Elevation of Nitric Oxide Synthase Activity by Dimethyladenosine from Silkworm Pupae in Aged Rats

This study examined the mechanisms underlying the effects of the vasorelaxation active substance (VAS), dimethyladenosine-5'-L-arabinose, and its partial purification fraction on nitric oxide synthase in improving erectile dysfunction with particular focus on the nitric oxide (NO)-cGMP pathways. Two rat models, 9-month-old SD rats and 11-month-old SD rats, were given VAS (40 mg/kg per day) for 4 days, The aqueous fraction of silworm male pupae extract; semi-purified VAS (100 mg/kg per day) for 10 days, respectively. The NOS activities of the following three enzymes were examined: neuronal NO synthase (nNOS), inducible NOS (iNOS), endothelial NOS (eNOS), vascular endothelial growth factor on endothelial cells (VEGF) and anti-inflammation effect of Tumor necrosis factor-α. The results showed increases in the nitric oxide synthase activities. Western blotting of the tissue homogenate showed an increase in the nNOS level in the brain and tongue, and an increase in the endothelial NO synthase (eNOS) level in penis. However, there was little association with VEGF production in HUVEC endothelial cells and no relationship with TNF-α which showed low levels.