Abstract. Previous studies have implicated erythropoietin (EPO) signaling in the regulation of glucose metabolism. Whether EPO can be used treat diabetes and the underlying mechanism remain to be elucidated. The present study aimed to investigate whether EPO affects glucose metabolism, and the underlying mechanisms, in experimental diabetic rats. The effects of EPO (300 U/kg three times a week for 4 weeks) on glucose metabolism, hematopoietic function, blood selenium content and the ultrastructure of pancreatic β-cells were investigated in low dose (25 mg/kg body weight) streptozotocin-induced experimental diabetic rats provided with a high-fat diet. The results demonstrated that EPO significantly decreased the fasting blood glucose, the area under the curve of the oral glucose tolerance and insulin tolerance tests and L-alanine gluconeogenesis. Ultrastructural examination of the pancreatic islets revealed that EPO prevented the dysfunction of pancreatic β-cells in experimental diabetic rats, ameliorated cytoplasmic vacuolation and fragmentation of mitochondria, and increased the number of secretory granules. EPO administration increased the activities of superoxide dismutase and glutathione peroxidase, and decreased the level of malondialdehyde. Additionally, EPO increased blood selenium in the diabetic rats and produced a hematopoietic effect. These results indicated that EPO modulated glucose metabolism and improved pancreatic β-cells damage by increasing anti-oxidation. The detailed mechanisms underlying these effects require further investigation.

This study was conducted to investigate the expression of insulin-like growth factor-1 (IGF-1) in elderly patients with diabetes and dementia and to analyze the expression mechanism. A total of 30 senior patients with diabetes and dementia (group A), 30 senior patients with dementia but no diabetes (group B), 30 senior patients with diabetes but no dementia (group C), and 30 healthy seniors (group D) were continuously selected. The ELISA method was used to test the level of serum IGF-1, β-amyloid peptide (Aβ) and the phosphorylation of immunohistochemical staining of microtubule associated protein (tau protein). Western blot analysis was utilized to test the level of prion protein (PrP), forkhead transcription factor O (FOXO) subfamily protein, p-PI3K and p-Akt. The levels of IGF-1, Aβ, tau protein positive rate, PrP, FOXO protein, p-PI3K, and p-Akt in group A were significantly higher than that in group B, which was higher than in groups C and D. The results between groups A and B, but not groups C and D, were statistically significant (P<0.05). IGF-1 was highly expressed in senior patients with diabetes and dementia. Thus, IGF-1 can adjust the expression of PrP and FOXO through p-PI3K/Akt pathway and further impact the formation of Aβ and tau protein, leading to dementia.