Protection by intragastric polyethylene glycol 400 in rat stomach against ethanol damage involves alpha2-adrenoceptors.
The aim of this study was to investigate the role of alpha2-adrenoceptors in the mechanism of intragastric polyethylene glycol 400 (PEG-400) protection against ethanol-induced gastric mucosal damage. In the injury study, 0.5 hr after subcutaneous control or yohimbine (5 mg/kg), a selective alpha2-adrenoceptor antagonist, rats were treated with intragastric vehicle or PEG-400 (5500 mg/kg). One hour later animals received 96% ethanol (gavage needle), 5 ml/kg, and the rats were killed after another hour. Total lengths of the gastric mucosal lesions were measured by an unbiased observer in a blinded fashion using a binocular magnifier having 5x magnification. In a separate set of experiments, 0.5 hr after subcutaneous control or yohimbine (5 mg/kg) rats received intragastric vehicle or PEG-400 (5500 mg/kg). One hour later gastric mucus volume, gastric juice volume, and gastric acid output in the gastric juice were measured. The protective effect offered by intragastric PEG-400 against ethanol-induced gastric mucosal damage was significantly diminished although not completely abolished by a selective alpha2-adrenoceptor antagonist (yohimbine). Yohimbine also significantly diminished both the basal and PEG-400-stimulated increase in gastric mucus volume. These findings suggest that the protective effect afforded by intragastric PEG-400 against ethanol-induced gastric mucosal damage is partially mediated by alpha2-adrenoceptors, and a mucus-dependent mechanism may be involved.
Gutiérrez-Cabano
C A
CA
Department of Surgical Pathology II, Faculty of Medical Sciences, National University of Rosario, Argentina.
D058669:Adrenergic alpha-2 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D000431:Ethanol / Q000633:toxicity*; D005260:Female; D005744:Gastric Acid / Q000378:metabolism; D005750:Gastric Juice / Q000378:metabolism; D005753:Gastric Mucosa / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D009093:Mucus / Q000378:metabolism; D011092:Polyethylene Glycols / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D018341:Receptors, Adrenergic, alpha-2 / Q000502:physiology; D013501:Surface-Active Agents / Q000008:administration & dosage / Q000494:pharmacology*; D015016:Yohimbine / Q000494:pharmacology*
D058669:Adrenergic alpha-2 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists; D018341:Receptors, Adrenergic, alpha-2; D013501:Surface-Active Agents; D015016:Yohimbine; D000431:Ethanol; D011092:Polyethylene Glycols