Intraperitoneal injection induces prostaglandin-mediated protection from bile acid intestinal mucosal injury in rats in vivo

The production of endogenous prostaglandins by the gastrointestinal mucosa can be induced by many processes. Whether the commonly used technique of intraperitoneal injection alone can also induce significant endogenous prostaglandin-mediated mucosal injury induced in vivo by perfusion for 45 min with 5 mM chenodeoxycholic acid. 10 control rats received 1 ml/kg of normal saline subcutaneously on abdomen tree hours before exposure to chenodeoxycholic acid. Another group of 10 rats received 1 ml/kg of saline intraperitoneally before injury. Mucosal injury was assessed histologically by measuring villus tip epithelial cell denudation by computerized quantitative morphology. Injury was assessed functionally by measuring water and mannitol absorption from the lumen. To examine the role of endogenous prostaglandins in this phenomenon, the above experiment was repeated with 10 and 12 rats respectively by replacing the saline with 10 mg/kg injections of indomethacin. Intraperitoneal injection of saline reduced the average denudation/villus caused by chenodeoxycholic acid: Subcutaneous = 100.8 microns +/- 14.7 (SEM). Intraperitoneal = 65.1 +/- 6.4 (p less than 0.5). Parallel reductions were noted in the increase in water secretion and mannitol absorption caused by chenodeoxycholic acid. All of these differences were reversed by exchanging indomethacin for saline. This study suggests there exists a mechanism by which the simple act of performing an intraperitoneal injection induces endogenous intestinal mucosal protection. That this protection is negated by pretreatment with indomethacin suggests it is prostaglandin mediated.