Changes in the Nitric Oxide System Contribute to Effect of Procyanidins Extracted from the Lotus Seedpod Ameliorating Memory Impairment in Cognitively Impaired Aged Rats

The major purpose of this study was to determine the effect of procyanidins extracted from the lotus seedpod (LSPC) on the nitric oxide (NO) system in the hippocampus and cerebral cortex in cognitively impaired aged rats. Using the Morris water maze, aged-unimpaired (AU) and aged-impaired (AI) rats were chosen from aged rats. All aged rats exhibited elevated inducible nitric oxide synthase (iNOS) activities and decreased neuronal nitric oxide synthase (nNOS) activities in the both brain regions. The changes were more pronounced in the brain of AI rats, especially in the hippocampus. Furthermore, AI rats greatly lowed the percentage of change of hippocampal nNOS activity in the presence of protein kinase inhibitors or phosphatase inhibitor, which meant that AI animals existed in a hardly modified nNOS dephosphorylated state in hippocampus. LSPC supplementation [50, 100mg/kg of body weight (BW), per os (p.o.)] for 7 weeks significantly decreased iNOS activities and improved hippocampal nNOS phosphorylation status in AI animals. These results suggested that changes in the NO system may involve in the ameliorative effects of LSPC on cognitive deficits in AI animals.