Circulating oestradiol determines liver lipid deposition in rats fed standard diets partially unbalanced with higher lipid or protein proportions

Abstract

The ingestion of excess lipids often produces the accumulation of liver fat. The modulation of diet energy partition affects this process and other metabolic responses, and oestrogens and androgens are implied in this process. Ten-week-old male and female rats were fed with either standard rat chow (SD), SD enriched with coconut oil (high-fat diet, HF), SD enriched with protein (high-protein diet, HP) or a 'cafeteria' diet (CAF) for one month. HF and CAF diets provided the same lipid-derived percentage of energy (40%), HP diet protein-energy derived was twice (40%) that of the SD. Animals were sacrificed under anaesthesia and samples of blood and liver were obtained. Hepatic lipid content showed sex-related differences: triacylglycerol accumulation tended to increase in HF and CAF fed males. Cholesterol content was higher only in the CAF males. Plasma oestradiol in HF and HP males was higher than in CAF. Circulating cholesterol inversely correlated with plasma oestradiol, which levels were proportional to lactate. These changes agreed with the differences in the expression of some enzymes related with lipid and energy metabolism, such as fatty acid synthetase or phosphoglycolate phosphatase. Oestrogen protective effects extend to males with 'normal' diets, i.e. not unbalanced by either lipid or protein, but this protection was not enough against the CAF diet. Oestradiol seems to actively modulate the liver core of 2C-3C partition of energy substrates, regulating cholesterol deposition and lactate production.