Effects Of Lipid Emulsion On Learning And Memory Function And Synaptic Plasticity After Bupivacaine-induced Seizures In Rats

Objective To explore the effect of lipid emulsion on learning and memory function and synaptic plasticity after bupivacaine-induced seizures in rats.Methods 1.96 SPF male SD rats were randomly divided into 4 groups(n=24): Control group,LE group,BPV+NS group,BPV+ LE group.Control group and LE group were infused with 0.9% sodium chloride injection(NS)and 20% lipid emulsion 1.5m L/kg,respectively,and then pumped at a rate of 0.25 m L/kg/min for 3min.In the BPV+NS group,0.75% bupivacaine was infused at a rate of 1.5m L/kg /min,and NS 1.5m L/kg was infused immediately after seizures,and then pumped at a rate of 0.25 m L/kg/min for 3min.The BPV+LE group was infused with 0.75% bupivacaine at a rate of 1.5m L/kg /min,and the rats were immediately given20% lipid emulsion at 1.5m L/kg after seizures,and then pumped at a rate of 0.25 m L/kg/min for 3min.All the above drugs were delivered via the tail vein.2.The time required for the occurrence and recovery of convulsions in each group during modeling was recorded.The neurobehavioral scores were performed at 0.5h,1h,1.5h,and 2h after modeling to evaluate the therapeutic effect of liped emulsion.3.After the success of modeling,6 rats from each group were randomly selected for the Morris water maze test to evaluate spatial learning and memory ability.4.Golgi staining was used to observe the density of dendritic branches and dendritic spines of nerve cells in the hippocampal CA1 region.5.The expressions of synaptic plasticityrelated proteins PSD95,Syn,GAP43,and neurotrophic factors BDNF and NGF in the hippocampus of each group were detected by immunohistochemistry and western blot.Results 1.Treatment effect: There was no convulsion in the Control group and the LE group.Compared with the BPV+NS group,there was no significant difference in T1(until convulsion occurred)and T3(positive righting reflex after convulsion)in the BPV+LE group,while T2(continuous convulsion),T4(righting reflex occurred until crawling started),and T5(crawling to normal walking)in the BPV+LE group.The neurobehavioral scores decreased at0.5h and 1h after modeling,while the differences between the scores at 1.5h and 2h were not statistically significant.The neurological function of the two groups returned to normal at 2h after modeling.The results showed that LE had a good therapeutic effect on BPV induced convulsion rats,which could quickly relieve the symptoms of convulsion,shorten the duration of convulsion,and antagonize the neurobehavioral damage.2.Learning and memory: compared with the Control group,there were no differences in escape latency,total swimming distance,percentage of target quadrant retention time,and the number of platform crossing in the LE group;There was no difference in the escape latency and total swimming distance between BPV+NS group and BPV+LE group on the first and second days of training,but the escape latency and total swimming distance increased on the third,fourth and fifth days,while the percentage of retention time in the target quadrant and the number of platform crossing decreased.Compared with the BPV+NS group,the escape latency and total swimming distance of the BPV+LE group had no difference on the first,second and third days,while the escape latency and total swimming distance of the BPV+LE group decreased on the fourth and fifth days,while the retention time percentage of the target quadrant and the number of platform crossing increased.The results indicated that LE treatment can improve the decrease of spatial learning and memory ability in BPV induced convulsion rats.3.Golgi staining: Compared with the Control group,the dendritic morphology of neurons in the LE group was not significantly changed;The number of dendritic branches and the density of dendritic spines was significantly decreased in the BPV+NS and BPV+LE groups.Compared with the BPV+NS group,the number of dendritic branches and the density of dendritic spines was increased in the BPV+LE group.These results suggest that LE treatment can slow down the pathological changes of nerve cells and synapses in the hippocampal CA1 region of BPV-induced convulsion rats.4.Immunohistochemistry: Compared with the Control group,there was no difference in the positive expression of LE histones;The positive expressions of PSD95,SYN,GAP43,BDNF,and NGF in the hippocampal CA1 region were decreased in the BPV+NS group and BPV+LE group.Compared with the BPV+NS group,the positive expression of PSD95,SYN,GAP43,BDNF,and NGF increased in the BPV+LE group.5.Western blot: Compared with the Control group,there was no difference in LE histone expression level;The protein expression levels of PSD95,SYN,GAP43,BDNF,and NGF were down-regulated in the BPV+NS group and BPV+LE group.Compared with the BPV+NS group,the protein expression levels of PSD95,SYN,GAP43,BDNF,and NGF were up-regulated in the BPV+LE group.These results indicated that LE upregulated the synaptic associated proteins(PSD95,SYN,GAP43)and neurotrophic factors(BDNF,NGF)in the hippocampus of BPV-induced convulsive rats,and antagonized the changes of learning and memory and synaptic plasticity induced by BPV neurotoxicity.Conclusion 1.After bupivacaine-induced convulsion,neurobehavior,learning,and memory ability decreased,nerve cells and dendrites showed pathological changes,and synapserelated protein expression was down-regulated.2.Liped emulsion alleviates the damage of hippocampal function after bupivacaine-induced convulsion in rats,antagonizes the neurotoxicity of bupivacaine,improves synaptic plasticity,and then improves the decline of learning and memory ability.