A maple syrup extract alters lipid metabolism in obese type 2 diabetic model mice [adipose]

Some polyphenols are known to improve the symptoms of diabetes. In the present study, we investigated the effects of a polyphenol-rich extract of maple syrup (MSx) on a diabetic mouse model. KK-Ay mice were fed a normal or 0.05% MSx-supplemented diet for 42 days. Body weight, food intake, serum biochemical parameters, and fecal total bile acid were measured. Gene expression of liver and epididymal white adipose tissue (WAT) and cecal microbiota were analyzed. Data were analyzed with an unpaired two-tailed Student’s t test or Welch’s t test according to the results of the F test. Serum low-density lipoprotein cholesterol levels were significantly reduced in mice that consumed MSx. Hepatic genes related to fatty acid degradation and cholesterol catabolism were upregulated in mice that consumed MSx. In contrast, the expression of genes related to lipid metabolism in WAT was unaffected by the intake of MSx. There were no significant differences between the two groups in terms of total bile acid level in the feces and the relative abundance of bacteria in the cecum. Our results primarily indicate that MSx can help alleviate one of the symptoms of dyslipidemia. Male KK-Ay mice 4 weeks of age were purchased from CLEA Japan (Tokyo, Japan). The mice were individually housed in a room maintained at a temperature ranging from 21 to 23 °C with 50–70% relative humidity and a 12:12-h light/dark cycle. Normal and 0.05% MSx-supplemented diets were prepared based on the AIN-93G formula by Oriental Yeast Co. (Tokyo, Japan). After 4 days of acclimation, the mice were divided into two groups (n = 8 each) with approximately equal mean body weights. Mice were fed the normal or MSx diet for 42 days and were allowed free access to the diet and ultrapure water during this period. Body weight and food intake were measured every 2 days. Feces were collected on days 36–38 of the testing period and were stored at − 80 °C until use. After 16 h of food deprivation, mice were sacrificed under sodium pentobarbital anesthesia.