Caloric restriction can improve learning and memory in C57/BL mice probably via regulation of the AMPK signaling pathway

Caloric restriction (CR) is effective in slowing aging and delaying aging-related diseases in many species, but the mechanism is complex and not fully elucidated. This study aimed to evaluate the beneficial effects of a caloric restriction diet on learning and memory, and further to elucidate the mechanisms. Thirty-six week-old male C57/BL mice were randomly divided into three groups: normal control (NC group), high-energy (HE group) and CR group. After 44 weeks, the Morris water maze was used to examine learning and memory abilities. Western blotting and immunohistochemistry were used to detect changes in proteins involved in the adenosine monophosphate-activated protein kinase (AMPK) pathway in the mouse hippocampus. Compared with NC group, the swimming distance and escape latency were shorter in the CR group. The protein and mRNA expression of AMPK and glucose transporter type 4 (GLUT4) in the CR group were significantly higher than that in HE group. CR increased serum insulin-like growth factor, adiponectin and vaspin, decreased blood glucose and serum malondialdehyde, and improved insulin sensitivity. Our findings demonstrate that a CR diet may improve hippocampus-dependent spatial learning ability of C57/BL mice, accompanied with an increase in AMPK and GLUT4 expression, which indicates AMPK pathway was associated with the neuroprotective effect of CR in mice.