Effects Of Preconditioning With Sevoflurane Inhalation On Postoperative Cognition Disorders Of Aged Rats

Objective: To investigate the effects of preconditioning with the halogenvolatile anesthetic sevoflurane pretreatment on postoperative cognitivedisorders of aged rats in this study, in order to provide reference for theclinical research and anesthetic management.Methods: One hundred and thirty eight healthy male SD rats, aged18months, weighing400-450g were randomly divided into3groups (n=46each):control group (group C), operation group (group O) and sevofluranepreconditioning group (group Sev).Group C: the rats were only anesthetized with intraperitoneal injection40mg/kg pentobarbital and not underwent any operation.Group O: the rats were anesthetized with intraperitoneal injection40mg/kgpentobarbital and underwent30min of exploratory laparotomy, that skinpreparation and sterilization of rat abdominal, abdominal incision3cm, forcepblunt dissection of muscles and revealed the peritoneum, dissecting scissor cutthe the peritoneum and exposed abdominal, probe needle sequence probe theliver, spleen, stomach, small intestine and large intestine of rats, total operativetime was30min. Suture wounds after the surgical, and in wound pastebreathable waterproof wound foil, intraperitoneal injection of penicillin toprevent postoperative wound infection in the end.Group Sev: the rats were placed in homemade plexiglass anesthesia box,the inlet end connected to sevoflurane vaporizer with oxygen as the carrier gas,the outlet end is connected anesthetic gas monitor, concentration wasmaintained inside sevoflurane anesthesia was2.4%, laying a small amount ofsoda lime at the bottom of the anesthetizing chamber to absorb carbon dioxide,continued30min，then treat like group O following by inhaled room air30min. 10rats in each group were randomly selected, the escape latency, thefrequency of crossing the original platform and the time of staying at theoriginal platform quadrant was assessed using Morris water maze on30minbefore operation and1st,3rd,5th,7th days after operation.10rats in eachgroup were randomly selected, were anesthetized with pentobarbital then thebrain tissues were taken for detecting the apoptotic index of hippocampalneuronal with TUNEL, the apoptotic rate and intracellular [Ca2+]iofhippocampal neuronal with flow cytometry and the ultrastructure ofhippocampal neuronal(mitochondria, endoplasmic reticulum, golgi apparatus,cytoplasm and nucleus) was observed with transmission electron microscopeat30min before operation and1st,7th days after operation.6rats in eachgroup were randomly selected, arterial blood samples were taken immediatelybefore surgery(T0) and at10min（T1）,20min (T2),30min（T3）in surgery forblood gas analysis and body temperature.Results: No significant change was found in the results of blood gasanalysis and body temperature at different time points in three groups(P>0.05).Compared with30min before operation, the time of staying at the originalplatform quadrant, the escape latency was prolonged and frequency ofcrossing the original platform were decreased after operation (P<0.05);intracellular [Ca2+]iand apoptotic index/rate of hippocampal neuronal wereincreased at1st,7th days after operation in the group O (P<0.05). The time ofstaying at the original platform quadrant, the escape latency was prolongedand frequency of crossing the original platform were decreased at1st,3th,5thdays after operation (P<0.05); the intracellular [Ca2+]iand apoptotic index/rateof hippocampal neuronal were increased at1st after operation in the group Sev(P<0.05). No significant change was found indicators of the above at the7thday after operation in the group SEV (P>0.05). No significant change wasfound indicators of the above at time points after operation in the group C(P>0.05).Compared with group C, The time of staying at the original platform quadrant, the escape latency was prolonged and frequency of crossing the original platform were decreased（P＜0.05); intracellular [Ca2+]iand apoptotic index/rate of hippocampal neuronal were increased after operation in group O (P＜0.05). The time of staying at the original platformquadrant, the escape latency was prolonged and frequency of crossing the original platform were decreased at1st,3th,5th days after operation(P<0.05); no significant change was found indicators of the above at the7th day after operation in the group SEV(P>0.05).Compared with group O, the time of staying at the original platformquadrant, the escape latency was shorten and frequency of crossing theoriginal platform were increased (P＜0.05); intracellular [Ca2+]iand apoptotic index/rate of hippocampal neuronal were decreased after operation in group Sev（P＜0.05).Microscopic examination showed normal hippocampal neuronal in group C;microscopic examination showed cytoplasm were severe edema, the inner andouter membranes of mitochondria were fusion and disappear, roughendoplasmic reticulum degranulation at1st after operation in group O;cytoplasmic edema was lighten, most of the mitochondria still showedvacuoles, the golgi apparatus and rough endoplasmic reticulum abnormalitiesat7th after operation in group O; microscopic examination showedcytoplasmic lighter edema, mitochondria showed vacuoles, the roughendoplasmic reticulum mildly abnormal, no expansion and degranulation at1stafter operation, vacuolization of mitochondria significantly reduced, Therough endoplasmic reticulum structure near normal at7th after operation ingroup Sev.Conclusions:12.4%Sevoflurane preconditioning can reduce postoperative cognitive function in aged rats.2The regulation imbalance of calcium homeostasis, reduction of cell intracellular [Ca2+]iand apoptosis are involved in the mechanism.