Predicting the effects of a high-energy diet on fatty liver and hippocampal-dependent memory in male rats.

OBJECTIVE

In rodents, diets exceeding nutritional requirements (i.e., high-energy diets; HED) impair hippocampal-dependent memory. Our research suggests that the effects likely involve HED-induced increases in liver lipids. In this experiment, rats were provided with diet choices to test whether voluntary consumption of a HED impairs spatial memory, whether differences in initial weight gain predict memory deficits, and whether increases in liver lipids are associated with the memory deficits.

DESIGN AND METHODS

Adult male Sprague-Dawley rats were given a control diet or cafeteria-style HED for 8 weeks. Weight gain during the first 5 days on the diet was used to divide rats into a HED-Lean group and a HED-Obese group. Spatial water maze memory was tested 8 weeks later and postmortem liver lipid concentrations were quantified.

RESULTS

Compared with the HED-Lean and control rats, the HED-Obese rats had impaired spatial memory and met the human diagnostic criterion of non-alcoholic fatty liver disease (>5% liver lipids relative to liver weight). Moreover, liver lipids were correlated with memory deficits.

CONCLUSIONS

These findings show that voluntary consumption of a HED impairs memory, that initial weight gain predicts fatty liver and memory deficits, and that fatty liver may contribute to the memory-impairing effects of obesity.