Saskatoon Berry Amelanchier alnifolia Regulates Glucose Metabolism and Improves Cardiovascular and Liver Signs of Diet-Induced Metabolic Syndrome in Rats

Abstract

Saskatoon berry (Amelanchier alnifolia) is a potential functional food containing anthocyanins and flavonols, as well as ellagitannins and phenolic acids. We have determined the potential therapeutic effects of Saskatoon berry in diet-induced metabolic syndrome. Nine- to ten-week-old male Wistar rats were randomly assigned to four groups. Two groups were fed on control diets, either corn starch (C) or high-carbohydrate, high-fat diet (H) respectively, for 16 weeks. Two further groups were fed on C or H diet for 16 weeks with Saskatoon berry powder added to the diet for the final 8 weeks (CSSK, HSSK). After 16 weeks, H rats showed symptoms of metabolic syndrome, including increased body weight, visceral adiposity, systolic blood pressure, cardiac fibrosis, plasma concentrations of triglycerides and non-esterified fatty acids, and plasma activities of alanine transaminase and aspartate transaminase. Saskatoon berry intervention normalised body weight and adiposity, improved glucose tolerance, decreased systolic blood pressure, improved heart and liver structure and function with decreased infiltration of inflammatory cells, and decreased plasma total cholesterol. Further, Saskatoon berry normalised liver expression of hexokinase 1 and glycogen phosphorylase and increased glucose 6-phosphatase relative to H rats. These results suggest that Saskatoon berry regulates glycolysis, gluconeogenesis and glycogenesis to improve metabolic syndrome.

Dose-Responses Relationship in Glucose Lowering and Gut Dysbiosis to Saskatoon Berry Powder Supplementation in High Fat-High Sucrose Diet-Induced Insulin Resistant Mice

“…A previous study by our group demonstrated that supplementation of 5% SB powder (SBp) in high fat-high sucrose (HFHS) diet significantly lowered fasting plasma glucose (FPG) and insulin resistance in mice, which was associated with reductions in inflammatory markers and gut dysbiosis [ 13 ]. Our findings regarding the glucose-lowering effect of SBp was supported by a separate group of researchers, in whose experiment rats were fed with high fat and high carbohydrate diet supplemented with 2.7% SBp [ 14 ]. The dose-response to SBp administration on glucose lowering, insulin resistance, inflammatory markers and gut microbiota in animal models remains unclear.…”

“…Previous studies on the hypoglycemic effects of SBp on HFHS or HFHS or high fat diet-induced hyperglycemia in mice or rats were only tested in one dose in mice (5% SBp) or rats (2.7% SBp) [ 13 , 14 ]. Dose-response of experimental animals to multiple dosages of oral administration of SBp on hyperglycemia is required to be determined for further pre-clinical and clinical studies.…”

“…HFHS diet increased the size of adipocytes, but the supplementation of SBp did not significantly affect the size of adipocytes compared to that in mice treated with HFHS diet alone [ 20 ]. However, du Preez et al found that SBp treatment significantly reduced body weight and adipose deposition in rats compared to those fed with high fat diet alone [ 14 ]. The glucose-lowering and liver-protective effects were detected in both mice [ 20 ] and rats [ 14 ].…”

Metabolic Impact of Flavonoids Consumption in Obesity: From Central to Peripheral

“…Anthocyanin compounds of purple sweet potato induced the hepatic protein levels of p-AMPK, glucose transporter type 2 (GLUT2), insulin receptor α (IRα), glucokinase (GK) , as well as the expression of phosphofructokinase (Pfk) and pyruvate kinase (Pk), while gluconeogenic genes, glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (Pepck) were downregulated [ 99 ]. Further, Saskatoon berry normalized liver expression of Gk and glycogen phosphorylase and increased G6Ppase in diet-induced MetS rats, thus suggesting that Saskatoon berry regulated glycolysis, gluconeogenesis and glycogenesis to improve MetS [ 100 ].…”

Anthocyanins as Antidiabetic Agents—In Vitro and In Silico Approaches of Preventive and Therapeutic Effects

“…Another pharmacological strategy against T2DM focuses on retarding glycogenolysis. Previous studies proposed that anthocyanin-rich foods also regulate this metabolic cascade by interfering with the activity of key enzymes, such as Glycogen phosphorylase (GP) [ 75 , 152 , 153 , 154 ]. GP catalyzes the rate-limiting step of glycogen breakdown, releasing glucose-1-phosphate.…”