The combined effect of sleep deprivation and Western diet on spatial learning and memory: role of BDNF and oxidative stress.

Either sleep deprivation or Western diet can impair learning and memory via induction of oxidative stress, which results in neuronal damage and interference with the neurotransmission. In this study, we examined the combined effect of sleep deprivation and Western diet on hippocampus-dependent spatial learning and memory. In addition, possible molecular targets for sleep deprivation and Western diet-induced cognitive impairments were investigated. Sleep deprivation was induced in rats using the modified multiple platform model simultaneous with the administration of Western diet for 6 weeks. Thereafter, spatial learning and memory were tested using radial arm water maze. At the molecular level, BDNF protein and antioxidant markers including superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione (GSH), oxidized glutathione (GSSG), GSH/GSSG, and thiobarbituric acid reactive substances (TBARS) were assessed. The results of this study revealed that sleep deprivation, Western diet, or a combination of both impair short- and long-term memory (P < 0.05). The magnitude of the impairment induced by the combined treatment at the 24-h long-term memory was higher than that caused by each factor alone (P < 0.05). In addition, the combined treatment reduced the levels of hippocampal BDNF, a reduction that was not detected with each factor alone. Moreover, the combined treatment reduced the hippocampal activities of SOD, catalase, GPx, ratio of GSH/GSSG, and elevated TBARS level (P < 0.05). In conclusion, the combination of sleep deprivation and Western diet decreases BDNF levels and increases oxidative stress in the hippocampus, thus inducing memory impairment that is greater than the impairment produced by each factor alone.