Schisandra chinensis polysaccharide attenuates diabetic islet cell injury by promoting autophagy via suppression of the PI3K/AKT/mTOR signaling cascade.

BACKGROUND: Schisandra chinensis polysaccharide (SCP) has demonstrated antidiabetic properties in previous studies; however, the mechanisms underlying its regulation of autophagy in pancreatic protection remain poorly understood. This study investigated how SCP modulates autophagic pathways to alleviate diabetic pathology. METHODS: Diabetic rats were administered SCP orally, followed by histopathological and biochemical assessments of pancreatic islet function and tissue damage. Beta-TC-6 pancreatic β-cells were exposed to SCP to evaluate cellular viability, insulin secretion, and autophagic processes using immunohistochemistry, Western blotting, immunofluorescence, and transmission electron microscopy. RESULTS: SCP dose-dependently attenuated diabetes-associated weight loss, reduced hyperglycemia, and improved β-cell function. Histological examination revealed amelioration of pancreatic islet disorganization, diminished collagen deposition, and reduced basement membrane thickening. Mechanistically, SCP enhanced autophagic activity in pancreatic tissues and Beta-TC-6 cells by inhibiting the PI3K/AKT/mTOR signaling cascade, with high-dose SCP exhibiting efficacy comparable to that of metformin. Chloroquine co-treatment abolished these effects, confirming autophagy dependence. CONCLUSION: This study demonstrates that SCP alleviates diabetes by restoring β-cell function and inducing protective autophagy via the inhibition of the PI3K/AKT/mTOR pathway. These findings indicate SCP as a potential candidate for diabetes therapy.