Hog millet (Panicum miliaceum L.)-supplemented diet ameliorates hyperlipidemia and hepatic lipid accumulation in C57BL/6J-ob/ob mice

Abstract

Dietary intake of whole grains reduces the incidence of chronic diseases such as obesity, diabetes, cardiovascular disease, and cancer. In an earlier study, we showed that Panicum miliaceum L. extract (PME) exhibited the highest anti-lipogenic activity in 3T3-L1 cells among extracts of nine different cereal grains tested. In this study, we hypothesized that PME in the diet would lead to weight loss and augmentation of hyperlipidemia by regulating fatty acid metabolism. PME was fed to ob/ob mice at 0%, 0.5%, or 1% (w/w) for 4 weeks. After the experimental period, body weight changes, blood serum and lipid profiles, hepatic fatty acid metabolism-related gene expression, and white adipose tissue (WAT) fatty acid composition were determined. We found that the 1% PME diet, but not the 0.5%, effectively decreased body weight, liver weight, and blood triglyceride and total cholesterol levels (P < 0.05) compared to obese ob/ob mice on a normal diet. Hepatic lipogenic-related gene (PPARα, L-FABP, FAS, and SCD1) expression decreased, whereas lipolysis-related gene (CPT1) expression increased in animals fed the 1% PME diet (P < 0.05). Long chain fatty acid content and the ratio of C18:1/C18:0 fatty acids decreased significantly in adipose tissue of animals fed the 1% PME diet (P < 0.05). Serum inflammatory mediators also decreased significantly in animals fed the 1% PME diet compared to those of the ob/ob control group (P < 0.05). These results suggest that PME is useful in the chemoprevention or treatment of obesity and obesity-related disorders.

Keywords: C57BL/6J-ob/ob; Panicum miliaceum L. extract; fatty acid; hyperlipidemia.

Fig. 1

Body weight changes in C57BL/6J and C57BL/6J-ob/ob mice fed the 0.5% or 1% Panicum miliaceum L. extract (PME) diet. Values are means ± SD (n = 10). ^*P < 0.05 vs. the obese control group.

Fig. 2

Blood glucose levels obtained during the intraperitoneal glucose tolerance test (IGTT). (A) Percent area under the curve (AUC) (B) and insulin level (C) after the IGTT (2 g/kg) in C57BL/6J and C57BL/6J-ob/ob mice fed the 0.5% or 1% Panicum miliaceum L. extract (PME) diet. The C57BL/6J-ob/ob mice were fed the PME-supplemented diets for 4 weeks, and then the IGTT was performed. White and black bars represent the lean (C57BL/6J) and obese (C57BL/6J-ob/ob) control mice, respectively. Each bar represents the mean ± SD (n = 10). Bars with different letters differ significantly (P < 0.05) from each other.

Fig. 3

Blood insulin levels in lean and obese mice fed the 0.5% or 1% Panicum miliaceum L. extract (PME) diet. The C57BL/6J-ob/ob mice were fed the PME-supplemented diets for 4 weeks. Values are means ± SDs (n = 10). Bars with different letters differ significantly (P < 0.05) from each other.

Fig. 4

Microphotographs of the liver and white adipose tissue (WAT) in lean and obese mice fed the 0.5% or 1% Panicum miliaceum L. extract (PME) diet. The C57BL/6J-ob/ob mice were fed the PME-supplemented diets for 4 weeks. After 4 weeks, liver and WAT sections were stained with hematoxylin and eosin and observed by microscopy using a 200 × objective. Representative images of the liver (A-D), adipose tissue (E-H), and relative adipocyte size (I). (A, E) C57BL/6J, (B, F) C57BL/6J-ob/ob, (C, G) C57BL/6J-ob/ob + 0.5% PME diet, (D, H) C57BL/6J-ob/ob + 1.0% PME diet. Values are means ± SDs (n = 10). Bars with different letters differ significantly (P < 0.05) from each other.

Fig. 5

Serum inflammatory mediators in lean and obese mice fed the 0.5% or 1% Panicum miliaceum L. extract (PME) diet. The C57BL/6J-ob/ob mice were fed the PME-supplemented diets for 4 weeks. After 4 weeks, tumor necrosis factor (TNF)-α, interleukin (IL)-6, and monocyte chemotactic protein-1 (MCP-1) levels were measured. White and black bars represent the lean (C57BL/6J) and obese (C57BL/6J-ob/ob) control mice, respectively. A, Serum TNF-α levels; B, Serum IL-6 levels; C, Serum MCP-1 levels. Each bar represents the mean ± SD (n = 10). Bars with different letters differ significantly (P < 0.05) from each other.