Olive leaf extract modulates cold restraint stress-induced oxidative changes in rat liver

Recently, the beneficial effects of different single doses of standardized dry olive (Olea europaea L.) leaf extract (OLE) in cold restraint stress (CRS)-induced gastric lesions in rats and its influence on oxidative parameters in gastric mucosa were demonstrated. The present study was undertaken to investigate the long-term pretreatment efficacy of OLE and its potential in the modulation of CRSinduced oxidative changes at the liver level. The experimental animals were divided into four groups, i.e., control, OLE-treated, CRS non-treated and CRS treated with OLE (CRS+OLE) groups. CRS caused severe gastric lesions in all non-pretreated animals and two-week pretreatment with OLE (80 mg per kg of body weight) attenuated stress-induced gastric lesions significantly. The malondialdehyde (MDA) level as an index of lipid peroxidation, superoxide dismutase (SOD) and catalase (CAT) activities were measured spectrophotometrically in liver tissue homogenates. The MDA level was increased in the CRS group and significantly decreased in the CRS+OLE group. The SOD and CAT activities were significantly decreased in the CRS group. In the CRS+OLE group, the activities of these two enzymes were significantly increased in comparison with the CRS group. The results obtained indicate that long-term supplementation with OLE provides oxidant/antioxidant balance in liver during stress condition.