Alcohol-induced c-Fos expression in the Edinger-Westphal nucleus: pharmacological and signal transduction mechanisms

J Pharmacol Exp Ther. 2002 Aug;302(2):516-24. doi: 10.1124/jpet.102.036046.

Abstract

Mapping inducible transcription factors has shown that the Edinger-Westphal nucleus is preferentially sensitive to alcohol intoxication. Herein, we characterize the pharmacological and signal transduction mechanisms related to alcohol-induced c-Fos expression in Edinger-Westphal neurons. Using immunohistochemistry, we show that pretreatment with gamma-aminobutyric acid (GABA)-ergic antagonists (4 mg/kg bicuculline and 45 mg/kg pentylenetetrazole) attenuates induction of c-Fos expression by alcohol (2.4 g/kg, intraperitoneal). In addition, 10 mg/kg 2-(2,3-dihydro-2-methoxy-1,4-benzodioxin-2-yl)4,5-dihydro-1H-imidazole (RX 821002), an alpha(2A/D)-adrenoceptor antagonist, and 20 mg/kg haloperidol, a dopamine antagonist, also block alcohol-induced c-Fos expression in Edinger-Westphal neurons. No effects were seen in alcohol-induced c-Fos after the pretreatment of 20 mg/kg propranolol (beta-adrenoceptor antagonist), 10 mg/kg 2-(2-(4-(2-methoxyphenyl)piperazin-1-yl) ethy)-4,4-dimethyl-1,3-(2H,4H)-isoquinolindione dihydrochloride (ARC 239) (alpha(2B/C)-adrenoceptor antagonist), or 30 mg/kg naltrexone (opioid antagonist). Although positive modulators for the GABA(A) receptor (20 mg/kg 3alpha-hydroxy-5alpha-pregnan-20-one and 10-30 mg/kg chlordiazepoxide) and opioid receptor (10 mg/kg morphine) produced significant elevations, agonists for alpha(2)-adrenoceptors (clonidine) and dopamine receptors (apomorphine) had no effect on Edinger-Westphal c-Fos expression. These findings suggest that alcohol-induced c-Fos expression in Edinger-Westphal results from direct interactions with GABA(A) receptors, which are modified by alpha(2A/D)-adrenoceptors and dopamine receptors. Also using immunohistochemistry to identify potential intracellular mechanisms associated with alcohol-induced c-Fos expression in Edinger-Westphal, we show time-dependent increases in serine 727 phospho-signal transducer and activator of transcription 3 (Stat3) but no changes in phospho-cAMP response element-binding protein and phospho-Elk1. Time-dependent increases in phospho-extracellular signal-regulated kinase (ERK) 1/2 were found to occur simultaneously with increases in serine 727 phospho-Stat3. Finally, blockade of ERK 1/2 phosphorylation with the mitogen-activated protein kinase (MEK) 1/2 inhibitor SL327 blocked alcohol-induced c-Fos expression, suggesting that alcohol induces c-Fos in Edinger-Westphal neurons through activation of the MEK1/2-ERK1/2-Stat3 pathway.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aminoacetonitrile / analogs & derivatives
  • Animals
  • Brain / drug effects
  • Brain / physiology*
  • Chlordiazepoxide / pharmacology
  • Dopamine / metabolism
  • Ethanol / pharmacology*
  • Gene Expression Regulation / drug effects*
  • Genes, fos / drug effects*
  • Haloperidol / pharmacology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Morphine / pharmacology
  • Norepinephrine / metabolism
  • Pregnanolone / pharmacology
  • Protease Inhibitors / pharmacology
  • Signal Transduction / drug effects
  • Tyrosine 3-Monooxygenase / metabolism
  • Yohimbine / pharmacology

Substances

  • Protease Inhibitors
  • SL 327
  • Yohimbine
  • Aminoacetonitrile
  • Ethanol
  • Chlordiazepoxide
  • Morphine
  • Pregnanolone
  • Tyrosine 3-Monooxygenase
  • Haloperidol
  • Dopamine
  • Norepinephrine