Cytoprotective effects of polyenoylphosphatidylcholine (PPC) on beta-cells during diabetic induction by streptozotocin.

Polyenoylphosphatidylcholine (PPC), a phosphatidylcholine-rich phospholipid extracted from soybean, has been reported to protect liver cells from alloxan-induced cytotoxicity. The present study aimed to investigate whether PPC protects pancreatic beta-cells from the cytotoxic injury induced by streptozotocin, thus preserving insulin synthesis and secretion. beta-Cells of the PPC-treated rats showed a significant reduction of cell death with lesser destruction of plasma membrane on streptozotocin insult. They demonstrated a rapid recovery of GLUT-2 expression, whereas almost irreversible depletion of membrane-bound GLUT-2 was seen in beta-cells of the rats treated with only streptozotocin. A similar cytoprotective effect of PPC was also monitored in the PPC-pretreated MIN6 cells. These beta-cells retained their ability to synthesize and secrete insulin and no alteration of glucose metabolism was detected. These results strongly suggest that PPC plays important roles not only in protecting beta-cells against cytotoxicity but also in maintaining their insulin synthesis and secretion for normal glucose homeostasis.