Dexmedetomidine Alleviates Cognitive Dysfunction And Sea In Aged Rats Induced By Sevoflurane Horse Neuronal Apoptosis

Objective: To investigate the effects of dexmedetomidine on cognitive dysfunction in aged rats induced by sevoflurane anesthesia,and to explore the apoptosis of hippocampal neurons in this process.Methods: 96 male Sprague-Dawley rats aged 18-20 months were randomly divided into 4 groups(n=24),which were C group(control group)and S group(sevoflurane group),DS1 group(low dose dexmedetomidine pretreated sevoflurane group)and DS2 group(high dose dexmedetomidine pretreated sevoflurane group),using sevoflurane anesthesia to establish cognitive function Obstacle model.Morris water maze test was performed 4 days after anesthesia,and the number of escape latency and the number of crossing the original platform were compared.After 4 days of anesthesia,18 rats were randomly selected from each group,using Real Time PCR and protein.The mRNA and protein levels of Caspase-3,Bax and Bcl-2 in hippocampus were determined by Western blotting.The remaining 6 rats in each group were observed by transmission electron microscopy to observe the pathological changes of hippocampal neurons.Results: 1.The differences in escape latency between the four groups were compared.There was no significant difference in the escape latency between the first day and the second day of the C group,S group,DS1 group and DS2 group(P>0.05).On the third day of the experiment,the escape latency of the S group was significantly higher than that of the C group(P<0.05),and there was no difference in the escape latency between the DS1 and the S group(P>0.05),while the escape latency of the DS2 group was shorter than that of the S group(P<0.05);On the fourth day of the experiment,the escape latency of S group was significantly higher than that of C group(P<0.05),and the DS1 group and DS2 group were significantly lower than the S group escape latency(P<0.01).2.The difference of the number of crossings of the four groups of rats through the original platform was compared.The C group was significantly higher than the S group and the DS1 group(P<0.05).Compared with the S group,the DS1 group and the DS2 group were significantly increased(P<0.05);Compared with the DS1 group,the DS2 group was significantly increased(P<0.05).3.The mRNA and protein levels of hippocampus in the four groups were significantly higher than those in the C group and the DS2 group(P<0.05).The Bax of each group was significantly higher than that of the C group(P<0.05);and the DS1 group was higher than the DS2 group(P<0.05).The Bcl-2 of each group was significantly lower than that of the C group(P<0.05);and the DS1 group was lower than the DS2 group(P<0.05).4.Comparison of TEM results.There was no significant change in theultrastructure of hippocampal neurons in group C;The hippocampal cells in group S showed nucleus pyknosis and lateral migration,mitochondria,endoplasmic reticulum degeneration,and obvious edema;The cells in the DS1 group showed nuclear pyknosis and lateral migration,and the mitochondria and endoplasmic reticulum edema were alleviated compared with the S group.The pyknosis and lateral migration,mitochondria and endoplasmic reticulum edema of hippocampal cells in DS2 group were all reduced compared with DS1 group.Conclusion: 1.Pretreatment with dexmedetomidine can effectively shorten the escape latency in the water maze test of sevoflurane anesthesia rats,increase the number of crossing the original platform,and effectively improve the cognitive dysfunction caused by sevoflurane anesthesia,50?g /kg dose is better.2.Pretreatment with dexmedetomidine can effectively reduce the expression of Caspase-3 and Bax in hippocampus of sevoflurane anesthetized rats,increase the expression of Bcl-2,and Inhibition of apoptosis in hippocampal cells of sevoflurane anesthetized rats,this effect is better at a dose of 50 ?g/kg3.dexmedetomidine pretreatment can effectively improve the ultrastructure of hippocampal cells in sevoflurane anesthetized rats.