Tetrahydrofolate Alleviates the Inhibitory Effect of Oxidative Stress on Neural Stem Cell Proliferation through PTEN/Akt/mTOR Pathway

Neural stem cell (NSC) proliferation is the initial step for NSC participating in neurorehabilitation after central nervous system (CNS) injury. During this process, oxidative stress is always involved in restricting the regenerative ability of NSC. Tetrahydrofolate (THF) is susceptible to oxidative stress and exhibits a high antioxidant activity. While its effect on NSC proliferation under oxidative stress condition remains obscure. Here, NSC were isolated from embryonic mice and identified using immunofluorescent staining. Meanwhile, the results showed that THF (5 μM and 10 μM) attenuated oxidative stress induced by 50 μM hydrogen peroxide (H₂O₂) in NSC using mitochondrial hydroxyl radical detection and Western blotting assays. Afterward, administration of THF markedly alleviated the inhibitory effect of oxidative stress on NSC proliferation, which was evidenced by Cell Counting Kit-8 (CCK8), neurosphere formation, and immunofluorescence of Ki67 assays. Thereafter, the results revealed that PTEN/Akt/mTOR signaling pathway played a pivotal role in counteracting oxidative stress to rescue the inhibitory effect of oxidative stress on NSC proliferation using Western blotting assays and gene knockdown techniques. Collectively, these results demonstrate that THF mitigates the inhibitory effect of oxidative stress on NSC proliferation via PTEN/Akt/mTOR signaling pathway, which provides evidence for administrating THF to potentiate the neuro-reparative capacity of NSC in the treatment of CNS diseases with the presence of oxidative stress.