Effect of Yam (Dioscorea batata)-Containing Diet on Memory Deterioration and Brain NOS Expression in Senescence-Accelerated Mice (SAM)

摘要

This study was undertaken to evaluate the effect of yam {Dioscorea batatd)-containing diets on memory deterioration, and neuronal and endothelial nitric oxide synthase (nNOS, eNOS) protein expression in brain in senescence-accelerated mice (SAMP8). The ohe-month-old SAMP8 fed commercial diet containing 0, 1.67 and .5% of yam powder for 10 months, respectively. Age-matched control (SAMR1) fed the commercial diet, Memory retention was estimated with passive avoidance (step-through) test. The TBARS in brain and plasma, and expressions of nNOS and eNOS proteins in the brain were examined. In the step-through test, the passive avoidance time in the untreated SAMP8 was significantly shorter than that in SAMR1. In contrast, the avoidance time in the 5% yam-treated SAMP8 was longer than that of the untreated SAMP8. Plasma TBARS levels in the yam-treated SAMP8 showed a tendency to decrease compared with that in the untreated SAMP8. In immunoblotting, there was no significant difference in the levels of nNOS protein expression in any groups. On the other hand, the level of eNOS protein in the 5% yam-treated SAMP8 was significantly higher than that in the untreated SAMP8. These results suggested that yam, at least in part, play a role in stimulating blood stream in brain via recovered eNOS protein expression, and that might lead to alleviate memory deterioration.