Effects of four Bifidobacteria on obesity in high-fat diet induced rats

Abstract

Aim: To compare the effects of four Bifidobacteria strains (Bifidobacteria L66-5, L75-4, M13-4 and FS31-12, originated from normal human intestines) on weight gain, lipid metabolism, glucose metabolism in an obese murine model induced by high-fat diet.

Methods: Forty-eight Sprague-Dawley rats were randomly divided into six groups. Control group received standard chow, model group received high-fat diet, and intervention groups received high-fat diet added with different Bifidobacteria strains isolated from healthy volunteers' fresh feces. All rats were executed at the 6th weekend. Body weight (BW), obese indexes, oral glucose tolerance test, serum and liver lipid and serum insulin (INS) were tested. Liver lipid deposition was classified pathologically.

Results: Compared with the model group, B. M13-4 improved BW gains (264.27 +/- 26.91 vs 212.55 +/- 18.54, P = 0.001) while B. L66-5 induced a decrease in BW (188.47 +/- 11.96 vs 212.55 +/- 18.54, P = 0.043). The rest two strains had no significant change in BW. All the four strains can reduce serum and liver triglyceride and significantly alleviate the lipid deposition in liver. All strains showed a trend of lowing serum and liver total cholesterol while B. L66-5 and B. FS31-12 did so more significantly. In addition, all the four strains showed no significant differences in serum INS and glucose level.

Conclusion: The response of energy metabolism to administration of Bifidobacteria is strain dependent. Different strains of Bifidobacteria might drive different directions of fat distribution.

Figure 1

Caloric intake, body weight increment and obesity indexes in high-fat diet treated rats with different strains of Bifidobacteria. A: Sum of caloric intake in all groups at the 6th weekend; B: Body weight (BW) increment in all groups for 6 wk; C: Liver index and body lipid index in all groups; D: Lee’s index in all groups. Results are shown as mean ± SD (n = 8). ^aP < 0.05 vs model group.

Figure 2

Effects of Bifidobacteria strains on glucose and lipid metabolism in high-fat diet treated rats. A: Effect of four Bifidobacteria strains on serum glucose; B: Serum insulin (INS) concentration in all groups; C: Serum and liver triglycerides (TG) in all groups; D: Serum and liver total cholesterol (TCH) in all groups. Results are shown as mean ± SD (n = 8), ^aP < 0.05 vs model group.

Figure 3

Hepatic tissue sections of each group in HE staining (HE, light microscope, × 400). A: Model; B: Control; C: B. L66-5; D: B. L75-4; E: B. M13-4; F: B. FS31-12.

Figure 4

Hepatic tissue sections of each group in Sudan IV-staining (Sudan IV, light microscope, × 400), and lipid droplets are scarlet. A: Model; B: Control; C: B. L66-5; D: B. L75-4; E: B. M13-4; F: B. FS31-12.