Oleic acid-induced lung injury in rats and effects of caffeic acid phenethyl ester.

Caffeic acid phenethyl ester (CAPE) is a phenolic antioxidant and is an active anti-inflammatory component of honeybee propolis. The authors evaluated the effects of CAPE on oxidative stress and lung damage in an oleic acid (OA)-induced lung-injury model. Rats were divided into 5 groups as sham, OA, CAPE, pre-OA-CAPE, and post-OA-CAPE. Acute lung injury was induced by intravenous administration of 100 mg/kg of OA. Pre-OA-CAPE group received CAPE (10 micromol/kg. intravenously) 15 minutes before OA infusion and post-OA-CAPE group received CAPE 2 hours after OA administration. Malondialdehyde (MDA) level of plasma, bronchoalveolar lavage fluid (BALF), and lung tissue; myeloperoxidase activity of BALF and lung tissue; Na(+)-K(+) ATPase activity of lung tissue; and total protein content of BALF were measured. Light microscopic analyses of lung specimens were performed. The increased MDA levels in lung homogenates (47.98+/-13.75 nmol/mL), BALF (31.12+/-3.07 nmol/mL), and plasma (61.84+/-15.34 nmol/mL) decreased significantly to 24.33+/-3.09 nmol/mL (P = 0.000), 23.19+/-4.97 nmol/mL (P = 0.002), and 27.36+/-5.37 nmol/mL (P = 0.000), respectively, following CAPE administration in pre-OA-CAPE group. Another important finding was the restoration of the enzymatic activity of Na(+)-K(+) ATPase from a value of 203.89+/-32.18 nmol Pi/mg Protein/h in OA group, to a value of 302.17+/-51.90 nmol Pi/mg Protein/h (P = 0.012) in pre-OA-CAPE group with CAPE treatment. CAPE has been shown to have a clear attenuating effect on oxidative damage in experimental animal studies. However, further investigations are necessary to suggest CAPE as a treatment agent in critically ill patients with lung injury.