Reduced adrenomedullin expression in gastric mucosa of portal hypertensive rats after ethanol-induced injury.
OBJECTIVE: To determine the expression and localization of adrenomedullin (AM) and its receptor (AM-R) in portal hypertensive (PHT) gastric mucosa after intragastric ethanol administration. SUMMARY BACKGROUND DATA: The repair of gastric mucosal injury requires reestablishment of the microvascular network. The authors previously demonstrated impaired angiogenesis of PHT gastric mucosa after ethanol-induced injury. Because AM, a potent vasodilatory peptide, is also a novel growth and angiogenic factor, the authors hypothesized that AM is involved in the impaired repair of PHT gastric mucosa and its microvasculature after damage. METHODS: Either PHT or sham-operated rats received intragastrically 100% ethanol, and the stomachs were excised at 1, 6, and 24 hours later. Expression and localization of AM and AM-R mRNA were examined by competitive reverse transcription-polymerase chain reaction and in situ hybridization. AM protein expression was examined by Western blot analysis. RESULTS: One hour after ethanol administration, AM mRNA expression in PHT gastric mucosa was significantly decreased by 81%, especially in the superficial mucosa, compared with the gastric mucosa in sham-operated rats. The significant decrease lasted for 24 hours. AM protein expression was significantly decreased by 43% compared with the sham-operated gastric mucosa. Although AM-R mRNA expression in both groups was significantly increased 1 hour after ethanol administration and lasted for 24 hours compared with baseline, there were no differences between the two groups. CONCLUSIONS: The expression of AM in PHT gastric mucosa after ethanol-induced injury is significantly decreased compared with controls. This finding could explain one mechanism for the impaired angiogenesis after injury of PHT gastric mucosa.