| Objective: Establishment of Hypoxic Ischemic Encephalopathy(HIE)model and Remote Ischemic post-conditioning(RIPC)model;to observe the protective effect of RIPC on HIE in neonatal rats.To investigate the effects of remote ischemic postconditioning on the expression of calcium sensitive receptor(CaSR)and serine/threonine protein kinase/phosphoinositol 3-kinase(Akt/Pi3k)signaling pathway in HIE rat brain tissue.Methods: 120 newborn Wistar rats aged 7 days were randomly divided into: Sham operation group(S group: only bilateral common carotid artery free treatment was performed),hypoxic-ischemic encephalopathy group(HIE group: bilateral common carotid artery ligation and hypoxia treatment were performed for 60 minutes),remote ischemic postconditioning 5 min group(R1 group: after ischemia and hypoxia treatment,rats underwent 5-minute ischemia/5-minute reperfusion of bilateral lower extremities with three cycles immediately),and remote ischemic 10 min group(R2 group: after ischemia and hypoxia treatment,rats underwent 10-minute ischemia/10-minute reperfusion of bilateral lower extremities with three cycles immediately).After the establishment of the hypoxic-ischemic encephalopathy model,the R1 group and the R2 group were treated with distant ischemia for 5 and 10 min cycles for 5 consecutive days.The behavior,weight gain rate,histopathological and ultrastructural changes of neurons were observed;immunohistochemical staining was used to detect the expression levels of CaSR,Bax,Bcl-2,p-Akt and Akt proteins,and western blot was used to detect the expression of p-akt,Bax and bcl-2 proteins.Results: Compared with group S,rats in HIE group showed abnormal behavior such as head tremor,unstable walking and poor turning ability.Compared with HIE group,the mental state,balance and turning ability of rats in R1 group and R2 group were improved,and limb shaking symptoms were alleviated.There was no significant difference in body weight among all rats at the age of 7 days(P>0.05).At the age of 12 days,the weight of rats in the S group was significantly higher than that in the HIE group,R1 group and R2 group(P<0.05).There was no significant difference in body weight between HIE group,R1 group and R2 group(P>0.05).The weight growth rate of HIE group was significantly lower than that of S group(P<0.05)and the weight growth rate of R1 group and R2 group was significantly higher than that of HIE group(P<0.05).The cell morphology and structure of cerebral cortex and hippocampus in group S were normal and orderly.In HIE group,cells were disorderly distributed,structure was absent,lysosomes were increased,mitochondria were edema and cells were severely damaged.The arrangement of neurons in group R1 and R2 was more orderly than that in group HIE,and the degree of cell edema and structural damage were reduced.CaSR and Bax proteins were significantly increased in HIE group compared with S group(P<0.05);the expression of p-Akt and Bcl-2 protein was significantly decreased compared with that of group S(P<0.05);CaSR and Bax proteins in R1 group and R2 group were significantly reduced compared with HIE group(P<0.05);p-Akt and Bcl-2 protein expressions were significantly increased compared with HIE group(P<0.05).There was no significant difference in each index between group R1 and group R2(P > 0.05).Conclusions: RIPC can inhibit the abnormal expression of CaSR in HIE rat brain tissue,activate the Akt/Pi3 k pathway and up-regulate the expression of p-Akt to protect the damaged brain tissue.RIPC,by promoting bcl-2 expression of bcl-2 family members and reducing Bax expression,participates in the protection of damaged neurons and plays a role in brain protection.RIPC with a 5min cycle repetition has an obvious protective effect on HIE,and there is no significant difference between RIPC with a 5min cycle and RIPC with a 10 min cycle on brain protection. |
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