Proteomic Analysis Of Hippocampus Synaptosomes In Aged Rat After Isoflurane Anesthesia

Objective Through measuring the alteration of proteome of hippocampus synaptosomes in aged rat after isoflurane anesthesia in order to demonstrate the possible mechnisms of isoflurane-induced behavioural changes in aged rats.Methods The first stage of the experiment:Twenty seven selected 22-month-old female Sprague Dawley (SD) rats were randomly divided into group C (n=6) and group I (n=21). The rats in group C inhaled 80% oxygen for 2 hours. The rats in group I were endotracheal intubated after induced by 3% isoflurane, then inhaled 2% isoflurane and 80% oxygen to maintain anesthesia for 2 hours. Vital signs were monitored during anesthesia. Behavioural changes were evaluated by open-field test and Y-maze 24 hours later. According to the Y-maze test, group I was divided to group IA and IB, group IA were rats which had a decline of learning and memory ability, and group IB were not. The bilateral hippocampus were cut down and stored into liquid nitrogen.The second stage of the experiment:After hippocampus synaptosomes (from six rats per group) were isolated with sucrose gradient centrifugation, the protein of synaptosomes was seperated in the gel by the means of two dimensional gel electrophoresis, and the commassie's blue staining were used to make the gel coloration. After matching the images, we got the different protein among the groups, which were removed and analyzed by mass chromatographic analysis. According to the peptides mass fingerprints, the different protein spots were identified by using database and software from internet.Results The vital signs of rats during anesthesia were stable, two rats were removed during anesthesia and six rats in group I had a decline of learning and memory ability after isoflurane anesthesia. The Y-maze test scores had no statistically significant differences between group IB and group C and there were no statistically significant differences in open-field test scores among the three groups. There were 518±12 protein spots in group IA,501±10 protein spots in group IB,508±11 protein spots in group C.There were 21 (11/10) different protein spots between group IB and group IA, and there were 19 (12/7) different protein spots between group C and group IA.31 protein spots of all spots were identified by the mean of MALDI-TOF-MS, and most of the different protein related to energy metabolism and cytoskeletal structure.Conclusions Some aged rats (6/19) had a decline of learning and memory ability 24h later after 2h isoflurane anesthesia.The decline of learning and memory ability may related to changes of the energy metabolism of synapse in hippocampus, and the change of cytoskeletal structure may involved in the process.