Protection of diabetic retinal ganglion cells by safflower yellow pigment regulated p38MAPK signaling pathway / 中草药

ABSTRACT

Objective: To investigate the protective effect of safflower yellow pigment (SYP) on diabetic (DM) retinal ganglion cells (RGC) by regulating p38 mitogen-activated protein kinase (MAPK) signaling pathway. Methods: Selected 50 rats and 40 of them were used to establish DM rat model by single intraperitoneal injection of streptozotocin. They were randomly divided into model group and safflower yellow pigment low, medium and high dose groups, and the remaining 10 rats was control group. Safflower yellow pigment low, medium and high dose groups were intraperitoneally injected with 20, 40, and 80 mg/kg of SYP. Model group and control group were intraperitoneally injected with the same amount of physiological saline solution for six weeks. The general state of the rats was observed, and the morphological changes of RGC were observed by hematoxylin-eosin (HE) staining, and the number of RGC cells was counted. RGC apoptosis rate was detected by in situ apoptosis (TUNEL) method. Real-time quantitative polymerase chain reaction (RT-PCR) and Western blotting were used to detect the mRNA and protein expressions of p38 mitogen-activated protein kinase (MAPK), phosphorylated p38MAPK (p-p38MAPK) and cysteine-containing aspartate proteolytic enzyme-3 (Caspasae-3), vascular endothelial growth factor polyclonal antibody (VEGF), and protein expression ratio of p-p38/p38MAPK was compared. Results: All the rats survived during the experiment. There were no abnormalities in the rats in the control group. The blood glucose in the model group was higher, the diet and urine volume were larger, and the body weight was reduced. The safflower yellow pigment low, medium and high dose groups were better than the model group. Pathological observation showed that there were no abnormalities in the cells of the retina of the control group, while the RGC cells in the model group were disordered arranged and the nucleus were sparse, and the number of cells in the bipolar cell layer and the photoreceptor layer was reduced, and the arrangement was sparse. The abnormalities of RGC cells and outer bipolar cells in the safflower yellow pigment low, medium and high dose groups were significantly lower than those in the model group, and the high dose groups was the most obvious. There was significant difference in the number of RGC between groups (P < 0.05). Compared with the control group, the number of RGC in the model group was significantly decreased (P < 0.05), the apoptotic rate was significantly increased (P < 0.05), the levels of Caspase-3 and VEGF in the retina were significantly increased (P < 0.05), and the values of p-p38MAPK/p38MAPK were significantly increased (P < 0.05). Compared with the model group, the number of RGC was increased significantly (P < 0.05), the apoptotic rate of RGC was decreased significantly (P < 0.05), the expression levels of Caspase-3, VEGF and protein in retina were decreased significantly (P < 0.05), and the value of p-p38MAPK/p38MAPK was decreased significantly (P < 0.05), and the differences among the dose groups were significant (P < 0.05). Conclusion: Safflower yellow pigment can protect RGC of DM rats by inhibiting p38MAPK signaling pathway, and reduce RGC apoptosis. The 80 mg/kg of SYP has the best protective effect.