Objective： To investigate the neuroprotective effects of icariin on formaldehyde （FA）-treated human neuroblastoma SH-SY5Y cells and the possible mechanisms involved. Methods： SH-SY5Y cells were divided into FA treatment group, FA treatment group with icariin, and the control group. Cell viability, apoptosis, and morphological changes were determined by cell counting kit-8 （CCK 8）, flow cytometry, and confocal microscopy, respectively. The phosphorylation of Tau protein was examined by western blotting. Results： FA showed a half lethal dose （LD50） of 0.3 mmol/L in SH-SY5Y cells under the experimental conditions. Icariin （1-10 μ mol/L） prevented FA-induced cell death in SH-SY5Y cells in a dose-dependent manner, with the optimal effect observed at 5 μmol/L. After FA treatment, the absorbance in FA group was 1.31±0.05, while in the group of icariin （5μmol/L） was 1.63±0.05. Examination of cell morphology by confocal microscopy demonstrated that 5 μmol/L icariin significantly attenuated FA-induced cell injury （P〈0.05）. Additionally, icariin inhibited FA-induced cell apoptosis in SH-SY5Y cells. Results from western blotting showed that icariin suppressed FA-induced phosphorylation at Thr 181 and Ser 396 of Tau protein, while having no effect on the expression of the total Tau protein level. Furthermore, FA activated Tau kinase glycogen synthase kinase 3 beta （GSK-3β） by enhancement of Y216 phosphorylation, but icariin reduced Y216 phosphorylation and increased Ser 9 phosphorylation. Conclusion： Icariin protects SH-SY5Y cells from FA-induced injury possibly through the inhibition of GSK-3β -mediated Tau phosphoryiation.
＂Qi＂ and ＂blood＂ are two essential concepts in Chinese medicine （CM）. As qi is intangible, the concept of qi is still controversial between CM and Western medicine. However, the endogenous hydrogen sulfide （H2S） and other gaseous signaling molecules provides a new approach for understanding the essence of qi in CM. Blood stasis syndrome is a common syndrome in CM. According to the CM theory, the incidence of blood stasis syndrome is closely correlated to the reckless movement of qi, as qi and blood are inseparable in regulating physiological functions. In recent years, more and more evidences suggest a close correlation between blood stasis syndrome and microcirculation dysfunction. In this paper, we discuss the relationship between endogenous H2S and blood stasis syndrome based on qi-blood theory of CM. We found that endogenous H2S maybe a material basis in concept of qi in CM, while dysfunctional microcirculation is the pathological basis of the blood stasis syndrome. As qi is closely associated with incidence and progression of blood stasis syndrome, endogenous H2S may play an important role in preventing and treating the blood stasis syndrome by improving the function of microcimulation.
