TDP-43 Participates In Cognitive Impairment In OSAS Rats By Regulating HDAC1

Objective: To construct an OSAS rat model by means of chronic intermittent hypoxia,to intervene TDP-43 by stereotaxic injection of lentivirus into the bilateral hippocampus,and to observe and explore the role of TDP-43 in the mechanism of OSAS cognitive impairment by regulating HDAC1,to provide new ideas and methods for further understanding and research on cognitive impairment caused by OSAS.Methods: Forty male SD rats were randomly divided into four groups: normal group(Con group),OSAS model group(OSAS group),TDP-43 knockdown group(TDP-43-KD group)and empty virus control group(Vehicle group).The Vehicle group and TDP-43-KD group screened the 117,118 and 119 sequences of TDP-43 lentivirus by bilateral hippocampal Stereotactic injection and Western blotting two weeks in advance,The viral transfection of lentivirus in rat hippocampus was detected by immunofluorescence technology.After the successful lentivirus transfection,OSAS rat models were constructed by chronic intermittent hypoxia in all groups except the normal control group.After the successful construction of the model,Morris water maze was used to evaluate the behavior of rats in each group and observe the learning and memory ability of rats.After that,the hippocampal tissue of rats was isolated and taken out,and the apoptosis of hippocampal neurons in each group was observed by Hoechst staining;The localization of TDP-43 and HDAC1 in nerve cells was observed by immunohistochemistry;The TDP-43 and HDAC1 proteins in the hippocampus of rats in each group were quantitatively analyzed by Western blotting.Results:1.Through the screening of lentivirus sequence by Western Blotting Technology,it can be found that the expression level of TDP-43 lentivirus 119 sequence is lower than that of TDP-43 lentivirus 117 sequence and 118 sequence in the hippocampus of rats injected with lentivirus.At the same time,the expression level of TDP-43 in 119 sequence was lower than that in con group(P < 0.05).Secondly,TDP-43 knockdown virus was injected into bilateral hippocampus and transfected for 2 weeks.The positive expression of TDP-43 in CA1 region of rat hippocampus was confirmed by immunofluorescence technique.2.Monitoring the changes of blood oxygen saturation in rat tail arteries under the condition of chronic hypoxia-reoxygenation,differences between the two could be found(P<0.05).Hypoxic interval(63.65±1.93),Reoxygenation interval(93.96±2.07).In the process of constructing the OSAS model of chronic hypoxia,it was found that the model rats show sleepiness during the day,irritability,deep and rapid breathing,and even abnormal breathing,which proved that the OSAS model was successfully constructed.3.Morris water maze behavioral observation results: Using the Morris water maze positioning navigation and space exploration test,it could be found that compared with the normal group,the OSAS group spends a longer time looking for the escape hidden platform,and after the platform was removed,the number of times of exploring and crossing the virtual platform was less,which was statistically significant(P<0.05).The Vehicle group took a long time to find the escape hidden platform,and the number of times of exploring and crossing the virtual platform was small,compared with the OSAS group,there was no significant difference in the time to find the platform and the times of crossing the platform,and there was no statistical significance(P>0.05).Compared with the Vehicle and OSAS group,the TDP-43-KD group had a shorter time to find the hidden platform and more times of crossing the virtual platform,both of which were statistically significant(P<0.05).4.Hoechst staining: Compared with the normal group,increased apoptosis was observed in OSAS group,and a large number of chromatin solid,dense and fragmented nuclei were observed in and near CA1,and the color was bluer and shinier compared with normal nerve cells.There was no significant difference in cell apoptosis between Vehicle group and OSAS group.Compared with the Vehicle and OSAS group,the apoptosis of rat nerve cells in the TDP-43-KD group was significantly reduced.5.Western blotting results: TDP-43 and HDAC1 protein expressions were detected in the hippocampus of rats in each group.Compared with the normal group,the protein expression of TDP-43 in the OSAS group increased,while the expression of HDAC1 decreased,with statistical significance(P<0.05).There was no significant difference in the expression of TDP-43 and HDAC1 between the OSAS group and the Vehicle group(P>0.05).Compared with Vehicle and OSAS group,the expression of TDP-43 protein in TDP-43-KD group decreased,while the expression of HDAC1 protein increased(P<0.05).6.Immunohistochemical results: The localization of TDP-43 and HDAC1 in neurons in the CA1 region of the rat hippocampus could be found by immunohistochemical experiments,TDP-43 was expressed in the nucleus,cytoplasm and membrane,while HDAC1 was mainly expressed in the cell membrane.Conclusion: TDP-43 can damage the cognitive function of OSAS rats.After down regulating the expression level of TDP-43 protein,it can increase the expression of HDAC1 protein,reduce the apoptosis of nerve cells and improve the cognitive function of OSAS rats.