Effects Of Inflammatory Insult In Late Pregnancy On Sleep,Anxiety And Memory Of CD-1 Mice Offspring In Middle And Old Age And The Moderating Effect Of Enriched Environment

Background: There have been various studies on the inheritance of emotional and cognitive disorders.So does sleep have the similar effect,what is the mechanism,and what are the implications for early prevention on a demographic scale? Epidemiological investigation has reflected the clinical phenomenon that stress in early life affected sleep in late life,and it was also consistent with some existing hypotheses about the pathogenesis of insomnia.Both prenatal and early life stress may affect the expression of glucocorticoid receptors in the developing of child’s brain.This kind of influence may ultimately lead to neurobiological changes persisting into adulthood,including increased activity and reactivity of the hypothalamic-pituitary-adrenal axis,increased activity of certain arousal promoting systems(such as the norepinergic system and the calcitoninurea system),and reduced neurogenesis and brain plasticity.Studies have shown that these changes significantly affected emotion and cognitive function,but there was lack of research on the sleep of offspring and no reports on which generation the effects can last,and whether there were cross-generational inheritance effects.The neurobiological changes that accompanyed sleep,anxiety and memory are also worth exploring.On the other hand,enriched environment has antagonistic effects on stress in many aspects,such as the recovery of HPA axis hyperactivity and neurological function.There was also a lack of research on the regulatory effects of enriched environment on sleep,anxiety and memory after inflammatory insult in late pregnancy.Objective: The aim of the current research was to observe: 1.The effects of injection of LPS in late pregnancy on sleep,anxiety and memory of offspring in middle and old age,as well as the moderating effect of enriched environment.2.The differences of intergenerations of maternal inflammatory insult on sleep,anxiety and memory in offspring(three generations).3.Whether the enriched environment has genetic effect,such as whether contemporary enriched environment or previous enriched environment was more conducive to the recovery of sleep,anxiety and memory.4.The persistence of the effects of early life stress on the sleep of offspring,verify the 3P hypothesis and the origin of life hypothesis about insomnia.5.Whether the sleep loss of the offspring was accompanied by the change of anxiety,providing the idea for establishment of the mouse model of chronic insomnia.In general,the purpose of the study was to verify whether the environment during pregnant and puer-peral period is related to the sleep,emotion and cognition of offspring,and to reveal the importance of avoiding early life stress in improving the quality of life of the social population.Methods: CD-1 maternal rats were exposed to LPS in the late trimester,and the offspring of F1 generation were divided into normal feeding and enriched environment feeding.F2 generation passed by F1 generation and F3 generation passed by F2 generation were also divided into normal environment and enriched environment.Sleep monitoring and behavioral monitoring(open field activity,elevated plus maze,black-white alley and Morris water maze),were performed at the age of 15 months to evaluate sleep status,anxiety behavior and spatial cognition,respectively.BDNF,S100 B,CRF and corticosterone levels were detected by enzymatic immunosorbent assay.The expression of CRF-R in PVN region,H1 R in cortex and VLPO region,GABA-AR in LH and TMN region were detected by immunohistochemical method.Results: 1.Inflammatory insult in late pregnancy reduced the sleep time of offspring in middle and old age,reflecting the number of sleep episodes.The genetic effect of reduced sleep was inherited into the F2 generation,anxiety basically disappeared in the F2 generation,and spatial memory impairment was inherited into the F3 generation.It was worth mentioning that inflammatory insult in late pregnancy did not have a cross-generational effect on sleep and anxiety,but had a cross-generational effect on spatial memory.The above results suggested that inflammatory insult in late pregnancy increases the insomnia quality(susceptibility)of offspring at least for the F2 generation,which tended to be pure insomnia with the disappearance of anxiety,while the spatial memory impairment caused by stress may last longer.2.In three generations of CD-1 male and female mice,the contemporary enriched environment did not show a significant sleep improvement effect,except that the average sleep time of LPS-EM was higher than that of LPS-CM(the increase in average sleep time did not lead to a statistically significant increase in total sleep time).However,in the F1 and F2 generations,the contemporary enriched environment tended to increase the sleep time of offspring mice with maternal exposure to inflammation in late pregnancy(no statistically significant difference).As for the regulating effect of enriched environment in previous generation on sleep,we found that in the F2 generation,the sleep time of LPS-ECM group was higher than that of LPS-CCM group,and the average sleep time was higher than that of LPS-CCM group,but this phenomenon was not observed in female mice(There was only a tendency to improve sleep).In the F3 generation,the sleep time and the average sleep time of LPS-EECM group was higher than those of LPS-CCCM group,and the female mice had the same performance.In general,the effect of the previous generation of enriched environment on the improvement of sleep was more prominent(compared with that of the contemporary enriched environment),suggesting that the effect of the enriched environment on the regulation of sleep was inherited(rather than cross-generational).3.For the moderating effects of contemporary enriched environment on anxiety and memory.In the F1 generation of male and female mice,the behavioral indicators of anxiety in the LPS-E group were lower than those in the LPS-C group,while there was no statistical difference in the indicators of spatial memory ability between the two groups,suggesting that the contemporary enriched environment(non-genetic)could improve their anxiety behavior,but could not improve their spatial memory impairment.In the F2 generation,the related behavioral results still suggested that the contemporary enriched environment could reduce the level of anxiety in mice,but did not improve the spatial memory ability.In the F3 generation,for male mice,the contemporary enriched environment increased the percentage of target distance in water maze,but had no effect on other anxious behaviors and spatial memory ability(it did not continue to reduce anxiety level as in the F2 generation).In the analysis of the influence of the enriched environment in previous generation on anxiety and memory in the F2 generation,for male mice,the two behavioral indicators reflecting the anxiety level showed different changes.Specifically,the open field experiment latency indicated that the enriched environment of the previous generation increased the anxious behavior,while the latency of black-white alley showed the opposite result.The swimming distance of LPS-ECM group was lower than that of LPS-CCM group,and the percentage of targeted distance in water maze was higher than that of LPS-CC group,which reflected that the enriched environment of the previous generation improved the spatial memory ability.For female mice,the number of blackterminal stay in LPS-ECF group was lower than that in LPS-CCF group,and the swimming distance in LPS-ECF group was lower than that in LPS-CCF group,suggesting that the enriched environment in the previous generation contributed to the improvement of anxiety level and the impairment of spatial memory ability.In the F3 generation,for male mice,LPS-EECM had a higher peripheral time in open field than LPS-CCCM group.In the water maze experiment,the swimming distance of LPS-EECM group was lower than that of LPS-CCCM group,and percentage of distance in target quadrant in water maze in LPS-EECM group was higher than that of LPS-CCCM group.For female mice,the swimming distance of LPS-EECF group was lower than that of LPS-CCCF group,and the percentage of targeted distance of water maze in LPS-EECF group was higher than that of LPS-CCCF group.It is suggested that the enriched environment increases the level of anxiety and improves the spatial memory ability.4.Exposure to inflammation in late pregnancy decreased the levels of BDNF in F1 and F2 generations,and increased the level of CRF in F1 generation and the levels of corticosterone in F1 and F2 generations.In the LPS treatment group,the expression of CRF-R in PVN region of F1 generation increased,the expression of H1 R in cortical region of F1 and F2 generations increased,and the expression of GABA-AR in LH region of F1 generation decreased.Enriched environment showed the antagonistic effect.Conclusion: Inflammatory insult in late pregnancy affected sleep time(decreased),anxiety behavior(increased),and spatial memory ability(impaired)of offspring,and this effects may be mediated by HPA axis activation.Corticosterone was mainly associated with sleep disturbance,BDNF was mainly associated with impaired spatial memory ability and reduced sleep was also associated with altered expression of neurotransmitter receptors.Enriched environment can adjust this adverse effects,and the effect of enriched environment inherited from the previous generation was more obvious.There were some genetic effects,but no cross-generational inheritance effect was observed except spatial memory impairment.Early life stress is associated with sleep,emotion and cognition of offspring,suggesting the importance of avoiding early life stress to improve the quality of life of social population.