title: Opposing actions of ethanol and nicotine on microRNAs are mediated by nicotinic acetylcholine receptors in fetal cerebral cortical-derived neural progenitor cells.
abstract: BACKGROUND
  Ethanol (EtOH) and nicotine are often co-abused. However, their combined effects on fetal neural development, particularly on fetal neural stem cells (NSCs), which generate most neurons of the adult brain during the second trimester of pregnancy, are poorly understood. We previously showed that EtOH influenced NSC maturation in part, by suppressing the expression of specific microRNAs (miRNAs). Here, we tested in fetal NSCs the extent to which EtOH and nicotine coregulated known EtOH-sensitive (miR-9, miR-21, miR-153, and miR-335), a nicotine-sensitive miRNA (miR-140-3p), and mRNAs for nicotinic acetylcholine receptor (nAChR) subunits. Additionally, we tested the extent to which these effects were nAChR dependent.
  
  
  METHODS
  Gestational day 12.5 mouse fetal murine cerebral cortical-derived neurosphere cultures were exposed to EtOH, nicotine, and mecamylamine, a noncompetitive nAChR antagonist, individually or in combination, for short (24 hour) and long (5 day) periods, to mimic exposure during the in vivo period of neurogenesis. Levels of miRNAs, miRNA-regulated transcripts, and nAChR subunit mRNAs were assessed by quantitative reverse transcription polymerase chain reaction.
  
  
  RESULTS
  EtOH suppressed the expression of known EtOH-sensitive miRNAs and miR-140-3p, while nicotine at concentrations attained by cigarette smokers induced a dose-related increase in these miRNAs. Nicotine's effect was blocked by EtOH and by mecamylamine. Finally, EtOH decreased the expression of nAChR subunit mRNAs and, like mecamylamine, prevented the nicotine-associated increase in α4 and β2 nAChR transcripts.
  
  
  CONCLUSIONS
  EtOH and nicotine exert mutually antagonistic, nAChR-mediated effects on teratogen-sensitive miRNAs in fetal NSCs. These data suggest that concurrent exposure to EtOH and nicotine disrupts miRNA regulatory networks that are important for NSC maturation.
authors.affiliation: Department of Neuroscience and Experimental Therapeutics , College of Medicine, Texas A&M Health Science Centre, Bryan, TX 77807-3260, USA.
authors.forename: Sridevi
authors.initials: S
authors.lastname: Balaraman
authors.forename: Ursula H
authors.initials: UH
authors.lastname: Winzer-Serhan
authors.forename: Rajesh C
authors.initials: RC
authors.lastname: Miranda
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000494:pharmacology*; D005260:Female; D053686:Fetal Stem Cells / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000502:physiology*; D058953:Neural Stem Cells / Q000187:drug effects / Q000502:physiology*; D009538:Nicotine / Q000494:pharmacology*; D011247:Pregnancy; D011978:Receptors, Nicotinic / Q000502:physiology*
chemical_list: D035683:MicroRNAs; D011978:Receptors, Nicotinic; D000431:Ethanol; D009538:Nicotine