| Alzheimer's disease(AD) is the most common neurodegeneration disease in central nervous system,as characterized by the senile plaques(SP) and neurofibrillary tangles (NFT) presented in cortex.Presenilin is the catalytic component ofγ-secretase complex,which is responsible for the amyloidogenic cleavage of amyloid precursor protein(APP).There are two kinds of presenilins,Presenilin-1(PS1) and Presenilin-2 (PS2),both related to familial Alzheimer's disease(FAD).The PS1/PS2 double knockout(dKO) mice,which are derived from PS1 forebrain-specific knockout mice and PS2 knockout mice,exhibit a series of AD-like symptoms,including the impairment of cognition and the degeneration of forebrain.But the mechanism has not been revealed yet.EUK4010 is a compound which was screened from approximately 2000 Chinese traditional medicines.It has been proved on cells that it has an effect on protect neurons from apoptosis as well as down-regulate the expression of Aβgene.To investigate the effect of EUK4010 on dKO mice,the drug was administrated to 2-month-old and 6-month-old dKO mice.After 5 months,behavioral and morphology tests were carried out to detect the effect of EUK4010.Furthermore,the effect of EUK4010 on oxidative stress and inflammation response mediators were also examined to determine the mechanism that the effect of EUK4010 on the neurodegenerative symptoms of dKO mice.1.Effect of EUK4010 on neurodegenerative symptoms of dKO miceEUK4010 was administrated on 2-month-old and 6-month-old dKO mice, respectively.Open-field test,novel object recognition task and fear conditioning were applied to test the abilities of locomotion as well as learning and memory.After 4 months' treatment,neither the 6-month-old mice nor the 10-month-old mice showed amelioration on these tested abilities.However,when concerned to the influence on average body weight,the mice treated with EUK4010 showed a higher increase than the untreated ones,of which the 2-6 months old mice exhibit a significant difference.Nissl staining was used on the brain slices from each group.It revealed that the enlargement of ventricles and the atrophy of hippocampus were significantly mitigated in the EUK4010-treated group,especially in the 6-11 months old mice. However,there was no significant difference in the thickness of cortex in either group. From the results,we can conclude that EUK4010 can ameliorate some of the neurodegeneration symptoms,but has no significant effect on learning and memory.2.Effect of EUK4010 on oxidative stress of dKO miceContent of MDA(product of lipid oxidation),activity of SOD and GSH-PX (anti-oxidant enzymes) in cortex,hippocampus,liver and kidney along with the concentration of free 8-OHdG(a marker of DNA damage) in urine were detected after a 5-month-treatment of EUK4010,to see if the ameliorations on neurodegeneration symptoms relied on the alteration of the level of oxidative stress.It was shown that the level of oxidative stress neither in cortex nor in hippocampus exhibited a significant alteration,while there were some alterations in liver and kidney.Furthermore,the concentration of free 8-OHdG decreased dramatically in dKO mice at both ages,that indicated a severely damage of DNA in dKO mice.After treatment,the content of MDA,activity of SOD and GSH-PX,and the concentration of free-8-OHdG were altered at different levels,which suggest that EUK4010 can alter the level of oxidative stress at a certain degree.3.Effect of EUK4010 on inflammation response mediators of dKO miceReal-Time PCR and Western blot were carried out to determine the effect of EUK4010 on the inflammation response mediators as GFAP,C1qαand C4.It is found that the relative expression level of GFAP,C1qαand C4 were all increased dramatically in both cortex and hippocampus of dKO mice at both ages.Some of these increases in cortex were mitigated after 5-months' treatment of EUK4010, especially in the mice of 6-11 months old.While in hippocampus,the effect of EUK4010 was not so evident.And the result of Western blot consisted with RT-PCR. Thus,we come to the conclusion that the amelioration of neurodegenerative symptoms in dKO mice of EUK4010 may due to its effect on down-regulate the up-regulation of these inflammation response mediators.
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