| Objective: Vascular dementia (VD) is a severe cognitive dysfunctionclinical syndrome caused by cerebrovascular disease, which often complicatedby cognitive dysfunction, or even dementia. With the aging of population andincrease of survival rate of stroke treatment, VD incidence increased year byyear, second only to Alzheimer’s disease, VD has become one of the diseasesseriously impacting on the quality of human life. Recent studies show that, inthe central nervous system, the activation of p38MAPK pathway can lead tocell death, and is closely related with cerebral ischemia. p38MAPK isactivated by phosphorylation, the phosphorylated substrate is an activatingtranscription factor (ATF-2, Elk-1, NF-KB, etc.), and also can activate MAPrCprotein kinase activation, The phosphorylated p38MAPK make effector cellsecrete a variety of cytokines and arachidonic acid metabolites mediating theprocess of neuronal damage.This study aims to understand the hippocampus ofrats with vascular dementia in phosphorylation of P38and P38change, tofurther explore the relationship between VD and oxidative damage, and tofurther explore effect of probucol on intelligence improvement in the VD ratsand the hippocampus P38and phosphorylated P38, and to provideexperimental basis for VD treatment by probucol.Methods: Healthy male SD rats were randomly divided into shamoperation group, model group and probucol group,10rats in each group. VDrat model was established by permanent ligation of bilateral common carotidartery. resulting in a state of chronic cerebral hypoperfusion associated withVD. The animal model was as follows: Morris water maze test was performedfor1day of training in all groups of rats7days after operation. According tothe reference value of the full-time average escape latency of the rats in thesham-operated group, we calculated the proportion-one minus the reference value divided by the full-time average escape latency of the operated groups.If the proportion>20%, the rat is regarded as VD rat. The rats in probucolgroup were intragastrically given probucol500mg/kg/d. While the rats insham operated group and model group were given the same volume sodiumcarboxymethyl cellulose. Morris water maze was used to evaluate learning andmemory ability of rats in each group after8weeks administration.Positioning navigation test was carried on to determine escape latency timefrom the first day to the fourth day, and the spatial exploration test was used todetect crossing platform frequency at the fifth day. After the water maze test,hippocampus HE sections were made to observe the morphological changes inhippocampal CA1region of rats by light microscopy; hippocampus P38andP38protein phosphorylation changes were detected using western blot andimmunohistochemical staining method.Results:1The general situation of observation1.1The results of escape latencyFrom the first day to the fourth day, escape latency time was tested toevaluate the learning ability of rats. The shorter escape latency time was, thestronger learning ability was. The escape latency time of rats was shortenedwith the increasing of the number of training days, indicating that training canenhance the learning ability, but there were differences in learning abilityamong the three groups. Within the first4days, escape latency time of rats inmodel group was significantly longer when compared with that in shamoperated group(P<0.05). There was no significant difference betweenprobucol group and model group at the first day(P﹥0.05), and from thesecond day to the fourth day, the escape latency time of probucol group wassignificantly shorter than that of model group(P﹤0.05). From the first day tothe fourth day, there was no significant difference between probucol group andsham operated group(P﹥0.05).1.2The results of crossing platform frequencyCrossing platform frequency which represented memory ability was tested at the fifth day. The more crossing platform frequency was, the strongermemory ability was. The frequency of crossing platform in model group ratssignificantly decreased than that in sham operated group rats(1.75±1.14VS5.58±1.83,P﹤0.05). The frequency of crossing platform in probucolgroup rats significantly increased compared with that in model group rats(4.50±1.38VS1.75±1.14,P﹤0.05). The frequency of crossing platform wasnot significantly different between probucol group and sham operatedgroup(4.50±1.38VS5.58±1.83,P﹥0.05).2. Effect of probucol on expression of p38MAPK and p-p38MAPK proteins invascular dementia rats hippocampus2.1The results of Western blot2.1.1The protein expression level of p38MAPK in hippocampus of ratsThe protein expression level of p38MAPK in hippocampus of modelgroup rats was not significantly reduced than that of sham operated grouprats(1.711±1.923VS1.728±2.045,P>0.05). The protein expression level ofp38MAPK in hippocampus of probucol group rats was not significantlyincreased than that of model group rats(1.835±2.139VS1.711±1.923,P>0.05). There was no significant difference in the protein expressionlevel of p38MAPK in rats’ hippocampus between probucol group and shamoperated group (1.835±2.139VS1.728±2.045,P﹥0.05).2.1.2The protein expression level of p-p38MAPK in hippocampus of ratsThe protein expression level of p-p38MAPK in hippocampus of modelgroup rats was significantly increased than that of sham operated grouprats(2.59±0.243VS0.35±0.586,P﹤0.05). The protein expression level ofp-p38MAPK in hippocampus of probucol group rats was significantly reducedthan that of model group rats(0.54±0.049VS2.59±0.243,P﹤0.05). Theprotein expression level of p-p38MAPK in rats’ hippocampus was notsignificantly different between probucol group and sham operated group(0.54±0.049VS0.35±0.586,P﹥0.05).2.2The results of immunohistochemical staining2.2.1The number of p38MAPK positive cells in hippocampal CA1region of ratsThe number of p38MAPK positive cells in hippocampal CA1region ofmodel group rats was not significantly increased than that of sham operatedgroup rats(30.00±1.0VS28.00±2.0,P>0.05). The number of p38MAPKpositive cells in hippocampal CA1region of probucol group rats was notsignificantly reduced than that of model group rats(29.00±1.732VS30.00±1.0,P>0.05). The number of p38MAPK positive cells in rats’ hippocampalCA1region was not significantly different between probucol group and shamoperated group(29.00±1.732VS28.00±2.0,P﹥0.05).2.2.2The number of p-p38MAPK positive cells in hippocampal CA1regionThe number of p-p38MAPK positive cells in hippocampal CA1region ofmodel group rats significantly increased than that of sham operated grouprats(25.33±2.08VS9.0±1.0,P﹤0.05). The number of p-p38MAPK positivecells in hippocampal CA1region of probucol group rats significantly reducedthan that of model group rats(15.11±7.87VS25.33±2.08,P﹤0.05). Thenumber of p-p38MAPK positive cells in rats’ hippocampal CA1region wasnot significantly different between probucol group and sham operatedgroup(15.11±7.87VS9.0±1.0,P﹥0.05).3Hippocampal nerve cell morphological observationThe structure of nerve cells in the hippocampus CA1region layer in thesham-operated group was compacted, nervous nuclei was integral, and thecytoplasm was rich. In the blank model group, the cells of the hippocampusCA1region were disordered, the number of nerve cells obviously reduced,many cells became incomplete, some formed pieces, matrix was loose andmicro empty bubble formed. In probucol group, the cells shape ofhippocampus CA1region closed to normal, the hippocampus cells arrangedclosely, the level of rich, cell number was significantly more than the modelgroup, nerve cells were intact, cytoplasm was abundant and a small amount ofcell degeneration was found.Conclusions:1The rat bilateral common carotid artery permanent ligation can create a ideal VD animal model.2The abnormal protein expression of apoptosis pathway exists in VDrats hippocampus, suggesting that apoptotic mechanisms are involved in thepathogenesis of vascular dementia.3Probucol can improve learning and memory ability and cognitivefunction of VD rats.4Probucol may inhibit hippocampal P38protein phosphorylation, therebyinhibit neuronal apoptosis and play a protective role in VD. |
PDF Full Text Request