Efficacy of quercetin, oleanolic acid, icariin on apoptosis and mitogen-activated protein kinases signaling pathways in hippocampal neurons of Sprague-Dawley rats cultured with high glucose medium

Objective: To investigate the effect of quercetin, oleanolic acid, icariin and their compatibility on the apoptosis of hippocampal neurons of Sprague-Dawley (SD) rats cultured with high glucose medium and the possible mechanism.

Methods: The extracts were purchased from China Food and Drug Control Institute and Sellect. Hippocampus was obtained from newborn 24 h SD rats. After culturing the hippocampus in different medium for 72 h, flow cytometry was used to detect the apoptosis of hippocampal neurons, and Western blot was utilized to test the expressions of p-p38, p38, p-c-Jun N-terminal kinase (JNK) and JNK.

Results: Compared with the control group (CG), the neuronal apoptosis rate and the ratios of p-p38/p38 and p-JNK/JNK were significantly increased in the high glucose group (GG) (P < 0.01); Compared with the GG, the apoptosis rate and the ratios of p-p38/p38 and p-JNK/JNK were significantly decreased in other drug groups (P < 0.01); Compared with the monomer groups respectively, the apoptosis rate and the ratios of p-p38/p38 and p-JNK/JNK in the two-drug groups and the three-drug group all decreased (P < 0.01); Compared with the two-drug groups, the neuronal apoptosis rate and the ratio of p-JNK/JNK of the three-drug group decreased (P < 0.05).

Conclusion: Under the condition of high glucose, the quercetin, oleanolic acid and icariin can alleviate the apoptosis of hippocampus neurons, reduce the phosphorylation of p38 and JNK in p38 mitogen-activated protein kinases and JNK signaling pathway. And the efficacy of the three drugs in combination with each other can be strengthened.