Polysaccharide isolated from Triticum aestivum stimulates insulin release             from pancreatic cells via the ATP-sensitive K+ channel.
Traditional natural plants have been used throughout the world for their             antidiabetic effects. The aim of the present study was to investigate the stimulating             activity of a polysaccharide extract derived from T. aestivum sprout (TASP) on             insulin secretion in vitro using the RIN-5F pancreatic β-cell line and rat pancreatic             islets. In these experiments, TASP (0.1 to 2 mg/ml) augmented glucose-stimulated             insulin secretion in a dose-dependent manner in the presence of a stimulatory             glucose concentration (16.7 mM), but not of a basal concentration (1.1 mM). Although             TASP failed to enhance the high K+-induced insulin secretion, the insulinotropic             effect of TASP was significantly inhibited by diazoxide, an opener of ATP-sensitive             K+ channel blocking insulin release. TASP potentiated the insulin secretion induced             by other secretagogues, such as IBMX and tolbutamide. Moreover, glucose-derived             blood insulin levels were significantly elevated by oral administration of TASP             to mice, similarly to antidiabetic drugs. We also demonstrated that TASP significantly             increased glucose-induced 45Ca2+ uptake and proinsulin mRNA expression in rat             islets. Overall, our results suggest that TASP has a stimulating effect on insulin             secretion and production in pancreatic β-cells via K+ channel closure and calcium             influx. These results suggest that TASP may be useful as a candidate for the therapy             of diabetes mellitus.
Department of Immunology and Institute of Medical Sciences, Chonbuk                     National University Medical School, Jeonju, Jeonbuk 561-180, Republic                     of Korea.
Sun-Hee
SH
Lee
Sung-Won
SW
Lim
Young-Mi
YM
Lee
Hoi-Seon
HS
Lee
Dae-Ki
DK
Kim
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D002460:Cell Line; D002478:Cells, Cultured; D007004:Hypoglycemic Agents / Q000302:isolation & purification / Q000494:pharmacology; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism; D054086:KATP Channels / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D011134:Polysaccharides / Q000302:isolation & purification / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014908:Triticum / Q000737:chemistry*
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D054086:KATP Channels; D010936:Plant Extracts; D011134:Polysaccharides; D011188:Potassium