Catecholamines appear to be involved in behavioral responses to acute and chronic ethanol consumption. Since tyrosine hydroxylase (TH) is the rate-limiting enzyme for catecholamine biosynthesis and is regulated by second messenger systems known to be modulated by ethanol, we studied ethanol-induced changes in TH gene expression. In the N1E-115 neural cell line, Northern and Western blot analyses showed that treatment with 25-200 mM ethanol for 3 days caused a dose-dependent increase in TH mRNA and protein levels. N1E-115 cells were also stably transfected with pTH5'CAT, a plasmid containing 773 base pairs of the TH promoter fused to a chloramphenicol acetyltransferase (CAT) reporter gene. Subclones expressing pTH5'CAT showed ethanol-induced increases in CAT activity, suggesting that ethanol modulates TH gene transcription. Furthermore, simultaneous treatment of transfected cells with 100 mM ethanol and 1 nM to 1 microM prostaglandin E1 increased prostaglandin E1-mediated stimulation of TH-promoter activity. Similarly, simultaneous treatment of transfected cells with 100 mM ethanol and either 10 mM (-)-N6-(R-phenylisopropyl)adenosine or 0.5 mM 8-bromo-cAMP also resulted in increased TH-promoter activity compared to treatment with these agents without ethanol. These results suggest that ethanol treatment of N1E-115 cells has a prominent effect on both basal and cAMP-regulated TH expression. Ethanol-induced changes in TH expression may be a critical molecular event in adaptation of the central nervous system to ethanol.