New biological function of bovine alpha-lactalbumin: Protective effect against ethanol- and stress-induced gastric mucosal injury in rats

• Published in: Bioscience, biotechnology, and biochemistry Vol. 65; no. 5; pp. 1104 - 1111
• Main Authors: Matsumoto, H. (Morinaga Milk Industry Co. Ltd., Zama, Kanagawa (Japan)), Shimokawa, Y, Ushida, Y, Toida, T, Hayasawa, H
• Format: Journal Article
• Language: English
• Published: Tokyo Japan Society for Bioscience, Biotechnology, and Agrochemistry 01-05-2001; Japan Society for Bioscience Biotechnology and Agrochemistry
• Subjects: ALBUMINS; Animals; Biological and medical sciences; Blotting, Western; BOVINAE; Cattle; endogenous prostaglandins; Ethanol - toxicity; Gastric Mucosa - drug effects; Gastric Mucosa - physiopathology; Gastroenterology. Liver. Pancreas. Abdomen; gastroprotection; Lactalbumin - metabolism; Male; Medical sciences; MILK PROTEIN; MUCOSAL DISEASE; Other diseases. Semiology; PHYSIOLOGICAL FUNCTIONS; PROSTAGLANDINS; Prostaglandins - physiology; PROTECTIVE MATERIALS; RATS; Rats, Wistar; STOMACH ULCER; Stomach Ulcer - chemically induced; Stomach Ulcer - etiology; Stomach Ulcer - prevention & control; Stomach. Duodenum. Small intestine. Colon. Rectum. Anus; STRESS; Stress, Physiological - physiopathology; ulcer; α-lactalbumin; Stomach; Animal model; Prostaglandin; Rat; Rodentia; Biological activity; Stress; Gastritis; Vertebrata; Experimental disease; Milk protein; Mammalia; Lactalbumin; Animal; Digestive diseases; Cow milk; Ulcer; Whey protein; Protection; Gastric disease
• ISSN: 0916-8451; 1347-6947
• DOI: 10.1271/bbb.65.1104

Although several studies have shown that milk protein components have a wide range of biological activities, the potential role of these proteins in the gastrointestinal mucosal defense system is less well elucidated. In this study, we investigated the effect of the major proteins in cow's milk on gastric mucosal injury by using two acute ulcer models in Wistar rats. Gastric mucosal injury was induced by either intragastric 60% ethanol-HCI or water-immersion restraint stress (23 deg C, 7 h). Each test milk protein was orally administered 30 min before the induction of gastric injury. Among the major milk proteins, alpha-lactalbumin (alpha-LA) is demonstrated to have a marked protective effect against ethanol-induced gastric injury, with the same potency as that of the typical antiulcer agent, Selbex. Whey protein isolate (WPI), which contained 25% alpha-LA, also protected against gastric injury, while casein showed no effect. Comparative studies on the protective effect of the four major components of WPI, beta-lactoglobulin, alpha-LA, bovine serum albumin and gamma-globulins (immunoglobulins), on the basis of their contents in WPI revealed that alpha-LA was responsible for the protective effect of WPI, being about 4-fold more effective than WPI itself. alpha-LA showed dosedependent protection against gastric injury induced by stress as well as ethanol. Pretreatment with indomethacin (10 mg/kg body weight, s.c.), which is a potent inhibitor of endogenous prostaglandin synthesis, resulted in a significant reduction in the protective effect of alpha-LA. These results indicate that alpha-LA has marked antiulcer activity as an active component of cow's milk protein, and suggest that alpha-LA intake may serve to protect against gastric mucosal injury, in part through endogenous prostaglandin synthesis.