ABSTRACT
BACKGROUND@#According to the amyloid, tau, neurodegeneration research framework classification, amyloid and tau positive (A+T+) mild cognitive impairment (MCI) individuals are defined as prodromal Alzheimer disease. This study was designed to compare the clinical and biomarker features between A+T+MCI individuals who progressed to progressive MCI (pMCI) and those who remained stable MCI (sMCI), and to identify relevant baseline clinical biomarker and features that could be used to predict progression to dementia within 2 years.@*METHODS@#We stratified 197 A+T+MCI individuals into pMCI (n = 64) and sMCI (n = 133) over 2 years. Demographics and cognitive assessment scores, cerebrospinal fluid (CSF), and neuroimaging biomarkers (18F-florbetapir positron emission tomography mean standardized uptake value ratios [SUVR] and structural magnetic resonance imaging [MRI]) were compared between pMCI and sMCI at baseline, 12- and 24-month follow-up. Logistic regression models then were used to evaluate clinical baseline and biomarker features that predicted dementia progression in A+T+MCI.@*RESULTS@#pMCI individuals had higher mean 18F-florbetapir SUVR, CSF total-tau (t-tau), and p-tau181P than those in sMCI individuals. pMCI individuals performed poorer in cognitive assessments, both global and domain specific (memory, executive, language, attention, and visuospatial skills) than sMCI. At baseline, there were significant differences in regions of interest of structural MRI between the two groups, including bilateral amygdala, hippocampus and entorhinal, bilateral inferior lateral ventricle, left superior and middle temporal, left posterior and caudal anterior cingulate (P < 0.05). Baseline CSF t-tau levels and cognitive scores of Montreal cognitive assessment, functional assessment questionnaire, and everyday cognition by the patient's study partner language domain could predict progression to dementia in A+T+MCI within 2 years.@*CONCLUSIONS@#In future clinical trials, specific CSF and cognitive measures that predict dementia progression in A+T+MCI might be useful risk factors for assessing the risk of dementia progression.
Subject(s)
Humans , Alzheimer Disease , Amyloid beta-Peptides , Biomarkers , Cognitive Dysfunction , Disease Progression , Peptide Fragments , Positron-Emission TomographyABSTRACT
Objective To explore the effects of chronic levodopa treatment on characteristics of N-methyl-D-aspartate(NMDA) receptor subunit 1(NR1) on the neurons of striatum in rat models of Parkinsonism related motor complications.Methods Rat models(n=25)of Parkinsonism related motor complications were established and were randomly divided into solvent treatment group(n=5,intraperitoneal injection with vitamin C),levodopa chronic treatment group(n=10,intraperitoneal injection with levodopa for 23 d) and MK-801 treatment group(n=10,intraperitoneal injection with MK-801 on d 23 after intraperitoneal injection with levodopa for 22 d).Another 5 rats were served as controls(sham-operation group,n=5).Locomotion changes of rats in MK-801 treatment group were recorded,and NR1 phosphorylation in the other three groups was detected by Western blotting. Results After chronic treatment with levodopa methylester for 1,8,15 and 22 d,rats in MK-801 treatment group displayed shortened rotational duration and increased peak rotation.Compared with d 22,MK-801 both prolonged rotational duration and reduced peak rotation(P0.05).The expression of NR1,phosphorylated NR1S890,NR1S896 and NR1S897 in striatal membranes in levodopa chronic treatment group was increased compared with that of solvent treatment group(P
ABSTRACT
Objective To explore the relationship between the genesis of dyskinesia and the degree of substantia nigra lesion in Parkinson disease(PD).Methods The hemi-parkinsonian rat model was established by injecting 6-OHDA stereotaxically to right medial forebrain bundle(MFB). Then the hemi-parkinsonian rat was injected intraperitoneally with levodopa methylester(25 mg?kg~(-1)?d~(-1),twice a day)for 21 days,the abnormal involuntary movements were estimated.After being sacrificed,the midbrain was removed,and the injured degree of dopaminergic neurons at substantia nigra was observed by tyrosine hydroxylase immunohistochemistry staining.The relationship between the abnormal involuntary movement scores and dopaminergic neurons loss at substantia nigra was evaluated by sigmoid equation analysis by using Excel software.Results The apomorphine-induced rotation rate above 7 r/min was found in 10 of 25 rats,those rats were regarded as successful hemi-parkinsonian model rats.After the treatment with levodopa methylester,8 of 10 rats displayed abnormal involuntary movements,including stereotype and contralateral rotation,the types of movements varied.Abnormal involuntary movements were appeared in the rats with dopaminergic neurons loss above 90%.The positive relationship was observed between the degree of lesion in substantia nigra and the severity of abnormal involuntary movements.Conclusions The severe loss of dopaminergic neurons at substantia nigra probably plays a role in the development of levodopa-induced dyskinesia in patient with Parkinson disease.
ABSTRACT
Objective To investigate cellular and behavioural effects of 5-HT1A receptor agonist 8- OH-DPAT in a rat model of levodopa-induced motor complications.Methods The hemi-parkinsonian rat model was produced by stereotaxically injecting 6-OHDA to right medial forebrain bundle(MFB).Two sets of experiments were performed.First,rats were intrapefitoneally treated with levodopa 50 mg/kg plus benserazide 12.5 mg/kg twice a day for 22 days.On day 23,rats intraperitoneally received either 8-OH- DPAT(1 mg/kg)or 8-OH-DPAT plus WAY-100635(0.1 mg/kg)or dissolvent with each levodopa dose as controls.In the second set,rats were intraperitoneally treated either with levodopa(50 mg/kg)plus 8-OH- DPAT(1 mg/kg)or levodopa 50 mg/kg plus dissolvent,administered twice daily for 22 consecutive days. Rotational duration and frequency of off period were estimated.After sacrificed,subcellualr distribution of GluR1 and GluR1Ser845 phosphorylation was observed by Western blot.Results 8-OH-DPAT,reversing the shortened rotational duration induced by levodopa,prolonged the rotational duration by 27.8%?6.1% and reduced the frequency of failures to levodopa by 7.2%?1.7%.Co-administration of WAY-100635,a 5-HT1A receptor antagonist,with 8-OH-DPAT eliminated the effect of 8-OH-DPAT on motor complications, indicating that the observed 8-OH-DPAT responses were probably mediated via the 5-HT1A autoreceptor. Moreover,8-OH-DPAT could regulate subcellular distribution of GluR1 and reduce hyperphosphorylation of GluR1 Ser845 by 22.1%?3.5%,which was closely associated with levodopa-induced motor complications. Conclusions These results suggest that pharmaceuticals stimulating 5-HT1A receptors could be useful in the treatment and prevention of the motor complications in parkinsonian patients.