Investigate The Role Of PTEN/TLR4/NF-?B/NLRP3 Signaling Pathway By Which Exercise Ameliorates Post-stroke Depression In Mice

Objective: Exercise exerts neuroprotective effect on post-stroke depression(PSD),but the underlying mechanisms remain unclear.The purpose of this study was to explore the possible molecular mechanisms of exercise training in the treatment of poststroke depression.Methods: Middle cerebral artery occlusion(MCAO)was performed with chronic unpredictable mild stimulation(CUMS)followed for PSD model with C57BL/6J mice.Mice were randomly divided into control group,sham group,High intensity interval training(HIIT)group and Medium intensity continuous training(MICT)group.Mice in the exercise group ran at HIIT or MICT intensity 24 hours after successful modeling,lasting four weeks,during which the running speed was adjusted based on the lactate threshold(LT)and maximum speed(Smax)measured weekly.In the sham group,only the internal carotid artery and the external carotid artery were separated without blocking the middle cerebral artery.Mice that were dead,infected,and failed in modeling were excluded during the experiment.We tested inflammation-related proteins via western blot and evaluated the loss of hippocampal DG neurons with Nissl staining in post-stroke depression mouse which was induced by middle cerebral artery occlusion(MCAO)with chronic unpredictable mild stimulation(CUMS)followed.Besides,forced swimming test(FST)and sucrose preference test(SPT)were used to estimate the neurological recovery.Results: In current study,we demonstrated that exercise prevented the loss of hippocampal neurons in the mouse PSD model.The difference was statistically significant(P <0.05).To further explore how exercise affects the number of hippocampal neurons,we designed the following experiment.First,we showed that the expression of phosphatase PTEN,Toll-like receptor 4(TLR4),NF-?B and the NOD-like receptor pyrin-containing 3(NLRP3),which are involved in inflammation response,were decreased in the hippocampus of PSD mice.Compared with the SHAM group,the differences were statistically significant(P <0.05).Because PTEN plays a wide role in the pathophysiology of the central nervous system,we predicted that exercise can inhibit neuronal death by down-regulating the expression of PTEN in the hippocampus and reducing the activation of inflammatory responses.In PTEN-mutant mice,PTEN deletion prevented the increase of TLR4,nuclear factor kappa-B(NF-k B)and NLRP3 in PSD conditions,and also reduced the loss of hippocampal neurons and improved the functional recovery of PSD mice.The difference was statistically significant(P <0.05).In the same experimental conditions,inhibition of PTEN by PTEN inhibitor exhibited the same results as in PTEN-mutant mice and the differences were statistically significant(P <0.05).These results confirmed that reduced expression or activity of PTEN can affect inflammation-related proteins.It further showed that PTEN is indeed upstream of molecules such as TLR4,NF-?B and NLRP3 in post-stroke depression.Moreover,our results confirmed our conjecture that exercise suppresses the increase of TLR4,NF-?B and NLRP3 in PSD mice and the difference were statistically significant(P <0.05).Conclusion: This study provides the first evidence indicating that both HIIT and MICT ameliorate PSD through inhibiting PTEN elevation-mediated upregulation of TLR4/NF-?B/NLRP3 signaling while HIIT is better than MICT.These results suggest that by targeting PTEN/TLR4/NF-?B/NLRP3-mediated inflammatory response,exercise is a potential therapeutics for PSD patient.