The Role Of IGF-1 In Cognitive Functions Impairment Caused By Sleep Fragmentation

Part one The effects of sleep fragmentation on cognitive function of rats and expression of IGF-1 in rat hippocampus[Objective] The aim is to explore the relationship between cognitive function,expression of IGF-1 in hippocampus and fragments sleeping deprivation in animal model.[Methods] In order to observe the influence of fragments sleeping deprivation on cognitive function and IGF-1 in mouse hippocampus,we set up the animal model.Eighteen mature male rats were divided into 3 groups including control group(CC),environmental control(TC)group and the fragments sleep deprivation(SD)group.All rats were trained via Morris water maze.Then,deprivation model was established for 5 days.We evaluated the memory ability of rats via space searching assay.The expression of IGF-1 in rat hippocampus was evaluated via enzyme-linked immunosorbent assay(Elisa).[Results] There is significant difference between control group(CC),environmental control(TC)group and the fragments sleep deprivation(SD)group in terms of the cognitive function(p<0.05).The expression of IGF-1 in rat hippocampus of SD group is significantly decreased comparing with CC and TC(p<0.05).[Conclusion] Fragments sleep phenomenon can lead to the impairment of cognitive function and reduce the secretion of IGF-1 in rat model.Part two The role of IGF-1 in mitigating the cognition impairment caused by sleep fragmentation and its mechanisms[Objective] The aim is to evaluate the effect of spatial memory impairment after supplying IGF-1 on fragments sleep deprivation models,and to investigate the protecting effect of IGF-1 on cognitive impairment induced by fragments sleep deprivation,and its relevant mechanism.[Methods] Eighteen adult male rats were randomly divided into three groups,including environmental control plus a CSF group(TC+a CSF),fragments sleep deprivation plus a CSF group(SD+a CSF)and fragments sleep deprivation plus IGF-1 group(SD+IGF-1).All rats were trained via Morris water maze.Then,deprivation model was established for 5 days.The immunohistochemical staining and image analysis(Image Pro Plus software)was used to examine the expression of p-Akt in rat hippocampus.[Results] There is significant difference between the fragments sleep deprivation plus a CSF(SD+a CSF)group from the environmental control plus a CSF(TC+a CSF)group,and from the fragments sleep deprivation plus IGF-1(SD+IGF-1)group respectively in terms of the index of searching space experiment(p < 0.01).The expression of p-Akt is significantly decreased in fragments sleep deprivation plus a CSF(SD+a CSF)group comparing with other two groups in hippocampus(p < 0.01).There is no significant difference between group(TC + a CSF)and group(SD + IGF-1)in the index of searching space experiment and the expression of p-Akt.[Conclusion] IGF-1 might restore cognitive impairment caused by fragments sleep deprivation by regulating the expression of p-Akt.