Liver of ovariectomized rats is resistant to resorption of lipids

Ovarian hormones have been shown to regulate liver lipid accumulation in rats. The present study was designed to evaluate liver lipid resorption in ovariectomized (Ovx) rats. Ovx and sham-operated (Sham) rats were submitted to a high-fat (HF; 43% kcal fat as energy) diet for 5 weeks and then either maintained on this diet or switched to a standard (SD; 12.5% kcal fat as energy) diet till weeks 8 and 13 (n = 8 rats/group). Body weight, energy intake, liver and intra-abdominal fat accumulation and plasma metabolic profile were determined. Body weight was significantly (P < 0.01) higher in Ovx than in Sham groups at all times and switching diet did not alter the body weight pattern. The weight of the intra-abdominal fat depots and plasma leptin levels, along with liver triacylglycerol (TAG) concentrations, were significantly higher (P < 0.01) in Ovx than in Sham rats. Switching diet reduced intra-abdominal fat depot weight and plasma leptin in all groups. Switching diet also resulted in a decrease in liver fat accumulation in Sham rats at all times. However, 8 weeks after the diet switch (week 13) liver fat accumulation was as high in Ovx rats as those maintained on the HF diet. When liver TAG values measured at week 13 were compared to initial pre-switching values (week 5), liver TAG levels in Ovx animals were maintained at the same level independently of the diet switch, while in Sham rats switching to a SD diet reduced liver TAG accumulation (P < 0.05). The same comparisons with plasma TAG levels revealed an opposite relationship. These data suggest that liver lipid resorption in Ovx animals is more related to the ovarian hormone status than to the type of ingested diet.