Polyphenol-rich black currant and cornelian cherry juices ameliorate metabolic syndrome induced by a high-fat high-fructose diet in Wistar rats

Abstract

Diets high in fat and sugar lead to metabolic syndrome (MetS) and related chronic diseases. We investigated the effects of commercially available, cold-pressed polyphenol-rich black currant (BC) and cornelian cherry (CC) juices on the prevention of MetS in Wistar rats induced by a 10-weeks high-fat high-fructose (HFF) diet. Juice consumption, either BC or CC, with a HFF diet resulted in lower serum triglycerides compared to only the HFF consumption. Both juices also mitigated the effects of HFF on the liver, pancreas, and adipose tissue, by preserving liver and pancreas histomorphology and reducing visceral fat and adipocyte size. Furthermore, supplementation with both juices reduced glucagon and up-regulated insulin expression in the pancreas of the rats on the HFF diet, whereas the BC also showed improved glucose regulation. BC juice also reduced the expression of IL-6 and hepatic inflammation compared to the group only on HFF diet. Both juices, especially BC, could be a convenient solution for the prevention of MetS in humans.

Keywords: Animal model; Black currant; Cornelian cherry; High-fat high-fructose diet; Metabolic syndrome; Polyphenol-rich juices.

Fig. 1

Intraperitoneal glucose tolerance test. HFF- rats on a high-fat high-fructose (HFF) diet, BC- rats on an HFF diet + 20% black currant juice, CC- rats on an HFF diet + 20% cornelian cherry juice. Values are expressed as means ± SEM (n = 9).

Fig. 2

Changes in liver histology after treatment with different types of diet. Cont.- Control group, HFF- rats on a high-fat high-fructose (HFF) diet, BC- rats on HFF diet + 20% black currant juice, CC- rats on HFF diet + 20% cornelian cherry juice. (cv-central vein, h-hepatocytes, s-sinusoid, fa-fat accumulation). Magnification ×20.

Fig. 3

Influence of modified diet on adipose tissue morphology. Cont.- Control group, HFF- rats on a high-fat high-fructose (HFF) diet, BC- rats on HFF diet + 20% black currant juice, CC- rats on HFF diet + 20% cornelian cherry juice. (blue arrow indicates adipocyte lumen). ***P < 0.001 vs control group, ^###P < 0.001 vs HFF group. Magnification ×20.

Fig. 4

A) Morphology of islet of Langerhans. B) Immunohistochemical staining of glucagon immunoreactive cells in the islet of Langerhans. Magnification ×20. C) Immunohistochemical staining of insulin immunoreactive cells in the islet of Langerhans. Cont.- Control group, HFF- rats on a high-fat high-fructose (HFF) diet, BC- rats on HFF diet + 20% black currant juice, CC- rats on HFF diet + 20% cornelian cherry juice. *P < 0.05, **P < 0.01, ***P < 0.001 vs control group; ^###P < 0.001 vs HFF group. Magnification ×20.

Fig. 4

A) Morphology of islet of Langerhans. B) Immunohistochemical staining of glucagon immunoreactive cells in the islet of Langerhans. Magnification ×20. C) Immunohistochemical staining of insulin immunoreactive cells in the islet of Langerhans. Cont.- Control group, HFF- rats on a high-fat high-fructose (HFF) diet, BC- rats on HFF diet + 20% black currant juice, CC- rats on HFF diet + 20% cornelian cherry juice. *P < 0.05, **P < 0.01, ***P < 0.001 vs control group; ^###P < 0.001 vs HFF group. Magnification ×20.

Fig. 5

Relative quantification of A) TNFα, B) IL-1β, and C) IL-6 mRNA in the liver after ten weeks of high-fat high-fructose HFF diet, and BC and CC juice supplementation. The gene expression was normalized to β-actin gene expression. Cont.- Control group, HFF- rats on a high-fat high-fructose (HFF) diet, BC- rats on HFF diet + 20% black currant juice, CC- rats on HFF diet + 20% cornelian cherry juice. Values are expressed as means ± SEM (n = 9); *P < 0.05 vs control group; #P < 0.05 vs HFF group.