Role Of Necroptosis In Sevoflurane Induced Cognitive Dysfunction In Aged Rats

Objective:Necroptosis is a newly proposed non-caspase-dependent cell death pattern,and studies have indicated that necroptosis is involved in a variety of central nervous system diseases.In this experiment,the cognitive impairment model of rats was established by inhalation of sevoflurane,and the effect of necroptosis in sevoflurane-induced cognitive dysfunction in aged rats was discussed.Methods:Ninety pathogen-free male Sprague-Dawley rats,aged 18months,weighing 500⁶00 g,were randomly divided into 3 groups?n=30each?:control group?C group?,cognitive dysfunction group?P group?and necroptosis inhibitor necrostatin-1 group?P+N group?.Rats in P group and P+N group were inhaled 2%sevoflurane for 5 h.Necrostatin-1 3.5 mg/kg was injected via the caudal vein in P+N group while the equal volume of DMSO and saline was given in P group and C group separately 5 min before anesthesia.Morris water maze test was performed on 1^st day before anesthesia and 1^st and 7^th days after anesthesia.Then the rats were sacrificed and the hippocampal tissues were obtained for detection of the expression of RIPl and RIP3 using Western blot and the cytosolic calcium concentration by flow cytometry.The histopathological changes of hippocampus were observed by HE staining under optical microscope.Results:1.Morris water maze test results:There was no significant difference among the 3 groups on escape latency and the number of crossing the original platform at 1^st day before anesthesia?P>0.05?.Compared with 1 ^st day before anesthesia,the escape latency was significantly prolonged and the number of crossing the original platform was decreased in P and P+N group at 1^st and 7^thh day after anesthesia?P<0.05?.Compared with C group,the escape latency was significantly prolonged and the number of crossing the original platform was decreased in P and P+N group at 1^st and 7^th day after anesthesia?P<0.05?.Compared with P group,the escape latency was significantly shortened and the number of crossing the original platform was increased in P+N group at 1 ^stt and 7 ^th day after anesthesia?P<0.05?.Western blot results:There was no significant difference among the 3groups on the expression of RIP1 and RIP3 at 1^st day before anesthesia?P>0.05?.Compared with 1^st day before anesthesia,the expression of RIP1and RIP3 was up-regulated in P group and P+N group at 1^st and 7^th day after anesthesia?P<0.05?.Compared with C group,the expression of RIP1 and RIP3 was up-regulated in P group and P+N group at 1^st and 7^th day after anesthesia?P<0.05?.Compared with P group,the expression of RIP1 and RIP3 was down-regulated in P+N group at 1^st and 7^th day after anesthesia?P<0.05?.Flow cytometry results:There was no significant difference on cytosolic calcium concentration among the 3 groups at 1^st day before anesthesia?P>0.05?.Compared with 1^st day before anesthesia,the cytosolic calcium concentration was increased in P group and P+N group at 1^st day after anesthesia?P<0.05?.Compared with C group,the cytosolic calcium concentration was increased in P group and P+N group at 1^st day after anesthesia?P<0.05?.Compared with P group,the cytosolic calcium concentration was decreased in P+N group at 1st day after anesthesia?P<0.05?.There was no significant difference on cytosolic calcium concentration among the 3 groups at 7^th day after anesthesia?P>0.05?.HE staining results:The morphological structure of hippocampal neurons in the 3 groups was normal at 1^st day before anesthesia.At 1^st day after anesthesia,the vertebral cells of P group and P+N group were disordered and loose,the boundary was blurred or even disappeared,and the nucleus was pyknosis.The P+N group was lighter than the P group.Conclusions:Necroptosis is partly involved in sevoflurane-induced cognitive dysfunction in aged rats and the mechanism of which may be related to the increase in cytosolic calcium concentration in neuron cells.