Anti-diabetic effects of lactic acid bacteria in normal and type 2 diabetic mice

Abstract

The antidiabetic effects of lactic acid bacteria were investigated using mice. In Experiment 1, normal ICR mice were loaded with sucrose or starch with or without viable Lactobacillus rhamnosus GG cells. GG significantly inhibited postprandial blood glucose levels when administered with sucrose or starch. In Experiment 2, KK-A(y) mice, a model of genetic type 2 diabetes, were given a basal diet containing viable GG cells or viable Lactobacillus delbrueckii subsp. bulgaricus cells for 6 weeks. Viable GG cells significantly inhibited fasting blood glucose, postprandial blood glucose in a glucose tolerance test and HbA1c. Such effects were not shown by viable L. bulgaricus cells. In Experiment 3, the KK-A(y) mice were given a basal diet containing viable GG cells or heat-treated GG cells for 3 weeks. The viable GG cells significantly suppressed fasting blood glucose and impaired glucose tolerance, but the heat-treated GG showed no effects. These results demonstrated that GG decreased the postprandial blood glucose in ICR mice, and that the antidiabetic activity of lactic acid bacteria on the KK-A(y) mice differed depending on the bacterial strain and whether the bacterium is viable when it arrives in the intestine. In the present study, we conclude that the antidiabetic activity may result from continuous inhibition of the postprandial blood glucose through suppression of glucose absorption from the intestine. These findings indicate that specific strains of lactic acid bacterium can be expected to be beneficial for the management of type 2 diabetes.

Keywords: KK-Ay mouse; Lactobacillus rhamnosus GG; antidiabetic effects; glucose tolerance test; lactic acid bacterium.

Fig. 1

Effect of administration of viable GG cells (V-GG) on sucrose (A) and starch (B) tolerance test. Each point represents the mean ± SE (n = 6). ◯, control; ●, V-GG. *Values with asterisks are significantly different from the control-group values at p<0.05 by Student’s t test.

Fig. 2

Effect of administration of L. GG or L. bulgaricus on body weight (A) and fasting blood glucose (B) in KK-A^y mice. Each point represents the mean ± SE (n = 7). ◯, control; ●, GG; ▲, bulgaricus. *Values with asterisks are significantly different from control-group values at p<0.05 by Dunnett’s test.

Fig. 3

Effect of administration of L. GG or L. bulgaricus on glucose tolerance test in KK-A^y mice at 6 weeks after the experiment began. Each point represents the mean ± SE (n = 7). ◯, control; ●, GG; ▲, bulgaricus. *Values with asterisks are significantly different from control-group values at p<0.05 by Dunnett’s test.

Fig. 4

Effect of administration of L. GG or L. bulgaricus on HbA1c in KK-A^y mice at 6 weeks after the experiment began. Each point represents the mean ± SE (n = 7). *Values with asterisks are significantly different from control-group values at p<0.05 by Dunnett’s test.

Fig. 5

Effect of administration of viable GG cells (V-GG) or heat-treated GG cells (HT-GG) on body weight (A) and fasting blood glucose (B) of KK-A^y mice. Each point represents the mean ± SE (n = 7). ◯, control; ●, V-GG; △, HT-GG. *Values with asterisks are significantly different from control-group values at p<0.05 by Dunnett’s test.

Fig. 6

Effect of administration of viable GG cells (V-GG) or heat-treated GG cells (HT-GG) on glucose tolerance test in KK-A^y mice at 3 weeks after the experiment began. Each point represents the mean ± SE (n = 7). ◯, control; ●, V-GG; △, HT-GG. *Values with asterisks are significantly different from control-group values at p<0.05 by Dunnett’s test.

Fig. 7

Effect of administration of viable GG cells (V-GG) or heat-treated GG cells (HT-GG) on plasma insulin in KK-A^y mice at 3 weeks after the experiment began. Each point represents the mean ± SE (n = 7).