| ObjectiveTo observe the effect of Iduna on the neuronal axon damage of neonatal rats caused by hypoxia-ischemia(HI).Methods1.7-day-old SD rats were randomly divided into Sham,HI-S,HI-M and HI-L groups.TTC staining was used to detect cerebral infarct volume of newborn rats in each group,and to determine the conditions of the HI brain injury model.Select stable model conditions,and28 rats were randomly divided into Sham and HI groups.24 hours after HI: Laser speckle imaging was used to observe cerebral blood flow;HE staining to observe brain tissue morphological changes;Transmission electron microscopy to observe neurons and axons microstructure;Immunofluorescence to detect the expression of axon marker proteins Tau and neuron marker protein Tuj1;Western blot was used to detect the expression of Iduna,Tau and Tuj1.2.102 newborn rats were randomly divided into Sham,Vehicle and Ad-Iduna groups.48 hours after HI: TTC staining was used to detect cerebral infarct volume;Laser speckle imaging was used to observe cerebral blood flow;HE staining to observe brain tissue morphological changes;Transmission electron microscope to observe neuron and axon microstructure;Immunohistochemistry to detect the expression of Iduna,Tau and Tuj1;Western blot to detect the expression of Iduna,Tau and Tuj1;Behavioral testing: righting reflex to evaluate the early nerves of HI neonatal rats developmental status;It was used to assess the long-term learning and memory ability of rats by Morris water maze after HI brain injury at 1 month.Results1.The infarct volume of HI brain damage model in neonatal rats prepared were recovered for 1 hour after ischemia,and were 2.5 hours of hypoxia was relatively stable.Compared with the Sham group,cerebral blood flow in the cerebral cortex of the ischemic side of the neonatal rats in the HI group was found to be significantly reduced(P<0.05),and the tissue structure of the ischemic side cortex and hippocampus was disordered after HI brain injury.The number of neurons survived was reduced,the structure of axon and cell subcellular organelles(mitochondria,etc.)was severely damaged.The expression of Tau and Tuj1 were both reduced(P<0.05),and the expression of Iduna protein in brain tissue was significantly reduced(P<0.05).2.Compared with the Sham group,it was found that the cerebral infarction of the injured side of the neonatal rats in the Vehicle group was increase obviously(P<0.05),the cerebral blood flow was significantly reduced(P<0.05),the structure of cerebral cortex and hippocampus on the injured part of the brain is loose,accompanied with irregular neuron arrangement,the nucleus pycnosis,cracking,karyopyknosis and cellular vacuolization,and the neuron damage score was increased(P<0.05);The structure of the nuclear double membrane in the vehicle group is changed,the chromatin distribution in the nucleus is uneven,and there is aggregation,cytoplasm and axon internal organelles decrease overall,mitochondrial cristae melts or disappears,showing vacuole-like changes,the number of synapses decreases,the synaptic gap disappears,the front and rear synaptic membranes fuse,and the synaptic vesicles within the axon are significantly reduced;The expression of Iduna in brain tissues was increased,but the expressions of Tau and Tuj1 were significantly reduced(P<0.05);The vehicle group’s righting reflex was increased significantly(P<0.05),the incubation period was significantly prolonged(P<0.05),and the total distance was also significantly increased(P<0.05)),but the number of times to find the platform was less than that of the Sham group(P<0.05).Compared with the Vehicle group,the cerebral infarction volume of neonatal rats in Ad-Iduna group was significantly reduced(P<0.05),the cerebral blood flow was significantly increased(P<0.05),and the degree of brain tissue pathological damage was significantly reduced(P<0.05),and the damage of axon structure has also improved,the number of organelles in the cytoplasm and axons has increased,the melting of mitochondrial cristae has been improved,the number of synapses has increased relatively,the synaptic space is obvious,and the synaptic vesicles in axons have increased significantly;The expression of Iduna,Tau and Tuj1 in brain tissue were increased(P<0.05);The righting reflex time of newborn rats was significantly shortened(P<0.05),the incubation period was significantly shortened(P<0.05),and the total distance was significantly reduced(P<0.05).The number of platforms increased significantly(P<0.05).ConclusionHypoxia-ischemia induced brain neuronal axon damage in neonatal rats may be related to the expression level of Iduna.Up-regulation of Iduna has a protective effect on neuronal axon damage in neonatal rats caused by hypoxia-ischemia,and can improve early neural development injury and long-term learning memory and spatial exploration ability in newborn rats caused by hypoxia-ischemia. |
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