ABSTRACT
Objective:To investigate the protective effect of intermittent fasting on radiation-induced cognitive impairment and the possible underlying mechanism.Methods:A total of 36 male 7-week old c57BL/6J mice were divided into Sham-irradiation and ad libitum (Sham-AL) group, irradiation and ad libitum (IR-AL) group, and irradiation add intermittent fasting (IR-IF) group according to the random number table method, with 12 mice in each group. The cognitive function of mice was assessed by novel object recognition task. The expressions of autophagy gene 5 (ATG5), microtubulesas sociated protein light chain II (LC3II), voltage dependent anion channel protein 1 (VDAC1), interleukin-1β (IL-1β), synaptophysin (SYP), synapsin I (SYN-1), and postsynaptic density 95 (PSD95) were tested by Western blot. The location of VDAC1 in mice hippocampus was detected by immunofluorescence.Results:The discrimination index (-22.45 ± 16.76) of IR-AL group was significantly ( t=3.032, P<0.05) lower than that of Sham-AL group (30.02 ± 9.05). Compared to Sham-AL group, IR-AL group had a decreased expressions of autophagy-related proteins (ATG5 and LC3II), mitochondrial marker (VDAC1), inflammatory factors (IL-1β) as well as synapse-associated proteins SYP, SYN-1 and PSD95 ( t=2.49, 2.19, 2.40, 3.47, 2.87, 2.25, 2.17, 2.31, P<0.05). Compared to IR-AL group, IR-IF group had an increased discrimination index (21.22 ± 5.62) and the increased expressions of ATG5, LC3II, VDAC1, IL-1β, SYP, SYN-1, and PSD95 ( t=2.70, 2.88, 2.71, 3.18, 3.18, 3.11, 3.30, 3.35, 2.53, P<0.05). The immunofluorescence assay revealed that VDAC1 was co-expressed with the markers of astrocytes (GFAP) and microglia (IBA-1), but not with neurons (NEUN). Conclusions:Intermittent fasting could greatly improve the cognitive function of irradiated mice possibly by upregulating VDAC1 expression, induce autophagy, and inhibit the release of inflammatory factors and protecting the synapticplasticity in the hippocampus.
ABSTRACT
Objective:To investigate the effect of MCC950 (a NLRP3 inflammasome inhibitor) on cognitive impairment in mice with radiation-induced inflammatory brain injury.Methods:Mice were divided into normal (NS) group, whole body irradiation (IR) group and MCC950 intervention post irradiation (IR+ MCC950) group according to the random number table method, with 15 mice in each group. The mice in IR group and IR+ MCC950 group were irradiated with a single dose of 4.0 Gy. The radiation source was 137Cs and the dose rate was 1.118 Gy/min. The mice in NS group were not irradiated. Mice in IR+ MCC950 group were injected intraperitoneally with MCC950 once a day (10 mg/kg each time) from 3 weeks after irradiation. Behavioral tests such as new and old things recognition experiment and social cognition experiment were used to detect the cognitive function of mice. Immunohistochemistry was used to detect the expression of NeuN protein in CA3 area of mouse hippocampus. PCR and Western blot were used to detect the expression of NLRP3 inflammatory body related protein. Results:Compared with NS group, the short-term and long-term recognition index of new and old things in the IR group decreased significantly ( t=4.321, 5.473, P<0.01), and the social cognitive recognition index of the IR group also decreased significantly ( t=2.097, P<0.05). MCC950 treatment reversed the above changes (short-term and long-term new and old thing recognition test: t=5.860, 4.598, P<0.05; new and old position recognition test: t=3.040, P<0.05; social cognition test: t=4.021, P<0.01). The expression of NLRP3, Caspase-1, IL-1 β and IL-18 in mice hippocampus of the IR group was significantly higher than that of the control group ( t=2.699, 8.515, 3.340, 3.950, P<0.05). Compared with NS mice, radiation significantly increased the expressions of Bax, Caspase-3 and PARP1 in hippocampus ( t=3.887, 2.742, 3.287, P<0.05), while MCC950 significantly decreased the expressions of Bax, Caspase-3 and PARP1( t=2.852, 4.090, 9.614, P<0.05). Conclusions:NLRP3 inflammasome inhibitor MCC950 could alleviate radiation-induced cognitive impairment, which may be due to the inhibition of hippocampal inflammatory and neuronal death.
ABSTRACT
Objective To examine role and possible mechanism of enriched environment (EE) on regulating recovery of visual function in adult monocular deprivation amblyopia mice.Methods A total of 72 healthyKunming mice were divided into normal control group,monocular deprivation (MD) group,MD+EE group and M D+ fluoxetine group by random number table.Except for the normal control group,the mice in the other groups were sutured on the right eyelid 21 days after birth to establish MD amblyopia model.the mice were fed in standard environment or EE for 4 weeks according to the group.Visual acuity and flash visual evoked potential (F-VEP) of mice in each group were detected.The distribution of microtubule associated protein 2 (MAP2) in visual cortex of adult amblyopic mice were detected by immunohistochemistry.The expression of MAP2,synaptophysin (SYP) and postsynaptic density protein-95 (PSD-95) protein in visual cortex of adult amblyopic mice were detected by western blot.The experimental protocol was approved by the Animal Care and Use Committee of Hunan Children's Hospital and conformed to the National Institutes of Health Guide for the Care and Use of Laboratory Animals.Results There was a significant difference in the visual acuity of deprived eye among each group (F=114.632,P＜0.001).The visual acuity in MD group is lower than that in normal control group,with a significant difference (t =15.480,P＜0.001).Compared with MD group,visual acuity was restored in MD+ EE group and MD +fluoxetine group,with significant differences (t =15.071,P ＜ 0.001;t =14.841,P ＜ 0.001).There was a significant difference in the P2 latency and amplitude of F-VEP in deprived eye among each group (F=36.510,P=0.000;F=34.140,P=0.000).Compare with normal control group,P2 latency was prolonged and P2 amplitude of F-VEP was decreased in deprived eye in MD group,with significant differences (t =10.220,P =0.000;t =10.09,P =0.000).Western blot assay showed that there was a significant difference in the expression of MAP2 in visual cortex contralateral deprived eye among each group (F=18.142,P=0.000).The expression of MAP2 in MD group was significantly lower than that in normal contral group (t=3.056,P＜0.01);Compared with MD group,MAP2 expression was increased in MD+EE group and MD+fluoxetine group (t =2.541,P =0.031;t =2.157,P =0.017).There were significant differences in the expression of SYP and PSD-95 in visual cortex contralateral to deprived eye among each group (F =12.871,P =0.000;F =25.060,P =0.000).Compared with normal contral group,SYP and PSD-95 expression in visual cortex were down-regulated in MD group,with significant differences (t =6.054,P =0.000;t =8.631,P =0.000).The expression of SYP and PSD-95 protein in MD+EE group and MD+fluoxetine group were significantly higher than those in MD group (all at P＜0.05).Conclusions EE can recover visual function through up-regulating the expression of MAP2,which can modulate the dendritic branch trim and neural plasticity of visual cortex in adult MD mice.
ABSTRACT
Objective To investigate the protective effect and mechanism of environmental enrichment(EE)on radiation induced cognitive dysfunction in mice.Methods A total of 45 female Kunming mice(2-month old)were randomly divided into control group,irradiation group and irradiation plus EE group with 15 in each group.Irradiation group and irradiation plus EE group were treated with a single dose of 4 Gy whole body irradiation,irradiation plus EE group were housed in EE condition for 35 d after irradiation.The object recognition task was used to evaluate the cognitive function of mice.The expression of microglial marker IBA-1 in hippocampus was determined by immunohistochemical staining.The expressions of CD68 and synaptophysin(SYP)proteins in hippocampus were assayed by Western blot.Results Compared with control group,the irradiation group had a low discrimination ratio in object recognition task and had a remarkable low level of SYP expression in hippocampus(t＝3.66,6.84,P＜0.05).In addition,radiation activated microglia in hippocampus by increasing the number of IBA-1-positive cells and enhancing the expression of CD 68(t ＝6.83,5.79,P ＜0.05).Compared with irradiation group,irradiation plus EE group increased the discrimination ratio and the expression of SYP in hippocampus(t＝3.56,4.06,P＜0.05),while the number of IBA-1-positive cells and the expression of CD68 were significantly reduced(t＝7.69,4.59,P＜0.05).Conclusions A single dose of 4 Gy whole body irradiation leads to cognitive dysfunction in mice,while EE could effectively improve the animals′cognitive behavior possibly by inhibiting microglial activation and preventing synapse loss in hippocampus.
ABSTRACT
Objective This study was to investigate the effect of caloric restriction on the plasticity of visual cortex in adult monocular deprivation (MD) amblyopic mice,as well as to promote the treatment of amblyopia,and to explore the possible molecular mechanism of this benefical effect.Methods Fifty healthy newborn Kunming mice of clean grade were randomly divided into 3 groups using a random number table method:normal control group (n =14),MD+ ad libitum group (n=18) and MD+ caloric restriction group (n=18).A mouse model of adult MD amblyopia was established,and caloric restriction intervention and ad libitum were performed on MD + caloric restriction group and MD+ ad libitum group,respectively.The visual acuity and flash visual evoked potential (F-VEP) of each group were detected.The synaptic structure of visual cortex neurons was observed by transmission electron microscope,and the expression of phosphorylated AMP-activated protein kinase-α(p-AMPKα) and silent information regulator 1 (SIRT1) in visual cortex were detected by Western blot.The animal feeding and use was in accordance with the standards set by the ARVO.Results The weight of mice in MD+ caloric restriction group increased from the beginning of the first week,and was significantly lower than that in the MD + ad libitum group (P＜0.05).Compared with the MD+ ad libitum group,the visual acuity was restored,the latency was shortened,and the amplitude of F-VEP was increased in the deprived eyes of MD+ caloric restriction group (all at P＜0.05).Transmission electron microscope observation showed that the width of synaptic gap of visual cortical neurons was significantly narrower,and the thickness of postsynaptic density was significantly thicker in MD+ caloric restriction group than that in the MD+ ad libitum group (both at P＜0.05);compared with the normal control group,the synaptic gap was widened and the postsynaptic density was significantly thicker than that in the MD+ ad libitum group (both at P＜0.05).Western blot showed that the expression of p-AMPKα in visual cortex in the normal control group,MD+ caloric restriction group and MD+ ad libitum group was 0.89±0.03,0.94±0.02 and 0.74 ±0.02,and the expression of SIRT1 was 0.97±0.11,0.95±0.14 and 0.58±0.13,respectively,showing significant differences among the three groups (F =14.57,P =0.00;F=23.91,P=0.00),the expressions of p-AMPKα and SIRT1 in visual cortex were increased in MD+ caloric restriction group than those in M D+ ad libitum group (both at P＜0.05).Conclusions Caloric restriction can restore the ultrastructure of synapses and improve the visual cortical plasticity in adult MD mice,so that help to improve visual function.Its mechanism may be related to the activation of AMPK-SIRT1 pathway.