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Diet supplementation with green tea extract epigallocatechin gallate prevents progression to glucose intolerance in db/db mice.

Ortsäter H, Grankvist N, Wolfram S, Kuehn N, Sjöholm A - Nutr Metab (Lond) (2012)

Bottom Line: EGCG supplementation reduces the number of pathologically changed islets of Langerhans, increases the number and the size of islets, and heightens pancreatic endocrine area.These effects occurred in parallel with a reduction in islet endoplasmic reticulum stress markers, possibly linked to the antioxidative capacity of EGCG.Dietary supplementation with EGCG could potentially contribute to nutritional strategies for the prevention and treatment of type 2 diabetes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Karolinska Institutet, Department of Clinical Science and Education, Södersjukhuset, SE-118 83 Stockholm, Sweden. ake.sjoholm@sodersjukhuset.se.

ABSTRACT

Background: Green tea was suggested as a therapeutic agent for the treatment of diabetes more than 70 years ago, but the mechanisms behind its antidiabetic effect remains elusive. In this work, we address this issue by feeding a green tea extract (TEAVIGO™) with a high content of epigallocatechin gallate (EGCG) or the thiazolidinedione PPAR-γ agonist rosiglitazone, as positive control, to db/db mice, an animal model for diabetes.

Methods: Young (7 week-old) db/db mice were randomized and assigned to receive diets supplemented with or without EGCG or rosiglitazone for 10 weeks. Fasting blood glucose, body weight and food intake was measured along the treatment. Glucose and insulin levels were determined during an oral glucose tolerance test after 10 weeks of treatment. Pancreata were sampled at the end of the study for blinded histomorphometric analysis. Islets were isolated and their mRNA expression analyzed by quantitative RT-PCR.

Results: The results show that, in db/db mice, EGCG improves glucose tolerance and increases glucose-stimulated insulin secretion. EGCG supplementation reduces the number of pathologically changed islets of Langerhans, increases the number and the size of islets, and heightens pancreatic endocrine area. These effects occurred in parallel with a reduction in islet endoplasmic reticulum stress markers, possibly linked to the antioxidative capacity of EGCG.

Conclusions: This study shows that the green tea extract EGCG markedly preserves islet structure and enhances glucose tolerance in genetically diabetic mice. Dietary supplementation with EGCG could potentially contribute to nutritional strategies for the prevention and treatment of type 2 diabetes.

No MeSH data available.


Related in: MedlinePlus

Improved glycemic control in db/db mice after 10 weeks of treatment with EGCG or rosiglitazone. Mice received dietary supplementation with 1% (w/w) EGCG or 0.0021% (w/w) rosiglitazone (Rosi) for 10 weeks. Shown are fasting blood glucose levels (A), fasting plasma insulin levels (B), blood glucose concentrations (C, D) and plasma insulin concentrations (E, F) during an oral glucose tolerance test (OGTT). Raw data from OGTT are presented in C and E while calculated area under the curve is presented in D and F for blood glucose and plasma insulin respectively. Values represent mean ± SEM for 9 mice in each group. * denotes P < 0.05 for a chance difference vs controls using one-way ANOVA in conjunction with Dunnett's multiple comparison test.
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Figure 1: Improved glycemic control in db/db mice after 10 weeks of treatment with EGCG or rosiglitazone. Mice received dietary supplementation with 1% (w/w) EGCG or 0.0021% (w/w) rosiglitazone (Rosi) for 10 weeks. Shown are fasting blood glucose levels (A), fasting plasma insulin levels (B), blood glucose concentrations (C, D) and plasma insulin concentrations (E, F) during an oral glucose tolerance test (OGTT). Raw data from OGTT are presented in C and E while calculated area under the curve is presented in D and F for blood glucose and plasma insulin respectively. Values represent mean ± SEM for 9 mice in each group. * denotes P < 0.05 for a chance difference vs controls using one-way ANOVA in conjunction with Dunnett's multiple comparison test.

Mentions: Fasting glycemia, plasma insulin values and glucose and insulin profiles during OGTT are shown in Figure 1 for db/db mice treated with EGCG or rosiglitazone for 10 weeks. Animals receiving EGCG or rosiglitazone had lower fasting blood glucose levels (Figure 1A) and but similar fasting plasma insulin levels (Figure 1B) after 10 weeks of treatment with EGCG or rosiglitazone compared with non-treated animals. Glycemic excursions (Figure 1C and 1D) during the OGTT were significantly smaller in animals receiving EGCG or rosiglitazone than in control mice, and essentially normalized at the end of the OGTT. Conversely, insulin responses (Figure 1E and 1F) to the OGTT were enhanced in EGCG- or rosiglitazone-treated animals. When insulin sensitivity was assessed (Figure 2A and 2B, respectively), it was evident that rosiglitazone enhanced insulin sensitivity significantly following 10 weeks of oral treatment. In contrast, EGCG failed to significantly improve insulin sensitivity after 10 weeks of treatment (Figure 2).


Diet supplementation with green tea extract epigallocatechin gallate prevents progression to glucose intolerance in db/db mice.

Ortsäter H, Grankvist N, Wolfram S, Kuehn N, Sjöholm A - Nutr Metab (Lond) (2012)

Improved glycemic control in db/db mice after 10 weeks of treatment with EGCG or rosiglitazone. Mice received dietary supplementation with 1% (w/w) EGCG or 0.0021% (w/w) rosiglitazone (Rosi) for 10 weeks. Shown are fasting blood glucose levels (A), fasting plasma insulin levels (B), blood glucose concentrations (C, D) and plasma insulin concentrations (E, F) during an oral glucose tolerance test (OGTT). Raw data from OGTT are presented in C and E while calculated area under the curve is presented in D and F for blood glucose and plasma insulin respectively. Values represent mean ± SEM for 9 mice in each group. * denotes P < 0.05 for a chance difference vs controls using one-way ANOVA in conjunction with Dunnett's multiple comparison test.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3298777&req=5

Figure 1: Improved glycemic control in db/db mice after 10 weeks of treatment with EGCG or rosiglitazone. Mice received dietary supplementation with 1% (w/w) EGCG or 0.0021% (w/w) rosiglitazone (Rosi) for 10 weeks. Shown are fasting blood glucose levels (A), fasting plasma insulin levels (B), blood glucose concentrations (C, D) and plasma insulin concentrations (E, F) during an oral glucose tolerance test (OGTT). Raw data from OGTT are presented in C and E while calculated area under the curve is presented in D and F for blood glucose and plasma insulin respectively. Values represent mean ± SEM for 9 mice in each group. * denotes P < 0.05 for a chance difference vs controls using one-way ANOVA in conjunction with Dunnett's multiple comparison test.
Mentions: Fasting glycemia, plasma insulin values and glucose and insulin profiles during OGTT are shown in Figure 1 for db/db mice treated with EGCG or rosiglitazone for 10 weeks. Animals receiving EGCG or rosiglitazone had lower fasting blood glucose levels (Figure 1A) and but similar fasting plasma insulin levels (Figure 1B) after 10 weeks of treatment with EGCG or rosiglitazone compared with non-treated animals. Glycemic excursions (Figure 1C and 1D) during the OGTT were significantly smaller in animals receiving EGCG or rosiglitazone than in control mice, and essentially normalized at the end of the OGTT. Conversely, insulin responses (Figure 1E and 1F) to the OGTT were enhanced in EGCG- or rosiglitazone-treated animals. When insulin sensitivity was assessed (Figure 2A and 2B, respectively), it was evident that rosiglitazone enhanced insulin sensitivity significantly following 10 weeks of oral treatment. In contrast, EGCG failed to significantly improve insulin sensitivity after 10 weeks of treatment (Figure 2).

Bottom Line: EGCG supplementation reduces the number of pathologically changed islets of Langerhans, increases the number and the size of islets, and heightens pancreatic endocrine area.These effects occurred in parallel with a reduction in islet endoplasmic reticulum stress markers, possibly linked to the antioxidative capacity of EGCG.Dietary supplementation with EGCG could potentially contribute to nutritional strategies for the prevention and treatment of type 2 diabetes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Karolinska Institutet, Department of Clinical Science and Education, Södersjukhuset, SE-118 83 Stockholm, Sweden. ake.sjoholm@sodersjukhuset.se.

ABSTRACT

Background: Green tea was suggested as a therapeutic agent for the treatment of diabetes more than 70 years ago, but the mechanisms behind its antidiabetic effect remains elusive. In this work, we address this issue by feeding a green tea extract (TEAVIGO™) with a high content of epigallocatechin gallate (EGCG) or the thiazolidinedione PPAR-γ agonist rosiglitazone, as positive control, to db/db mice, an animal model for diabetes.

Methods: Young (7 week-old) db/db mice were randomized and assigned to receive diets supplemented with or without EGCG or rosiglitazone for 10 weeks. Fasting blood glucose, body weight and food intake was measured along the treatment. Glucose and insulin levels were determined during an oral glucose tolerance test after 10 weeks of treatment. Pancreata were sampled at the end of the study for blinded histomorphometric analysis. Islets were isolated and their mRNA expression analyzed by quantitative RT-PCR.

Results: The results show that, in db/db mice, EGCG improves glucose tolerance and increases glucose-stimulated insulin secretion. EGCG supplementation reduces the number of pathologically changed islets of Langerhans, increases the number and the size of islets, and heightens pancreatic endocrine area. These effects occurred in parallel with a reduction in islet endoplasmic reticulum stress markers, possibly linked to the antioxidative capacity of EGCG.

Conclusions: This study shows that the green tea extract EGCG markedly preserves islet structure and enhances glucose tolerance in genetically diabetic mice. Dietary supplementation with EGCG could potentially contribute to nutritional strategies for the prevention and treatment of type 2 diabetes.

No MeSH data available.


Related in: MedlinePlus