Epigallocatechin Gallate in the Regulation of Insulin Secretion

In both Type 1 diabetes (T1D) and Type 2 diabetes (T2D), inadequate beta-cell mass and beta-cell dysfunction lead to impaired insulin secretion, and ultimately worsen glycemic control. Green tea has drawn wide attention due to its possible health-promoting properties, including enhancement of beta-cell function. We assessed the acute and relative long-term effects of epigallocatechin gallate (EGCG) on insulin secretion and synthesis from clonal beta-cells (INS1E cells), rat islets, and human islets, using 0.1, 1, or 5 µM. We determined if EGCG decreased blood glucose in healthy rats acutely, using 50 or 150 mg/kg body weight (BW), and after 12 days of supplementation in drinking water, using 0.1% and 0.5%. In the in vitro studies, EGCG significantly potentiated glucose-stimulated insulin secretion (GSIS) in rat islets (at 0.1, 1, and 5 µM) and human islets (at 1 µM), and elevated insulin content within INS1E cells (at 0.1, 1, and 5 µm) and human islets (at 1 µM), (P<0.05). Nutritional supplementation of EGCG (0.5% in drinking water) for 12 days in healthy rats significantly increased insulin synthesis, compared to that of controls, from 0.2 ± 0.02 to 1.4 ± 0.2 ng/mg protein, without alteration of insulin secretion in isolated islets (P<0.05). These findings demonstrate that EGCG may play a role in the regulation of pancreatic beta-cell function, thereby contributing to an anti-diabetic effect of this agent.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Human Nutrition, Foods, and Exercise

Department dc:contributor.department

Human Nutrition, Foods, and Exercise

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2008

Author dc:creator

• Yuskavage, Julia Kathryn

Chair dc:contributor.committeechair

• Liu, Dongmin

Committee members dc:contributor.committeemember

• Gwazdauskas, Francis C.
• Barbeau, William E.

• insulin
• catechin
• diabetes
• green tea
• EGCG
• islets
• pancreatic β-cell

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-05142008-162857

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/32761