Metabolic syndrome is a disorder of energy metabolism characterized by persistently high prevalence and significant medical and economic burden on society. An effective animal model that closely replicates the key features of the syndrome in humans is essential for evaluating therapeutic strategies aimed at improving health outcomes. High-calorie diet-induced animal models of metabolic syndrome are preferred by many research groups for studying its pathogenesis, prevention and therapy. However, there are numerous variations in the types and proportions of carbohydrates and/or fats in the diets used. In 2015, our research team developed a diet-induced model of metabolic syndrome in young adult male Wistar rats that was based on adding 17% animal fat and 17% fructose to the standard rat chow and 10% fructose to the drinking water. This model reliably induced the morphometric and biochemical alterations that represent the core diagnostic features of the syndrome in humans. Since its initial introduction, we have utilized the high-fat high-fructose diet-induced model of metabolic syndrome/obesity in ten experimental studies. The current paper provides a protocol for applying the model, presents its repeatability and discusses the variability in the morphometric, biochemical, histopathological, immunohistochemical, and behavioral data of 10 experimental studies on Wistar rats.

Introduction: Metabolic syndrome (MS) is often associated with anxiety and depression. Chaenomeles japonica (Thunb.) Lindl, also known as Chaenomeles maulei or Japanese quince, is a medicinal plant with a long history of use forits health-promoting properties. Aim: The aim of this study was to investigate the effects of Japanese quince fruit juice (JQFJ) administration on locomotor activity, anxiety and depressive behavior in rats with diet-induced MS. Materials and methods: Forty adult male Wistar rats were divided into 4 groups: MS, MS+JQFJ2.5, MS+JQFJ5 and MS+JQFJ10. All groups received a high-fat high-fructose diet for the induction of MS. MS animals were daily orally treated with distilled water and the other groups with JQFJ at doses of 2.5 ml/kg, 5 ml/kg and 10 ml/kg, respectively. During the 10th week of the experiment, behavioral tests were carried out. Results: In the open Held test, no effect of JQFJ treatment on locomotor activity was observed. In the elevated plus maze test, a dose-dependent increase in the time spent in the open arms (OA) of the apparatus and in the ratio time spent in OA vs. total time spent in any of the arms was interpreted as an anxiolytic effect. The immobility time in the forced swim test did not differ significantly among the groups, which demonstrated a lack of anti-depressant action. Conclusions: Chronic Japanese quince fruit juice administration produced a dose-dependent anxiolytic-like effect in rats with diet-induced MS, probably due to its high content of polyphenols.

Background/Objectives: Metabolic syndrome (MS) is associated with an increased cardiovascular risk. The aim of this study was to reveal the effects of Chaenomeles japonica fruit juice (CJFJ) on energy balance and biochemical and histological parameters in rats with diet-induced MS. Methods: Fifty Wistar rats were allocated into five groups. For ten weeks, the Control group received a standard laboratory diet and tap water, while the other groups were given a high-fat high-fructose (HFHF) diet. The Control and MS groups were treated with distilled water, while the other three groups were treated with CJFJ at increasing doses. Results: Rats on an HFHF diet consumed less food and more liquids and had a higher caloric intake than the Control group. Among the CJFJ-treated animals, an increased food consumption, as well as an increased total caloric intake, and no difference in body weight gain were observed in comparison with the MS group. CJFJ did not affect glucose tolerance or the triglyceride and total cholesterol levels. CJFJ prevented an HFHF-induced decrease in superoxide dismutase and caused a decrease in thiobarbituric acid-reactive substances in serum. The medium CJFJ dose prevented an HFHF-induced increase in adipose tissue indices. Liver and adipose tissue histology revealed a protective effect of CJFJ. Conclusions: CJFJ may exert beneficial effects on visceral adiposity, oxidative status, and histopathological changes in the liver and adipose tissue in rats with diet-induced MS.

Background/Objectives: Metabolic syndrome (MS) is associated with an increased cardi-ovascular risk. The aim of this study was to reveal the effects of Chaenomeles japonica fruit juice (CJFJ) on energy balance, biochemical and histological parameters in rats with di-et-induced MS. Methods: Fifty Wistar rats were allocated into 5 groups. For ten weeks, the Control group received a standard laboratory diet and tap water, while the other groups were given a high-fat high-fructose (HFHF) diet. Control and MS groups were treated with distilled water, while the other three groups – with CJFJ at increasing doses. Results: Rats on HFHF diet consumed less food, more liquids and had a higher caloric intake than group Control. Among the CJFJ-treated animals, increased food consumption, as well as increased total caloric intake, and no difference in body weight gain were observed in comparison with group MS. CJFJ did not affect glucose tolerance, triglyceride and total cholesterol levels. CJFJ prevented HFHF-induced decrease in superoxide dismutase and caused a decrease in thiobarbituric acid reactive substances in serum. The medium CJFJ dose prevented HFHF-induced increase in adipose tissue indices. Liver and adipose tissue histology revealed a protective effect of CJFJ. Conclusions: CJFJ exhibited appe-tite-stimulating, antioxidant, antiobesogenic and liver-protective properties in rats with diet-induced MS.