α-Lactalbumin suppresses interleukin-6 release after intestinal ischemia/reperfusion via nitric oxide in rats

Abstract

Male Sprague-Dawley rats were underwent superior mesenteric artery occlusion for 45 min followed by reperfusion under urethane anesthesia. Each milk proteins (300 mg/ kg) were injected into the duodenum 1 h before the induction of ischemia. IL-6 release in the blood was measured in course of time. Whey protein isolate (WPI) had the suppressive effect against ischemia/reperfusion-induced IL-6 release, while casein and bovine serum albumin had no effect. Both a-lactal- bumin (aLA) and β-lactoglobulin (bLG), major components contained in WPI, significantly inhibited the increase of IL-6. However, aLA had more potent activity compared with bLG. Positive correlation between serum aLA level and efficacy for Ischmia/reperfusion was observed. N^G-nitro-L-arginine methyl ester, nitric oxide (NO) synthase inhibitor, significantly reversed suppressive effect on IL-6 release by aLA. These findings show that aLA has a marked suppressive effect on pro-inflammatory cytokine release, at least in part, through NO -mediated mechanism.