Effects of Pycnogenol and vitamin E on cognitive deficits and oxidative damage induced by intracerebroventricular streptozotocin in rats

Oxidative stress plays a crucial role in the progression of cognitive decline in Alzheimer's disease (AD). Considerable attention has been focused on increasing the internal antioxidant defenses in response to AD. This study was designed to examine and compare the pretreatment effects of Pycnogenol (PYC) and vitamin E (Vit E) on cognitive deficits and oxidative damage in the hippocampus and cerebral cortex of intracerebroventricular streptozotocin (ICV-STZ)-infused rats. Rats pretreated with PYC (10 mg/kg), Vit E (100 mg/kg), and vehicle (intraperitoneal; once daily for 3 weeks) were bilaterally injected with ICV-STZ (3 mg/kg), whereas sham rats received the same volume of vehicle. After 2 weeks of ICV-STZ infusion, rats were tested for cognitive performance using passive avoidance and water maze tasks, and then killed for biochemical assays. ICV-STZ induced significant declines in cognitive performance and choline acetyltransferase activity in the hippocampus, which were significantly attenuated with PYC and Vit E. Pretreatment with PYC and Vit E produced a significantly enhanced glutathione level and Na/K-ATPase activity and decreased thiobarbituric acid reactive substances and protein carbonyl. These findings suggest that PYC and Vit E may provide a promising approach for the treatment of oxidative stress-related neurodegeneration in conditions such as AD.