EFFECT OF ACUTE ETHANOL TREATMENT ON EPIDERMAL GROWTH-FACTOR RECEPTOR IN THE RAT STOMACH

The present study investigated the effect of acute ethanol (ETOH) treatment on the epidermal growth factor (EGF) receptor in rat gastric mucosa using two different experimental models. In the in vitro experiments, gastric mucosal cells were incubated with 0, 0.05, 0.1, 0.25, and 0.5% ethanol in Dulbecco's modified Eagle's medium (DMEM) for 30 min and then used for the membrane preparation. The EGF receptor binding assay indicated that cells incubated in the presence of ethanol displayed a concentration-dependent increase (r = 0.85) in the I-125-EGF binding. The Western blot analysis using anti-EGF-receptor antibody revealed that ethanol in vitro caused reduction in the immunoreactivity of the major 170-kDa protein. There were also alterations in the minor protein bands(140, 120, and 50 kDa). In the in vivo experiments, rats that fasted overnight were given 1.0 mi of saline or ethanol (5, 10, or 15%) by gastric intubation 30 min before sacrifice. In comparison with the saline controls, ethanol treatment caused a decrease of the EGF receptor binding to the gastric mucosal membrane (saline: 5%:10%:15% ETOH, 1.46 +/- 0.18:1.13 +/- 0.17:1.27 +/- 0.19:0.84 +/- 0.14, p < 0.02; mean a SEM, n = 9). Furthermore, the immunoblot analysis revealed concentration-dependent decrease in the intensity of the major 170-kDa protein with ethanol. The reduction in the EGF receptor binding and the impairment of the receptor protein might be due to the nonspecific damage of the gastric mucosal membrane by ethanol.