Epidermal Growth Factor Content of Submandibular Glands is Increased in Rats with Experimentally Induced Gastric Lesions

Occurrence and growth-promoting effect suggest that epidermal growth factor (EGF) is involved in the maintenance of the gastrointestinal mucosa. The aim of this study was to ascertain whether rats with gastric lesions, induced by cold-water stress, ethanol, or indomethacin, have altered EGF levels in their gastrointestinal tract compared with controls. For this purpose we established a solid-phase enzyme immunoassay and measured the amount of immunoreactive EGF (IR-EGF) in extracts of the submandibular gland, stomach, duodenum, jejunum, ileum, and colon. In the submandibular glands of control rats the IR-EGF content was 100-400 times higher than in the gastrointestinal tract. In animals with experimentally induced ulcer the IR-EGF content was increased in the submandibular glands (1480 versus 423 ng/g), duodenum (11.4 versus 5.8 ng/g), and colon (4.1 versus 1 ng/g), whereas no change was observed in the stomach and jejunum. When the formation of lesions was prevented by omeprazole (stress) or prostaglandin E2 (ethanol and indomethacin), the IR-EGF increase in submandibular glands and duodenum was abolished. This indicates that mechanisms regulating the synthesis and secretion of submandibular EGF might be of importance in the development of gastric and duodenal ulcers.