Prostaglandins in commercial milk preparations. Their effect in the prevention of stress-induced gastric ulcer

To determine if prostaglandins might be the gastroduodenal mucosal protective components in milk, concentrations of prostaglandin E2 (PGE2), thromboxane B2, and 6-keto-PGF(1α) (the major metabolite of prostacyclin) were measured in aliquots of commercial milk. Whole milk, heavy cream, and yogurt each contained more than 3 ng/mL of PGE2, whereas low-fat milk (2.04 ± 0.18 ng/mL) and milk from three nursing mothers (0.66 ± 0.05 ng/mL) contained substantially less. Levels of thromboxane and prostacyclin were much lower, in general, less than 500 pg/mL. In a cold-restraint stress ulcer model in rats, milk was able to inhibit the development of gastric ulcers (50% and ulcer index 5.0 ± 2.1 v control, 90% and 18.9 ± 3.8, respectively). Charcoal treatment, which depleted more than 95% of the prostaglandins, rendered the milk non-protective (80% and ulcer index 15.0 ± 1.4). These observations are consistent with the concept that prostaglandins may be responsible for the presumed beneficial effects of milk in the prevention and treatment of peptic ulcer disease.