title: Inhibitory effects of alcohol on glucose transport across the blood-brain barrier leads to neurodegeneration: preventive role of acetyl-L: -carnitine.
abstract: Evidence shows that alcohol intake causes oxidative neuronal injury and neurocognitive deficits that are distinct from the classical Wernicke-Korsakoff neuropathy. Our previous findings indicated that alcohol-elicited blood-brain barrier (BBB) damage leads to neuroinflammation and neuronal loss. The dynamic function of the BBB requires a constant supply and utilization of glucose. Here we examined whether interference of glucose uptake and transport at the endothelium by alcohol leads to BBB dysfunction and neuronal degeneration.
  
  
  
  We tested the hypothesis in cell culture of human brain endothelial cells, neurons and alcohol intake in animal by immunofluorescence, Western blotting and glucose uptake assay methods.
  
  
  
  We found that decrease in glucose uptake correlates the reduction of glucose transporter protein 1 (GLUT1) in cell culture after 50 mM ethanol exposure. Decrease in GLUT1 protein levels was regulated at the translation process. In animal, chronic alcohol intake suppresses the transport of glucose into the frontal and occipital regions of the brain. This finding is validated by a marked decrease in GLUT1 protein expression in brain microvessel (the BBB). In parallel, alcohol intake impairs the BBB tight junction proteins occludin, zonula occludens-1, and claudin-5 in the brain microvessel. Permeability of sodium fluorescein and Evans Blue confirms the leakiness of the BBB. Further, depletion of trans-endothelial electrical resistance of the cell monolayer supports the disruption of BBB integrity. Administration of acetyl-L: -carnitine (a neuroprotective agent) significantly prevents the adverse effects of alcohol on glucose uptake, BBB damage and neuronal degeneration.
  
  
  
  These findings suggest that alcohol-elicited inhibition of glucose transport at the blood-brain interface leads to BBB malfunction and neurological complications.
authors.affiliation: Laboratory of Neurovascular Oxidative Injury, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA.
authors.forename: P M A
authors.initials: PMA
authors.lastname: Muneer
authors.forename: Saleena
authors.initials: S
authors.lastname: Alikunju
authors.forename: Adam M
authors.initials: AM
authors.lastname: Szlachetka
authors.forename: James
authors.initials: J
authors.lastname: Haorah
mesh_terms: D000108:Acetylcarnitine / Q000627:therapeutic use*; D000438:Alcohols / Q000494:pharmacology*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects*; D018916:Blood-Aqueous Barrier / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D004195:Disease Models, Animal; D004347:Drug Interactions; D017097:Electric Impedance; D042783:Endothelial Cells / Q000187:drug effects; D005070:Evans Blue; D005333:Fetus; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D051272:Glucose Transporter Type 1 / Q000378:metabolism; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009433:Neural Inhibition / Q000187:drug effects; D019636:Neurodegenerative Diseases / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control; D016900:Neurofilament Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects; D018697:Nootropic Agents / Q000627:therapeutic use*; D010750:Phosphoproteins / Q000378:metabolism; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D062826:Zonula Occludens-1 Protein; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D000438:Alcohols; D005904:Glial Fibrillary Acidic Protein; D051272:Glucose Transporter Type 1; D008565:Membrane Proteins; D016900:Neurofilament Proteins; D018697:Nootropic Agents; D010750:Phosphoproteins; C495677:SLC2A1 protein, human; C569042:TJP1 protein, human; C569043:Tjp1 protein, mouse; D062826:Zonula Occludens-1 Protein; D014841:von Willebrand Factor; D005070:Evans Blue; D000108:Acetylcarnitine; D014446:Tyrosine 3-Monooxygenase; D002795:Choline O-Acetyltransferase; D005947:Glucose