Daily cycle in hepatic lipid metabolism in obese mice, Neotomodon alstoni: Sex differences.

Disruption of circadian rhythms influences the pathogenesis of obesity, particularly with the basic regulation of food intake and metabolism. A link between metabolism and the circadian clock is the peroxisome proliferator-activated receptors (PPARs). The Neotomodon alstoni mouse, known as the "Mexican volcano mouse," may develop obesity if fed a normo-caloric diet. This manuscript documents the changes in part of the hepatic lipid homeostasis in both sexes of lean and obese N. alstoni mice, comparing the daily changes in the BMAL1 clock protein, in regulators of lipid metabolism (PGC-1α, PPARα-γ, SREBP-1c, and CPT-1α) and in free fatty acid (FFA) and hepatic triacylglyceride (TAG) metabolites in light-dark cycles. Hepatic tissue and blood were collected at 5, 10, 15, 19, and 24 h. Samples were analyzed by western blotting to determine the relative presence of protein. The results indicate that obesity affects daily changes in lipid metabolism and the BMAL1 profile in females considerably more than in males. These results suggest that the impact of obesity on lipid metabolism has important differences according to sex.

Time-caloric restriction inhibits the neoplastic transformation of cirrhotic liver in rats treated with diethylnitrosamine.

Hepatocellular cancer is the most common type of primary liver cancer. Cirrhosis is the main risk factor that generates this malady. It has been proven that caloric restriction protocols and restricted feeding schedules are protective in experimental carcinogenic models. We tested the influence of a time-caloric restriction protocol (2 h of food access during the daytime for 18 weeks) in an experimental model of cirrhosis-hepatocarcinoma produced by weekly administration of diethylnitrosamine. Our results indicate that time-caloric restriction reduced hepatomegaly and prevented the increase in blood leukocytes promoted by diethylnitrosamine. Strikingly, time-caloric restriction preserved functional and histological characteristics of the liver in fibrotic areas compared to the cirrhotic areas of the Ad Libitum-fed group. Tumoural masses in the restricted group were well differentiated; consider a neoplastic or early stage of HCC. However, time-caloric restriction enhanced collagen deposits. With regard to the cancerous process, food restriction prevented systemic inflammation and an increase in carcinoembryonic antigen, and it favoured the occurrence of diffuse multinodular tumours. Histologically, it prevented hepatocyte inflammation response, the regenerative process, and neoplastic transformation. Time-caloric restriction stimulated circadian synchronization in fibrotic and cancerous liver sections, and it increased BMAL1 clock protein levels. We conclude that time-caloric restriction prevents fibrosis from progressing into cirrhosis, thus avoiding chronic inflammation and regenerative processes. It also prevents, probably through circadian entrainment and caloric restriction, the neoplastic transformation of tumoural lesions induced by diethylnitrosamine.