Study Of Total Inhalational Anaesthesia With Isoflurane For Learning-memory In Adult Rats

Objective:To investigate whether postoperative cognitive dysfunction (POCD) is related to isoflurane by observing the capacity of space learning and memory of the adult male SD rats after isoflurane anesthesia.Methods:Before the experiment, all adult male SD rats were given place navigation test training and space exploration test for 5d, (1) escape latency, path length, the residence time and length in the first quadrant were recorded to calculate the percentage of residence time in escape latency and residence length. (2) The total distance, frequency of crossing platform, velocity of swimming, the residence time and length in the first quadrant were recorded to calculate the percentage of residence time in escape latency and residence length in path length. (3) After training, all rats were divided randomly into six groups (n=12), group A (control group,n=12), group B (O2 grou p,n=12), group C (group of 2 hours after inhalation ISO, n=12), group D(group of Id after inhalation ISO, n=12), group E (group of 7d after inhalation ISO, n=12), group F(group of 14d after inhalation ISO, n=12),.4 Group A were trained again without any intervention; group B were given oxygen for 2h before training again; respiration rate were recorded before 2.0% ISO, during administration, and after ISO in group C, D, E and F.5 All groups were trained again after anesthesia recovery, and the same observation indexes were recorded.Results:(1) Before administration and after recovery, respiration rates were respectively 83.5±6.2 and 82.3±6.4 without significant difference (P>0.05); After anesthesia, within the first hour and the second hour respiration rates were respectively 62.7±4.8bpm and 63.1±8.2bpm showing no significant difference (P>0.05) which were significantly reduced than group control (P<0.01).The time of loss and recovery of righting reflex were 8.0±4.1min and 7.5±4.6 min respectively with no significant difference (P>0.05). The time of abolition and total recovery of clamp-tail reflex were 13.1±3.9min and 12.2±4.3min without significant difference (P>0.05).(2) Before anesthesia, the training results of escape latency in the first day to the fifth day were 54.1±20.1s,26.7±15.5s,19.4±9.9s,16.5±8.0s, 13.1±6.5s; The training results of total distance were 1266.5±405.0cm,768.3±487.0cm, 501.5±241.3cm,428.0±212.7cm,372.7±166.2cm; the residence time in the first quadrant were 14.2±5.6s,8.1±4.2s,7.9±4.1s,6.4±2.9s,5.8±3.41s respectively; The residence length in the first quadrant were 272.9±85.3,197.0±106.4,181.0±79.8,144.3±62.1, 150.4±57.9(cm); the percentage of the residence time in the first quadrant to the escape latency were 26%,30%,41%,39%,44%; The percentage of the residence length in the first quadrant to the total distance were 22%,26%,36%,34%,40%. Comparing with group A, escape latency, total distance, residence time and length in the first quadrant of group D were significantly prolonged (P<0.05), the percentage of the residence time in the first quadrant to the escape latency and the percentage of the residence length in the first quadrant to the total distance of group D were significantly smaller than other groups. All observation indexes in place navigation task were with no significant difference in all groups but in group A and D. In the space exploration test, total distance in group A to F were separately 3170.8±271.4cm,3633.7±249.5cm,3138.7±357.0cm,2588.6±165.7cm, 3694.6±201.6cm,2828.9±284.8; the number of times of crossing platform were 2.3±1.5times,1.8±1.3times,2.1±1.0 times,1.5±1.0 times,2.3±1.4 times,2.1±1.0 times; Average velocity were 26.5±2.2,30.3±2.1,26.2±3.0,21.7±1.3,26.3±1.6,26.6±2.3(s); Residence time in the first quadrant were 53.1±5.5s,46.8±6.5s,47.6±11.6s,40.3±10.0s, 45.2±6.3s,49.9±5.9s; Residence distance in the first quadrant were 1267.5±189.1, 1271.8±124.0,1089.3±217.7,963.8±264.6,1190.1±132.5,1327.2±147.5(cm); the percentage of residence time in total time were 44%,39%,40%,34%,38%,42%; the percentage of residence length in total distance were 40%,35%,35%,30%,37%,42%. The total distance of group B and D were with significant difference comparing with group A (P<0.01), the total distance of group B was longer than group A, but group D was shorter than group A. The frequency of crossing platform of group B and D were significantly reduced (P<0.05); The average velocity of group B was significantly higher than group A (P<0.05), but group D was lower than group control (P<0.01). The total distance, the frequency of crossing platform, the percentage of residence time to total time and the percentage residence distance to total length were all reduced in group D. The total length and average velocity were with no significant difference between group A and C, between group E and F (p>0.05). The residence time and distance in the first quadrant, the percentage of residence time to total time and the percentage of residence distance to total length in all groups but group B were with no significant difference (P>0.05) Conclusion:Within 24h after anesthesia, domestic isoflurane may influence learning-memory in rats which can be improved gradually to total recovery within 7 to 14d. It can be supposed from the experiment that postoperative early POCD is related with domestic isoflurane. Objective:To investigate the relationship between isoflurane and postoperative cognitive dysfunction (POCD). The variation were determined, which plasma corticosterone, hippocampal BDNF and NGF in adult rats which were trained by morris water maze and inhaled isoflurane.Methods:After morris water maze training, rats which inhaled isoflurane were randomly assigned into two subgroups:one of the subgroups was divided into:Al (control group, n=6), B1 (O2 group, n=6), C1 (group of 2 hours after inhalation ISO, n=6), D1 (group of lday after isoflurane inhalation, short for ISO 1, n=6), E1 (group of 7day after isoflurane inhalation, short for ISO7, n=6), F1 (group of 14day after isoflurane inhalation, short for ISO14, n=6). After revival from anesthesia and performance of morris water maze (C group), the blood of rats in group A1, Bl and C1 were immediately collected for extracting plasma, after which these rats were killed for extracting the supernatant fluid of hippocampal homogenate.24h (Dl),7d (El) and 14d (F1) after rats of D, E and F group reviving from anesthesia, the extraction of plasma and homogenate of hippocampal tissue was executed respectively. ELISA test was used to detect the plasma corticosterone, hippocampal BDNF and NGF.Results:(1) the plasma corticosterones (ng/ml) of rats in each group were respectively: 663.3±209.0,395.0±219.8,647.3±101.4,865.5±127.4,658.0±258.0,534.2±167.9; (2) hippocampal BDNFs (pg/mg) of each group were respectively:142.7±44.2,126.8±48.2, 140.8±25.8,449.5±60.5,156.7±72.5,170.3±75.6; (3) hippocampal NGFs (pg/mg) of each group were:90.0±49.1,75.0±36.4,93.7±40.8,75.2±50.9,92.8±26.4,99.6±38.3. the contents of plasma corticosterone and hippocampal BDNF in ISO1 group were significantly higher than other groups (P<0.01). Plasma corticosterone of B1 group was lower than other groups (P<0.01). There was not significant change in NGF contents between each group.Conclusions:1 day after isoflurane inhalation, plasma corticosterone and hippocampal BDNF increased significantly.7-14 days after isoflurane inhalation, plasma corticosterone and hippocampal BDNF recovered to normal level, which was consistent with behavioral observations of part one. Therefore, it could be inferred that the change of plasma corticosterone and hippocampal BDNF after isoflurane inhalation is one of the reasons which induce recent POCD after anesthesia in rats. Objective:To further observed the relationship between inhalation of Isoflurane and postoperative cognitive dysfunction (POCD). We have observed the BDNF, NGF expression in hippocampal of adult rats after morris water maze training and inhalation of isoflurane.Methods:After the random distribution of PartⅠ, the remaining rats in each group were divided into 6 groups:A2(Control group, n=6), B2(O2 group, n=6), C2(2 hours after inhalation of Isoflurane, n=6), D2(lday after inhalation of Isoflurane, short for ISOl,n=6), E2(7 days after inhalation of Isoflurane, short for ISO7, n=6), F2(14 days after inhalation of Isoflurane, short for ISO14, n=6). At 2 hours later after group C fully recovery from anesthesia, plasma corticosterone levels of group A2, B2, C2 were examined. rats systemic perfusion polyphosphate formaldehyde after exsanguinate.The immunohistochemistry(SABC dyeing) were done after taking the brain slices and fixation paraffin embedding, and investigated the expression of BDNF and NGF.Results:(1)After hippocampus had dyed of, the nuclei are violet blue, BDNF or NGF reaction district appear yellow or tan, the BDNF or NGF express area located in cytoplasm of hippocampal cell; (2) The mean optical density of BDNF in hippocampus DG area of A2, B2, C2, D2, E2 and F2 group:1.140±0.041,0.155±0.032,0.144±0.019,0.225±0.076, 0.165±0.040,0.147±0.053; CA3 area:0.131±0.043,0.123±0.031,0.138±0.014, 0.236±0.053,0.126±0.052,0.132±0.075; CA2 area:0.156±0.036,0.142±0.056, 0.151±0.023,0.222±0.054,0.161±0.047,0.151±0.082; CA1 area:0.158±0.021, 0.163±0.027,0.154±0.019,0.223±0.057,0.146±0.039,0.156±0.028.The D2 group were higher than other group (P<0.05).The value of other group and other interval compare no difference. (3) The mean optical density of NGF in hippocampus DG area of each group: 0.164±0.031,0.165±0.074,0.164±0.016,0.164±0.059,0.166±0.060,0.156±0.077; CA3 area:0.174±0.029,0.174±0.075,0.165±0.023,0.170±0.053,0.176±0.060,0.172±0.068; CA2 area:0.178±0.032,0.177±0.061,0.162±0.067,0.173±0.065,0.169±0.059, 0.168±0.041; CA1 area:0.163±0.028,0.178±0.072,0.166±0.004,0.163±0.045,0.170±0.054 0.162±0.046. The value of each group (P>0.05 and each area of one group (P>0.05) compare no difference.Conclusions:A certain degree of damage of hippocampus organization was observed at lday after after total inhalational anaesthesia of Isoflurane, it may be the major factor of POCD after anesthesia. The damage recovered during 7-14 days after inhalation of Isoflurane. This results are consistent with Part1 and Part 2.