Alcohol-induced c-Fos expression in the Edinger-Westphal nucleus: pharmacological and signal transduction mechanisms.
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.
Department of Behavioral Neuroscience, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97201, USA.
Ryan K
RK
Bachtell
Natalia O
NO
Tsivkovskaia
Andrey E
AE
Ryabinin
D000607:Aminoacetonitrile / Q000031:analogs & derivatives; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D002707:Chlordiazepoxide / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism; D000431:Ethanol / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D016762:Genes, fos / Q000187:drug effects*; D006220:Haloperidol / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009020:Morphine / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism; D011280:Pregnanolone / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D015016:Yohimbine / Q000494:pharmacology
D011480:Protease Inhibitors; C424127:SL 327; D015016:Yohimbine; D000607:Aminoacetonitrile; D000431:Ethanol; D002707:Chlordiazepoxide; D009020:Morphine; D011280:Pregnanolone; D014446:Tyrosine 3-Monooxygenase; D006220:Haloperidol; D004298:Dopamine; D009638:Norepinephrine