High-fat diet induces learning and memory impairments and hippocampal dendritic spine density in rats

Abstract

Objective To explore the influence of high fat diet on learning and memory, as well as the alteration of the number of neurons and morphology of dendritic spines in rat hippocampi. Methods 24 male adult SD rats were randomly assigned to high fat diet group or control group. The rats were fed with high-fat diet or standard laboratory rodent chow diet for 12 weeks. Learning and memory were tested by Morris water maze and object recognition tests, and mood and motor ability were tested by open field tests.Golgi staining detected dendritic spine density of hippocampal neurons, and Nissl staining was used to observe the number of hippocampal neurons and pathological changes. Results High-fat diet induced rat spatial learning deficits, which was demonstrated by the prolonged escape latency ((38.50±9.70)s, (20.08±7.35)s, (19.96±10.56)s, (22.75±12.51)s, (14.56±4.82)s) compared with the control ((33.61±12.41)s, (14.25±7.89)s, (15.06±7.59)s, (5.53±2.81)s, (4.7±1.58)s). The spatial memory deficits demonstrated that the latency reaching platform ((30.46±21.43)s) was prolonged compared with control ((5.18±1.33)s). The working memory was impaired, which was demonstrated by the prolonged escape latency compared with control group(P<0.05). Discrimination index lowered than control group ((0.67±0.12) vs (0.81±0.08)), and the difference was significant (P=0.038), but no anxiety behaviors were observed(P=0.461). The neuron number of hippocampal neurons and dendritic spine density were significantly lowered than those in the control group((209.73±24.29)vs(262.2±18.94), (17.9±2.84)vs(21.93±2.56), respectively)(P<0.05). Conclusion Intake of high-fat diet can impair learning and memory in rats, as well as decrease the number of neurons and the density of dendritic spines in the hippocampus. Key words: High fat diet; Cognitive impairment; Hippocampus; Dendritic spine