Showing papers on "Monoamine oxidase B published in 2014"

GABA from reactive astrocytes impairs memory in mouse models of Alzheimer's disease

Abstract: In Alzheimer's disease (AD), memory impairment is the most prominent feature that afflicts patients and their families. Although reactive astrocytes have been observed around amyloid plaques since the disease was first described, their role in memory impairment has been poorly understood. Here, we show that reactive astrocytes aberrantly and abundantly produce the inhibitory gliotransmitter GABA by monoamine oxidase-B (Maob) and abnormally release GABA through the bestrophin 1 channel. In the dentate gyrus of mouse models of AD, the released GABA reduces spike probability of granule cells by acting on presynaptic GABA receptors. Suppressing GABA production or release from reactive astrocytes fully restores the impaired spike probability, synaptic plasticity, and learning and memory in the mice. In the postmortem brain of individuals with AD, astrocytic GABA and MAOB are significantly upregulated. We propose that selective inhibition of astrocytic GABA synthesis or release may serve as an effective therapeutic strategy for treating memory impairment in AD.

Monoamine oxidase B prompts mitochondrial and cardiac dysfunction in pressure overloaded hearts.

Abstract: Aims: Monoamine oxidases (MAOs) are mitochondrial flavoenzymes responsible for neurotransmitter and biogenic amines catabolism. MAO-A contributes to heart failure progression via enhanced norepinephrine catabolism and oxidative stress. The potential pathogenetic role of the isoenzyme MAO-B in cardiac diseases is currently unknown. Moreover, it is has not been determined yet whether MAO activation can directly affect mitochondrial function. Results: In wild type mice, pressure overload induced by transverse aortic constriction (TAC) resulted in enhanced dopamine catabolism, left ventricular (LV) remodeling, and dysfunction. Conversely, mice lacking MAO-B (MAO-B−/−) subjected to TAC maintained concentric hypertrophy accompanied by extracellular signal regulated kinase (ERK)1/2 activation, and preserved LV function, both at early (3 weeks) and late stages (9 weeks). Enhanced MAO activation triggered oxidative stress, and dropped mitochondrial membrane potential in the presence of ATP synthase inhibi...

Glial GABA, synthesized by monoamine oxidase B, mediates tonic inhibition

Abstract: GABA is the major inhibitory transmitter in the brain and is released not only from a subset of neurons but also from glia. Although neuronal GABA is well known to be synthesized by glutamic acid decarboxylase (GAD), the source of glial GABA is unknown. After estimating the concentration of GABA in Bergmann glia to be around 5-10 mM by immunogold electron microscopy, we demonstrate that GABA production in glia requires MAOB, a key enzyme in the putrescine degradation pathway. In cultured cerebellar glia, both Ca 2+ -induced and tonic GABA release are significantly reduced by both gene silencing of MAOB and the MAOB inhibitor selegiline. In the cerebellum and striatum of adult mice, general gene silencing, knock out of MAOB or selegiline treatment resulted in elimination of tonic GABA currents recorded from granule neurons and medium spiny neurons. Glial-specific rescue of MAOB resulted in complete rescue of tonic GABA currents. Our results identify MAOB as a key synthesizing enzyme of glial GABA,whichisreleasedviabestrophin1(Best1)channeltomediatetonicinhibitioninthebrain.

Kinetic Modeling of the Monoamine Oxidase B Radioligand [11C]SL25.1188 in Human Brain with High-Resolution Positron Emission Tomography:

Abstract: This article describes the kinetic modeling of [11C]SL25.1188 ([(S)-5-methoxymethyl-3-[6-(4,4,4-trifluorobutoxy)-benzo[d]isoxazol-3-yl]-oxazolidin-2-[11C]one]) binding to monoamine oxidase B (MAO-B...

Multipotent cholinesterase/monoamine oxidase inhibitors for the treatment of Alzheimer's disease: design, synthesis, biochemical evaluation, ADMET, molecular modeling, and QSAR analysis of novel donepezil-pyridyl hybrids.

Abstract: The design, synthesis, and biochemical evaluation of donepezil-pyridyl hybrids (DPHs) as multipotent cholinesterase (ChE) and monoamine oxidase (MAO) inhibitors for the potential treatment of Alzheimer's disease (AD) is reported. The 3D-quantitative structure-activity relationship study was used to define 3D-pharmacophores for inhibition of MAO A/B, acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE) enzymes and to design DPHs as novel multi-target drug candidates with potential impact in the therapy of AD. DPH14 (Electrophorus electricus AChE [EeAChE]: half maximal inhibitory concentration [IC50] =1.1±0.3 nM; equine butyrylcholinesterase [eqBuChE]: IC50 =600±80 nM) was 318-fold more potent for the inhibition of AChE, and 1.3-fold less potent for the inhibition of BuChE than the reference compound ASS234. DPH14 is a potent human recombinant BuChE (hBuChE) inhibitor, in the same range as DPH12 or DPH16, but 13.1-fold less potent than DPH15 for the inhibition of human recombinant AChE (hAChE). Compared with donepezil, DPH14 is almost equipotent for the inhibition of hAChE, and 8.8-fold more potent for hBuChE. Concerning human monoamine oxidase (hMAO) A inhibition, only DPH9 and 5 proved active, compound DPH9 being the most potent (IC50 [MAO A] =5,700±2,100 nM). For hMAO B, only DPHs 13 and 14 were moderate inhibitors, and compound DPH14 was the most potent (IC50 [MAO B] =3,950±940 nM). Molecular modeling of inhibitor DPH14 within EeAChE showed a binding mode with an extended conformation, interacting simultaneously with both catalytic and peripheral sites of EeAChE thanks to a linker of appropriate length. Absortion, distribution, metabolism, excretion and toxicity analysis showed that structures lacking phenyl-substituent show better druglikeness profiles; in particular, DPHs13-15 showed the most suitable absortion, distribution, metabolism, excretion and toxicity properties. Novel donepezil-pyridyl hybrid DPH14 is a potent, moderately selective hAChE and selective irreversible hMAO B inhibitor which might be considered as a promising compound for further development for the treatment of AD.

Empirical valence bond simulations of the hydride transfer step in the monoamine oxidase B catalyzed metabolism of dopamine: EVB Simulations of Hydride Transfer in MAO B

Abstract: Monoamine oxidases (MAOs) A and B are flavoenzymes responsible for the metabolism of biogenic amines such as dopamine, serotonin and noradrenaline. In this work, we present a comprehensive study of the rate‐limiting step of dopamine degradation by MAO B, which consists in the hydride transfer from the methylene group of the substrate to the flavin moiety of the FAD prosthetic group. This article builds on our previous quantum chemical study of the same reaction using a cluster model (Vianello et al., Eur J Org Chem 2012; 7057), but now considering the full dimensionality of the hydrated enzyme with extensive configurational sampling. We show that MAO B is specifically tuned to catalyze the hydride transfer step from the substrate to the flavin moiety of the FAD prosthetic group and that it lowers the activation barrier by 12.3 kcal mol−1 compared to the same reaction in aqueous solution, a rate enhancement of more than nine orders of magnitude. Taking into account the deprotonation of the substrate prior to the hydride transfer reaction, the activation barrier in the enzyme is calculated to be 16.1 kcal mol−1, in excellent agreement with the experimental value of 16.5 kcal mol−1. Additionally, we demonstrate that the protonation state of the active site residue Lys296 does not have an influence on the hydride transfer reaction. Proteins 2014; 82:3347–3355. © 2014 Wiley Periodicals, Inc.

The multiple pharmaceutical potential of curcumin in Parkinson's disease.

Abstract: Parkinson's disease (PD) is one of the most common neurodegenerative diseases in the elderly. In recent years increasing evidence supports the pharmaceutical potential of curcumin, a polyphenolic compound in the spice turmeric, against PD. Here we briefly summarize the pharmacological activities of curcumin in vitro and in animal models of PD, including counteracting oxidative stress and inflammation, preventing α-synuclein aggregation and fibrillation, and inhibiting monoamine oxidase B, which endow curcumin with multiple pharmaceutical activities against PD and encourage further studies to investigate its clinical effects.

Catecholamine metabolism drives generation of mitochondrial DNA deletions in dopaminergic neurons.

Abstract: Accumulation of mitochondrial DNA deletions is observed especially in dopaminergic neurons of the substantia nigra during ageing and even more in Parkinson's disease. The resulting mitochondrial dysfunction is suspected to play an important role in neurodegeneration. However, the molecular mechanisms involved in the preferential generation of mitochondrial DNA deletions in dopaminergic neurons are still unknown. To study this phenomenon, we developed novel polymerase chain reaction strategies to detect distinct mitochondrial DNA deletions and monitor their accumulation patterns. Applying these approaches in in vitro and in vivo models, we show that catecholamine metabolism drives the generation and accumulation of these mitochondrial DNA mutations. As in humans, age-related accumulation of mitochondrial DNA deletions is most prominent in dopaminergic areas of mouse brain and even higher in the catecholaminergic adrenal medulla. Dopamine treatment of terminally differentiated neuroblastoma cells, as well as stimulation of dopamine turnover in mice over-expressing monoamine oxidase B both induce multiple mitochondrial DNA deletions. Our results thus identify catecholamine metabolism as the driving force behind mitochondrial DNA deletions, probably being an important factor in the ageing-associated degeneration of dopaminergic neurons.

Polymorphisms in genes implicated in dopamine, serotonin and noradrenalin metabolism suggest association with cerebrospinal fluid monoamine metabolite concentrations in psychosis

Abstract: Homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) are the major monoamine metabolites in the central nervous system (CNS). Their cerebrospinal fluid (CSF) concentrations, reflecting the monoamine turnover rates in CNS, are partially under genetic influence and have been associated with schizophrenia. We have hypothesized that CSF monoamine metabolite concentrations represent intermediate steps between single nucleotide polymorphisms (SNPs) in genes implicated in monoaminergic pathways and psychosis. We have searched for association between 119 SNPs in genes implicated in monoaminergic pathways [tryptophan hydroxylase 1 (TPH1), TPH2, tyrosine hydroxylase (TH), DOPA decarboxylase (DDC), dopamine beta-hydroxylase (DBH), catechol-O-methyltransferase (COMT), monoamine oxidase A (MAOA) and MAOB] and monoamine metabolite concentrations in CSF in 74 patients with psychotic disorder. There were 42 nominally significant associations between SNPs and CSF monoamine metabolite concentrations, which exceeded the expected number (20) of nominal associations given the total number of tests performed. The strongest association (p = 0.0004) was found between MAOB rs5905512, a SNP previously reported to be associated with schizophrenia in men, and MHPG concentrations in men with psychotic disorder. Further analyses in 111 healthy individuals revealed that 41 of the 42 nominal associations were restricted to patients with psychosis and were absent in healthy controls. The present study suggests that altered monoamine turnover rates in CNS reflect intermediate steps in the associations between SNPs and psychosis.

Insight into the functional and structural properties of 3-arylcoumarin as an interesting scaffold in monoamine oxidase B inhibition.

Abstract: The design, synthesis, pharmacological evaluation, and theoretical studies of a new series of halogenated 3-arylcoumarins were carried out with the aim of finding new structural and biological features. This series displays several alkyl, hydroxy, halogen, and/or alkoxy groups in both benzene rings of the 3-arylcoumarin scaffold. Most of the compounds studied show high affinity and selectivity for the human monoamine oxidase B (hMAO-B) isoenzyme, with IC 50 values in the low nanomolar and picomolar range. Most of the evaluated compounds display higher MAO-B inhibitory activity and selectivity than selegiline (the reference compound). Coumarin 12 (3-(3-bromophenyl)-6- methylcoumarin) is the most active compound (IC50=134 pM), being 140-fold more active than selegiline and showing the highest specificity for hMAO-B. To better understand the structure-activity relationships, docking experiments were carried out on human monoamine oxidase (A and B) structures. Finally, the prediction of passive blood-brain partitioning, based on in silico derived physicochemical descriptors, was performed. Coumarins crossing the barrier: The design and synthesis of a new series of halogenated 3-arylcoumarins are described. Monoamine oxidase A and B in vitro inhibition studies, in silico prediction of passive blood-brain partitioning, and docking calculations showed most of the 3-arylcoumarin compounds to be potent and selective. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Predominant role of plasma membrane monoamine transporters in monoamine transport in 1321N1, a human astrocytoma‐derived cell line

Abstract: Monoamine neurotransmitters should be immediately removed from the synaptic cleft to avoid excessive neuronal activity. Recent studies have shown that astrocytes and neurons are involved in monoamine removal. However, the mechanism of monoamine transport by astrocytes is not entirely clear. We aimed to elucidate the transporters responsible for monoamine transport in 1321N1, a human astrocytoma-derived cell line. First, we confirmed that 1321N1 cells transported dopamine, serotonin, norepinephrine, and histamine in a time- and dose-dependent manner. Kinetics analysis suggested the involvement of low-affinity monoamine transporters, such as organic cation transporter (OCT) 2 and 3 and plasma membrane monoamine transporter (PMAT). Monoamine transport in 1321N1 cells was not Na(+) /Cl(-) dependent but was inhibited by decynium-22, an inhibitor of low-affinity monoamine transporters, which supported the importance of low-affinity transporters. RT-PCR assays revealed that 1321N1 cells expressed OCT3 and PMAT but no other neurotransmitter transporters. Another human astrocytoma-derived cell line, U251MG, and primary human astrocytes also exhibited the same gene expression pattern. Gene-knockdown assays revealed that 1321N1 and primary human astrocytes could transport monoamines predominantly through PMAT and partly through OCT3. These results might indicate that PMAT and OCT3 in human astrocytes are involved in monoamine clearance.

Chronic monoamine oxidase-B inhibitor treatment blocks monoamine oxidase-A enzyme activity

Abstract: Patients with Parkinson's disease receive selective irreversible monoamine oxidase (MAO)-B inhibitors, but their effects on MAO-A activity are not known during long-term application. We determined MAO-A inhibition in plasma samples from patients with MAO-B inhibitor intake or without MAO-B inhibitor treatment and from healthy controls. We detected a 70 % reduction of MAO-A activity in patients with MAO-B inhibitor therapy in comparison to the other groups. Our results suggest that treatment with MAO-B inhibitor may also influence MAO-A activity in vivo, when administered daily.

Elevated Brain Monoamine Oxidase Activity in SIV- and HIV-associated Neurological Disease

Abstract: We recently demonstrated direct evidence of increased monoamine oxidase (MAO) activity in the brain of a simian immunodeficiency virus (SIV) model of human immunodeficiency virus (HIV)-associated central nervous system (CNS) disease, consistent with previously reported dopamine deficits in both SIV and HIV infection. In this study, we explored potential mechanisms behind this elevated activity. MAO B messenger RNA was highest in macaques with the most severe SIV-associated CNS lesions and was positively correlated with levels of CD68 and GFAP transcripts in the striatum. MAO B messenger RNA also correlated with viral loads in the CNS of SIV-infected macaques and with oxidative stress. Furthermore, in humans, striatal MAO activity was elevated in individuals with HIV encephalitis, compared with activity in HIV-seronegative controls. These data suggest that the neuroinflammation and oxidative stress caused by SIV infection in the CNS may provide the impetus for increased transcription of MAO B and that MAO, and more broadly, oxidative stress, have significant potential as therapeutic targets in CNS disease due to HIV.

Effects of novel monoamine oxidases and cholinesterases targeting compounds on brain neurotransmitters and behavior in rat model of vascular dementia

Abstract: Neurodegenerative disorders are associated with different neurochemical and morphological alterations in the brain leading to cognitive and behavioural impairments. New therapeutic strategies comprise multifunctional drugs. The aim of the presented studies is to evaluate in vivo the novel compounds - ASS188 and ASS234 – which combine the benzylpiperidine moiety of the acetylcholinesteras (AChE) inhibitor donepezil and the indolyl propargylamino moiety of the monoaminooxidase (MAO) inhibitor, N-[(5-benzyloxy-1- methyl-1H-indol-2-yl)methyl]-N-methylprop-2-yn-1-amine, with respect to their influence on cerebral amine neurotransmitters systems and neuroprotective activity. The presumed therapeutic potential of these compounds has been evaluated following their administration to rats with experimental vascular dementia. A rat model of the permanent bilateral occlusion of the common carotid arteries (BCCAO) and the holeboard memory test were employed for this purpose. Wistar rats were used, either intact or 1 day after BCCAO. ASS188 (1 mg/kg) and ASS234 (5 mg/kg) were given s.c. for 5 consecutive days. Working and reference memory in rats was evaluated by holeboard tests before- and 7 and 12 days after BCCAO. The activities of MAOs, AChE and histamine N-methyltransferase (HMT), as well as cerebral amines concentrations were assayed. A significant inhibition of brain MAO A (>95%) and weaker MAO B (ca 60%) and HMT (<30%) and reduced AChE activities were recorded with a pronounced (2 - 10 fold) increase in the cerebral concentrations of serotonin, dopamine, and noradrenaline and smaller rises (up to 30%) of histamine. The BCCAO rats treated with ASS188 or ASS234 tended to perform holeboard tests better than the BCCAO untreated group, indicating a beneficial effect of the administered therapeutics.

MAOA/B deletion syndrome in male siblings with severe developmental delay and sudden loss of muscle tonus.

Abstract: Deletion of the monoamine oxidase (MAO)-A and MAO-B was detected in two male siblings and in their mother. The approximately 800-kb deletion, extending from about 43.0MB to 43.8MB, was detected by array comparative genomic hybridization analysis. The MAOA and MAOB genes were included in the deletion, but the adjacent Norrie disease gene, NDP, was not deleted. The boys had short stature, hypotonia, severe developmental delays, episodes of sudden loss of muscle tone, exiting behavior, lip-smacking and autistic features. The serotonin levels in their cerebrospinal fluid were extremely elevated. Another set of siblings with this deletion was reported previously. We propose recognition of MAOA/B deletion syndrome as a distinct disorder.

Case report MAOA/B deletion syndrome in male siblings with severe developmental delay and sudden loss of muscle tonus

Abstract: Deletion of the monoamine oxidase (MAO)-A and MAO-B was detected in two male siblings and in their mother. The approximately 800-kb deletion, extending from about 43.0 MB to 43.8 MB, was detected by array comparative genomic hybridization analysis. The MAOA and MAOB genes were included in the deletion, but the adjacent Norrie disease gene, NDP, was not deleted. The boys had short stature, hypotonia, severe developmental delays, episodes of sudden loss of muscle tone, exiting behavior, lip-smacking and autistic features. The serotonin levels in their cerebrospinal fluid were extremely elevated. Another set of siblings with this deletion was reported previously. We propose recognition of MAOA/B deletion syndrome as a distinct disorder.

Computational comparison of imidazoline association with the I2 binding site in human monoamine oxidases.

Abstract: Imidazoline ligands in I2-type binding sites in the brain alter monoamine turnover and release. One example of an I2 binding site characterized by binding studies, kinetics, and crystal structure has been described in monoamine oxidase B (MAO B). MAO A also binds imidazolines but has a different active site structure. Docking and molecular dynamics were used to explore how 2-(2-benzofuranyl)-2-imidazoline hydrochloride (2-BFI) binds to MAO A and to explain why tranylcypromine increases tight binding to MAO B. The energy for 2-BFI binding to MAO A was comparable to that for tranylcypromine-modified MAO B, but the location of 2-BFI in the MAO A could be anywhere in the monopartite substrate cavity. Binding to the tranylcypromine-modified MAO B was with high affinity and in the entrance cavity as in the crystal structure, but the energies of interaction with the native MAO B were less favorable. Molecular dynamics revealed that the entrance cavity of MAO B after tranylcypromine modification is both smaller a...

Monoamine oxidase and α-synuclein as targets in Parkinson's disease therapy.

Abstract: The degeneration of dopaminergic neurons in Parkinson’s disease (PD) is suggested to be associated with the generation of cytotoxic products from dopamine (DA) metabolism and the formation of fibrillar inclusions of the protein α-synuclein (AS). Despite of the role of AS in the pathogenesis of PD is not completely understood, the stabilization of nontoxic aggregates could represent a potential therapeutic route. In respect to the DA metabolism, a well-established strategy is the inhibition of the enzyme monoamine oxidase, which is responsible to catalyze the major route of inactivation of neurotransmitters. Although pharmacological strategies to treat different aspects of the parkinsonian condition are under investigation, the development of multifunctional molecules that act simultaneously on different targets associated to PD has gained attention only recently. In this work we examine the biochemical properties of synthetic and natural molecules that are capable of interfering on both DA system (via mon...

The Expression of KLF11 (TIEG2), a Monoamine Oxidase B Transcriptional Activator in the Prefrontal Cortex of Human Alcohol Dependence

Abstract: Background The biochemical pathways underlying alcohol abuse and dependence are not well understood, although brain cell loss and neurotoxicity have been reported in subjects with alcohol dependence. Monoamine oxidase B (MAO B; an enzyme that catabolizes neurotransmitters such as dopamine) is consistently increased in this psychiatric illness. MAO B has been implicated in the pathogenesis of alcohol dependence and alcohol-induced brain neurotoxicity. Recently, the cell growth inhibitor protein, Kruppel-like factor 11 (KLF11), has been reported to be an MAO transcriptional activator. KLF11 is also known as TIEG2 (transforming growth factor-beta-inducible early gene 2) and mediates apoptotic cell death. This study investigates the protein expression of KLF11 and its relationship with MAO B using human postmortem prefrontal cortex from subjects with alcohol dependence. Methods Twelve subjects with alcohol dependence and the respective psychiatrically normal control subjects were investigated. Expression of KLF11 and MAO B proteins in the prefrontal cortex was measured by Western blot analysis. Correlation studies involving KLF11 and MAO B protein expression were performed. Localization of KLF11 in the human prefrontal cortex was also determined by immunohistochemistry. Results Levels of KLF11 protein were significantly increased by 44% (p < 0.03) in the postmortem prefrontal cortex of subjects with alcohol dependence as compared to age- and gender-matched, psychiatrically normal control subjects. Furthermore, KLF11 levels were significantly and positively correlated with both the increased MAO B protein levels and blood alcohol content in alcohol-dependent subjects. In addition, KLF11 protein expression was visualized in both neuronal and glial cells. Conclusions This novel study shows the important role of KLF11, an MAO transcriptional activator, in human alcohol dependence. It further supports that the KLF11-MAO B cell death cascade may contribute to chronic alcohol-induced brain damage. This argues a case for KLF11-MAO B inhibition as a novel therapeutic strategy that may impact this highly prevalent illness.

3,4-Methylenedioxymethamphetamine Induces Gene Expression Changes in Rats Related to Serotonergic and Dopaminergic Systems, But Not to Neurotoxicity

Abstract: 3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) is an amphetamine derivative widely abused by young adults. Although many studies have reported that relatively high doses of MDMA deplete serotonin (5-HT) content and decrease the availability of serotonin transporters (5-HTT), limited evidence is available as to the adaptive mechanisms taking place in gene expression levels in the brain following a dosing regimen of MDMA comparable to human consumption. In order to further clarify this issue, we used quantitative PCR to study the long-term changes induced by acute administration of MDMA (5 mg/kg × 3) in the expression of genes related to serotonergic and dopaminergic systems, as well as those related to cellular toxicity in the cortex, hippocampus, striatum, and brain stem of rats. Seven days after MDMA administration, we found a significantly lower expression of the 5-HTT (Slc6a4) and the vesicular monoamine transporter (Slc18a2) genes in the brain stem area. In the hippocampus, monoamine oxidase B (Maob) and tryptophan hydroxylase 2 (Tph2) gene expressions were increased. In the striatum, tyrosine hydroxylase (Th) expression was decreased, and a lower expression of α-synuclein (Snca) was observed in the cortex. In contrast, no significant changes were observed in the genes considered to be biomarkers of toxicity including the glial fibrillary acidic protein (Gfap) and the heat-shock 70 kD protein 1A (Hspa1a) in any of the structures assayed. These results suggest that MDMA promotes adaptive changes in genes related to serotonergic and dopaminergic functionality, but not in genes related to neurotoxicity.

The relationship between monoamine oxidase B (MAOB) A644G polymorphism and Parkinson disease risk: a meta-analysis.

Abstract: BACKGROUND AND OBJECTIVES: Many studies were conducted to assess the relationship between Monoamine oxidase B (MAOB) A644G polymorphism and susceptibility to Parkinson disease (PD). However, the re...