Complex Effects of Round-The-Clock Light and High-Calorie Carbohydrate-Lipid Diet on Carbohydrate and Lipid Metabolism in Rats

Abstract

Background. Experimental and clinical studies show that hypomelatoninemia is accompanied by alterations in carbohydrate and lipid metabolism, the development of systemic inflammatory response, hypertension, endothelial dysfunction and oxidative stress. The purpose of this study was to investigate complex effects of round-the-clock light and HCCLD on carbohydrate and lipid metabolism in rats. Materials and methods. The experiment was carried out on 28 male adult rats of Wistar line weighting 215-255 g. The animals were divided into 4 groups of 7 animals in each: control, exposed to the round-the-clock light (with an intensity of 1500 lx), kept on HCCLD (20 % fructose solution and the diet), and the mixed group exposed to the combined effect of the round-the-clock light and HCCLD. The experiment in the groups 2 and 4 lasted 60 days. We assessed the melatonin concentration, indices of carbohydrate and lipid metabolism. Results. The study has demonstrated that the combination of HCCLD and the round-the-clock light course reduces the melatonin concentration in the blood serum by 55.6 % compared with the results obtained in the animals exposed to the round-the clock light only. Herewith, the animals developed the insulin resistance, which was accompanied by more marked manifestations of its characteristic metabolic symptoms as hyperinsulinemia, dyslipoproteinemia, hypo-α-lipoproteinemia, hypertrialcylglycerolemia, and increased visceral fat mass in comparison with the animals kept on the HCCLD only. Conclusions. High-calorie carbohydrate-lipid diet through the period of the round-the-clock light exposure aggravates hypomelatoninemia, enhances insulin resistance, and lipid metabolism disorders.