γ-Tocopherol, but not α-tocopherol, decreases proinflammatory eicosanoids and inflammation damage in rats

gamma-Tocopherol (gammaT), the major form of vitamin E in U.S. diets, and its physiological metabolite 2, 7, 8-trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman (gamma-CEHC), in contrast to alpha-tocopherol (alphaT), the primary vitamin E in supplements, inhibit cyclooxygenase-catalyzed synthesis of prostaglandin E-2 (PGE(2)) in activated macrophages and epithelial cells. Here we report that in carrageenan-induced inflammation in male Wistar rats, administration of gammaT (33 or 100 mg/kg) and gamma-CEHC (2 mg/pouch), but not alphaT (33 mg/kg), significantly reduced PGE(2) synthesis at the site of inflammation. gammaT, but not alphaT, significantly inhibited the formation of leukotriene B-4, a potent chemotactic agent synthesized by the 5-lipoxygenase of neutrophils. Although gammaT had no effect on neutrophil infiltration, it significantly attenuated the partial loss of food consumption caused by inflammation-associated discomfort. Administration of gammaT led consistently to a significant reduction of inflammation-mediated increase in 8-isoprostane, a biomarker of lipid peroxidation. gammaT at 100 mg/kg reduced TNF-alpha (65%; P=0.069), total nitrate/nitrite (40%; P=0.1), and lactate dehydrogenase activity (30%; P=0.067). Collectively, gammaT inhibits proinflammatory PGE(2) and LTB4, decreases TNF-alpha, and attenuates inflammation-mediated damage. These findings provide strong evidence that gammaT shows anti-inflammatory activities in vivo that may be important for human disease prevention and therapy.