Alcohol and Alcoholism Advance Access originally published online on March 6, 2007
Alcohol and Alcoholism 2007 42(5):385-399; doi:10.1093/alcalc/agl120
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Effects of chronic ethanol drinking on the blood–brain barrier and ensuing neuronal toxicity in alcohol-preferring rats subjected to intraperitoneal LPS injection
Department of Veterinary Population Medicine, University of Minnesota, Twin Cities Campus, St Paul, MN 55108, USA
* Author to whom correspondence should be addressed at: Department of Population Diagnostic Medicine, College of Veterinary Medicine, 1333 Gortner Av., St Paul, MN 55108, USA; Tel.: 01 612 625 6782; Fax: 01 612 624 8707; E-mail: singh001{at}umn.edu
Received 10 October 2006; in revised form 6 December 2006; accepted 8 December 2006
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Abstract |
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Aims: Although alcohol drinking impairs the blood–brain barrier (BBB), the underlying mechanism is not fully understood. Thus, the effects of chronic ethanol drinking on the BBB were studied in vivo. Methods: Alcohol-preferring rats were given for 70 days free choice water and 15% ethanol. Then, they received LPS by i.p. injection. Efflux of [14C]sucrose or [14C]dextran was measured by their microinjection into the brain. Endothelial cells and neurons were isolated from the brain and analysed for mitogen-activated protein kinase (MAPK) and the tight-junction (TJ) protein phosphorylation, NF
B activation, mRNA levels of TJ proteins, inducible nitric oxide synthase, tumour necrosis factor 
, interleukin-1 ß (IL-1ß), IL-10, CASPASE-8, and DNA damage. Results: LPS transiently increased [14C]sucrose efflux in water drinking, while it caused a lasting increase in [14C]sucrose and [14C]dextran efflux in ethanol-drinking rats. The time-course of changes in the TJ correlated with (i) an increase in extracellular signal-regulated kinase (ERK), p38mapk Jun-N-terminal Kinase (JNK), and TJ protein phosphorylation, (ii) RelA-p50 and p50-p50 activation, and (iii) a decrease in the TJ proteins' mRNA levels in endothelial cells and neurons. Apoptotic cells were detected in water drinking and LPS (WC-LPS) neurons at 24 h after LPS exposure. Neurons from Et-LPS rats did not exhibit apoptosis. Conclusions: LPS injection in WC-LPS rats transiently disrupted the BBB. Lack of JNK activation and CASPASE-8 may be responsible for lack of apoptosis in endothelial cells and vice versa in neurons. Chronic alcohol drinking in ethanol drinking and LPS (Et-LPS) rats augmented and dysregulated the LPS-induced BBB abnormalities but suppressed apoptosis in neurons.