GASTRIC ANTIGEN CHALLENGE RELEASES GASTRIN AND EICOSANOIDS AND PROTECTS AGAINST ETHANOL

Various gastrointestinal functions such as mucosal blood flow and mucu s secretion can be influenced immunologically. Rats were systemically sensitized with 4-hydroxy-3-iodo-5-nitro-phenylacetic acid (NIP), a sy nthetic antigen, Mucosal release of gastrin, prostaglandin F-2 alpha, 6-keto-prostaglandin F-1 alpha, and leukotriene C-4 was measured after intragastric or in vitro antigen challenge, Gastric protection from e thanol was determined. In sensitized rats, intragastric antigen challe nge increased release of gastrin from the antral mucosa ex vivo and te nded to increase release of prostaglandin F-2 alpha. Likewise, antral mucosa of sensitized rats released significantly more gastrin and pros taglandin F-2 alpha during in vitro antigen challenge than during incu bation in the absence of antigen. Release of 6-keto-prostaglandin F-1 alpha and leukotriene C-4 was not affected by the immunologic reaction , Topical antigen challenge in sensitized rats reduced gastric mucosal damage caused by ethanol by 50%. The immunologically induced gastropr otection was significantly attenuated by pretreatment with indomethaci n, The findings show that specific antigen challenge renders the gastr ic mucosa more resistant against the injurious effect of ethanol indic ating that the stomach is a target organ of immunological reactions, A s gastrin and prostaglandins exert potent protective effects, release of these mediators may contribute to the protective response to gastri c mucosal immune activation. (C) 1997 Academic Press.