Promethazine protects against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine neurotoxicity

Non-Negative Matrix Tri-Factorization for Representation Learning in Multi-Omics Datasets with Applications to Drug Repurposing and Selection

The vast corpus of heterogeneous biomedical data stored in databases, ontologies, and terminologies presents a unique opportunity for drug design. Integrating and fusing these sources is essential to develop data representations that can be analyzed using artificial intelligence methods to generate novel drug candidates or hypotheses. Here, we propose Non-Negative Matrix Tri-Factorization as an invaluable tool for integrating and fusing data, as well as for representation learning. Additionally, we demonstrate how representations learned by Non-Negative Matrix Tri-Factorization can effectively be utilized by traditional artificial intelligence methods. While this approach is domain-agnostic and applicable to any field with vast amounts of structured and semi-structured data, we apply it specifically to computational pharmacology and drug repurposing. This field is poised to benefit significantly from artificial intelligence, particularly in personalized medicine. We conducted extensive experiments to evaluate the performance of the proposed method, yielding exciting results, particularly compared to traditional methods. Novel drug-target predictions have also been validated in the literature, further confirming their validity. Additionally, we tested our method to predict drug synergism, where constructing a classical matrix dataset is challenging. The method demonstrated great flexibility, suggesting its applicability to a wide range of tasks in drug design and discovery.

3-aminohydantoin derivate as a promising scaffold in dopaminergic neuroprotection and neurorescue in the in vivo and in vitro 6-hydroxydopamine models of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder characterized by a progressive loss of dopaminergic neurons in the substantia nigra, for which no disease-modifying treatments are available yet. Thus, developing new neuroprotective drugs with the potential to delay or stop the natural course of the disease is necessary. The aim of the present study was to evaluate the neuroprotective effects of a newly synthesized 3-aminohydantoin derivative named 3-amino-5-benzylimidazolidine-2,4-dione (PHAH). The possible neuroprotective and neurorescue effects of the synthesized compound were tested: (i) in N27 dopaminergic and BV-2 microglial cell lines treated with 6-hydroxydopamine (6-OHDA) and (ii) in the 6-OHDA rat model of PD. PHAH administration reduced proinflammatory markers, including nitric oxide synthase and interleukin-1β, in BV-2 cells activated by lipopolysaccharide. Although PHAH did not restore cell death induced by 6-OHDA, it was not cytotoxic for dopaminergic cells since cell viability, under the effect of the two concentrations, remained comparable to that of the control cells. Most interestingly, PHAH restored 6-OHDA-induced dopaminergic neurodegeneration in the substantia nigra and striatum and ameliorated 6-OHDA-induced oxidative stress in the rat brain. In summary, we have proven that in PD models, PHAH has neuroprotective effects in vivo and anti-inflammatory effects in vitro; however, these effects remain to be confirmed by carrying out certain specific behavioural tests as well as by exploring other neuroinflammatory markers. The present work also suggests that PHAH is a promising scaffold that can serve as the basis for the design and synthesis of other derivatives that can be potent antiparkinsonian agents.

Hibernation-like neuroprotection in stroke by attenuating brain metabolic dysfunction

Many mammalian species naturally undergo hibernation, a process that is associated with drastic changes in metabolism and systemic physiology. Their ability to retain an undamaged central nervous system during severely reduced cerebral blood flow has been studied for possible therapeutic application in human ischemic stroke. By inducing a less extreme 'hibernation-like' state, it has been hypothesized that similar neuroprotective effects reduce ischemia-mediated tissue damage in stroke patients. This manuscript includes reviews and evaluations of: (1) true hibernation, (2) hibernation-like state and its neuroprotective characteristics, (3) the preclinical and clinical methods for induction of artificial hibernation (i.e., therapeutic hypothermia, phenothiazine drugs, and ethanol), and (4) the mechanisms by which cerebral ischemia leads to tissue damage and how the above-mentioned induction methods function to inhibit those processes.

Mechanism of oxidative stress in neurodegeneration

Biological tissues require oxygen to meet their energetic demands. However, the consumption of oxygen also results in the generation of free radicals that may have damaging effects on cells. The brain is particularly vulnerable to the effects of reactive oxygen species due to its high demand for oxygen, and its abundance of highly peroxidisable substrates. Oxidative stress is caused by an imbalance in the redox state of the cell, either by overproduction of reactive oxygen species, or by dysfunction of the antioxidant systems. Oxidative stress has been detected in a range of neurodegenerative disease, and emerging evidence from in vitro and in vivo disease models suggests that oxidative stress may play a role in disease pathogenesis. However, the promise of antioxidants as novel therapies for neurodegenerative diseases has not been borne out in clinical studies. In this review, we critically assess the hypothesis that oxidative stress is a crucial player in common neurodegenerative disease and discuss the source of free radicals in such diseases. Furthermore, we examine the issues surrounding the failure to translate this hypothesis into an effective clinical treatment.

Mitochondrial permeability transition pore component cyclophilin D distinguishes nigrostriatal dopaminergic death paradigms in the MPTP mouse model of Parkinson's disease

AIMS

Mitochondrial damage due to Ca(2+) overload-induced opening of permeability transition pores (PTP) is believed to play a role in selective degeneration of nigrostriatal dopaminergic neurons in Parkinson's disease (PD). Genetic ablation of mitochondrial matrix protein cyclophilin D (CYPD) has been shown to increase Ca(2+) threshold of PTP in vitro and to prevent cell death in several in vivo disease models. We investigated the role of CYPD in a mouse model of MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)-induced PD.

RESULTS

We demonstrate that in vitro, brain mitochondria isolated from CYPD knockout mice were less sensitive to MPP+ (1-methyl-4-phenyl-pyridinium ion)-induced membrane depolarization, and free radical generation compared to wild-type mice. CYPD knockout mitochondria isolated from ventral midbrain of mice treated with MPTP in vivo exhibited less damage as judged from respiratory chain Complex I activity, State 3 respiration rate, and respiratory control index than wild-type mice, whereas assessment of apoptotic markers showed no differences between the two genotypes. However, CYPD knockout mice were significantly resistant only to an acute regimen of MPTP neurotoxicity in contrast to the subacute and chronic MPTP paradigms.

INNOVATION

Inactivation of CYPD is beneficial in preserving mitochondrial functions only in an acute insult model of MPTP-induced dopaminergic neurotoxicity.

CONCLUSION

Our results suggest that CYPD deficiency distinguishes the modes of dopaminergic neurodegeneration in various regimens of MPTP-neurotoxicity.

Methylenedioxymethamphetamine inhibits mitochondrial complex I activity in mice: a possible mechanism underlying neurotoxicity

BACKGROUND AND PURPOSE

3,4-methylenedioxymethamphetamine (MDMA) causes a persistent loss of dopaminergic cell bodies in the substantia nigra of mice. Current evidence indicates that such neurotoxicity is due to oxidative stress but the source of free radicals remains unknown. Inhibition of mitochondrial electron transport chain complexes by MDMA was assessed as a possible source.

EXPERIMENTAL APPROACH

Activities of mitochondrial complexes after MDMA were evaluated spectrophotometrically. In situ visualization of superoxide production in the striatum was assessed by ethidium fluorescence and striatal dopamine levels were determined by HPLC as an index of dopaminergic toxicity.

KEY RESULTS

3,4-methylenedioxymethamphetamine decreased mitochondrial complex I activity in the striatum of mice, an effect accompanied by an increased production of superoxide radicals and the inhibition of endogenous aconitase. alpha-Lipoic acid prevented superoxide generation and long-term toxicity independent of any effect on complex I inhibition. These effects of alpha-lipoic acid were also associated with a significant increase of striatal glutathione levels. The relevance of glutathione was supported by reducing striatal glutathione content with L-buthionine-(S,R)-sulfoximine, which exacerbated MDMA-induced dopamine deficits, effects suppressed by alpha-lipoic acid. The nitric oxide synthase inhibitor, N(G)-nitro-L-arginine, partially prevented MDMA-induced dopamine depletions, an effect reversed by L-arginine but not D-arginine. Finally, a direct relationship between mitochondrial complex I inhibition and long-term dopamine depletions was found in animals treated with MDMA in combination with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.

CONCLUSIONS AND IMPLICATIONS

Inhibition of mitochondrial complex I following MDMA could be the source of free radicals responsible for oxidative stress and the consequent neurotoxicity of this drug in mice.

Phenothiazines interfere with dopaminergic neurodegeneration in Caenorhabditis elegans models of Parkinson's disease

Oxidative stress is involved in the pathogenesis of various neurodegenerative disorders, conventional antioxidant strategies have yet been of limited success. We have employed transgenic Caenorhabditis elegans expressing DsRed2 in dopaminergic neurons and CFP pan-neuronally, to characterize in larval and adult animals the effects of rotenone and 1-methyl-4-phenyl-pyridinium (MPP(+)) on the dopaminergic system. Investigating the antioxidant phenothiazine and different derived antipsychotic drugs, it was found that free phenothiazine exerted strong neuroprotection at the cellular level and resulted in a better performance in behavioral assays, whereas apomorphine and other dopamine agonists only rescued adult locomotor parameters. Phenothiazine antipsychotics with dopamine antagonist properties were likewise not cytoprotective, but even induced motor deficits by themselves. Beyond phenothiazine, other tricyclic imines elicited significant neuroprotection at considerably lower doses than different natural antioxidants. Mitochondrially targeted antioxidants were more potent than these untargeted natural antioxidants, yet not as potent as the untargeted compound phenothiazine. Thus, dopaminergic toxicity of rotenone and MPP(+)in vivo can be forestalled by nanomolar concentrations of certain chain-breaking antioxidants irrespective of dopamine receptor modulation or mitochondrial targeting.

Promethazine protects against 3-nitropropionic acid-induced neurotoxicity

Promethazine (PMZ), an FDA-approved antihistaminergic drug, was identified as a potentially neuroprotective compound in a NINDS screening program. It was shown to protect against ischemia in mice, to delay disease onset in a mouse model of amyotrophic lateral sclerosis and to inhibit Ca(2+)-induced mitochondrial permeability transition in rat liver mitochondria. We investigated whether PMZ could protect against the neurotoxic effects induced by 3-nitropropionic acid (3-NP), an inhibitor of the succinate dehydrogenase, used to model Huntington's disease (HD) in rats. Lewis rats receiving chronic subcutaneous infusion of 3-NP were treated with PMZ. The findings indicate that chronic PMZ treatment significantly reduced 3-NP-induced striatal lesion volume, loss of GABAergic neurons and number of apoptotic cells in the striatum. PMZ showed a strong neuroprotective effect against 3-NP toxicity in vivo.

Cell death pathways in Parkinson's disease: role of mitochondria

Parkinson's disease (PD) is a progressive neurodegenerative disease and is characterized pathologically by selective loss of nigrostriatal dopaminergic neurons and the formation of Lewy bodies. Although in the majority of cases the cause of PD is unknown, mitochondrial dysfunction, environmental toxins, oxidative stress, and abnormal protein accumulation may all be involved in disease pathogenesis. The discovery of genes causing rare familial forms of PD (including alpha-synuclein, parkin, DJ-1, PINK1, and LRRK2) has shed light on our understanding of the molecular mechanisms of the development of the disease. Further studies from transgenic or toxin-induced experimental models have also provided insights into the etiology of human disease. Recently, accumulating evidence has suggested that mitochondrial dysfunction is one of the key players in molecular cell death pathways of PD. In this review, we provide an overview of the role of mitochondria in the pathogenesis of both sporadic and familial forms of PD. We also discuss the links between different pathways and highlight novel therapeutic opportunities which target mitochondria.

Evaluation of putative inhibitors of mitochondrial permeability transition for brain disorders--specificity vs. toxicity

Inhibition of mitochondrial permeability transition (mPT) has emerged as a promising approach for neuroprotection and development of well-tolerated mPT inhibitors with favorable blood-brain barrier penetration is highly warranted. In a recent study, 28 clinically available drugs with a common heterocyclic structure were identified as mPT inhibitors e.g. trifluoperazine, promethazine and nortriptyline. In addition, neuroprotection by structurally unrelated drugs e.g. neurosteroids, 4-hydroxy-tamoxifen and trimetazidine has been attributed to direct inhibition of mPT. The regulation of mPT is complex and highly dependent on the prevailing experimental conditions. Several features of mPT, such as swelling, depolarization or NADH oxidation, can also occur independently of the mPT phenomenon. Here, in isolated rodent brain-derived and human liver mitochondria, we re-evaluate drugs promoted as potent mPT inhibitors. We address the definition of an mPT inhibitor and present strategies to reliably detect mPT inhibition in vitro. Surprisingly, none of the 12 compounds tested displayed convincing mPT inhibition or effects comparable to cyclophilin D inhibition by the non-immunosuppressive cyclophilin inhibitor D-MeAla(3)-EtVal(4)-Cyclosporin (Debio 025). Propofol and 2-aminoethoxydiphenyl borate (2-APB) inhibited swelling in de-energized mitochondria but did not increase calcium retention capacity (CRC). Progesterone, trifluoperazine, allopregnanolone and 4-hydroxy-tamoxifen dose-dependently reduced CRC and respiratory control and were thus toxic rather than beneficial to mitochondrial function. Interestingly, topiramate increased CRC at high concentrations likely by a mechanism separate from direct mPT inhibition. We conclude that a clinically relevant mPT inhibitor should have a mitochondrial target and increase mitochondrial calcium retention at concentrations which can be translated to human use.

Neuroprotective effects of the triterpenoid, CDDO methyl amide, a potent inducer of Nrf2-mediated transcription

The NF-E2-related factor-2 (Nrf2)/antioxidant response element (ARE) signaling pathway regulates phase 2 detoxification genes, including a variety of antioxidative enzymes. We tested neuroprotective effects of the synthetic triterpenoid CDDO-MA, a potent activator of the Nrf2/ARE signaling. CDDO-MA treatment of neuroblastoma SH-SY5Y cells resulted in Nrf2 upregulation and translocation from cytosol to nucleus and subsequent activation of ARE pathway genes. CDDO-MA blocked t-butylhydroperoxide-induced production of reactive oxygen species (ROS) by activation of ARE genes only in wild type, but not Nrf2 knockout mouse embryonic fibroblasts. Oral administration of CDDO-MA resulted in significant protection against MPTP-induced nigrostriatal dopaminergic neurodegeneration, pathological alpha-synuclein accumulation and oxidative damage in mice. Additionally, CDDO-MA treatment in rats produced significant rescue against striatal lesions caused by the neurotoxin 3-NP, and associated increases in the oxidative damage markers malondialdehyde, F₂-Isoprostanes, 8-hydroxy-2-deoxyguanosine, 3-nitrotyrosine, and impaired glutathione homeostasis. Our results indicate that the CDDO-MA renders its neuroprotective effects through its potent activation of the Nrf2/ARE pathway, and suggest that triterpenoids may be beneficial for the treatment of neurodegenerative diseases like Parkinson's disease and Huntington's disease.

Mitochondrial dysfunction in the limelight of Parkinson's disease pathogenesis

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder with unknown etiology. It is marked by widespread neurodegeneration in the brain with profound loss of A9 midbrain dopaminergic neurons in substantia nigra pars compacta. Several theories of biochemical abnormalities have been linked to pathogenesis of PD of which mitochondrial dysfunction due to an impairment of mitochondrial complex I and subsequent oxidative stress seems to take the center stage in experimental models of PD and in postmortem tissues of sporadic forms of illness. Recent identification of specific gene mutations and their influence on mitochondrial functions has further reinforced the relevance of mitochondrial abnormalities in disease pathogenesis. In both sporadic and familial forms of PD abnormal mitochondrial paradigms associated with disease include impaired functioning of the mitochondrial electron transport chain, aging associated damage to mitochondrial DNA, impaired calcium buffering, and anomalies in mitochondrial morphology and dynamics. Here we provide an overview of specific mitochondrial functions affected in sporadic and familial PD that play a role in disease pathogenesis. We propose to utilize these gained insights to further streamline and focus the research to better understand mitochondria's role in disease development and exploit potential mitochondrial targets for therapeutic interventions in PD pathogenesis.

Inhibition of the leucine-rich repeat protein LINGO-1 enhances survival, structure, and function of dopaminergic neurons in Parkinson's disease models

The nervous system-specific leucine-rich repeat Ig-containing protein LINGO-1 is associated with the Nogo-66 receptor complex and is endowed with a canonical EGF receptor (EGFR)-like tyrosine phosphorylation site. Our studies indicate that LINGO-1 expression is elevated in the substantia nigra of Parkinson's disease (PD) patients compared with age-matched controls and in animal models of PD after neurotoxic lesions. LINGO-1 expression is present in midbrain dopaminergic (DA) neurons in the human and rodent brain. Therefore, the role of LINGO-1 in cell damage responses of DA neurons was examined in vitro and in experimental models of PD induced by either oxidative (6-hydroxydopamine) or mitochondrial (N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) toxicity. In LINGO-1 knockout mice, DA neuron survival was increased and behavioral abnormalities were reduced compared with WT. This neuroprotection was accompanied by increased Akt phosphorylation (p-Akt). Similar neuroprotective in vivo effects on midbrain DA neurons were obtained in WT mice by blocking LINGO-1 activity using LINGO-1-Fc protein. Neuroprotection and enhanced neurite growth were also demonstrated for midbrain DA neurons in vitro. LINGO-1 antagonists (LINGO-1-Fc, dominant negative LINGO-1, and anti-LINGO-1 antibody) improved DA neuron survival in response to MPP+ in part by mechanisms that involve activation of the EGFR/Akt signaling pathway through a direct inhibition of LINGO-1's binding to EGFR. These results show that inhibitory agents of LINGO-1 activity can protect DA neurons against degeneration and indicate a role for the leucine-rich repeat protein LINGO-1 and related classes of proteins in the pathophysiological responses of midbrain DA neurons in PD.

The mitochondrial permeability transition in neurologic disease

Mitochondria, being the principal source of cellular energy, are vital for cell life. Yet, ironically, they are also major mediators of cell death, either by necrosis or apoptosis. One means by which these adverse effects occur is through the mitochondrial permeability transition (mPT) whereby the inner mitochondrial membrane suddenly becomes excessively permeable to ions and other solutes, resulting in a collapse of the inner membrane potential, ultimately leading to energy failure and cell necrosis. The mPT may also bring about the release of various factors known to cause apoptotic cell death. The principal factors leading to the mPT are elevated levels of intracellular Ca2+ and oxidative stress. Characteristically, the mPT is inhibited by cyclosporin A. This article will briefly discuss the concept of the mPT, its molecular composition, its inducers and regulators, agents that influence its activity and describe the consequences of its induction. Lastly, we will review its potential contribution to acute neurological disorders, including ischemia, trauma, and toxic-metabolic conditions, as well as its role in chronic neurodegenerative conditions such as Alzheimer's disease, Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis.

Does treating schizophrenia reduce the chances of developing amyotrophic lateral sclerosis?

The development of amyotrophic lateral sclerosis (ALS) in the relatively common psychiatric disorder schizophrenia is very rare. This observation has been made by us and a number of other neuromuscular specialists at large ALS centers. We propose that the use of neuroleptics and some antidepressants, which are chronically prescribed to schizophrenics and which have neuroprotective properties and some of which promote neurogenesis, may confer protection against this deadly neurodegenerative disease ALS. Such an observation may have important implications towards the therapy and understanding the pathophysiology of this deadly neurodegenerative disease.