Effect Of Polysaccharide Of Dendrobium Candidum On Insulin Secretion And The Signal Transduction Of NF-κB-iNOS-NO In The Mouse Pancreatic Islet Cell Tumor Line Min6Cells

OBJECTIVE:To explore the effects of dendrobium candidum (DC) on the insulin secretion, theproduction of nitrogen monoxidum(NO) and the expression of NF-κ B in ratpancreatic islet Min6cell lines under the high glucose environment, and probe intothe probable mechanism of hypoglycemic effect and protection of pancreatic islet batecell induced by polysaccharide of dendrobium candidum PDC..METHODS:Under the glucose environment (35.0mmol/L), the Min6cell lines were culturedfor48hours to induce damage, at the same time, treated the Min6cell lines withPDC(100、200and400μg/mL) for48hours. The cells were divide into four groups,they are the control group, high glucose group, PDC with differentconcentration(100、200and400μg/mL) group and high glucose plus different PDCconcentration group(100、200and400μg/mL).1.The cell viability were examinedby MTT method and the rate of apoptosis of cells were measured by flow cytometry.2. Nitrate reductase assay was used to measured the levels of nitrogen monoxidum inthe culture medium of each group.3.The level of insulin secretion was measured bythe radio-immunity assay.4. Western blot was used to detect the expression level ofiNOS and NF-κB protein in the cell lines.RESULTS:1. In the high glucose group, the cell viability of Min6cells and the level ofinsulin in the culture medium decreased sharply(p<0.05) and the rate of apoptosis ofcells、the expression of NF-κB protein and the iNOS protein in the MIN6cellsincreased insignificantly (p<0.05),compared with control group, also the level of NO content(p<0.05) in the culture medium is higher than other groups.2.Compared with the control group, the PDC with different concentration(100、200and400μg/mL) have no significant influence on the viability and the rate ofapoptosis (p>0.05) of cells, the level of insulin and nitrogen monoxidum in the culturemedia, as well as the expression level of NF-κB protein and iNOS protein (all p>0.05)all without significant increase.3.In the high glucose plus different PDC concentration group(100、200and400μg/mL), the viability in the Min6cells and the level of insulin in the culture mediumincreased sharply; the rate of apoptosis of cells、 the level of NO content in theculture medium and the expression of NF-κB protein and iNOS protein in MIN6cells decreased insignificantly.CONCLUSIONS:(1) The Polysaccharide of Dendrobium Candidum (PDC) can boost insulin secretionof pancreatic beta-cell, increase its viability and reduce the apoptosis of the cells.(2) Under the high glucose environment, the PDC can significantly suppress theexpression of NF-κB and iNOS protein, and inhibit the increase of NO secretion inthe pancreatic islets.(3) The protect effect to pancreatic islet bate cell, offered by the PDC, would relatedto the signaling pathway of NF-κB-iNOS-NO.