the central nervous system [16], we used microglial cells (BV2) to investigate the combined effects of As and EtOH on microglia. Our results showed that As and EtOH increased RBE4 cell monolayer permeability. As-EtOH combined treatment increased the permeability more than As or EtOH treatment alone. RBE4 cells and BV2 cells showed an increase in ROS by the combined treatment. Mitochondrial ROS generation was increased by the combined treatment of As and EtOH but reduced by antioxidant Tempol in RBE4 cells and microglia BV2 cells. The combined treatment of As and EtOH decreased mitochondrial bioenergetics (mtBE) in RBE4 cells but increased by antioxidant Tempol. BV2 cells viability decreased as As or EtOH concentration increased and further decreased by the combined treatment. In conclusion, our results suggest that the combined treatment of As and EtOH induced toxicity on both endothelial cells and microglial cells via increased oxidative stress induced by mitochondrial dysfunction. | |
