Repeated measures analysis of opioid use disorder treatment on clinical opiate withdrawal scale in a randomized clinical trial: sex differences.

PURPOSE: Sex differences may exist in opioid use disorder (OUD) treatment. This study examined the treatment effects of buprenorphine/naloxone (BUP/NX) and methadone (MET) on the Clinical Opiate Withdrawal Scale (COWS) score in individuals with OUD and tested whether the associations differ by sex. METHOD: We performed a secondary analysis of the data from the National Drug Abuse Treatment Clinical Trials Network (CTN) protocol-0027. A total of 1269 participants (861 males and 408 females) being aged 18 or older with OUD were randomly assigned to receive BUP/NX (n = 740) or MET (n = 529). The paired t test was initially used to compare the COWS scores between pre-dose and post-dose for BUP/NX and MET treatments, separately. The linear mixed model was used to examine the changes in COWS score adjusted for baseline demographic, substance use, and mental health disorders. The interaction of sex and treatment was detected and stratified analysis by sex was conducted. RESULTS: The paired t test showed that both BUP/NX and MET treatments significantly reduced the COWS scores (p values <0.0001). BUP/NX revealed higher COWS scores than MET (p = 0.0008) and females demonstrated significantly higher COWS scores than males (p = 0.0169). Stratified by sex, BUP/NX compared with MET revealed higher COWS scores only in males (p = 0.0043), whereas baseline amphetamines use disorder and major depressive disorder were significantly associated with COWS scores in females (p = 0.0158 and 0.0422, respectively). CONCLUSIONS: Both BUP/NX and MET are effective in decreasing opioid withdrawal symptoms via COWS scores, however, treatment plans for OUD by clinical providers should consider sex differences.

Association of APOE gene with longitudinal changes of CSF amyloid beta and tau levels in Alzheimer's disease: racial differences.

BACKGROUND: The Apolipoprotein E (APOE) ε4 allele is a risk factor for late-onset Alzheimer's disease (AD). However, no investigation has focused on racial differences in the longitudinal effect of APOE genotypes on CSF amyloid beta (Aß42) and tau levels in AD. METHODS: This study used data from the Alzheimer's Disease Neuroimaging Initiative (ADNI): 222 participants with AD, 264 with cognitive normal (CN), and 692 with mild cognitive impairment (MCI) at baseline and two years follow-up. We used a linear mixed model to investigate the effect of APOE-ε4-genotypes on longitudinal changes in the amyloid beta and tau levels. RESULTS: Individuals with 1 or 2 APOE ε4 alleles revealed significantly higher t-Tau and p-Tau, but lower amyloid beta Aß42 compared with individuals without APOE ε4 alleles. Significantly higher levels of log-t-Tau, log-p-Tau, and low levels of log-Aß42 were observed in the subjects with older age, being female, and the two diagnostic groups (AD and MCI). The higher p-Tau and Aß42 values are associated with poor Mini-Mental State Examination (MMSE) performance. Non-Hispanic Africa American (AA) and Hispanic participants were associated with decreased log-t-Tau levels (ß = - 0.154, p = 0.0112; ß = - 0.207, and p = 0.0016, respectively) as compared to those observed in Whites. Furthermore, Hispanic participants were associated with a decreased log-p-Tau level (ß = - 0.224, p = 0.0023) compared to those observed in Whites. There were no differences in Aß42 level for non-Hispanic AA and Hispanic participants compared with White participants. CONCLUSION: Our study, for the first time, showed that the APOE ε4 allele was associated with these biomarkers, however with differing degrees among racial groups.

Deep learning analysis of UPLC-MS/MS-based metabolomics data to predict Alzheimer's disease.

OBJECTIVE: Metabolic biomarkers can potentially inform disease progression in Alzheimer's disease (AD). The purpose of this study is to identify and describe a new set of diagnostic biomarkers for developing deep learning (DL) tools to predict AD using Ultra Performance Liquid Chromatography Mass Spectrometry (UPLC-MS/MS)-based metabolomics data. METHODS: A total of 177 individuals, including 78 with AD and 99 with cognitive normal (CN), were selected from the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort along with 150 metabolomic biomarkers. We performed feature selection using the Least Absolute Shrinkage and Selection Operator (LASSO). The H2O DL function was used to build multilayer feedforward neural networks to predict AD. RESULTS: The LASSO selected 21 metabolic biomarkers. To develop DL models, the 21 biomarkers identified by LASSO were imported into the H2O package. The data was split into 70% for training and 30% for validation. The best DL model with two layers and 18 neurons achieved an accuracy of 0.881, F1-score of 0.892, and AUC of 0.873. Several metabolomic biomarkers involved in glucose and lipid metabolism, in particular bile acid metabolites, were associated with APOE-ε4 allele and clinical biomarkers (Aß42, tTau, pTau), cognitive assessments [the Alzheimer's Disease Assessment Scale-cognitive subscale 13 (ADAS13), the Mini-Mental State Examination (MMSE)], and hippocampus volume. CONCLUSIONS: This study identified a new set of diagnostic metabolomic biomarkers for developing DL tools to predict AD. These biomarkers may help with early diagnosis, prognostic risk stratification, and/or early treatment interventions for patients at risk for AD.

Clusters of substance use and mental health variables with emergency room visits in U.S. adults: The 2020 National Survey on Drug Use and Health.

BACKGROUND: This study evaluated the prevalence of emergency room (ER) visits, given numerous substance use and mental health variables in the past year. METHODS: Data from 5206 emergency room visits out of 27,170 adults were extracted from the 2020 National Survey on Drug Use and Health. Oblique principal component cluster analysis was used to classify 39 substance use and mental health variables into disjoint clusters. RESULTS: In 2020, the overall prevalence of ER visits was 21.9 %. Being female, age above 65 years, with insurance, low income and low education levels, and being African American increased the risk of ER visit. Nine clusters were made out of 39 substance use and mental health variables. Multivariate stepwise logistic regression analysis showed 15 substance use and mental health variables were significantly associated with ER visits including heavy alcohol use past 30 days in cluster 3, nicotine dependence and cigarettes use in cluster 4, major depressive episode, serious psychological distress, and suicidal plans in past year in cluster 5, any psychotherapeutics use in cluster 7, tranquilizers use and lorazepam products use in cluster 8, and any pain reliever, pain reliever misuse, hydrocodone products use, oxycodone products use, tramadol products use, and codeine products use in cluster 9. CONCLUSIONS: Several substance use and mental health problems, including nicotine dependence, illicit drugs, and serious mental health problems were among the common reasons for ER visits. These findings suggest the effective use of ER as the venue to implement interventions for substance use and mental health.

Linear Mixed Model Analysis of Polygenic Hazard Score on Verbal Memory Decline in Alzheimer's Disease.

BACKGROUND: Alzheimer's disease (AD) is a chronic, progressive, degenerative disease characterized by cognitive dysfunction, including verbal memory loss. Studies were lacking in examining the longitudinal effect of polygenic hazard score on the Rey Auditory Verbal Learning Test-Delayed Total (AVDELTOT) score (a common measure of verbal memory). A key step in analyzing longitudinal changes in cognitive measures using a linear mixed model (LMM) is choosing a suitable covariance structure. OBJECTIVES: The study aims to determine the association between the polygenic hazard score and the AVDELTOT score accounting for repeated measures (the covariance structure). METHODS: The AVDELTOT scores were collected at baseline, 12 months, 24 months, 36 months, and 48 months from 283 participants with AD, 347 with cognitive normal, and 846 with mild cognitive impairment in the Alzheimer's Disease Neuroimaging Initiative. The Bayesian information criterion statistic was used to select the best covariance structure from 10 covariance structures in longitudinal analysis of AVDELTOT scores. The multivariable LMM was used to investigate the effect of polygenic hazard score status (low vs. medium vs. high) on changes in AVDELTOT scores while adjusted for age, gender, education, APOE-ε4 genotype, and baseline Mini-Mental State Examination score. RESULTS: One-way analysis of variance revealed significant differences in AVDELTOT scores, Mini-Mental State Examination scores, and polygenic hazard scores among AD diagnoses at baseline. Bayesian information criterion favored the compound symmetry covariance structure in the LMM analysis. Using the multivariate LMM, the APOE-ε4 allele and high polygenic hazard score value was significantly associated with AVDELTOT declines. Significant polygenic hazard score status by follow-up visit interactions was discovered. CONCLUSION: Our findings provide the first evidence of the effect of polygenic hazard score status and APOE-ε4 allele on declines in verbal memory in people with AD.

White matter integrity and key structures affected in Alzheimer's disease characterized by diffusion tensor imaging.

White matter (WM) degeneration is suggested to predict the early signs of Alzheimer's disease (AD). The exact structural regions of brain circuitry involved are not known. This study aims to examine the associations between WM tract integrity, represented by the diffusion tensor imaging (DTI) measures, and AD diagnosis and to denote the key substrates in predicting AD. It included DTI measures of mean diffusivity (MD), fractional anisotropy, radial diffusivity and axial diffusivity of 18 main WM tracts in 84 non-Hispanic white participants from the Alzheimer's Disease Neuroimaging Initiative dataset. The multivariable general linear model was used to examine the association of AD diagnosis with each DTI measure adjusting for age, gender and education. The corpus callosum, fornix, cingulum hippocampus, uncinate fasciculus, sagittal striatum, left posterior thalamic radiation and fornix-stria terminalis showed significant increases in MD, radial and axial diffusivity, whereas the splenium of corpus callosum and the fornix showed significant decreases in fractional anisotropy among AD patients. Variable cluster analysis identified that hippocampus volume, mini-mental state examination (MMSE), cingulate gyrus/hippocampus, inferior fronto-occipital fasciculus and uncinate fasciculus are highly correlated in one cluster with MD measures. In conclusion, there were significant differences in DTI measures between the brain WM of AD patients and controls. Age is the risk factor associated with AD, not gender or education. Right cingulum gyrus and right uncinate fasciculus are particularly affected, correlating well with a cognitive test MMSE and MD measures for dementia in AD patients and could be a region of focus for AD staging.

Associations of ARHGAP26 Polymorphisms with Alzheimer's Disease and Cardiovascular Disease.

The Rho GTPase activating protein 26 (ARHGAP26) gene has been reported to be associated with neuropsychiatric diseases and neurodegenerative diseases including Parkinson's disease. We examined whether the ARHGAP26 gene is associated with Alzheimer's disease (AD) and/or cardiovascular disease (CVD). Multivariable logistic regression model was used to examine the associations of 154 single nucleotide polymorphisms (SNPs) within the ARHGAP26 gene with AD and CVD using the Alzheimer's Disease Neuroimaging Initiative 1 (ADNI-1) cohort. Fourteen SNPs were associated with AD (top SNP rs3776362 with p = 3.43 × 10-3), while 37 SNPs revealed associations with CVD (top SNP rs415235 with p = 2.06 × 10-4). Interestingly, 13 SNPs were associated with both AD and CVD. SNP rs3776362 was associated with CVD, Functional Activities Questionnaire (FAQ), and Clinical Dementia Rating Sum of Boxes (CDR-SB). A replication study using a Caribbean Hispanics sample showed that 17 SNPs revealed associations with AD, and 12 SNPs were associated with CVD. The third sample using a family-based study design showed that 9 SNPs were associated with AD, and 3 SNPs were associated with CVD. SNP rs6836509 within the ARHGAP10 gene (an important paralogon of ARHGAP26) was associated with AD and cerebrospinal fluid total tau (t-tau) level in the ADNI sample. Several SNPs were functionally important using the RegulomeDB, while a number of SNPs were associated with significant expression quantitative trait loci (eQTLs) using Genotype-Tissue Expression (GTEx) databases. In conclusion, genetic variants within ARHGAP26 were associated with AD and CVD. These findings add important new insights into the potentially shared pathogenesis of AD and CVD.

ClC-c regulates the proliferation of intestinal stem cells via the EGFR signalling pathway in Drosophila.

OBJECTIVES: Adult stem cells uphold a delicate balance between quiescent and active states, which is crucial for tissue homeostasis. Whereas many signalling pathways that regulate epithelial stem cells have been reported, many regulators remain unidentified. MATERIALS AND METHODS: Flies were used to generate tissue-specific gene knockdown and gene knockout. qRT-PCR was used to assess the relative mRNA levels. Immunofluorescence was used to determine protein localization and expression patterns. Clonal analyses were used to observe the phenotype. RNA-seq was used to screen downstream mechanisms. RESULTS: Here, we report a member of the chloride channel family, ClC-c, which is specifically expressed in Drosophila intestinal stem/progenitor cells and regulates intestinal stem cell (ISC) proliferation under physiological conditions and upon tissue damage. Mechanistically, we found that the ISC loss induced by the depletion of ClC-c in intestinal stem/progenitor cells is due to inhibition of the EGFR signalling pathway. CONCLUSION: Our findings reveal an ISC-specific function of ClC-c in regulating stem cell maintenance and proliferation, thereby providing new insights into the functional links among the chloride channel family, ISC proliferation and tissue homeostasis.

Pathways for Memory, Cognition and Emotional Context: Hippocampal, Subgenual Area 25, and Amygdalar Axons Show Unique Interactions in the Primate Thalamic Reuniens Nucleus.

The reuniens nucleus (RE) is situated at the most ventral position of the midline thalamus. In rats and mice RE is distinguished by bidirectional connections with the hippocampus and medial prefrontal cortex (mPFC) and a role in memory and cognition. In primates, many foundational questions pertaining to RE remain unresolved. We addressed these issues by investigating the composition of the rhesus monkey RE in both sexes by labeling for GABA, a marker of inhibitory neurons, and for the calcium-binding proteins parvalbumin (PV), calbindin (CB), and calretinin (CR), which label thalamic excitatory neurons that project to cortex. As in rats and mice, the macaque RE was mostly populated by CB and CR neurons, characteristic of matrix-dominant nuclei, and had bidirectional connections with hippocampus and mPFC area 25 (A25). Unlike rodents, we found GABAergic neurons in the monkey RE and a sparser but consistent population of core-associated thalamocortical PV neurons. RE had stronger connections with the basal amygdalar complex than in rats or mice. Amygdalar terminations were enriched with mitochondria and frequently formed successive synapses with the same postsynaptic structures, suggesting an active and robust pathway to RE. Significantly, hippocampal pathways formed multisynaptic complexes that uniquely involved excitatory projection neurons and dendrites of local inhibitory neurons in RE, extending this synaptic principle beyond sensory to high-order thalamic nuclei. Convergent pathways from hippocampus, A25, and amygdala in RE position it to flexibly coordinate activity for memory, cognition, and emotional context, which are disrupted in several psychiatric and neurologic diseases in humans.SIGNIFICANCE STATEMENT The primate RE is a central node for memory and cognition through connections with the hippocampus and mPFC. As in rats or mice, the primate RE is a matrix-dominant thalamic nucleus, suggesting signal traffic to the upper cortical layers. Unlike rats or mice, the primate RE contains inhibitory neurons, synaptic specializations with the hippocampal pathway, and robust connections with the amygdala, suggesting unique adaptations. Convergence of hippocampal, mPFC, and amygdalar pathways in RE may help unravel a circuit basis for binding diverse signals for conscious flexible behaviors and the synthesis of memory with affective significance in primates, whereas disruption of distinct circuit nodes may occur in psychiatric disorders in humans.

Longitudinal analysis of APOE-ɛ4 genotype with the logical memory delayed recall score in Alzheimer's disease.

No study has focussed on the longitudinal effect of APOE-ɛ4 genotype on the logical memory delayed recall total (LDELTOTAL) score in late-onset Alzheimer's disease (AD). The LDELTOTAL scores were collected at baseline, 12, 24, 36 and 48 months from 382 participants with AD, 503 with cognitive normal (CN), 1293 with mild cognitive impairment (MCI) in the Alzheimer's Disease Neuroimaging Initiative (ADNI). A linear mixed model (LMM) was used to investigate the effect of APOE-ɛ4 on the longitudinal changes in the LDELTOTAL scores adjusted for age, gender, education and baseline Mini Mental State Examination score. There were significant differences in LDELTOTAL scores among AD, CN, and MCI (P<0.0001) and among APOE-ɛ4 alleles at baseline (P<0.0001). In the multivariable LMM, elders with 75+ years (P = 0.0051), females (P<0.0001), lower education (P<0.0001), AD and MCI (both P values <0.0001) were associated with decreased LDELTOTAL values, while the individuals with 1 or 2 APOE-ɛ4 allele revealed significantly lower LDELTOTAL scores (both P values<0.0001) compared with individuals without APOE-ɛ4 allele. Further, APOE-ɛ4 alleles had significant interactions with four follow-up visits, where all follow-up visits showed significantly higher LDELTOTAL score. In addition, gender showed interaction with age, education and APOE-ɛ4 with follow-up visits. Our findings provide the first evidence of the effect of APOE-ɛ4 genotype on the logical memory declines related to AD. Further, APOE-ɛ4 alleles showed interactions with gender and follow-up visits.

Genome-wide association study identified INSC gene associated with Trail Making Test Part A and Alzheimer's disease related cognitive phenotypes.

BACKGROUND: The Trail Making Test (TMT) Part A (TMT-A) is a good measure of performance on cognitive processing speed. This study aimed to perform a genome-wide association study of TMT-A in Alzheimer's disease (AD). METHODS: A total of 757 individuals with TMT-A phenotypes and 620,901 single nucleotide polymorphisms (SNPs) were extracted from the Alzheimer's Disease Neuroimaging Initiative 1 (ADNI-1) cohort. AD related cognitive phenotypes include TMT-A, TMT-B, Functional Activities Questionnaire (FAQ), Clinical Dementia Rating Sum of Boxes (CDR-SB), and Alzheimer's Disease Assessment Scale-Cognitive Subscale 13 (ADAS13). Multivariable linear regression analysis of TMT-A was conducted using PLINK software. The most TMT-A associated gene was tested with Color Trails Test 1 Form A (CTTA), a culturally fair analog of the TMT-A. Functional annotation of SNPs was performed using the RegulomeDB and Genotype-Tissue Expression (GTEx) databases. RESULTS: The best signal with TMT-A was rs1108010 (p = 4.34 × 10-8) at 11p15.2 within INSC gene, which was also associated with TMT-B, FAQ, CDR-SB, and ADAS13 (p = 2.47 × 10-4, 8.56 × 10-3, 0.0127 and 0.0188, respectively). Furthermore, suggestive loci were identified such as FOXD2 and CLTA with TMT-A, GBP1/GBP3 with TMT-B, GRIK2 with FAQ, BAALC and CCDC146 with CDR-SB, BAALC and NKAIN2 with ADAS13. Additionally, the best SNP within INSC associated with CTTA was rs7931705 (p = 6.15 × 10-5). Several SNPs had significant eQTLs using GTEx. CONCLUSIONS: We identified several genes/loci associated with TMT-A and AD related phenotypes. These findings offer the potential for new insights into the pathogenesis of cognitive function and Alzheimer's disease.

TRF2 recruits nucleolar protein TCOF1 to coordinate telomere transcription and replication.

Telomeres are transcribed into telomeric RNA termed as TERRA. However, the transcription itself and excessive TERRA may interfere with telomere replication during S phase. The mechanism that coordinates telomere transcription and replication is unknown. Here, we report that TCOF1 leaves the nucleolus and is recruited to telomeres specifically during S phase by interacting with TRF2. Therein, TCOF1 acts to suppress telomere transcription by binding and inhibiting Pol II. Thus, TERRA is limited to low levels in S phase. Depletion of TCOF1 leads to abnormally elevated TERRA and formation of DNA/RNA hybrids (R-loops) at telomeres, which induces replication fork stalling and fragile telomeres. Importantly, telomere replication defect induced by TCOF1 deficiency can be rescued by either masking TERRA or expressing an R-loop eraser RNase H1, demonstrating a critical role of TCOF1 in coordinating telomere transcription and replication. These findings link nucleolus to telomeres and uncover a novel function of TCOF1 on ensuring telomere integrity.

Peroxisome Elevation Induces Stem Cell Differentiation and Intestinal Epithelial Repair.

Epithelial-repair-dependent mucosal healing (MH) is associated with a more favorable prognosis for patients with inflammatory bowel disease (IBD). MH is accomplished via repair and regeneration of the intestinal epithelium. However, the mechanism underlying MH is ill defined. We found a striking upregulation of peroxisomes in the injured crypts of IBD patients. By increasing peroxisome levels in Drosophila midguts, we found that peroxisome elevation enhanced RAB7-dependent late endosome maturation, which then promoted stem and/or progenitor-cell differentiation via modulation of Janus Kinase (JAK) and Signal Transducer and Activator of Transcription (STAT)-SOX21A signaling. This in turn enhanced ISC-mediated regeneration. Importantly, RAB7 and SOX21 were upregulated in the crypts of IBD patients. Moreover, administration of drugs that increased peroxisome levels reversed the symptoms of dextran sulfate sodium (DSS)-induced colitis in mice. This study demonstrates a peroxisome-mediated epithelial repair mechanism, which opens a therapeutic avenue for the enhancement of MH in IBD patients.

Age-associated de-repression of retrotransposons in the Drosophila fat body, its potential cause and consequence.

Eukaryotic genomes contain transposable elements (TE) that can move into new locations upon activation. Since uncontrolled transposition of TEs, including the retrotransposons and DNA transposons, can lead to DNA breaks and genomic instability, multiple mechanisms, including heterochromatin-mediated repression, have evolved to repress TE activation. Studies in model organisms have shown that TEs become activated upon aging as a result of age-associated deregulation of heterochromatin. Considering that different organisms or cell types may undergo distinct heterochromatin changes upon aging, it is important to identify pathways that lead to TE activation in specific tissues and cell types. Through deep sequencing of isolated RNAs, we report an increased expression of many retrotransposons in the old Drosophila fat body, an organ equivalent to the mammalian liver and adipose tissue. This de-repression correlates with an increased number of DNA damage foci and decreased level of Drosophila lamin-B in the old fat body cells. Depletion of the Drosophila lamin-B in the young or larval fat body results in a reduction of heterochromatin and a corresponding increase in retrotransposon expression and DNA damage. Further manipulations of lamin-B and retrotransposon expression suggest a role of the nuclear lamina in maintaining the genome integrity of the Drosophila fat body by repressing retrotransposons.

[Application of continuous video-electroencephalographic monitoring in patients with consciousness disorders in intensive care unit].

OBJECTIVE: To evaluate the application value of continuous video-electroencephalographic (cVEEG) monitoring in patients with consciousness disorders in intensive care unit (ICU). METHODS: Retrospective analyses were conducted for applying cVEEG in the clinical diagnosis and outcome evaluation of 54 patients with consciousness disorders in intensive care unit (ICU) at our hospital from January 2008 to April 2014. RESULTS: The most common cause was cerebrovascular disease (46.3%) followed by ischemic-hypoxic encephalopathy after cadio-pulmonary resuscitation (18.5%). And 49 cases (90.7%) showed an abnormal background on initial cVEEG, 19 cases (35.2%) had epileptic discharge and 8 cases (14.8%) were diagnosed with nonconvulsive status epilepticus (NCSE). Among 6 cases of convulsive patients, only 1 had epileptic discharge patterns of isoelectric, invariable low amplitude. Burst-suppression, persistent θ rhythm-like background activity, persistent diffuse epileptic discharge and periodic waves had high mortality rate. CONCLUSION: Stroke is a major cause of consciousness disorders. And continuous VEEG monitoring is beneficial for clinical diagnosis, differential diagnosis and outcome evaluation.

Acupuncture for Parkinson's Disease: a review of clinical, animal, and functional Magnetic Resonance Imaging studies.

Acupuncture has been commonly used as an adjuvant therapy or monotherapy in the treatment of Parkinson's disease in China and in other countries. Animal studies have consistently show that this treatment is both neuroprotective, protecting dopaminergic neurons from degeneration and also restorative, restoring tyrosine hydroxylase positive dopaminergic terminals in striatum, resulting in improvements in motor performance in animal models of Parkinsonism. Studies show that this protection is mediated through the same common mechanisms as other neuroprotective agents, including anti-oxidative stress, anti-inflammatory and anti-apoptotic pathways at molecular and cellular levels. Restoration of function seems to involve activation of certain compensatory brain regions as a mechanism at the network level to correct the imbalances to the nervous system resulting from loss of dopaminergic neurons in substantia nigra. Clinical studies in China and Korea, in particular, have shown a positive benefit of acupuncture in treating Parkinson's disease, especially in reducing the doses of dopaminergic medications and the associated side effects. However, large and well-controlled clinical trials are still needed to further demonstrate the efficacy and effectiveness of acupuncture in the treatment of Parkinson's disease.

Deletion of adenosine A1 or A(2A) receptors reduces L-3,4-dihydroxyphenylalanine-induced dyskinesia in a model of Parkinson's disease.

Adenosine A(2A) receptor antagonism provides a promising approach to developing nondopaminergic therapy for Parkinson's disease (PD). Clinical trials of A(2A) antagonists have targeted PD patients with L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia (LID) in an effort to improve parkinsonian symptoms. The role of adenosine in the development of LID is little known, especially regarding its actions via A1 receptors. We aimed to examine the effects of genetic deletion and pharmacological blockade of A1 and/or A(2A) receptors on the development of LID, on the induction of molecular markers of LID including striatal preprodynorphin and preproenkephalin (PPE), and on the integrity of dopaminergic nigrostriatal neurons in hemiparkinsonian mice. Following a unilateral 6-hydroxydopamine lesion A1, A(2A) and double A1-A(2A) knockout (KO) and wild-type littermate mice, and mice pretreated with caffeine (an antagonist of both A1 and A(2A) receptors) or saline were treated daily for 18-21 days with a low dose of L-DOPA. Total abnormal involuntary movements (AIMs, a measure of LID) were significantly attenuated (p<0.05) in A1 and A(2A) KOs, but not in A1-A(2A) KOs and caffeine-pretreated mice. An elevation of PPE mRNA ipsilateral to the lesion in WT mice was reduced in all KO mice. In addition, neuronal integrity assessed by striatal dopamine content was similar in all KOs and caffeine-pretreated mice following 6-hydroxydopamine lesioning. Our findings raise the possibility that A1 or A(2A) receptors blockade might also confer a disease-modifying benefit of reduced risk of disabling LID, whereas the effect of their combined inactivation is less clear.

Protective effect of metabotropic glutamate mGluR5 receptor elimination in a 6-hydroxydopamine model of Parkinson's disease.

Pharmacologic or genetic blockade of metabotropic glutamate mGlu5 receptors (mGluR5) has been shown to attenuate parkinsonian motor deficits and protect nigrostriatal neurons from damage in the acute MPTP model of Parkinson's disease (PD), suggesting that therapeutically targeting the mGluR5 receptor may offer a novel approach to improving motor symptoms and/or slowing neurodegeneration in PD. This study further explored the neuroprotective potential of targeting mGluR5 receptors. We examined the behavioral and neurochemical effects of receptor elimination on toxicity induced by intra-striatal application of 6-hydroxydopamine (6-OHDA), thought to represent a comparatively progressive model of PD. mGluR5 knockout (KO) mice and wild-type (WT) littermates received unilateral 6-OHDA infusions. Reflecting the imbalance expected following unilateral infusion, WT but not KO mice demonstrated predominantly ipsilateral forepaw use and robust ipsilateral amphetamine-induced rotation. Further, performance on the vertical pole descent task was profoundly impaired in WT mice, while KO mice completed the task significantly faster. Consistent with the behavioral observations, neurochemical analyses of striatal dopamine depletion showed significantly diminished severity in KO mice with only 64% of striatal dopamine lost, compared to 92% in WT mice. The absence of brain mGluR5 receptors in living KO mice was verified using positron emission tomography (PET). Our findings substantiate the key role of mGluR5 receptors in animal models of PD, strengthening the rationale for the development of mGluR5 antagonists for their neuroprotective, as well as symptomatic, benefit.

Role of adenosine A2A receptors in parkinsonian motor impairment and l-DOPA-induced motor complications.

Adenosine A2A receptors have a unique cellular and regional distribution in the basal ganglia, being particularly concentrated in areas richly innervated by dopamine such as the caudate-putamen and the globus pallidus. Adenosine A2A receptors are selectively located on striatopallidal neurons and are capable of forming functional heteromeric complexes with dopamine D2 and metabotropic glutamate mGlu5 receptors. Based on the unique cellular and regional distribution of this receptor and in line with data showing that A2A receptor antagonists improve motor symptoms in animal models of Parkinson's disease (PD) and in initial clinical trials, A2A receptor antagonists have emerged as an attractive non-dopaminergic target to improve the motor deficits that characterize PD. Experimental data have also shown that A2A receptor antagonists do not induce neuroplasticity phenomena that complicate long-term dopaminergic treatments. The present review provides an updated summary of results reported in the literature concerning the biochemical characteristics and basal ganglia distribution of A2A receptors. We subsequently aim to examine the effects of adenosine A2A antagonists in rodent and primate models of PD and of l-DOPA-induced dyskinesia. Finally, concluding remarks are made on post-mortem human brains and on the translation of adenosine A2A receptor antagonists in the treatment of PD.

Forebrain adenosine A2A receptors contribute to L-3,4-dihydroxyphenylalanine-induced dyskinesia in hemiparkinsonian mice.

Adenosine A2A receptor antagonists provide a promising nondopaminergic approach to the treatment of Parkinson's disease (PD). Initial clinical trials of A2A antagonists targeted PD patients who had already developed treatment complications known as L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia (LID) in an effort to improve symptoms while reducing existing LID. The goal of this study is to explore the effect of A2A antagonists and targeted A2A receptor depletion on the actual development of sensitized responses to L-DOPA in mouse models of LID in PD. Hemiparkinsonian mice (unilaterally lesioned with 6-OHDA) were treated daily for 3 weeks with a low dose of L-DOPA (2 mg/kg) preceded by a low dose of selective A2A antagonist (KW-6002 [(E)-1,3-diethyl-8-(3,4-dimethoxystyryl)-7-methyl-3,7-dihydro-1H-purine-2,6-dione] at 0.03 or 0.3 mg/kg, or SCH58261 [5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine] at 0.03 mg/kg) or vehicle intraperitoneally. In control mice, contralateral rotational responses to daily L-DOPA gradually increased over the initial week before reaching a persistent maximum. Both A2A antagonists inhibited the development of sensitized contralateral turning, with KW-6002 pretreatment reducing the sensitized rotational responses by up to threefold. The development of abnormal involuntary movements (a measure of LID) as well as rotational responses was attenuated by the postnatal depletion of forebrain A2A receptors in conditional (Cre/loxP system) knock-out mice. These pharmacological and genetic data provide evidence that striatal A2A receptors play an important role in the neuroplasticity underlying behavioral sensitization to L-DOPA, supporting consideration of early adjunctive therapy with an A2A antagonist to reduce the risk of LID in PD.