Cytoprotective effects of polyenoylphosphatidylcholine (PPC) on β-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 β-cells from the cytotoxic injury induced by streptozotocin, thus preserving insulin synthesis and secretion. β-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 β-cells of the rats treated with only streptozotocin. A similar cytoprotective effect of PPC was also monitored in the PPC-pretreated MIN6 cells. These β-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 β-cells against cytotoxicity but also in maintaining their insulin synthesis and secretion for normal glucose homeostasis.