Prof. Dorit Ben-Shachar | Technion - Israel Institute of Technology (original) (raw)

Papers by Prof. Dorit Ben-Shachar

Advances in …, 1984

... Or filter your current search. Ben-Shachar D, Find all citations by this author (default). ..... more ... Or filter your current search. Ben-Shachar D, Find all citations by this author (default). ... The function of the large amounts of iron in certain brain areas, such as the pallidum, caudate nucleus, substantia nigra, nucleus accumbens, and olfactory tubercule, is not known. ...

Biological Psychiatry, 2018

Methods: SZ patients were randomized to treatment as usual (TAU; n¼24) or treatment as usual + TC... more Methods: SZ patients were randomized to treatment as usual (TAU; n¼24) or treatment as usual + TCT (n¼22). Average duration of illness was approximately 15 years. Auditory discriminability (Word-In-Noise test, WIN), cognitive functioning (MATRICS Consensus Cognitive Battery, MCCB), as well as positive (SAPS) and negative symptoms scores (SANS) were assessed before and after TCT. Data were analyzed using linear mixed effects models. Results: At follow up, TCT was associated with significant improvements in WIN (d¼0.63, p<0.04), verbal learning and memory (d¼0.82 p<0.01), and SAPS (d¼-0.62, p<0.05). Age was a significant moderator of verbal learning gains with TCT; older patients exhibited greater improvements (p<0.01). Conclusions: TCT significantly improved auditory discrimination, verbal learning and positive symptoms in SZ patients in community-based residential care. Our results suggest older SZ patients may be able to benefit from TCT. Improving the fidelity of low-level auditory sensory information processing via TCT may yield clinically meaningful outcomes, even in patients with chronic illness.

Biological Psychiatry, 1997

been emphasised In the recent literature. In the central nervous system NO Is supposed to be the ... more been emphasised In the recent literature. In the central nervous system NO Is supposed to be the retrograde messenger In those parts which are connected with memory fixation and retention. Presumably we may suggest that behavioral changes reported above could be a result of excessive NO amount In the brain.

Neuroprotection in Autism, Schizophrenia and Alzheimer's Disease

Abstract Heme plays a role in major cellular processes such as signal transduction, protein synth... more Abstract Heme plays a role in major cellular processes such as signal transduction, protein synthesis, and complex assembly and regulation of transcription and translation. As such, it is essential for brain metabolism, oxygen sensing, and neuronal survival. Its synthesis is composed of eight distinct steps; the first and last three steps take place in the mitochondria. Accumulating evidence point at mitochondrial dysfunction and altered heme metabolism in neuropsychiatric disorders. Here, we will review the growing number of experimental data demonstrating deficits in heme, mitochondria, and specifically the first complex (Co-I) of the electron transport chain in three neuropsychiatric disorders—Alzheimer’s disease (AD), Parkinson’s disease (PD), and schizophrenia (SZ). Furthermore, we will provide evidence for an association between mitochondrial Co-I dysfunction and heme metabolism and suggest their potential to become additional therapeutic targets that will improve the efficiency of the current treatments.

Clinical and Experimental Pharmacology and Physiology, 2018

Chemotherapy-induced cognitive changes is a major burden on a substantial number of cancer surviv... more Chemotherapy-induced cognitive changes is a major burden on a substantial number of cancer survivors. The mechanism of this sequel is unknown. In this study, we followed long-term effects of early in life mithramycin (MTR) treatment on behavior and on the normal course of alterations of gene expression in brain. Between post-natal days (PND) 7-10 male rats were divided into two groups, one receiving MTR (0.1mg/Kg s.c./day) and the other saline. At PND11, frontal cortex tissue samples were dissected from four rats from each group. At PND 65 the remaining rats underwent behavioral tests after which all the rats were decapitated and their prefrontal cortex incised. Rats treated transiently with MTR early in life, showed impairments in spatial working memory and anxious-like behavior in adulthood. The immediate molecular effect of MTR was expressed in a limited number of altered genes of different unconnected trajectories, which were simultaneously distorted by the drug. In contrast, three months later we observed a change in the expression of more than 1000 genes that converged into specific cellular processes. Time-dependent gene expression dynamics of several genes was significantly different between treated and untreated rats. The differences in the total number of altered genes and in gene expression trends, immediately and long after MTR treatment cessation, suggest the evolvement of a new cellular homeostatic set point, which can lead to behavioral abnormalities following chemotherapy treatment.

Methods in Molecular Biology, 2021

Mitochondria, similar to living cells and organelles, have a negative membrane potential, which r... more Mitochondria, similar to living cells and organelles, have a negative membrane potential, which ranges between (-108) and (150) mV as compared to (-70) and (-90) mV of the plasma membrane. Therefore, permeable lipophilic cations tend to accumulate in the mitochondria. Those cations which exhibit fluorescence activity after accumulation into energized systems are widely used to decipher changes in membrane potential by imaging techniques. Here we describe the use of two different dyes for labeling mitochondrial membrane potential (Δψm) in live cells. One is the lipophilic cation 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazol-carbocyanine iodide (JC-1), which alters reversibly its color from green (J-monomer, at its low concentration in the cytosol) to red (J-aggregates, at its high concentration in active mitochondria) with increasing mitochondrial membrane potential (Δψm). The other is MitoTracker® Orange, a mitochondrion-selective probe which passively diffuses across the plasma membrane and accumulates in active mitochondria depending on their Δψm. We show that in addition to changes in Δψm, these specific dyes can be used to follow alterations in mitochondrial distribution and mitochondrial network connectivity. We suggest that JC-1 is a preferable probe to compare between different cell types and cell state, as a red to green ratio of fluorescence intensities is used for analysis. This ratio depends only on the mitochondrial membrane potential and not on other cellular and/or mitochondrial-dependent or independent factors that may alter, for example, due to treatment or disease state. However, in cells labeled either with green or red fluorescence protein, JC-1 cannot be used. Therefore, other dyes are preferable. We demonstrate various applications of JC-1 and MitoTracker Orange staining to study mitochondrial abnormalities in different cell types derived from schizophrenia patients and healthy subjects.

Scientific Reports, 2020

Pharmacological treatment of mental disorders is currently decided based on "trial and error... more Pharmacological treatment of mental disorders is currently decided based on "trial and error" strategy. Mitochondrial multifaceted dysfunction is assumed to be a major factor in the pathophysiology and treatment of schizophrenia (SZ) and bipolar disorder (BD). This study aimed to explore the feasibility of using a profile of mitochondrial function parameters as a tool to predict the optimal drug for an individual patient (personalized medicine). Healthy controls (n = 40), SZ (n = 48) and BD (n = 27) patients were recruited. Mental and global state of the subjects, six mitochondrial respiration parameters and 14 mitochondrial function-related proteins were assessed in fresh lymphocytes following in-vitro or in-vivo treatment with five antipsychotic drugs and two mood-stabilizers. In healthy controls, hierarchal clustering shows a drug-specific effect profile on the different mitochondrial parameters following in-vitro exposure. Similar changes were observed in untreated SZ ...

Biological Psychiatry, 2020

Background: Prenatal maternal immune activation (MIA) is associated with alterations in offspring... more Background: Prenatal maternal immune activation (MIA) is associated with alterations in offspring brain development and risk of psychiatric disorders. Human studies of MIA in association with early brain development are sparse. We hypothesized that higher levels of MIA as measured by maternal interleukin-6 (IL-6) and C-reactive protein (CRP) are associated with variation in gray and white matter organizational properties in neonates. Methods: At 24-27 weeks gestation, 49 healthy pregnant women underwent assessments and blood draws. IL-6 and CRP were measured using the ELISA. The neonates underwent a MRI scan and analyses of the directional diffusion of water indexed by fractional anisotropy (FA) were performed. Results: Higher levels of maternal IL-6 were associated with increased FA values in the basal ganglia and thalamus, and across the occipital and right anterior temporal regions. Higher levels of CRP were associated with decreased FA values across the frontal and occipital lobes, and the anterior limb of the internal capsules, and increased FA values of the posterior limb. Conclusions: We demonstrate that both immune markers have shared and distinct patterns of association with brain tissue organization but differ in their associations with brain metabolites. The findings emphasize the value of considering multiple measures of MIA and imaging in this emerging area of research.

Journal of Neural Transmission, 2019

Parkinson's disease (PD) and schizophrenia (SZ) are two CNS disorders in which dysfunctions in th... more Parkinson's disease (PD) and schizophrenia (SZ) are two CNS disorders in which dysfunctions in the dopaminergic system and mitochondria are major pathologies. The symptomology of both, PD a neurodegenerative disorder and SZ a neurodevelopmental disorder, is completely different. However, the pharmacological treatment of each of the diseases can cause a shift of symptoms into those characteristic of the other disease. In this review, I describe a pathological interaction between dopamine and mitochondria in both disorders, which due to differences in the extent of oxidative stress leads either to cell death and tissue degeneration as in PD substantia nigra pars compacta or to distorted neuronal activity, imbalanced neuronal circuitry and abnormal behavior and cognition in SZ. This review is in the honor of Moussa Youdim who introduced me to the secrets of research work. His enthusiasm, curiosity and novelty-seeking inspired me throughout my career. Thank you Moussa.

Biological Psychiatry, 2018

Background: Mitochondrial complex I (CoI) deficit, associated with alterations in mitochondrial a... more Background: Mitochondrial complex I (CoI) deficit, associated with alterations in mitochondrial and neuronal differentiation has been consistently observed in schizophrenia. We aimed to unravel the mechanism that underlies CoI homeostasis defects. Methods: EBV transformed B lymphocyte lines were analyzed for CI-driven respiration, CoI synthesis and degradation rate, in-gel activity and levels. Import, transcripts sequence and expression of several CoI subunits were analyzed. Results: CoI-driven respiration deficits were associated with reduced in-gel activity of isolated holo-CoI, CoI synthesis and degradation rates and levels of its labile subunits in patients. Import into mitochondria of NDUFV2, the most affected subunit in schizophrenia, was impaired in patients, due to both protein and mitochondria source (patients or controls). Despite the above deficits, CoI and CoI-bound NDUFV2 levels were normal. This discrepancy probably stems from decreased degradation rate of NDUFV2. To study the mechanism responsible for NDUFV2 deficits we studied its transcription, as deduced from the import study. While transcript sequence was similar in both cohorts, a mix of products was observed in schizophrenia, suggesting interference with the reverse transcriptase. NDUFV2 has a pseudogene (NDUFV2P1), which is an attractive candidate for the regulation of transcription. Indeed, NDUFV2P1 transcript levels were significantly increased in both lymphoblast and frontal cortex specimens in patients, which showed a significant inverse correlation with NDUFV2 pre-protein levels and cell respiration. Conclusions: Increased NDUFV2P1 transcripts can interfere with NDUFV2 reverse transcription, translation and import, leading to changes in synthesis and degradation rates and activity of CoI and ultimately to mitochondrial dysfunction in schizophrenia.

European Neuropsychopharmacology, 2019

Accumulating data point to heme involvement in neuropsychiatric disorders. Heme plays a role in m... more Accumulating data point to heme involvement in neuropsychiatric disorders. Heme plays a role in major cellular processes such as signal transduction, protein complex assembly and regulation of transcription and translation. Its synthesis involves the mitochondria, which dysfunction, specifically that of the complex I (Co-I) of the electron transport chain is involved in the pathophysiology of schizophrenia (SZ). Here we aimed to demonstrate that deficits in Co-I affect heme metabolism. We show a significant decrease in heme levels in Co-I deficient SZ-derived EBV transformed lymphocytes (lymphoblastoid cell lines - LCLs) as compared to healthy subjects-derived cells (n = 9/cohort). Moreover, protein levels assessed by immunoblotting and mRNA levels assessed by qRT-PCR of heme catabolic enzyme, heme Oxygenase 1 (HO-1), and protein levels of heme downstream target phosphorylated eukaryotic initiation factor 2-alpha (Peif2a/eif2a) were significantly elevated in SZ-derived cells. In contrast, protein and mRNA levels of heme synthesis rate limiting enzyme aminolevulinic acid synthase-1 (ALAS1) were unchanged in SZ derived LCLs. In addition, inhibition of Co-I by rotenone in healthy subjects-derived LCLs (n = 4/cohort) exhibited an initial increase followed by a later decrease in heme levels. These findings were associated with opposite changes in heme's downstream target and HO-1 level, similar to our findings in SZ-derived cells. We also show a brain region specific pattern of impairment in Co-I subunits and in HO-1 and PeIF2α/eIF2α in the Poly-IC rat model of SZ (n = 6/cohort). Our results provide evidence for a link between CoI and heme metabolism both in-vitro and in-vivo suggesting its contribution to SZ pathophysiology.

European Neuropsychopharmacology, 2019

Mitochondrial complex I (NADH-dehydrogenase) and complex IV (cytochrome-c-oxidase) are reported t... more Mitochondrial complex I (NADH-dehydrogenase) and complex IV (cytochrome-c-oxidase) are reported to be affected by drugs used to treat psychiatric or neurodegenerative diseases, including antidepressants, antipsychotics, anxiolytics, mood stabilizers, stimulants, antidementia, and antiparkinsonian drugs. We conducted meta-analyses examining the effects of each drug category on complex I and IV. The electronic databases Pubmed, EMBASE, CENTRAL, and Google Scholar were searched for studies published between 1970 and 2018. Of 3105 screened studies, 68 articles covering 53 drugs were included in the meta-analyses. All studies assessed complex I and IV in rodent brain at the level of enzyme activity. Results revealed that selected antidepressants increase or decrease complex I and IV, antipsychotics and stimulants decrease complex I but increase complex IV, whereas anxiolytics, mood stabilizers, antidementia, and antiparkinsonian drugs preserve or even enhance both complex I and IV. Potential contributions to the drug effects were found to be related to the drugs' neurotransmitter receptor profiles with adrenergic (α1B), dopaminergic (D1/2), glutaminergic (NMDA1,3),

Frontiers in Cellular Neuroscience, 2018

In the last decade, there is an increasing application of induced pluripotent stem cells (iPSCs) ... more In the last decade, there is an increasing application of induced pluripotent stem cells (iPSCs) for disease modeling. The iPSC technology enables the study of patient-specific neuronal cell lines in vitro to evaluate dysfunction at the cellular level and identify the responsible genetic factors. This approach might be particularly valuable for filling the gap of knowledge at the cellular and molecular levels underlying the pathophysiology of various neurodevelopmental and/or psychiatric disorders, such as attention-deficit hyperactivity disorder (ADHD). However, the invasiveness of skin biopsy or blood withdrawal might represent a major impediment in such protected population. Using hair derived keratinocytes as starting somatic cells circumvents this problem as sample collections can be performed non-invasively. Here we describe an improved, convenient, standardized and effective method to culture and reprogram hair derived keratinocytes from three healthy controls and one ADHD patient into iPSCs, which in turn will be used to generate differentiated neuronal cells. All the cell types were maintained in highly defined, serum-free conditions and showed expression of the respective key marker genes, assessed by both immunocytochemistry and qRT-PCR. The described in vitro personalized neuronal model has its advantage in modeling neurodevelopmental trajectories since it can recapitulate key processes of brain development at the cellular and molecular level and is intended to be used as for example studying ADHD etiopathology.

Molecular Psychiatry, 2018

Mitochondria together with other cellular components maintain a constant crosstalk, modulating tr... more Mitochondria together with other cellular components maintain a constant crosstalk, modulating transcriptional and posttranslational processes. We and others demonstrated mitochondrial multifaceted dysfunction in schizophrenia, with aberrant complex I (CoI) as a major cause. Here we show deficits in CoI activity and homeostasis in schizophrenia-derived cell lines. Focusing on a core CoI subunit, NDUFV2, one of the most severely affected subunits in schizophrenia, we observed reduced protein level and functioning, with no change in mRNA transcripts. We further show that NDUFV2 pseudogene (NDUFV2P1) expression is increased in schizophrenia-derived cells and in postmortem brain specimens. In schizophrenia and controls pooled samples, NDUFV2P1 level demonstrated a significant inverse correlation with NDUFV2 pre-and matured protein level and with CoI-driven cellular respiration. Our data suggest a role for a pseudogene in its parent-gene regulation and possibly in CoI dysfunction in schizophrenia. The abnormal expression of the pseudogene may be one element of a vicious circle in which CoI deficits lead to mitochondrial dysfunction potentially affecting genome-wide regulation of gene expression, including the expression of pseudogenes.

The American Journal of Clinical Nutrition, 1989

An animal model of nutritional iron deficiency (ID) is described that demonstrates a reduction of... more An animal model of nutritional iron deficiency (ID) is described that demonstrates a reduction of brain nonheme iron. The most prominent feature of ID is the significant and selective diminution of central dopamine neurotransmission resulting from the decreased number of dopamine D2 receptors in the caudate nucleus, nucleus accumbens, pituitary, and in all probability the frontal cortex. The consequences of diminished dopaminergic neurotransmission is a modification of dopamine-dependent behaviors and biochemical reactions, the most important of which is the reduction in learning processes. The role of iron in maintaining the homeostasis of normally functioning dopamine neurons and their involvement in cognitive processes cannot be excluded. An interference with iron metabolism at an early age can result in irreversible damage to developing dopamine neurons, with consequences that may manifest themselves in adult life.

Mitochondrial transplantation is currently being explored as a means to repair and restore proper... more Mitochondrial transplantation is currently being explored as a means to repair and restore proper organelle function in a variety of inherited and acquired disorders of energy metabolism. The optimal preparation and application of donor mitochondria is unknown, but most studies in vivo have used injection techniques or, for tissue studies, unpackaged mitochondria (organelles isolated and suspended in buffer) in transplant experiments. Packaging in lipid rafts can increase recipient cell uptake of some compounds and objects. We present the first data comparing recipient cell uptake of unpackaged mitochondria to recipient cell uptake of mitochondria packaged in cell membrane lipids. Mitochondria and membranes were prepared from autologous cells and applied to cells (fibroblasts) in culture. Both unpackaged and lipid-packaged mitochondria were taken into recipient cells and the donor mitochondria showed evidence, in each case, of retained functionality and the ability to merge with the...

Biological Psychiatry, 2017

The neurobiology of psychiatric disorders is still unclear, although changes in multiple neuronal... more The neurobiology of psychiatric disorders is still unclear, although changes in multiple neuronal systems, specifically the dopaminergic, glutamatergic and GABAergic systems as well as abnormalities in synaptic plasticity and neural connectivity, are currently suggested to underlie their pathophysiology. A growing body of evidence suggests multifaceted mitochondrial dysfunction in mental disorders, which is in line with their role in neuronal activity, growth, development and plasticity. In this review, we will describe the main endeavors towards development of treatments that will enhance mitochondrial function and their transition into clinical use, in congenital mitochondrial diseases and chronic disorders such as diabetes type I&II, cardiovascular disorders and cancer. In addition, we will discuss the relevance of mitochondrial targeted treatments to mental disorders and their potential to become a novel therapeutic strategy that will improve the efficiency of the current treatments.

European Neuropsychopharmacology, 2017

Abstract Schizophrenia (SZ) is conceptualized as a neurodevelopmental disorder, involving dysfunc... more Abstract Schizophrenia (SZ) is conceptualized as a neurodevelopmental disorder, involving dysfunction of dopaminergic and glutamatergic systems as well as of mitochondria. Among the major obstacles in studying pathological processes in SZ are the inaccessibility of the brain and inability to study brain processes prior to the onset of this disorder. Animal models of the disease can shed light on possible developmental aberration in the disease. An additional attractive experimental tool to study neurodevelopmental impairments together with mitochondrial dysfunction in SZ, is differentiation of induced pluripotent stem cells (iPSC) into neurons. iPSC from SZ patients and healthy controls were reprogrammed from hair follicle keratinocytes and differentiated into dopaminergic and glutamatergic neurons. Mitochondria were assessed by analyzing mitochondrial membrane potential, network dynamics and apoptosis markers. The effect of transferring isolated active normal mitochondria (IAN-MIT) into SZ- iPSCs was studied. Furthermore, mitochondrial complex I subunits expression was followed in brains of neonatal ventral hippocampal (nVH) damage rat model of SZ. SZ-derived dopaminergic cells showed severely impaired ability to differentiate, whereas glutamatergic cells were unable to maturate. Mitochondrial complex I driven respiration was impaired in SZ-derived keratinocytes and iPSC along with perturbations in mitochondrial membrane potential and in mitochondrial network in neurons. However, amending mitochondrial function by IAN-MIT transfer improved differentiation of SZ-iPSC derived glutamatergic neurons. In prefrontal cortex, but not the cingulate cortex, of nVH damage rat model of SZ we observed a significant prepubertal increase and postpubertal decrease in mitochondrial complex I subunits. No such change was observed in neonatal exposure to hypoxia rat model. Our study shows perturbations in neural differentiation and mitochondrial function, which are interconnected and of relevance to early neurodevelopmental processes in SZ.

Advances in …, 1984

... Or filter your current search. Ben-Shachar D, Find all citations by this author (default). ..... more ... Or filter your current search. Ben-Shachar D, Find all citations by this author (default). ... The function of the large amounts of iron in certain brain areas, such as the pallidum, caudate nucleus, substantia nigra, nucleus accumbens, and olfactory tubercule, is not known. ...

Biological Psychiatry, 2018

Methods: SZ patients were randomized to treatment as usual (TAU; n¼24) or treatment as usual + TC... more Methods: SZ patients were randomized to treatment as usual (TAU; n¼24) or treatment as usual + TCT (n¼22). Average duration of illness was approximately 15 years. Auditory discriminability (Word-In-Noise test, WIN), cognitive functioning (MATRICS Consensus Cognitive Battery, MCCB), as well as positive (SAPS) and negative symptoms scores (SANS) were assessed before and after TCT. Data were analyzed using linear mixed effects models. Results: At follow up, TCT was associated with significant improvements in WIN (d¼0.63, p<0.04), verbal learning and memory (d¼0.82 p<0.01), and SAPS (d¼-0.62, p<0.05). Age was a significant moderator of verbal learning gains with TCT; older patients exhibited greater improvements (p<0.01). Conclusions: TCT significantly improved auditory discrimination, verbal learning and positive symptoms in SZ patients in community-based residential care. Our results suggest older SZ patients may be able to benefit from TCT. Improving the fidelity of low-level auditory sensory information processing via TCT may yield clinically meaningful outcomes, even in patients with chronic illness.

Biological Psychiatry, 1997

been emphasised In the recent literature. In the central nervous system NO Is supposed to be the ... more been emphasised In the recent literature. In the central nervous system NO Is supposed to be the retrograde messenger In those parts which are connected with memory fixation and retention. Presumably we may suggest that behavioral changes reported above could be a result of excessive NO amount In the brain.

Neuroprotection in Autism, Schizophrenia and Alzheimer's Disease

Abstract Heme plays a role in major cellular processes such as signal transduction, protein synth... more Abstract Heme plays a role in major cellular processes such as signal transduction, protein synthesis, and complex assembly and regulation of transcription and translation. As such, it is essential for brain metabolism, oxygen sensing, and neuronal survival. Its synthesis is composed of eight distinct steps; the first and last three steps take place in the mitochondria. Accumulating evidence point at mitochondrial dysfunction and altered heme metabolism in neuropsychiatric disorders. Here, we will review the growing number of experimental data demonstrating deficits in heme, mitochondria, and specifically the first complex (Co-I) of the electron transport chain in three neuropsychiatric disorders—Alzheimer’s disease (AD), Parkinson’s disease (PD), and schizophrenia (SZ). Furthermore, we will provide evidence for an association between mitochondrial Co-I dysfunction and heme metabolism and suggest their potential to become additional therapeutic targets that will improve the efficiency of the current treatments.

Clinical and Experimental Pharmacology and Physiology, 2018

Chemotherapy-induced cognitive changes is a major burden on a substantial number of cancer surviv... more Chemotherapy-induced cognitive changes is a major burden on a substantial number of cancer survivors. The mechanism of this sequel is unknown. In this study, we followed long-term effects of early in life mithramycin (MTR) treatment on behavior and on the normal course of alterations of gene expression in brain. Between post-natal days (PND) 7-10 male rats were divided into two groups, one receiving MTR (0.1mg/Kg s.c./day) and the other saline. At PND11, frontal cortex tissue samples were dissected from four rats from each group. At PND 65 the remaining rats underwent behavioral tests after which all the rats were decapitated and their prefrontal cortex incised. Rats treated transiently with MTR early in life, showed impairments in spatial working memory and anxious-like behavior in adulthood. The immediate molecular effect of MTR was expressed in a limited number of altered genes of different unconnected trajectories, which were simultaneously distorted by the drug. In contrast, three months later we observed a change in the expression of more than 1000 genes that converged into specific cellular processes. Time-dependent gene expression dynamics of several genes was significantly different between treated and untreated rats. The differences in the total number of altered genes and in gene expression trends, immediately and long after MTR treatment cessation, suggest the evolvement of a new cellular homeostatic set point, which can lead to behavioral abnormalities following chemotherapy treatment.

Methods in Molecular Biology, 2021

Mitochondria, similar to living cells and organelles, have a negative membrane potential, which r... more Mitochondria, similar to living cells and organelles, have a negative membrane potential, which ranges between (-108) and (150) mV as compared to (-70) and (-90) mV of the plasma membrane. Therefore, permeable lipophilic cations tend to accumulate in the mitochondria. Those cations which exhibit fluorescence activity after accumulation into energized systems are widely used to decipher changes in membrane potential by imaging techniques. Here we describe the use of two different dyes for labeling mitochondrial membrane potential (Δψm) in live cells. One is the lipophilic cation 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazol-carbocyanine iodide (JC-1), which alters reversibly its color from green (J-monomer, at its low concentration in the cytosol) to red (J-aggregates, at its high concentration in active mitochondria) with increasing mitochondrial membrane potential (Δψm). The other is MitoTracker® Orange, a mitochondrion-selective probe which passively diffuses across the plasma membrane and accumulates in active mitochondria depending on their Δψm. We show that in addition to changes in Δψm, these specific dyes can be used to follow alterations in mitochondrial distribution and mitochondrial network connectivity. We suggest that JC-1 is a preferable probe to compare between different cell types and cell state, as a red to green ratio of fluorescence intensities is used for analysis. This ratio depends only on the mitochondrial membrane potential and not on other cellular and/or mitochondrial-dependent or independent factors that may alter, for example, due to treatment or disease state. However, in cells labeled either with green or red fluorescence protein, JC-1 cannot be used. Therefore, other dyes are preferable. We demonstrate various applications of JC-1 and MitoTracker Orange staining to study mitochondrial abnormalities in different cell types derived from schizophrenia patients and healthy subjects.

Scientific Reports, 2020

Pharmacological treatment of mental disorders is currently decided based on "trial and error... more Pharmacological treatment of mental disorders is currently decided based on "trial and error" strategy. Mitochondrial multifaceted dysfunction is assumed to be a major factor in the pathophysiology and treatment of schizophrenia (SZ) and bipolar disorder (BD). This study aimed to explore the feasibility of using a profile of mitochondrial function parameters as a tool to predict the optimal drug for an individual patient (personalized medicine). Healthy controls (n = 40), SZ (n = 48) and BD (n = 27) patients were recruited. Mental and global state of the subjects, six mitochondrial respiration parameters and 14 mitochondrial function-related proteins were assessed in fresh lymphocytes following in-vitro or in-vivo treatment with five antipsychotic drugs and two mood-stabilizers. In healthy controls, hierarchal clustering shows a drug-specific effect profile on the different mitochondrial parameters following in-vitro exposure. Similar changes were observed in untreated SZ ...

Biological Psychiatry, 2020

Background: Prenatal maternal immune activation (MIA) is associated with alterations in offspring... more Background: Prenatal maternal immune activation (MIA) is associated with alterations in offspring brain development and risk of psychiatric disorders. Human studies of MIA in association with early brain development are sparse. We hypothesized that higher levels of MIA as measured by maternal interleukin-6 (IL-6) and C-reactive protein (CRP) are associated with variation in gray and white matter organizational properties in neonates. Methods: At 24-27 weeks gestation, 49 healthy pregnant women underwent assessments and blood draws. IL-6 and CRP were measured using the ELISA. The neonates underwent a MRI scan and analyses of the directional diffusion of water indexed by fractional anisotropy (FA) were performed. Results: Higher levels of maternal IL-6 were associated with increased FA values in the basal ganglia and thalamus, and across the occipital and right anterior temporal regions. Higher levels of CRP were associated with decreased FA values across the frontal and occipital lobes, and the anterior limb of the internal capsules, and increased FA values of the posterior limb. Conclusions: We demonstrate that both immune markers have shared and distinct patterns of association with brain tissue organization but differ in their associations with brain metabolites. The findings emphasize the value of considering multiple measures of MIA and imaging in this emerging area of research.

Journal of Neural Transmission, 2019

Parkinson's disease (PD) and schizophrenia (SZ) are two CNS disorders in which dysfunctions in th... more Parkinson's disease (PD) and schizophrenia (SZ) are two CNS disorders in which dysfunctions in the dopaminergic system and mitochondria are major pathologies. The symptomology of both, PD a neurodegenerative disorder and SZ a neurodevelopmental disorder, is completely different. However, the pharmacological treatment of each of the diseases can cause a shift of symptoms into those characteristic of the other disease. In this review, I describe a pathological interaction between dopamine and mitochondria in both disorders, which due to differences in the extent of oxidative stress leads either to cell death and tissue degeneration as in PD substantia nigra pars compacta or to distorted neuronal activity, imbalanced neuronal circuitry and abnormal behavior and cognition in SZ. This review is in the honor of Moussa Youdim who introduced me to the secrets of research work. His enthusiasm, curiosity and novelty-seeking inspired me throughout my career. Thank you Moussa.

Biological Psychiatry, 2018

Background: Mitochondrial complex I (CoI) deficit, associated with alterations in mitochondrial a... more Background: Mitochondrial complex I (CoI) deficit, associated with alterations in mitochondrial and neuronal differentiation has been consistently observed in schizophrenia. We aimed to unravel the mechanism that underlies CoI homeostasis defects. Methods: EBV transformed B lymphocyte lines were analyzed for CI-driven respiration, CoI synthesis and degradation rate, in-gel activity and levels. Import, transcripts sequence and expression of several CoI subunits were analyzed. Results: CoI-driven respiration deficits were associated with reduced in-gel activity of isolated holo-CoI, CoI synthesis and degradation rates and levels of its labile subunits in patients. Import into mitochondria of NDUFV2, the most affected subunit in schizophrenia, was impaired in patients, due to both protein and mitochondria source (patients or controls). Despite the above deficits, CoI and CoI-bound NDUFV2 levels were normal. This discrepancy probably stems from decreased degradation rate of NDUFV2. To study the mechanism responsible for NDUFV2 deficits we studied its transcription, as deduced from the import study. While transcript sequence was similar in both cohorts, a mix of products was observed in schizophrenia, suggesting interference with the reverse transcriptase. NDUFV2 has a pseudogene (NDUFV2P1), which is an attractive candidate for the regulation of transcription. Indeed, NDUFV2P1 transcript levels were significantly increased in both lymphoblast and frontal cortex specimens in patients, which showed a significant inverse correlation with NDUFV2 pre-protein levels and cell respiration. Conclusions: Increased NDUFV2P1 transcripts can interfere with NDUFV2 reverse transcription, translation and import, leading to changes in synthesis and degradation rates and activity of CoI and ultimately to mitochondrial dysfunction in schizophrenia.

European Neuropsychopharmacology, 2019

Accumulating data point to heme involvement in neuropsychiatric disorders. Heme plays a role in m... more Accumulating data point to heme involvement in neuropsychiatric disorders. Heme plays a role in major cellular processes such as signal transduction, protein complex assembly and regulation of transcription and translation. Its synthesis involves the mitochondria, which dysfunction, specifically that of the complex I (Co-I) of the electron transport chain is involved in the pathophysiology of schizophrenia (SZ). Here we aimed to demonstrate that deficits in Co-I affect heme metabolism. We show a significant decrease in heme levels in Co-I deficient SZ-derived EBV transformed lymphocytes (lymphoblastoid cell lines - LCLs) as compared to healthy subjects-derived cells (n = 9/cohort). Moreover, protein levels assessed by immunoblotting and mRNA levels assessed by qRT-PCR of heme catabolic enzyme, heme Oxygenase 1 (HO-1), and protein levels of heme downstream target phosphorylated eukaryotic initiation factor 2-alpha (Peif2a/eif2a) were significantly elevated in SZ-derived cells. In contrast, protein and mRNA levels of heme synthesis rate limiting enzyme aminolevulinic acid synthase-1 (ALAS1) were unchanged in SZ derived LCLs. In addition, inhibition of Co-I by rotenone in healthy subjects-derived LCLs (n = 4/cohort) exhibited an initial increase followed by a later decrease in heme levels. These findings were associated with opposite changes in heme's downstream target and HO-1 level, similar to our findings in SZ-derived cells. We also show a brain region specific pattern of impairment in Co-I subunits and in HO-1 and PeIF2α/eIF2α in the Poly-IC rat model of SZ (n = 6/cohort). Our results provide evidence for a link between CoI and heme metabolism both in-vitro and in-vivo suggesting its contribution to SZ pathophysiology.

European Neuropsychopharmacology, 2019

Mitochondrial complex I (NADH-dehydrogenase) and complex IV (cytochrome-c-oxidase) are reported t... more Mitochondrial complex I (NADH-dehydrogenase) and complex IV (cytochrome-c-oxidase) are reported to be affected by drugs used to treat psychiatric or neurodegenerative diseases, including antidepressants, antipsychotics, anxiolytics, mood stabilizers, stimulants, antidementia, and antiparkinsonian drugs. We conducted meta-analyses examining the effects of each drug category on complex I and IV. The electronic databases Pubmed, EMBASE, CENTRAL, and Google Scholar were searched for studies published between 1970 and 2018. Of 3105 screened studies, 68 articles covering 53 drugs were included in the meta-analyses. All studies assessed complex I and IV in rodent brain at the level of enzyme activity. Results revealed that selected antidepressants increase or decrease complex I and IV, antipsychotics and stimulants decrease complex I but increase complex IV, whereas anxiolytics, mood stabilizers, antidementia, and antiparkinsonian drugs preserve or even enhance both complex I and IV. Potential contributions to the drug effects were found to be related to the drugs' neurotransmitter receptor profiles with adrenergic (α1B), dopaminergic (D1/2), glutaminergic (NMDA1,3),

Frontiers in Cellular Neuroscience, 2018

In the last decade, there is an increasing application of induced pluripotent stem cells (iPSCs) ... more In the last decade, there is an increasing application of induced pluripotent stem cells (iPSCs) for disease modeling. The iPSC technology enables the study of patient-specific neuronal cell lines in vitro to evaluate dysfunction at the cellular level and identify the responsible genetic factors. This approach might be particularly valuable for filling the gap of knowledge at the cellular and molecular levels underlying the pathophysiology of various neurodevelopmental and/or psychiatric disorders, such as attention-deficit hyperactivity disorder (ADHD). However, the invasiveness of skin biopsy or blood withdrawal might represent a major impediment in such protected population. Using hair derived keratinocytes as starting somatic cells circumvents this problem as sample collections can be performed non-invasively. Here we describe an improved, convenient, standardized and effective method to culture and reprogram hair derived keratinocytes from three healthy controls and one ADHD patient into iPSCs, which in turn will be used to generate differentiated neuronal cells. All the cell types were maintained in highly defined, serum-free conditions and showed expression of the respective key marker genes, assessed by both immunocytochemistry and qRT-PCR. The described in vitro personalized neuronal model has its advantage in modeling neurodevelopmental trajectories since it can recapitulate key processes of brain development at the cellular and molecular level and is intended to be used as for example studying ADHD etiopathology.

Molecular Psychiatry, 2018

Mitochondria together with other cellular components maintain a constant crosstalk, modulating tr... more Mitochondria together with other cellular components maintain a constant crosstalk, modulating transcriptional and posttranslational processes. We and others demonstrated mitochondrial multifaceted dysfunction in schizophrenia, with aberrant complex I (CoI) as a major cause. Here we show deficits in CoI activity and homeostasis in schizophrenia-derived cell lines. Focusing on a core CoI subunit, NDUFV2, one of the most severely affected subunits in schizophrenia, we observed reduced protein level and functioning, with no change in mRNA transcripts. We further show that NDUFV2 pseudogene (NDUFV2P1) expression is increased in schizophrenia-derived cells and in postmortem brain specimens. In schizophrenia and controls pooled samples, NDUFV2P1 level demonstrated a significant inverse correlation with NDUFV2 pre-and matured protein level and with CoI-driven cellular respiration. Our data suggest a role for a pseudogene in its parent-gene regulation and possibly in CoI dysfunction in schizophrenia. The abnormal expression of the pseudogene may be one element of a vicious circle in which CoI deficits lead to mitochondrial dysfunction potentially affecting genome-wide regulation of gene expression, including the expression of pseudogenes.

The American Journal of Clinical Nutrition, 1989

An animal model of nutritional iron deficiency (ID) is described that demonstrates a reduction of... more An animal model of nutritional iron deficiency (ID) is described that demonstrates a reduction of brain nonheme iron. The most prominent feature of ID is the significant and selective diminution of central dopamine neurotransmission resulting from the decreased number of dopamine D2 receptors in the caudate nucleus, nucleus accumbens, pituitary, and in all probability the frontal cortex. The consequences of diminished dopaminergic neurotransmission is a modification of dopamine-dependent behaviors and biochemical reactions, the most important of which is the reduction in learning processes. The role of iron in maintaining the homeostasis of normally functioning dopamine neurons and their involvement in cognitive processes cannot be excluded. An interference with iron metabolism at an early age can result in irreversible damage to developing dopamine neurons, with consequences that may manifest themselves in adult life.

Mitochondrial transplantation is currently being explored as a means to repair and restore proper... more Mitochondrial transplantation is currently being explored as a means to repair and restore proper organelle function in a variety of inherited and acquired disorders of energy metabolism. The optimal preparation and application of donor mitochondria is unknown, but most studies in vivo have used injection techniques or, for tissue studies, unpackaged mitochondria (organelles isolated and suspended in buffer) in transplant experiments. Packaging in lipid rafts can increase recipient cell uptake of some compounds and objects. We present the first data comparing recipient cell uptake of unpackaged mitochondria to recipient cell uptake of mitochondria packaged in cell membrane lipids. Mitochondria and membranes were prepared from autologous cells and applied to cells (fibroblasts) in culture. Both unpackaged and lipid-packaged mitochondria were taken into recipient cells and the donor mitochondria showed evidence, in each case, of retained functionality and the ability to merge with the...

Biological Psychiatry, 2017

The neurobiology of psychiatric disorders is still unclear, although changes in multiple neuronal... more The neurobiology of psychiatric disorders is still unclear, although changes in multiple neuronal systems, specifically the dopaminergic, glutamatergic and GABAergic systems as well as abnormalities in synaptic plasticity and neural connectivity, are currently suggested to underlie their pathophysiology. A growing body of evidence suggests multifaceted mitochondrial dysfunction in mental disorders, which is in line with their role in neuronal activity, growth, development and plasticity. In this review, we will describe the main endeavors towards development of treatments that will enhance mitochondrial function and their transition into clinical use, in congenital mitochondrial diseases and chronic disorders such as diabetes type I&II, cardiovascular disorders and cancer. In addition, we will discuss the relevance of mitochondrial targeted treatments to mental disorders and their potential to become a novel therapeutic strategy that will improve the efficiency of the current treatments.

European Neuropsychopharmacology, 2017

Abstract Schizophrenia (SZ) is conceptualized as a neurodevelopmental disorder, involving dysfunc... more Abstract Schizophrenia (SZ) is conceptualized as a neurodevelopmental disorder, involving dysfunction of dopaminergic and glutamatergic systems as well as of mitochondria. Among the major obstacles in studying pathological processes in SZ are the inaccessibility of the brain and inability to study brain processes prior to the onset of this disorder. Animal models of the disease can shed light on possible developmental aberration in the disease. An additional attractive experimental tool to study neurodevelopmental impairments together with mitochondrial dysfunction in SZ, is differentiation of induced pluripotent stem cells (iPSC) into neurons. iPSC from SZ patients and healthy controls were reprogrammed from hair follicle keratinocytes and differentiated into dopaminergic and glutamatergic neurons. Mitochondria were assessed by analyzing mitochondrial membrane potential, network dynamics and apoptosis markers. The effect of transferring isolated active normal mitochondria (IAN-MIT) into SZ- iPSCs was studied. Furthermore, mitochondrial complex I subunits expression was followed in brains of neonatal ventral hippocampal (nVH) damage rat model of SZ. SZ-derived dopaminergic cells showed severely impaired ability to differentiate, whereas glutamatergic cells were unable to maturate. Mitochondrial complex I driven respiration was impaired in SZ-derived keratinocytes and iPSC along with perturbations in mitochondrial membrane potential and in mitochondrial network in neurons. However, amending mitochondrial function by IAN-MIT transfer improved differentiation of SZ-iPSC derived glutamatergic neurons. In prefrontal cortex, but not the cingulate cortex, of nVH damage rat model of SZ we observed a significant prepubertal increase and postpubertal decrease in mitochondrial complex I subunits. No such change was observed in neonatal exposure to hypoxia rat model. Our study shows perturbations in neural differentiation and mitochondrial function, which are interconnected and of relevance to early neurodevelopmental processes in SZ.