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Báo cáo khoa học: Expression, localization and potential physiological significance of alcohol dehydrogenase in the gastrointestinal tract

ADH1 and ADH4 are the major alcohol dehydrogenases (ADH) in ethanol and retinol oxidation. ADH activity and protein expression were investigated in rat gastrointestinal tissuehomogenates by enzymatic andWesternblot analyses. In addition, sections of adult rat gastrointestinal tract were examined byin situ hybridization and immunohistochem-istry.ADH1andADH4weredetectedalong thewhole tract, changing their localization and relative content as a function of the area studied. | Eur. J. Biochem. 270 2652-2662 2003 FEBS 2003 doi 10.1046 j.1432-1033.2003.03642.x Expression localization and potential physiological significance of alcohol dehydrogenase in the gastrointestinal tract Julia Vaalenova1 Susana E Martinez1 t.t. Seraio Porte1. Greaa Duester2. Jaume Farres1 IV w B B 4 V 4 w F FF V 4 I F F w FV FF M F F B vl B FF B FF B FF FV B FF F F B F w FF FV FF B IV FF w B B B FF B FF B B FF FV and Xavier Pares1 1 Department of Biochemistry and Molecular Biology Universitat Autonoma de Barcelona Spain 2OncoDevelopmental Biology Program The Burnham Institute La Jolla CA USA ADH1 and ADH4 are the major alcohol dehydrogenases ADH in ethanol and retinol oxidation. ADH activity and protein expression were investigated in rat gastrointestinal tissue homogenates by enzymatic and Western blot analyses. In addition sections of adult rat gastrointestinal tract were examined by in situ hybridization and immunohistochemistry. ADH1 and ADH4 were detected along the whole tract changing their localization and relative content as a function of the area studied. While ADH4 was more abundant in the upper esophagus and stomach and lower colorectal regions ADH1 was predominant in the intestine but also present in stomach. Both enzymes were detected in mucosa but in general ADH4 was found in outer cell layers lining the lumen while ADH1 was detected in the inner cell layers. Of interest were the sharp discontinuities in the expression found in the pyloric region ADH1 and the gastroduodenal junction ADH4 reflecting functional changes. The precise localization of ADH in the gut reveals the cell types where active alcohol oxidation occurs during ethanol ingestion providing a molecular basis for the gastrointestinal alcohol pathology. Localization of ADH acting as retinol dehydro-genase retinal reductase also indicates sites of active retinoid metabolism in the gut essential for mucosa function and vitamin A absorption. Keywords ethanol immunohistochemistry in situ .