Olive leaves have an antioxidant capacity,and olive leaf extract can protect the blood,spleen and hippocampus in lead-poisoned mice.However,little is known about the effects of olive leaf extract on lead-induced brain injury.This study was designed to determine whether olive leaf extract can inhibit lead-induced brain injury,and whether this effect is associated with antioxidant capacity.First,we established a mouse model of lead poisoning by continuous intragastric administration of lead acetate for 30 days.Two hours after successful model establishment,lead-poisoned mice were given olive leaf extract at doses of 250,500 or 1000 mg/kg daily by intragastric administration for 50 days.Under the transmission electron microscope,olive leaf extract attenuated neuronal and capillary injury and reduced damage to organelles and the matrix around the capillaries in the frontal lobe of the cerebral cortex in the lead-poisoned mice.Olive leaf extract at a dose of 1000 mg/kg had the greatest protective effect.Spectrophotometry showed that olive leaf extract significantly increased the activities of superoxide dismutase,catalase,alkaline phosphatase and acid phosphatase,while it reduced malondialdehyde content,in a dose-dependent manner.Furthermore,immunohistochemical staining revealed that olive leaf extract dose-dependently decreased Bax protein expression in the cerebral cortex of lead-poisoned mice.Our findings indicate that olive leaf extract can inhibit lead-induced brain injury by increasing antioxidant capacity and reducing apoptosis. Olive leaves have an antioxidant capacity, and olive leaf extract can protect the blood, spleen and hippocampus in lead-poisoned mice. Yet, little is known about the effects of olive leaf extract on lead-induced brain injury. This study was designed to determine whether olive leaf extract can inhibit lead-induced brain injury, and whether this effect is associated with an antioxidant capacity. First, we established a mouse model of lead poisoning by continuous intragastric administration of lead acetate for 30 days. Two hours after successful model establishment, lead-poisoned mice were given olive leaf extract at doses of 250,500 or 1000 mg / kg daily by intragastric administration for 50 days. Under the transmission electron microscope, olive leaf extract attenuated neuronal and capillary injury and reduced damage to organelles and the matrix around the capillaries in the frontal lobe of the cerebral cortex in the lead-poisoned mice. Olive leaf extract at a dose of 1000 mg / kg had the greatest proton ective effect.Spectrophotometry showed that olive leaf extract significantly increased the activities of superoxide dismutase, catalase, alkaline phosphatase and acid phosphatase, while it reduced malondialdehyde content, in a dose-dependent manner. Durthermore, immunohistochemical staining revealed that olive leaf extract dose-dependently decreased Bax protein expression in the cerebral cortex of lead-poisoned mice. Our findings indicate that olive leaf extract can inhibit lead-induced brain injury by increasing antioxidant capacity and reducing apoptosis.