Sampling issues of cerebrospinal fluid and plasma monoamines: Investigation of the circadian rhythm and rostrocaudal concentration gradient

Cerebrospinal fluid concentration gradients of catechols in synucleinopathies

The synucleinopathies Parkinson disease (PD), multiple system atrophy (MSA), and the Lewy body form of pure autonomic failure (PAF) entail intra-cytoplasmic deposition of the protein alpha-synuclein and pathogenic catecholaminergic neurodegeneration. Cerebrospinal fluid (CSF) levels of catecholamines and their metabolites are thought to provide a "neurochemical window" on central catecholaminergic innervation and can identify specific intra-neuronal dysfunctions in synucleinopathies. We asked whether there are CSF concentration gradients for catechols such as 3,4-dihydroxyphenylacetic acid (DOPAC), the main neuronal metabolite of dopamine, and if so whether the gradients influence neurochemical differences among synucleinopathies. In a retrospective cohort study, we reviewed data about concentrations of catechols in the first, sixth, and twelfth 1-mL aliquots from 33 PD, 28 MSA, and 15 PAF patients and 41 controls. There were concentration gradients for DOPAC, dopamine, norepinephrine, and 3,4-dihydroxyphenylglycol (the main neuronal metabolite of norepinephrine) and gradients in the opposite direction for 5-S-cysteinyldopa and 5-S-cysteinyldopamine. In all 3 aliquots, CSF DOPAC was low in PD and MSA compared with controls (p < 0.0001 each) and normal in PAF. Synucleinopathies differ in CSF catechols regardless of concentration gradients. Concentration gradients for 5-S-cysteinyl derivatives in opposite directions from the parent catechols may provide biomarkers of spontaneous oxidation in the CSF space.

The causal effect of Alzheimer's disease and family history of Alzheimer's disease on non-ischemic cardiomyopathy and left ventricular structure and function: a Mendelian randomization study

Background

Previous studies have shown that Alzheimer's disease (AD) can cause myocardial damage. However, whether there is a causal association between AD and non-ischemic cardiomyopathy (NICM) remains unclear. Using a comprehensive two-sample Mendelian randomization (MR) method, we aimed to determine whether AD and family history of AD (FHAD) affect left ventricular (LV) structure and function and lead to NICM, including hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM).

Methods

The summary statistics for exposures [AD, paternal history of AD (PH-AD), and maternal history of AD (MH-AD)] and outcomes (NICM, HCM, DCM, and LV traits) were obtained from the large European genome-wide association studies. The causal effects were estimated using inverse variance weighted, MR-Egger, and weighted median methods. Sensitivity analyses were conducted, including Cochran's Q test, MR-Egger intercept test, MR pleiotropy residual sum and outlier, MR Steiger test, leave-one-out analysis, and the funnel plot.

Results

Genetically predicted AD was associated with a lower risk of NICM [odds ratio (OR) 0.9306, 95% confidence interval (CI) 0.8825-0.9813, p = 0.0078], DCM (OR 0.8666, 95% CI 0.7752-0.9689, p = 0.0119), and LV remodeling index (OR 0.9969, 95% CI 0.9940-0.9998, p = 0.0337). Moreover, genetically predicted PH-AD was associated with a decreased risk of NICM (OR 0.8924, 95% CI 0.8332-0.9557, p = 0.0011). MH-AD was also strongly associated with a decreased risk of NICM (OR 0.8958, 95% CI 0.8449-0.9498, p = 0.0002). Different methods of sensitivity analysis demonstrated the robustness of the results.

Conclusion

Our study revealed that AD and FHAD were associated with a decreased risk of NICM, providing a new genetic perspective on the pathogenesis of NICM.

[Biobanking in clinical trials involving multiple sclerosis patients]

Investigation of multiple sclerosis (MS) pathogenesis requires sophisticated analytical tools of precision medicine, such as omics research, which include genomics, microbiomics and metabolomics (proteomics, lipidomics and glycomics). Such sensitive methods are based on careful preanalytical work with biomaterials to maintain quality and obtain objective results. Implementation of biobanking as a universal method for working with biomaterials will help to standardize the stages of research, compare different scientific team's results. Collaboration of MS researchers with large biobanks can also help to conduct multicenter and long-term prospective studies, to include a wide number of patients. In this article, we analyze the experience of biobanking practice technologies in studies of MS patients and share the experience of partnership between the Center for MS of the Tomsk Region and the Bank of Biological Material of the Siberian State Medical University.

Dysfunction of norepinephrine and its metabolites in Alzheimer's dementia - A review with meta-analysis

Some studies point locus coeruleus cell loss, the central nervous system main source of norepinephrine, to be one of the earliest neuropathological events of Alzheimer's disease (AD). However, there are conflicting reports regarding the level of norepinephrine and its metabolites (3-Methoxy-4-hydroxyphenylglycol (MHPG), 3,5-dihydroxyphenylglycine (DHPG) and 3,4 -dihydroxyphenylglycolaldehyde (DOPEGAL)) in AD patients. Uncover these alterations may be a key factor for understanding cognitive deficits and AD pathology. We review the literature that compare norepinephrine and its metabolites between AD patients and non-demented controls. A meta-analysis did not reveal significant statistical differences, but there was a trend towards a lower level of norepinephrine of AD, with almost no difference in MHPG in the cerebrospinal fluid. Regarding MHPG in plasma, DHPG and DOPEGAL we only performed a qualitative analyse due to the small or absent number of studies. These findings point to a decrease in norepinephrine, what is in line with locus coeluleus cell loss in AD. The absence of statistical difference and an equal level of MHGP could indicate a compensatory mechanism.

LC-MS/MS combined with blood-brain dual channel microdialysis for simultaneous determination of active components of astragali radix-safflower combination and neurotransmitters in rats with cerebral ischemia reperfusion injury: Application in pharmacokinetic and pharmacodynamic study

BACKGROUND

Astragali Radix-Safflower combination (ARSC) is widely utilized in clinic to treat cerebral ischemia/reperfusion injury (CI/RI). Whereas, there is no in-depth research of the pharmacokinetics (PK) and pharmacodynamics (PD) analysis of ARSC after intragastric administration in rats with CI/RI.

PURPOSE

The purpose of this research is to investigate the PK characteristics of eight active ingredients (astragaloside IV, calycosin, calycosin-7-O-β-glucoside, formononetin, ononin, hydroxysafflor yellow A, syringin and vernine) of ARSC, and the regulation of neurotransmitters disorders, revealing the pharmacodynamic substance basis and the mechanism of ARSC in treating CI/RI from the molecular level.

METHODS

We established a new method which based on blood-brain dual channel microdialysis (MD) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to continuously gather, and determine the components of ARSC and neurotransmitters related to CI/RI in vivo. The collected data were analyzed by sigmoid-E_max function. The neurotransmitters primarily regulated in CI/RI rat were discussed by principal component analysis and the compound most associated with total pharmacodynamics was chosen by partial least squares regression.

RESULTS

The validated LC-MS/MS method had specificity and selectivity to simultaneously analyze the concentration of eight active components of ARSC extract and five neurotransmitters of CI/RI rats. The recovery rates of brain MD probe and blood MD probe were stable within six hours. The MD probes recovery rates decreased with the increase of flow rates, but the solution concentration had little effect on the probes recovery rates. It was feasible to correct the recovery rates of probes in vivo by using reverse dialysis method. All eight active ingredients of ARSC could pass across the blood brain barrier after CI/RI. ARSC regulated the release of glutamate (Glu), γ-aminobutyric acid (GABA), dopamine (DA), 5-hydroxytryptamine (5-HT) and aspartic acid (Asp). Notably, astragaloside IV and hydroxysafflor yellow A might have better regulatory effect on neurotransmitters in comparison with other six measured components of ARSC, and Glu was the neurotransmitter mainly regulated in CI/RI rats.

CONCLUSION

The ARSC was able to treat CI/RI through ameliorating neurotransmitters disorders. There was a hysteresis between the peaked drug concentration and maximum therapeutic effect of ARSC. The drug effective concentrations range of ASIV, calycosin, calycosin-7-O-β-glucoside, syringin and vernine in blood microdialysate and calycosin, syringin, vernine in brain microdialysate were narrow, which need be paid attention in clinical use.

Cerebrospinal fluid catecholamines in Alzheimer's disease patients with and without biological disease

Noradrenergic and dopaminergic neurons are involved in cognitive functions, relate to behavioral and psychological symptoms in dementia and are affected in Alzheimer's disease (AD). Amyloid plaques (A), neurofibrillary tangles (T) and neurodegeneration (N) hallmarks the AD neuropathology. Today, the AT(N) pathophysiology can be assessed through biomarkers. Previous studies report cerebrospinal fluid (CSF) catecholamine concentrations in AD patients without biomarker refinement. We explored if CSF catecholamines relate to AD clinical presentation or neuropathology as reflected by CSF biomarkers. CSF catecholamines were analyzed in AD patients at the mild cognitive impairment (MCI; n = 54) or dementia stage (n = 240) and in cognitively unimpaired (n = 113). CSF biomarkers determined AT status and indicated synaptic damage (neurogranin). The AD patients (n = 294) had higher CSF noradrenaline and adrenaline concentrations, but lower dopamine concentrations compared to the cognitively unimpaired (n = 113). AD patients in the MCI and dementia stage of the disease had similar CSF catecholamine concentrations. In the CSF neurogranin positively associated with noradrenaline and adrenaline but not with dopamine. Adjusted regression analyses including AT status, CSF neurogranin, age, gender, and APOEε4 status verified the findings. In restricted analyses comparing A+T+ patients to A-T- cognitively unimpaired, the findings for CSF adrenaline remained significant (p < 0.001) but not for CSF noradrenaline (p = 0.07) and CSF dopamine (p = 0.33). There were no differences between A+T+ and A-T- cognitively unimpaired. Thus, we find alterations in CSF catecholamines in symptomatic AD and the CSF adrenergic transmitters to increase simultaneously with synaptic damage as indexed by CSF neurogranin.

Circadian rhythms in neurodegenerative disorders

Endogenous biological clocks, orchestrated by the suprachiasmatic nucleus, time the circadian rhythms that synchronize physiological and behavioural functions in humans. The circadian system influences most physiological processes, including sleep, alertness and cognitive performance. Disruption of circadian homeostasis has deleterious effects on human health. Neurodegenerative disorders involve a wide range of symptoms, many of which exhibit diurnal variations in frequency and intensity. These disorders also disrupt circadian homeostasis, which in turn has negative effects on symptoms and quality of life. Emerging evidence points to a bidirectional relationship between circadian homeostasis and neurodegeneration, suggesting that circadian function might have an important role in the progression of neurodegenerative disorders. Therefore, the circadian system has become an attractive target for research and clinical care innovations. Studying circadian disruption in neurodegenerative disorders could expand our understanding of the pathophysiology of neurodegeneration and facilitate the development of novel, circadian-based interventions for these disabling disorders. In this Review, we discuss the alterations to the circadian system that occur in movement (Parkinson disease and Huntington disease) and cognitive (Alzheimer disease and frontotemporal dementia) neurodegenerative disorders and provide directions for future investigations in this field.

Serum Daytime Melatonin Levels Reflect Cerebrospinal Fluid Melatonin Levels in Alzheimer's Disease but Are Not Correlated with Cognitive Decline

Background:

Nocturnal cerebrospinal fluid (CSF) and blood melatonin levels are altered in Alzheimer’s disease (AD). However, literature remains inconclusive on daytime blood melatonin levels. A positive correlation between melatonin levels and Mini-Mental State Examination (MMSE) scores in AD subjects has been evidenced following cross-sectional analyses. Whereas a correlation between serum and spinal CSF melatonin has been shown in healthy volunteers, an equal investigation in AD patients still has to be undertaken.

Objective:

1) To evaluate whether serum melatonin levels correlate with spinal CSF melatonin levels in AD. 2) To compare daytime CSF and serum melatonin levels between patients with AD dementia, mild cognitive impairment due to AD, and healthy controls, and to evaluate whether melatonin can affect cognitive decline in AD.

Methods:

Subjects with AD and healthy controls included in two existing cohorts, of whom a CSF and serum sample was available at the neurobiobank and had at least 6 months of neuropsychological follow-up, were included in the present study. Melatonin concentrations were measured with liquid chromatography-mass spectrometry.

Results:

Daytime serum melatonin levels correlated with spinal CSF melatonin levels in AD (r = 0.751, p < 0.001). No significant differences regarding daytime melatonin levels were found between patients and controls. No correlations were observed between daytime melatonin levels and MMSE score changes.

Conclusion:

Daytime serum melatonin accurately reflects CSF melatonin levels in AD, raising the possibility to assess melatonin alterations by solely performing blood sampling if also confirmed for night-time values. However, daytime melatonin levels are not associated with changes of cognitive impairment.

Comparison between cerebrospinal fluid and serum levels of myelin-associated glycoprotein, total antioxidant capacity, and 8-hydroxy-2'-deoxyguanosine in patients with multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a chronic inflammatory disease characterized by demyelinated lesions in the brain, the spinal cord, and the optic nerve. It is one of the most common neurological disorders. In this study, serum and cerebrospinal fluid (CSF) levels of total antioxidant capacity (TAC), myelin-associated glycoprotein (MAG), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) were investigated to determine their effects on MS.

MATERIALS AND METHOD

In this study, 25 serum and cerebrospinal samples from MS patients as a case group and 40 serum and CSF samples from healthy participants as a control group were collected and analyzed. Concentrations of TAC, MAG, and 8-OhdG were determined in the samples using a dedicated kit and relayed using the ELISA device.

RESULTS

The mean serum antibody levels of MAG and TAC were higher in the case group than the control group, although the difference in the MAG level was not significant (P > 0.05). However, the mean serum level of -8 OHdG was lower in the case group than the control group. Moreover, the mean levels of the evaluated biomarkers in the CSF samples were higher in the case group than in the control group. Still, the difference was only significant in terms of TAC levels (P < 0.05). Receiver operating characteristics curve analysis showed that the area under the curve was 0.71 and 0.69 for 8-OhdG and TAC serum levels, respectively, and 0.73 for both TAC and CSF levels, which was not significantly different from that in other biomarkers.

CONCLUSION

Elevated TAC levels in serum and CSF samples and 8-OhdG in serum samples may be associated with MS pathogenesis. However, further investigation is needed to consider these cases as a follow-up to the therapeutic goals or treatment process.

COMT val158met genotype alters the effects of methamphetamine dependence on dopamine and dopamine-related executive function: preliminary findings

The Met-allele of the COMT Val158Met polymorphism slows metabolism and increases bioavailability of dopamine (DA) in the prefrontal cortex compared to the Val-allele. Healthy Met-carriers outperform Val-carriers on executive function (EF) tests, yet this 'advantage' disappears in methamphetamine (METH) dependence. Met-carriers may be disproportionately vulnerable to METH-related perturbations of DA, yet it is unknown whether COMT modulates METH effects on CSF DA biomarkers. Participants were 75 METH+ and 47 METH- men who underwent neurocognitive testing, COMT genotyping, and lumbar puncture. CSF was assayed for DA and its metabolite, homovanillic acid (HVA). Separate linear models regressed DA, HVA, and HVA/DA ratios on COMT, METH and their interaction. Pearson correlations examined associations between DA and EF. Significant interactions indicated that METH+ had lower DA and higher HVA/DA ratios among Met/Met, but not Val/Met-or Val/Val. Met/Met-exhibited the highest DA levels among METH-, whereas DA levels were comparable between Met/Met-and Val-carriers among METH+. Higher DA correlated with better EF in METH- Met/Met, but did not predict EF in the entire sample. DA was expectedly higher in METH- Met/Met, yet a discordant genotype-phenotype profile emerged in METH+ Met/Met, consistent with the notion that slow DA clearance exacerbates METH-associated DA dysregulation.

Biofluid Markers for Prodromal Parkinson's Disease: Evidence From a Catecholaminergic Perspective

Parkinson's disease (PD) is the most frequent of all Lewy body diseases, a family of progressive neurodegenerative disorders characterized by intra-neuronal cytoplasmic inclusions of α-synuclein. Its most defining features are bradykinesia, tremor, rigidity and postural instability. By the time PD manifests with motor signs, 70% of dopaminergic midbrain neurons are lost, and the disease is already in the middle or late stage. However, there are various non-motor symptoms occurring up to 20 years before the actual parkinsonism that are closely associated with profound deficiency of myocardial noradrenaline content and peripheral sympathetic denervation, as evidenced by neuroimaging experiments in recent years. Additionally, there is an inherent autotoxicity of catecholamines in the neuronal cells in which they are produced, forming toxic catecholaldehyde intermediates that make α-synuclein prone to aggregation, initiating a cascade of events that ultimately leads to neuronal death. The etiopathogenesis of PD and related synucleinopathies thus may well be a prototypical example of a catecholamine-regulated neurodegeneration, given that the synucleinopathy in PD spreads in synergy with central and peripheral catecholaminergic dysfunction from the earliest phases onward. That is why catecholamines and their metabolites, precursors, or derivatives in cerebrospinal fluid or plasma could be of particular interest as biomarkers for prodromal and de novo PD. Because there is great demand for such markers, this mini-review summarizes all catecholamine-related studies to date, in addition to providing profound neurochemical evidence on a systemic and cellular level to further emphasize this hypothesis and with emphasis on extracellular vesicles as a novel diagnostic and therapeutic incentive.

Monoamines and their Derivatives on GPCRs: Potential Therapy for Alzheimer's Disease

Albeit cholinergic depletion remains the key event in Alzheimer's Disease (AD), recent information describes stronger links between monoamines (trace amines, catecholamines, histamine, serotonin, and melatonin) and AD than those known in the past century. Therefore, new drug design strategies focus efforts to translate the scope on these topics and to offer new drugs which can be applied as therapeutic tools in AD. In the present work, we reviewed the state-of-art regarding genetic, neuropathology and neurochemistry of AD involving monoamine systems. Then, we compiled the effects of monoamines found in the brain of mammals as well as the reported effects of their derivatives and some structure-activity relationships. Recent derivatives have triggered exciting effects and pharmacokinetic properties in both murine models and humans. In some cases, the mechanism of action is clear, essentially through the interaction on G-protein-coupled receptors as revised in this manuscript. Additional mechanisms are inhibition of enzymes for their biotransformation, regulation of free-radicals in the central nervous system and others for the effects on Tau phosphorylation or amyloid-beta accumulation. All these data make the monoamines and their derivatives attractive potential elements for AD therapy.