Exploring the Complementary Influence of an Oleuropein-Enriched Phytochemical Extract on Neuro-biochemistry, Behavior, and Histopathology in Aging and Depressed Male Rats

Aging correlates with neurodegenerative diseases such as depression, marked by neuro-biochemical changes triggering neuronal loss. Nutraceuticals exhibit antioxidant and neuroprotective properties and offer potential intervention. Our study examines the preventive effects of an olive leaf extract consisting of 20% pure oleuropein in an animal model of aging and depression. Aging in Wistar rats was induced by intraperitoneal injections of 150 mg of D-galactose/kg body weight for 6 weeks. The depression was caused by forced swimming. We examined Monoamine oxidase and acetylcholinesterase activities, histopathology of the brain, and the serum plasminogen activator inhibitor-1, superoxide dismutase, and monoaldehyde levels of all animal groups. Depressed and aged rats showed increased Monoamine oxidase, acetylcholinesterase, and plasminogen activator inhibitor-1 levels, and a decrease in superoxide dismutase levels. The administration of 200 mg of extract before depression or aging inductions significantly reduced the Monoamine oxidase and acetylcholinesterase activities. Degeneration/necrosis was observed in neurons of all experimental animal groups. We demonstrate that the olive leaf extract with 20% pure oleuropein markedly maintained the neurotransmitter levels in the brain and enhanced the antioxidant defense system in depressed and aged animal models but was unable to yield behavioral benefits.