The Role Of Brain Derived Neurotrophic Factor Mediated Synaptic Morphological Changes In Postoperative Cognitive Dysfunction

Objective:Exploratory laparotomy with sevoflurane anesthesia and to prepare for postoperative cognitive dysfunction model in aged mice.After postoperative cognitive dysfunction model appeared,the relationship between the expression changes of brain-derived neurotrophic factor(BDNF)and its precursor and the morphological changes of neurons in the hippocampal area is investigated.To explore the possible mechanism of postoperative cognitive function protection.Methods:Healthy and clean elderly male C57BL6 mice were selected 108 and they were aged from 17 to 18 months.The mice were divided into 3 groups by random number table method and 36 of each group(n = 36): control group(group C),anesthesia group(group A),surgical group(group S).The group S used 4% sevoflurane to anesthetize the mice under the special anesthesia apparatus and the surgical model was established by laparotomy;The group A only used 4% sevoflurane to anesthetize the mice and the time of anesthesia was the same as that of group S;The group C did not do special treatment.The Morris water maze test was used as the model to establish successful judgment criteria.The swimming distance and escape latency of the mice water maze were recorded.The average of the recorded results were used as the preoperative results.The operation of preoperative test was repeated on the 3rd and 7th day after surgery.The swimming distance and escape latency of the mice water maze were recorded.The average of the recorded results were used as the postoperative results.Specimens were collected on the 3rd and 7th day after the Morris water maze test.Respectively by using HE staining and Golgi histological staining(Golgi-Cox)method to observe the occurrence of postoperative cognitive dysfunction in aging mice compared with normal aged mice hippocampus neuron histopathologic changes and morphological changes.The expression of brain-derived neurotrophic factor(BDNF)and precursors of brain-derived neurotrophic factor(pro BDNF)in hippocampus of rats was determined by immunoimprinting(Western Blot).The expression of tissue plasminogen activator(t PA)was determined by enzyme-linked immunosorbent assay(ELISA).Results:1.Compared with group C,the swimming distance and the escape latency of the water maze test in group A and group S were prolonged(P < 0.05);The expression level of BDNF and pro BDNF protein was up-regulated(P < 0.05);The expression level of t PA protein was up-regulated(P < 0.05);HE staining showed that the pyramidal cells in the hippocampal CA1 region were disordered.The cytoplasm was deeply stained and the nuclei were solid;Golgi staining showed that the axons of hippocampal neurons and dendritic branches were sparse and the length decreased.2.Compared with group A,the swimming distance and the escape latency of the water maze test in group S were prolonged(P < 0.05);The expression level of BDNF and pro BDNF protein was up-regulated(P < 0.05);The expression level of t PA protein was up-regulated(P < 0.05);HE staining showed that the pyramidal cells in the hippocampal CA1 region were disordered.The cytoplasm was deeply stained and the nuclei were solid;Golgi staining showed that the axons of hippocampal neurons and dendritic branches were sparse and the length decreased(P < 0.05).Conclusion:1.The postoperative cognitive ability of the aged mice were all reduced after the operation of sevoflurane anesthesia and sevoflurane anesthesia without surgery.After the operation of sevoflurane anesthesia postoperative cognitive decline was more obvious in elderly mice.2.The expression of BDNF and pro BDNF and t PA in old mice were all up-regulated after the operation of sevoflurane anesthesia and sevoflurane anesthesia without surgery.The increase of BDNF and pro BDNF and t PA protein expression was more obvious after the operation of sevoflurane anesthesia.3.The stimulation can induce the apoptosis and neuronal morphological changes in the hippocampal area of the aged mice after the operation of sevoflurane anesthesia and sevoflurane anesthesia without surgery.The apoptosis and neuronal morphological changes in the hippocampal area of the aged mice were more obvious after the operation of sevoflurane anesthesia.