Arachidonic acid protection of gastric mucosa against alcohol injury: sequential analysis of morphologic and functional changes.

We have shown previously that arachidonic acid (AA) prevents gastric mucosal injury by ethanol (ETOH). The present study was designed to determine the sequence of morphological and functional changes in the gastric mucosa during ETOH-induced injury and AA-promoted protection. Fasted male rats received intragastrically 1 ml of vehicle (PL) or 1 ml of 120 mM AA followed 1 hr later by 2 ml of absolute ETOH. Mucosal changes were assessed at 10, 15, and 30 min and 1, 2, 3, 6, and 15 hr after ETOH: (1) macroscopically, histologically, and by scanning EM; and (2) by determinations of (a) mitotic activity and 3H-thymidine incorporation in vivo, (b) gastric volume, pH, and electrolytes, and (c) gastric PD. Macroscopic necrotic changes were present in PL-but not AA-pretreated animals throughout the 15 hr after ETOH. Histological examination and scanning EM showed desquamation of the surface epithelium at 10 min to 2 hr and deep necrotic lesions throughout the 15 hr after ETOH in PL-pretreated animals. In AA-pretreated rats, deep necrotic lesions did not occur, but desquamation of the surface epithelium was seen during the initial 30 min after ETOH. A continuous layer of the surface epithelium was restored within 3 hr after ETOH in AA group, with resumption of the transport and barrier functions. The main feature of AA protection of gastric mucosa against ETOH injury is preservation of the mucosal proliferative zone.