Abstract
This study evaluates the progressive participation of enzymes involved in lipolysis and lipogenesis, leading to adipocyte hypertrophy in a metabolic syndrome (MS) rat model caused by chronic consumption of 30% sucrose in drinking water. A total of 70 male Wistar rats were divided into two groups: C and MS. Each of these groups were then subdivided into five groups which were sacrificed as paired groups every month from the beginning of the treatment until 5 months. The intra-abdominal fat was dissected, and the adipocytes were extracted. Lipoprotein lipase (LPL), hormone-sensitive lipase (HSL), protein kinases A (PKA), and perilipin A expressions were determined. The LPL and HSL activities were evaluated by spectrophotometry. Histological staining was performed in adipose tissue. Significant increases were observed in blood pressure, HOMA-IR, leptin, triglycerides, insulin, intra-abdominal fat, and number of fat cells per field (p = 0.001) and in advanced glycosylation products, adipocyte area, LPL, HSL activities and/or expression (p ≤ 0.01) in the MS groups progressively from the third month onward. Lipogenesis and lipolysis were increased by LPL activity and HSL activity and/or expression. This was associated with hyperinsulinemia and release of non-esterified fatty acids causing a positive feedback loop that contributes to the development of adipocyte hypertrophy.
Highlights
According to the World Health Organization, metabolic syndrome (MS) is defined as the prevalence of three or more of the following risk factors: obesity, hypertension, hypertriglyceridemia, hypercholesterolemia, decrease in high density lipoproteins, hyperinsulinemia, and insulin resistance (IR) [1]
The aim of this study was to evaluate how chronic consumption of 30% sucrose progressively alters the main enzymes that participate in lipolysis and lipogenesis, which may contribute to adipocyte alters the main enzymes that participate in lipolysis and lipogenesis, which may contribute to hypertrophy in a MS rat model
Our results show that the Lipoprotein lipase (LPL) activity was progressively increased from the third month on, which suggests that the chronic consumption of carbohydrate induces a progressive elevation in the activity of this enzyme, favoring adipocyte hypertrophy
Summary
According to the World Health Organization, metabolic syndrome (MS) is defined as the prevalence of three or more of the following risk factors: obesity, hypertension, hypertriglyceridemia, hypercholesterolemia, decrease in high density lipoproteins, hyperinsulinemia, and insulin resistance (IR) [1]. During the development of obesity, the positive energy balance promotes adipocyte hypertrophy associated to hypertriglyceridemia, an increase in very low density lipoprotein and non-esterified fatty acids (NEFAs), ectopic storage of triglycerides (TG), and IR [2]. Adipose tissue is composed of fat cells adapted to store and release NEFAs. Two variants are distinguished; the white and the brown adipose tissue [5]. White adipose tissue is composed of mature adipocytes and a stromal vascular fraction. It has two metabolic functions: lipogenesis and lipolysis.
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