Milk protection against experimental ulcerogenesis in rats.

The antiulcer activity in pasteurized/homogenized bovine milk and a lipid extract of this milk was tested in an attempt to isolate and identify the active component. Using 0.6 N HCl as a damaging agent in pylorus-ligated rats, the protective property of milk appeared to be related to its phospholipid content and not its protein constituents. With intact (non-pylorus-ligated) rats, milk had demonstrable protective activity against 0.6 N HCl, as well as 100% ethanol and 160 mM taurocholic acid. The increasing phospholipid concentrations in skim, whole, and buttermilk paralleled their antiulcer efficacy. A lipid extract of whole milk showed significant protection against 0.6 N HCl when given alone or following indomethacin treatment. Measurements of the contact angle (hydrophobicity) of the gastric surface showed that it was maintained near control levels in the presence of 0.6 N HCl, if rats were first pretreated with milk. These results are consistent with the possibility that surface-active lipids in dairy milk, such as phospholipids, may account for a significant portion of milk's antiulcer activity by maintaining the hydrophobicity of the luminal surface of the gastric mucosa in the presence of a damaging agent.