| Objective: Through simulating the chronic intermittent hypoxia(CIH)which is the pathological feature of obstructive sleep apnea syndrome(OSAS)to establish OSAS animal model.To observe the effects of beta carotene(β-C)on learning and memory and the expression of Caspase-3 and p-tau in hippocampus of OSAS rats.Methods: 24 adult SD rats were randomly divided into three groups: normal group,OSAS model group and β-C intervention group,eight in each group.Using the low oxygen chamber to build OSAS in rats.The β-C was dissolved in distilled water and give it to rats by intragastric administration before modeling.The normal team were not treated specially.After modeling,the Morris water maze was used to test the study and memory of rats.HE staining was used to observe the pathological changes in the hippocampus of rats.The expression sites of phosphoric acid tau protein(p-tau)in rat hippocampus were detected by immunohistochemical staining and the protein expression of Caspase-3 and p-tau in hippocampus was detected by Western blot.Results: OSAS rats model determination results: Rat tail artery blood oxygen saturation in CIH hypoxia period for the average was(69.72±1.64)%,compared to the reoxygenation period(95.38±1.53)% decreased and this decreased range has exceeded 4%.Symptoms such as rising head breathing,waking up and abdominal respiration accelerated,which met the criteria of the OSAS rats model.Behavioral test results of Morris water maze: About the escape latency time in the place navigation test,the first day,the normal group was(36.06±7.61)seconds,the model group was(71.38±11.63)seconds,and the intervention group was(46.78±11.49)seconds.The Second day,the normal group was(26.44±6.46)seconds,the model group was(63.12±9.06)seconds,and the intervention group was(37.16±5.66)seconds.The Third day,the normal group was(23.86±6.08)seconds,the model group was(57.65±7.33)seconds,the intervention group was(34.76±8.57)seconds.The Fourth day,normal group was(20.25±4.81)seconds,the model group was(51.89±7.21)seconds,the intervention group was(30.40±6.85)seconds and the fifth day,the normal group was(17.52±4.33)seconds,the model group was(51.57±7.32)seconds,the intervention group was(25.75±5.46)seconds.Compared with the normal group,the time the model group taken was increased significantly(P<0.05),while the intervention group was lessened than the latter(P<0.05).About the number of times traversing the platform in the space exploration experiment,the normal group was(7.03±1.49)times,the model group was(3.06±1.07),and the intervention group was(5.13±1.36).Compared with the normal group and the intervention group,the number of traversing platforms in the model group was decreased significantly,and the results were significantly different(P<0.05).HE staining result: In the model group and the intervention group,the neurons in the hippocampus showed sparse and disorderly arrangement,irregular cell morphology,pyknosis and lysis of nuclei,degeneration and necrosis of cells,compared with the normal group but the intervention group was lighter than the model group.Immunohistochemistry stain result: P-tau positive cells were brownish yellow in the hippocampus of OSAS rats.It was mainly expressed in the envelope of nerve cells and partly expressed in nucleus and cytoplasm.Western Blot results : The expression of caspase-3 and p-tau in hippocampus of model group were much higher than that in normal group and β-C intervention group,and the difference were statistically significant(P<0.05).Conclusion: β-C can alleviate the impairment of learning and memory induced by OSAS,which might be related to inhibiting the expression of caspase-3 and p-tau. |
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