Walnut diets up-regulate the decreased hippocampal neurogenesis and age-related cognitive dysfunction in d-galactose induced aged rats.

Recently, dietary intervention has been considered as a prospective strategy in delaying age-related cognitive dysfunction and brain plasticity degeneration. This study explored the effect of walnut diets (6% and 9%, 8 weeks) on cognitive behavior, hippocampal neurogenesis and the neurotrophic signaling pathway in d-galactose (d-gal) model rats. Behavioral tests showed that walnut diets significantly reversed spatial memory loss in the Morris water test, locomotor activity deficiency in an open field test, and a recognition behavior reduction in a novel object recognition task. Immunohistochemistry analysis demonstrated walnut diets significantly increased the hippocampal neurogenesis in d-gal model rats. Moreover, western blot results indicated that walnut diets reserved a d-gal induced decrease of hippocampal pCREB (Ser133) and BDNF expression, two crucial intracellular molecules involved in hippocampal neurogenesis. These findings confirmed that chronic walnut-rich diets could ameliorate cognitive dysfunction in d-gal model rats, and the up-regulation of neurogenesis, as well as the expression of pCREB and BDNF in hippocampus, may be one of the molecular and cellular mechanisms underlying these effects.