Background and Purpose
Neurodegenerative diseases are now recognized to be multifunctional, whereby a heterogeneous set of reactions acts independently or cooperatively, leading eventually to the ...demise of neurons. This has led our group to design and synthesize the multifunctional, nontoxic, brain‐permeable, iron chelator compound M30 with a range of pharmacological properties. Here, we have characterized the molecular targets of M30 in the brains of animal models of type 2 diabetes mellitus (T2DM).
Experimental Approach
Effects of M30 on molecular mechanisms associated with neuroprotection in the CNS were investigated‐in the high‐fat diet (HFD) and ob/ob transgenic mouse models of T2DM, using real‐time PCR and Western blotting analyses. Brain monoamine oxidase (MAO) activity and catecholamine levels, and peripheral glucose tolerance were assayed after treatment in vivo.
Key Results
M30 increased cerebral levels of insulin and insulin receptor and phosphorylated‐GSK‐3β in HFD mice, compared with vehicle‐treated HFD mice. In both T2DM mice models, M30 treatment significantly up‐regulated cerebral hypoxia‐inducible factor (HIF)‐1α protein levels and induced the expression of several HIF‐1 target genes involved in neuroprotection, glycolysis, neurogenesis, oxidative stress and anti‐inflammation. Additionally, M30 inhibited MAO‐A and ‐B activities in the cerebellum. Accordingly, M30 administration significantly reduced brain levels of dopamine metabolites and increased levels of 5‐HT and noradrenaline. Glucose tolerance was also improved after M30 treatment in both models of T2DM.
Conclusions and Implications
In the brain of HFD and ob/ob transgenic mice, M30 exerted a variety of beneficial neuroprotective regulatory effects that may act synergistically to delay or prevent neurodegenerative processes associated with T2DM.
Iron‐dependent oxidative stress, elevated levels of iron and of monoamine oxidase (MAO)‐B activity, and depletion of antioxidants in the brain may be major pathogenic factors in Parkinson's disease, ...Alzheimer's disease and related neurodegenerative diseases. Accordingly, iron chelators, antioxidants and MAO‐B inhibitors have shown efficacy in a variety of cellular and animal models of CNS injury. In searching for novel antioxidant iron chelators with potential MAO‐B inhibitory activity, a series of new iron chelators has been designed, synthesized and investigated. In this study, the novel chelators were further examined for their activity as antioxidants, MAO‐B inhibitors and neuroprotective agents in vitro. Three of the selected chelators (M30, HLA20 and M32) were the most effective in inhibiting iron‐dependent lipid peroxidation in rat brain homogenates with IC50 values (12–16 µm), which is comparable with that of desferal, a prototype iron chelator that is not has orally active. Their antioxidant activities were further confirmed using electron paramagnetic resonance spectroscopy. In PC12 cell culture, the three novel chelators at 0.1 µm were able to attenuate cell death induced by serum deprivation and by 6‐hydroxydopamine. M30 possessing propargyl, the MAO inhibitory moiety of the anti‐Parkinson drug rasagiline, displayed greater neuroprotective potency than that of rasagiline. In addition, in vitro, M30 was a highly potent non‐selective MAO‐A and MAO‐B inhibitor (IC50 < 0.1 µm). However, HLA20 was more selective for MAO‐B but had poor MAO inhibition, with an IC50 value of 64.2 µm. The data suggest that M30 and HLA20 might serve as leads in developing drugs with multifunctional activities for the treatment of various neurodegenerative disorders.
ABSTRACTThe anti‐Parkinson drug, rasagiline (N‐propargyl‐(1R)‐aminoindan) promotes neuronal survival, via neuroprotective activity related to its propargyl moiety (propargylamine). We have ...investigated the neurorescue effects of propargylamine, in a progressive neuronal death model, induced by long‐term serum deprivation in human SH‐SY5Y neuroblastoma cells. Propargylamine (0.1–10 µM) dose‐dependently reduced the levels of the early apoptosis‐associated phosphorylated protein, H2A‐X (ser 139), as well as decreased the cleavage of caspase‐3 and its substrate poly‐ADP ribose polymerase (PARP). In addition, the compound markedly reversed the apoptotic effects induced by long‐term serum withdrawal, including down‐regulation of the antiapoptotic protein, Bcl‐2, as well as up‐regulation of the proapoptotic proteins, Bax, Bad, and Bim. Real‐time RT‐PCR demonstrated that propargylamine elevated gene expression levels of Bcl‐2, and the neurotrophic factors glial cell line‐derived neurotrophic factor (GDNF) and brain‐derived neurotrophic factor (BDNF) and reduced Bax gene expression. Serum deprivation increased mRNA and protein levels of holo‐amyloid precursor protein (APP), which was markedly decreased by propargylamine. This was accompanied by inducing the release of the nonamyloidogenic α‐secretase form of soluble APP (sAPPα) into the medium. Similar effects on cell survival and APP regulation/processing were demonstrated for rasagiline. These results indicate that both rasagiline and propargylamine possess neurorescue activity, associated with regulation of Bcl‐2 family proteins, neurotrophic factors, and APP metabolism.
J. Neurochem. (2010) 112, 1131-1137. The anti-parkinsonian drug, rasagiline N-propargyl-1-(R)-aminoindan; Azilect®, is a secondary cyclic benzylamine and indane derivative, which provides ...irreversible, potent monoamine oxidase-B (MAO-B) inhibition and possesses neuroprotective and neurorestorative activities. A prospective clinical trial has shown that rasagiline confers significant symptomatic improvement and demonstrated alterations in Parkinson's disease progression. Rasagiline is primarily metabolized by hepatic cytochrome P-450 to form its major metabolite, 1-(R)-aminoindan, a non-amphetamine, weak reversible MAO-B inhibitor compound. Recent studies indicated the potential neuroprotective effect of 1-(R)-aminoindan, suggesting that it may contribute to the overall neuroprotective and antiapoptotic effects of its parent compound, rasagiline. This review article briefly highlights the molecular mechanisms underlying the neuroprotective properties of the active metabolite of rasagiline, 1-(R)-aminoindan, supporting the valuable potential of rasagiline for disease modification.
The anti-Parkinson, selective irreversible monoamine oxidase B inhibitor drug, rasagiline (Azilect), recently approved by the US Food and Drug Administration, has been shown to possess ...neuroprotective-neurorescue activities in in vitro and in vivo models. Recent preliminary studies indicated the potential neuroprotective effect of the major metabolite of rasagiline, 1-(R)-aminoindan. In the current study, the neuroprotective properties of 1-(R)-aminoindan were assessed employing a cytotoxic model of human neuroblastoma SK-N-SH cells in high-density culture-induced neuronal death. We show that aminoindan (0.1-1 μmol/L) significantly reduced the apoptosis-associated phosphorylated protein, H2A.X (Ser139), decreased the cleavage of caspase 9 and caspase 3, while increasing the anti-apoptotic proteins, Bcl-2 and Bcl-xl. Protein kinase C (PKC) inhibitor, GF109203X, prevented the neuroprotection, indicating the involvement of PKC in aminoindan-induced cell survival. Aminoindan markedly elevated pPKC(pan) and specifically that of the pro-survival PKC isoform, PKCε. Additionally, hydroxyaminoindan, a metabolite of a novel bifunctional drug, ladostigil (N-propargyl-(3R) aminoindan-5yl)-ethyl methyl carbamate, combining cholinesterase and monoamine oxidase inhibitor activity, exerted similar neuroprotective properties. Aminoindan and hydroxyaminoindan also protected rat pheochromacytoma PC-12 cells against the neurotoxin, 6-hydroxydopamine. Our findings suggest that both metabolites may contribute to the overall neuroprotective activity of their respective parent compounds, further implicating rasagiline and ladostigil as potentially valuable drugs for treatment of a wide variety of neurodegenerative disorders of aging.
The anti-Parkinson selective irreversible monoamine oxidase B inhibitor drugs, rasagiline and selegiline, have been shown to possess neuroprotective activities in cell culture and in vivo models. ...While rasagiline is metabolized to its major metabolite aminoindan, selegiline gives rise to
l-methamphetamine. Cultured PC-12 cells in absence of serum and nerve growth factor (NGF) die by an apoptotic process. Pretreatment of PC12 cells in absence of serum and NGF for 24 h with either rasagiline (1 μM) or selegiline (1 μM) is neuroprotective and anti-apoptotic as determined by Eliza and MTT tests. However, while aminoindan (1 μM), the major metabolite of rasagiline does not interfere with the neuroprotective activities of rasagiline or selegiline in PC-12 cells deprived of serum and NGF, the major metabolite of selegiline,
l-methamphetamine (1 μM), inhibits them. In contrast to
l-methamphetamine, aminoindan is itself is neuroprotective in this system. Recently it has been demonstrated that rasagiline directly activates PKC-MAP kinase pathway by a concentration and time dependent phosphorylation of p42 and p44 MAP kinase. In the present studies the neuroprotective activity of rasagiline is blocked by ERK inhibitor, PD98059 (20 μM), suggesting the involvement of PKC-MAP kinase pathway in the neuroprotection. These findings may have implication for the possible disease modifying action of rasagiline in treatment of Parkinson's disease.
The current therapeutic advance in which future drugs are designed to possess varied pharmacological properties and act on multiple targets has stimulated the development of the multimodal drug, ...ladostigil (TV3326; (
N
-propargyl-(3R) aminoindan-5yl)-ethyl methyl carbamate). Ladostigil combines neuroprotective effects with monoamine oxidase (MAO)-A and MAO-B and cholinesterase (ChE) inhibitory activities in a single molecule, as a potential treatment for Alzheimer’s disease (AD) and Lewy body disease. In the present study, we demonstrate that ladostigil (10
−6
–10 μM) dose-dependently increased cell viability, associated with increased activity of catalase and glutathione reductase and decrease of intracellular reactive oxygen species production in a cytotoxic model of human SH-SY5Y neuroblastoma cells exposed to hydrogen peroxide (H
2
O
2
). In addition, ladostigil significantly upregulated mRNA levels of several antioxidant enzymes (catalase, NAD(P)H quinone oxidoreductase 1 and peroxiredoxin 1) in both H
2
O
2
-treated SH-SY5Y cells, as well as in the high-density human SK-N-SH neuroblastoma cultured apoptotic models. In vivo chronic treatment with ladostigil (1 mg/kg per os per day for 30 days) markedly upregulated mRNA expression levels of various enzymes involved in metabolism and oxidation processes in aged rat hippocampus. In addition to its unique combination of ChE and MAO enzyme inhibition, these results indicate that ladostigil displays neuroprotective activity against oxidative stress-induced cell apoptosis, which might be valuable for aging and age-associated neurodegenerative diseases.
We have recently shown that the anti‐Parkinson‐propargyl‐containing monoamine oxidase B (MAO‐B) inhibitor drug, rasagiline N‐propargyl‐(1R)‐aminoindan, and its cholinesterase inhibitor derivatives ...TV3326 and TV3279, regulate amyloid precursor protein (APP) processing by a protein kinase C (PKC)‐dependent mechanism in SH‐SY5Y neuroblastoma and PC12 cells. In the present study, we investigated the effect of rasagiline and its derivatives on the regulation of the PKC‐dependent mechanism and APP processing under in vivo conditions. Administration of rasagiline (0.1 mg/kg) to male C57/BL mice for 14 days significantly decreased membrane‐bound holoprotein APP levels in the hippocampus. Additionally, we observed that rasagiline up‐regulated p‐PKC levels and the expression of α and ε PKC isozymes in the hippocampus, indicating that the mechanism by which rasagiline affects APP processing may be related to PKC‐associated signalling. The results also demonstrate that rasagiline treatment significantly elevated the levels of phosphorylated myristoylated alanine‐rich C kinase substrate (p‐MARCKS), a major substrate for PKC, as well as the levels of receptors for activated C kinase 1 (RACK1). Similar effects on APP and PKC levels were also demonstrated for the two cholinesterase inhibitor derivatives of rasagiline, TV3326 and TV3279. These results indicate that rasagiline and its derivatives regulate PKC‐dependent mechanisms and APP processing. The activation and induction of PKC and MARCKS by these drugs may have a crucial role not only in their neuroprotective activity, but also in their ability to affect neuronal plasticity and spatial learning processes.
Alzheimer's disease (AD) is accepted nowadays as a complex neurodegenerative disorder with multifaceted cerebral pathologies, including extracellular deposition of amyloid β peptide‐containing ...plaques, intracellular neurofibrillary tangles, progressive loss of cholinergic neurons, metal dyshomeostasis, mitochondrial dysfunction, neuroinflammation, glutamate excitoxicity, oxidative stress and increased MAO enzyme activity. This may explain why it is currently widely accepted that a more effective therapy for AD would result from the use of multifunctional drugs, which may affect more than one brain target involved in the disease pathology. The current review will discuss the potential benefits of novel multimodal neuroprotective, brain permeable drugs, recently developed by Youdim and collaborators, as a valuable therapeutic approach for AD treatment. The pharmacological and neuroprotective properties of these multitarget‐directed ligands, which target MAO enzymes, the cholinergic system, iron accumulation and amyloid β peptide generation/aggregation are described, with a special emphasis on their potential therapeutic value for ageing and AD‐associated cognitive functions. This review is conceived as a tribute to the broad neuropharmacology work of Professor Moussa Youdim, Professor Emeritus in the Faculty of Medicine and Director of Eve Topf Center of Excellence in Technion‐Israel Institute of Technology, and Chief Scientific Officer of ABITAL Pharma Pipeline Ltd., at the occasion of his 75th birthday.
Linked Articles
This article is part of a themed section on Updating Neuropathology and Neuropharmacology of Monoaminergic Systems. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v173.13/issuetoc
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