title: Structural constraints for alcohol-stimulated Ca2+ release in neural crest, and dual agonist/antagonist properties of n-octanol.
abstract: BACKGROUND
  Prenatal ethanol exposure is a leading cause of mental retardation. Alcohol damages susceptible neuronal populations through its alteration of signaling pathways that direct cellular activity and survival. In early neural crest cells, ethanol elicits an intracellular Ca2+ transient that is necessary and sufficient to cause apoptosis. We tested the hypothesis that ethanol's activity represents a saturable and selective effect of alcohols upon this pathway.
  
  
  METHODS
  Fura-2-loaded chick embryos, at the 3-somite stage, were exposed to n-alcohols ranging in size from ethanol (C2) to decanol (C10). Thereafter, Ca2+ mobilization was measured using Fura-2 and ratiometric imaging. Apoptosis was assessed using acridine orange uptake.
  
  
  RESULTS
  Ethanol caused the dose-dependent mobilization of intracellular Ca2+ within neural crest populations, with an EC50 of 52.0 mM. n-Alcohols displayed increasing potency for Ca2+ mobilization through pentanol. Hexanol and heptanol were inactive. Unexpectedly, micromolar n-octanol concentrations triggered significant Ca2+ release and apoptosis in a G-protein-dependent manner. Decanol was inactive. Coaddition of either octanol or decanol antagonized the ability of ethanol to stimulate Ca2+ release.
  
  
  CONCLUSIONS
  The selective, saturable effect of n-alcohols upon Ca2+ mobilization in neural crest is consistent with a hypothesis that ethanol stimulates these signals through specific interaction with one or more alcohol-binding sites on a target protein. Octanol may overcome structural constraints imposed upon C6 and C7 in interacting with this protein target; alternatively, it may interact through a unique binding site.
authors.affiliation: Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Ana
authors.initials: A
authors.lastname: Garic-Stankovic
authors.forename: Marcos
authors.initials: M
authors.lastname: Hernandez
authors.forename: George R
authors.initials: GR
authors.lastname: Flentke
authors.forename: Susan M
authors.initials: SM
authors.lastname: Smith
mesh_terms: D020003:1-Octanol / Q000494:pharmacology*; D000438:Alcohols / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D002417:Cattle; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D000431:Ethanol / Q000494:pharmacology*; D005456:Fluorescent Dyes; D016257:Fura-2; D009432:Neural Crest / Q000187:drug effects / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000187:drug effects; D013268:Stimulation, Chemical; D013329:Structure-Activity Relationship
chemical_list: D000438:Alcohols; D002492:Central Nervous System Depressants; D005456:Fluorescent Dyes; D043562:Receptors, G-Protein-Coupled; D000431:Ethanol; D020003:1-Octanol; D002118:Calcium; D016257:Fura-2