Regulation of epidermal growth factor receptors in rat gastric mucosa: effect of fasting and sialoadenectomy.

The effect of fasting and sialoadenectomy on the binding of human epidermal growth factor (hEGF), beta-urogastrone, to plasma membranes isolated from rat gastric mucosa was studied to investigate the physiological changes in gastric EGF receptors for developing hEGF as an anti-ulcer drug. The binding of [125I]hEGF to the gastric membranes was significantly decreased after 40 h of fasting. Maximal binding was decreased to 74% of the control value without alteration of the binding affinity (Kd = 0.42 and 0.44 nM for the control and fasting group, respectively). There was little change in the binding of [125I]insulin to the gastric plasma membranes in response to fasting. Removal of the submandibular glands did not decrease EGF binding to the gastric membranes. These results indicate that changes in EGF binding to its receptors occur on plasma membranes of the rat gastric mucosa depending on the nutrient state.