mTOR/NF-κB signaling pathway protects hippocampal neurons from injury induced by intermittent hypoxia in rats

Objective: To expound the roles of mTOR and NF-kB signaling pathway in intermittent hypoxia (IH)-induced damage of hippocampal neurons. Methods: For rat experiments, mTOR inhibitor (Rapamycin, Rapa) and NF-kappa B signaling inhibitor (ammonium pyrrolidine dithiocarbamate, PDTC) were applied to inhibit mTOR and NF-kappa B signaling, respectively. For neuron experiments, hippocampal neurons from rat were successfully cultured. Different concentrations of Rapa and PDTC were added to the cultured hippocampal neurons. Rat or primary hippocampal neurons were exposed to normoxic or IH conditions after administration of Rapa and PDTC. The effects of Rapa and PDTC administration on learning and memory ability of rats and hippocampal injury after IH exposure were assayed by Morris water maze and H&E staining. Electron microscope was utilized to examine primary hippocampal neuron ultrastructure changes after IH exposure and Rapa or PDTC administration. The expressions of NF-kappa B-p65, I kappa B alpha, IKK beta, BDNF, TNF-alpha, IL-1 beta, PSD-95 and SYN in hippocampal neurons were examined. Results: Compared with normal control rats or neurons, IH-treated group had elevated expression levels of NF-kB, TNF-alpha and IL-1 beta and suppressed expression level of BDNF, PSD-95 and SYN. These results were reversed upon pre-treatment with Rapa and PDTC. Furthermore, I kappa B alpha and IKK beta expressions were down-regulated in IH group. No notable difference was manifested in PDTC pre-treatment group, while a prominent increase was shown after Rapa pre-administration. Conclusion: The administration of PDTC and Rapa could prevent IH-induced hippocampal neuron impairment, indicating that inhibition of the mTOR and NF-kappa B pathway may likely act as a therapeutic target for obstructive sleep apnea.

Automated summary

In the IH-treated group, the expression levels of NF-kB, TNF-alpha, and IL-1 beta were elevated, while BDNF, PSD-95, and SYN were suppressed; these results were reversed with pre-treatment of Rapa and PDTC. Additionally, I kappa B alpha and IKK beta expressions were down-regulated in the IH group, but prominently increased after Rapa pre-administration.