The protective effect of MT-α-glucan against streptozotocin (STZ)-induced NIT-1 pancreatic β-cell damage.

The protective effect of an alpha-glucan (designated here as MT-α-glucan) from fruit body of maitake (Grifola frondosa) on NIT-1 pancreatic β-cells damaged by streptozotocin (STZ) in vitro was investigated. The cell viability, insulin secretion, the activity of superoxide dismutase (SOD), glutathione peroxidase (GSHpx) and the content of reduced glutathione (GSH) increased significantly when the cells were incubated with MT-α-glucan (400, 200 μg ml(-1)). The content of malondialdehyde (MDA), nitric oxide (NO) production, and the activity of NO synthase (NOS), inducible NOS (iNOS) decreased significantly when the cells were incubated with MT-α-glucan. The destructive changes of NIT-1 cells ameliorated when incubated with MT-α-glucan under microscopic observation. These data suggested that MT-α-glucan had obvious protective effect on NIT-1 pancreatic β-cells damaged by STZ, which might be related to its effects of decreasing levels of β-cell-destroying factors such as oxidative stress and NO synthesis.