Dietary fat up-regulates the apolipoprotein E mRNA level in the Zucker lean rat brain

High-fat diet alters apo E-dependent processing of beta-amyloid precursor protein. Here we have evaluated the effects of dietary fat on brain apo E mRNA in Zucker lean and obese rats. After approximately 2 months on a high-fat diet, there was significant up-regulation of brain apo E mRNA in the Zucker lean rat in parallel with weight gain. Densitometric quantification revealed a 17% increase in apo E mRNA in the brains of lean rats fed high-fat diet compared with those of lean rats fed rat chow. No significant difference in brain apo E mRNA of Zucker obese rats fed different diets was found. These results suggest that dietary fat alters brain apo E levels, which may be regulated, in part, through the leptin receptor.