Accumulation of 8-oxodG within the human mitochondrial genome positively associates with transcription

Mitochondrial DNA (mtDNA) can be subject to internal and environmental stressors that lead to oxidatively generated damage and the formation of 8-oxo-7,8-dihydro-2'-deoxyguanine (8-oxodG). The accumulation of 8-oxodG has been linked to degenerative diseases and aging, as well as cancer. Despite the well-described implications of 8-oxodG in mtDNA for mitochondrial function, there have been no reports of mapping of 8-oxodG across the mitochondrial genome. To address this, we used OxiDIP-Seq and mapped 8-oxodG levels in the mitochondrial genome of human MCF10A cells. Our findings indicated that, under steady-state conditions, 8-oxodG is non-uniformly distributed along the mitochondrial genome, and that the longer non-coding region appeared to be more protected from 8-oxodG accumulation compared with the coding region. However, when the cells have been exposed to oxidative stress, 8-oxodG preferentially accumulated in the coding region which is highly transcribed as H1 transcript. Our data suggest that 8-oxodG accumulation in the mitochondrial genome is positively associated with mitochondrial transcription.

TFEB and TFE3 control glucose homeostasis by regulating insulin gene expression

To fulfill their function, pancreatic beta cells require precise nutrient-sensing mechanisms that control insulin production. Transcription factor EB (TFEB) and its homolog TFE3 have emerged as crucial regulators of the adaptive response of cell metabolism to environmental cues. Here, we show that TFEB and TFE3 regulate beta-cell function and insulin gene expression in response to variations in nutrient availability. We found that nutrient deprivation in beta cells promoted TFEB/TFE3 activation, which resulted in suppression of insulin gene expression. TFEB overexpression was sufficient to inhibit insulin transcription, whereas beta cells depleted of both TFEB and TFE3 failed to suppress insulin gene expression in response to amino acid deprivation. Interestingly, ChIP-seq analysis showed binding of TFEB to super-enhancer regions that regulate insulin transcription. Conditional, beta-cell-specific, Tfeb-overexpressing, and Tfeb/Tfe3 double-KO mice showed severe alteration of insulin transcription, secretion, and glucose tolerance, indicating that TFEB and TFE3 are important physiological mediators of pancreatic function. Our findings reveal a nutrient-controlled transcriptional mechanism that regulates insulin production, thus playing a key role in glucose homeostasis at both cellular and organismal levels.

EGR1 drives cell proliferation by directly stimulating TFEB transcription in response to starvation

The stress-responsive transcription factor EB (TFEB) is a master controller of lysosomal biogenesis and autophagy and plays a major role in several cancer-associated diseases. TFEB is regulated at the posttranslational level by the nutrient-sensitive kinase complex mTORC1. However, little is known about the regulation of TFEB transcription. Here, through integrative genomic approaches, we identify the immediate-early gene EGR1 as a positive transcriptional regulator of TFEB expression in human cells and demonstrate that, in the absence of EGR1, TFEB-mediated transcriptional response to starvation is impaired. Remarkably, both genetic and pharmacological inhibition of EGR1, using the MEK1/2 inhibitor Trametinib, significantly reduced the proliferation of 2D and 3D cultures of cells displaying constitutive activation of TFEB, including those from a patient with Birt-Hogg-Dubé (BHD) syndrome, a TFEB-driven inherited cancer condition. Overall, we uncover an additional layer of TFEB regulation consisting in modulating its transcription via EGR1 and propose that interfering with the EGR1-TFEB axis may represent a therapeutic strategy to counteract constitutive TFEB activation in cancer-associated conditions.

The Intertwined Role of 8-oxodG and G4 in Transcription Regulation

The guanine base in nucleic acids is, among the other bases, the most susceptible to being converted into 8-Oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) when exposed to reactive oxygen species. In double-helix DNA, 8-oxodG can pair with adenine; hence, it may cause a G > T (C > A) mutation; it is frequently referred to as a form of DNA damage and promptly corrected by DNA repair mechanisms. Moreover, 8-oxodG has recently been redefined as an epigenetic factor that impacts transcriptional regulatory elements and other epigenetic modifications. It has been proposed that 8-oxodG exerts epigenetic control through interplay with the G-quadruplex (G4), a non-canonical DNA structure, in transcription regulatory regions. In this review, we focused on the epigenetic roles of 8-oxodG and the G4 and explored their interplay at the genomic level.

OxiDIP-Seq for Genome-wide Mapping of Damaged DNA Containing 8-Oxo-2'-Deoxyguanosine

8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) is considered to be a premutagenic DNA lesion generated by 2'-deoxyguanosine (dG) oxidation due to reactive oxygen species (ROS). In recent years, the 8-oxodG distribution in human, mouse, and yeast genomes has been underlined using various next-generation sequencing (NGS)-based strategies. The present study reports the OxiDIP-Seq protocol, which combines specific 8-oxodG immuno-precipitation of single-stranded DNA with NGS, and the pipeline analysis that allows the genome-wide 8-oxodG distribution in mammalian cells. The development of this OxiDIP-Seq method increases knowledge on the oxidative DNA damage/repair field, providing a high-resolution map of 8-oxodG in human cells.

OUP accepted manuscript

8-Oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG), a major product of the DNA oxidization process, has been proposed to have an epigenetic function in gene regulation and has been associated with genome instability. NGS-based methodologies are contributing to the characterization of the 8-oxodG function in the genome. However, the 8-oxodG epigenetic role at a genomic level and the mechanisms controlling the genomic 8-oxodG accumulation/maintenance have not yet been fully characterized. In this study, we report the identification and characterization of a set of enhancer regions accumulating 8-oxodG in human epithelial cells. We found that these oxidized enhancers are mainly super-enhancers and are associated with bidirectional-transcribed enhancer RNAs and DNA Damage Response activation. Moreover, using ChIA-PET and HiC data, we identified specific CTCF-mediated chromatin loops in which the oxidized enhancer and promoter regions physically associate. Oxidized enhancers and their associated chromatin loops accumulate endogenous double-strand breaks which are in turn repaired by NHEJ pathway through a transcription-dependent mechanism. Our work suggests that 8-oxodG accumulation in enhancers–promoters pairs occurs in a transcription-dependent manner and provides novel mechanistic insights on the intrinsic fragility of chromatin loops containing oxidized enhancers-promoters interactions.

Autophagy Roles in Genome Maintenance

In recent years, a considerable correlation has emerged between autophagy and genome integrity. A range of mechanisms appear to be involved where autophagy participates in preventing genomic instability, as well as in DNA damage response and cell fate decision. These initial findings have attracted particular attention in the context of malignancy; however, the crosstalk between autophagy and DNA damage response is just beginning to be explored and key questions remain that need to be addressed, to move this area of research forward and illuminate the overall consequence of targeting this process in human therapies. Here we present current knowledge on the complex crosstalk between autophagy and genome integrity and discuss its implications for cancer cell survival and response to therapy.

Histone methyl-transferases and demethylases in the autophagy regulatory network: the emerging role of KDM1A/LSD1 demethylase

Macroautophagy/autophagy is a physiological mechanism that is essential for the maintenance of cellular homeostasis and stress adaptation. Defective autophagy is associated with many human diseases, including cancer and neurodegenerative disorders. The emerging implication of epigenetic events in the control of the autophagic process opens new avenues of investigation and offers the opportunity to develop novel therapeutic strategies in diseases associated with dysfunctional autophagy-lysosomal pathways. Accumulating evidence reveals that several methyltransferases and demethylases are essential regulators of autophagy, and recent studies have led to the identification of the lysine demethylase KDM1A/LSD1 as a promising drug target. KDM1A/LSD1 modulates autophagy at multiple levels, participating in the transcriptional control of several downstream effectors. This review summarizes our current understanding of the role of KDM1A/LSD1 in the autophagy regulatory network.

Targeting Histone Demethylase LSD1/KDM1a in Neurodegenerative Diseases

The autophagy-lysosome pathway sustains cellular homeostasis and is a protective mechanism against neurodegenerative diseases. Recent findings highlight the role of the histone demethylases LSD1/LDM1A as a pivotal regulator of autophagy process, by controlling the mTORC1 cascade, in neuroblastoma cells. LSD1 binds to the promoter region of the SESN2 gene, where LSD1-mediated demethylation leads to the accumulation of repressive histone marks that maintain SESN2 expression at low levels. LSD1 depletion results in enhanced SESN2 expression and consequently mTORC1 inhibition, thereby triggering the induction of autophagy. Our study provides important insight into neuroepigenetic mechanisms regulating the autophagic process, offering additional opportunities for the development of novel therapeutic strategies in diseases associated with dysfunctional autophagy-lysosomal pathway.

LSD1 mediates MYCN control of epithelial-mesenchymal transition through silencing of metastatic suppressor NDRG1 gene

Neuroblastoma (NB) with MYCN amplification is a highly aggressive and metastatic tumor in children. The high recurrence rate and resistance of NB cells to drugs urgently demands a better therapy for this disease. We have recently found that MYCN interacts with the lysine-specific demethylase 1 (LSD1), a histone modifier that participates in key aspects of gene transcription. In cancer cells, LSD1 contributes to the genetic reprogramming that underlies to Epithelial-Mesenchymal Transition (EMT) and tumor metastasis. Here, we show that LSD1 affects motility and invasiveness of NB cells by modulating the transcription of the metastasis suppressor NDRG1 (N-Myc Downstream-Regulated Gene 1). At mechanistic level, we found that LSD1 co-localizes with MYCN at the promoter region of the NDRG1 gene and inhibits its expression. Pharmacological inhibition of LSD1 relieves repression of NDRG1 by MYCN and affects motility and invasiveness of NB cells. These effects were reversed by overexpressing NDRG1. In NB tissues, high levels of LSD1 correlate with low levels of NDRG1 and reduced patients survival. Collectively, our findings elucidate a mechanism of how MYCN/LSD1 control motility and invasiveness of NB cells through transcription regulation of NDRG1 expression and suggest that pharmacological targeting of LSD1 represents a valuable approach for NB therapy.

Epigenetic regulation of epithelial to mesenchymal transition by the Lysine-specific demethylase LSD1/KDM1A

The Lysine-specific demethylase 1, KDM1A/LSD1, plays a central role in the regulation of Pol II transcription through the removal of the activation mark (mono- and dimethyl lysine 4 of histone H3). LSD1 is often deregulated in human cancers, and it is frequently overexpressed in human solid cancers and leukemia. LSD1 regulates the epithelial mesenchymal transition (EMT) in epithelial cells, i.e., the ability to transition into mesenchymal cells, to lose homotypic adhesion and to acquire migratory capacity. From its initial discovery as a component of the Snail complex, multiple studies highlighted the causative role of LSD1 in cell invasiveness and EMT, describing its direct involvement in different molecular processes through the interaction with specific partners. Here we present an overview of the role of LSD1 in the EMT process, summarizing recent findings on its emerging functions in cell migration and invasion in cancer.

Cell cycle-dependent resolution of DNA double-strand breaks

DNA double strand breaks (DSBs) elicit prompt activation of DNA damage response (DDR), which arrests cell-cycle either in G₁/S or G₂/M in order to avoid entering S and M phase with damaged DNAs. Since mammalian tissues contain both proliferating and quiescent cells, there might be fundamental difference in DDR between proliferating and quiescent cells (or G₀-arrested). To investigate these differences, we studied recruitment of DSB repair factors and resolution of DNA lesions induced at site-specific DSBs in asynchronously proliferating, G₀-, or G₁-arrested cells. Strikingly, DSBs occurring in G₀ quiescent cells are not repaired and maintain a sustained activation of the p53-pathway. Conversely, re-entry into cell cycle of damaged G₀-arrested cells, occurs with a delayed clearance of DNA repair factors initially recruited to DSBs, indicating an inefficient repair when compared to DSBs induced in asynchronously proliferating or G₁-synchronized cells. Moreover, we found that initial recognition of DSBs and assembly of DSB factors is largely similar in asynchronously proliferating, G₀-, or G₁-synchronized cells. Our study thereby demonstrates that repair and resolution of DSBs is strongly dependent on the cell-cycle state.

Lysine-specific demethylase (LSD1/KDM1A) and MYCN cooperatively repress tumor suppressor genes in neuroblastoma

The chromatin-modifying enzyme lysine-specific demethylase 1, KDM1A/LSD1 is involved in maintaining the undifferentiated, malignant phenotype of neuroblastoma cells and its overexpression correlated with aggressive disease, poor differentiation and infaust outcome. Here, we show that LSD1 physically binds MYCN both in vitro and in vivo and that such an interaction requires the MYCN BoxIII. We found that LSD1 co-localizes with MYCN on promoter regions of CDKN1A/p21 and Clusterin (CLU) suppressor genes and cooperates with MYCN to repress the expression of these genes. KDM1A needs to engage with MYCN in order to associate with the CDKN1A and CLU promoters. The expression of CLU and CDKN1A can be restored in MYCN-amplified cells by pharmacological inhibition of LSD1 activity or knockdown of its expression. Combined pharmacological inhibition of MYCN and LSD1 through the use of small molecule inhibitors synergistically reduces MYCN-amplified Neuroblastoma cell viability in vitro. These findings demonstrate that LSD1 is a critical co-factor of the MYCN repressive function, and suggest that combination of LSD1 and MYCN inhibitors may have strong therapeutic relevance to counteract MYCN-driven oncogenesis.

Prevalence of insulin resistance and diabetes mellitus type II in bipolar disorders

Introduction

Bipolar disorder (BD) is associated with high morbidity and mortality. Patients are symptomatic almost half of their lives and experience significant disability. One subtype of BD is associated with a more chronic course, refractoriness to treatment and poor outcome. Diabetes mellitus type 2 (T2D) and insulin resistance (IR) have been identified as risk factors for this more severe form of BD.

Objectives and aims

We investigated the rates of IR and T2D in patients with BD and whether this comorbidity is associated with specific clinical features of BD such as rapid cycling or treatment resistance.

Methods

IR and T2D were screened in patients with BD types I or II, who were on stable treatment with mood stabilizers. The response to treatment was assessed by means of the Alda scale.

Results

In a preliminary sample, we made a new diagnosis of IR in 40% of patients. The 1% of this sample had a diagnosis of T2D. The treatment response was worse in BD patients with comorbid IR or T2D as compared to those without metabolic abnormalities.

Conclusions

These findings show that IR and T2D have high prevalence in BD patients and have negative impact on treatment response.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

MYC impairs resolution of site-specific DNA double-strand breaks repair

Although it is established that when overexpressed, the MYC family proteins can cause DNA double-stand breaks (DSBs) and genome instability, the mechanisms involved remain unclear. MYC induced genetic instability may result from increased DNA damage and/or reduced DNA repair. Here we show that when overexpressed, MYC proteins induce a sustained DNA damage response (DDR) and reduce the wave of DSBs repair. We used a cell-based DSBs system whereby, upon induction of an inducible restriction enzyme AsiSI, hundreds of site-specific DSBs are generated across the genome to investigate the role of MYC proteins on DSB. We found that high levels of MYC do not block accumulation of γH2AX at AsiSI sites, but delay its clearance, indicating an inefficient repair, while the initial recognition of DNA damage is largely unaffected. Repair of both homologous and nonhomologous repair-prone segments, characterized by high or low levels of recruited RAD51, respectively, was delayed. Collectively, these data indicate that high levels of MYC proteins delay the resolution of DNA lesions engineered to occur in cell cultures.

Sequence-specific double strand breaks trigger P-TEFb-dependent Rpb1-CTD hyperphosphorylation

Double strand DNA breaks (DSBs) are one of the most challenging forms of DNA damage which, if left unrepaired, can trigger cellular death and can contribute to cancer. A number of studies have been focused on DNA-damage response (DDR) mechanisms, and most of them rely on the induction of DSBs triggered by chemical compounds or radiations. However, genotoxic drugs and radiation treatments of cultured cell lines induce random DSBs throughout the genome, thus heterogeneously across the cell population, leading to variability of the cellular response. To overcome this aspect, we used here a recently described cell-based DSBs system whereby, upon induction of an inducible restriction enzyme, hundreds of site-specific DSBs are generated across the genome. We show here that sequence-specific DSBs are sufficient to activate the positive transcription elongation factor b (P-TEFb), to trigger hyperphosphorylation of the largest RNA polymerase II carboxyl-terminal-domain (Rpb1-CTD) and to induce activation of p53-transcriptional axis resulting in cell cycle arrest.

Prosurvival effect of human wild-type alpha-synuclein on MPTP-induced toxicity to central but not peripheral catecholaminergic neurons isolated from transgenic mice

In the present work we report the generation of a new line of alpha-synuclein (alpha-SYN) transgenic mice in which the human wild-type alpha-SYN cDNA is expressed under the control of a tyrosine hydroxylase (TH) promoter. We provide evidence that the ectopic protein is found in TH expressing neurons of both central and peripheral nervous systems. The transgene is expressed very early in development coinciding with the activity of the TH promoter and in the adult brain the human protein distributes normally to the nerve endings and cell bodies of dopaminergic nigral neurons without any evidence of abnormal aggregation. Our results indicate that expression of human wild-type alpha-SYN does not affect normal development or maintenance of TH immunoreactive nigral neurons, striatal dopamine content, or locomotor activity. Systemic administration of the parkinsonian neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induces a loss of TH immunoreactive nigral neurons and terminals and of dopamine levels to the same degree in both transgenic and non-transgenic adult mice. Intoxication also results in a similar loss of cardiac noradrenaline in both genotypes. Surprisingly, cultured transgenic ventral mesencephalic fetal dopaminergic neurons exhibit complete resistance to cell death induced by 1-methyl-4-phenylpyridinium ion (MPP(+)) intoxication, without changes in dopamine transporter (DAT) surface levels. Interestingly, this protection is not observed in other populations of catecholaminergic neurons such as peripheral sympathetic neurons, despite their high sensitivity to MPP(+)in vitro.

The decrease of NAD(P)H has a prominent role in dopamine toxicity

We characterized dopamine toxicity in human neuroblastoma SH-SY5Y cells as a direct effect of dopamine on cell reductive power, measured as NADH and NADPH cell content. In cell incubations with 100 or 500 microM dopamine, the accumulation of dopamine inside the cell reached a maximum after 6 h. The decrease in cell viability was 40% and 75%, respectively, after 24 h, and was not altered by MAO inhibition with tranylcypromine. Dopamine was metabolized to DOPAC by mitochondrial MAO and, at 500 microM concentration, significantly reduced mitochondrial potential and oxygen consumption. This DA concentration caused only a slight increase in cell peroxidation in the absence of Fe(III), but a dramatic decrease in NADH and NADPH cell content and a concomitant decrease in total cell NAD(P)H/NAD(P)+ and GSH/GSSG and in mitochondrial NADH/NAD+ ratios. Dopaminechrome, a product of dopamine oxidation, was found to be a MAO-A inhibitor and a strong oxidizer of NADH and NADPH in a cell-free system. We conclude that dopamine may affect NADH and NADPH oxidation directly. When the intracellular concentrations of NAD(P)H and oxidized dopamine are similar, NAD(P)H triggers a redox cycle with dopamine that leads to its own consumption. The time-course of NADH and NADPH oxidation by dopamine was assessed in cell-free assays: NAD(P)H concentration decreased at the same time as dopamine oxidation advanced. The break in cell redox equilibrium, not excluding the involvement of free oxygen radicals, could be sufficient to explain the toxicity of dopamine in dopaminergic neurons.

Abnormal alpha-synuclein interactions with rab3a and rabphilin in diffuse Lewy body disease

The present study examines alpha-synuclein interactions with rab3a and rabphilin by antibody arrays, immunoprecipitation and pull-down methods in the entorhinal cortex of control cases and in diffuse Lewy body disease (LBD) cases. Alpha-synuclein immunoprecipitation revealed alpha-synuclein binding to rabphilin in control but not in LB cases. Immunoprecipitation with rab3a disclosed rab3a binding to rabphilin in control but not in LB cases. Moreover, rab3a interacted with high molecular weight (66 kDa) alpha-synuclein only in LB cases, in agreement with parallel studies using antibody arrays. Results were compared with pull-down assays using His(6)/Flag-tagged rab3, rab5 and rab8, and anti-Flag immunoblotting. Weak bands of 17 kDa, corresponding to alpha-synuclein, were obtained in LB and, less intensely, in control cases. In addition, alpha-synuclein-immunoreactive bands of high molecular weight (36 kDa) were seen only in LB cases after pull-down assays with rab3a, rab5 or rab8. These findings corroborate previous observations showing rab3a-rabphilin interactions in control brains, and add substantial information regarding decreased binding of rab3a to rabphilin and increased binding of rab3a to alpha-synuclein aggregates in LB cases. Since, alpha-synuclein, rab3a and rabphilin participate in the docking and fusion of synaptic vesicles, it can be suggested that exocytosis of neurotransmitters may be impaired in LB diseases.

Abnormal α-Synuclein Interactions with Rab Proteins in α-Synuclein A30P Transgenic Mice

Mutation A30P in the alpha-synuclein gene is a cause of familial Parkinson disease. Transgenic mice expressing wild mouse and mutant human A30P alpha-synuclein, Tg5093 mice (Tg), show a progressive motor disorder characterized by tremor, rigidity, and dystonia, accompanied by accumulation of alpha-synuclein in the soma and neurites and by a conspicuous gliosis beginning in the hippocampal formation at the age of 7 to 8 months and spreading throughout the CNS. Impaired short-term changes in synaptic strength have also been documented in hippocampal slices from Tg mice. Alpha-synuclein aggregates of approximately 34 and 70 kDa, in addition to the band of 17 kDa, corresponding to the molecular weight of alpha-synuclein, were recovered in the PBS-soluble fraction of brain homogenates from Tg mice but not from brain samples from age-matched wildtype littermates. MPTP-treated Tg and wildtype mice produced alpha-synuclein aggregates in the PBS-, deoxycholate-, and SDS-soluble fractions. Aggregates of alpha-synuclein, although with different molecular weights, were also observed in rotenone-treated Tg and wildtype mice. Pull-down studies with members of the Rab protein family have shown that alpha-synuclein from Tg mice interacts with Rab3a, Rab5, and Rab8. This binding is not due to the amount of alpha-synuclein (levels of which are higher in Tg mice) and it is not dependent on the amount of Rab protein used in the assay. Rather, alpha-synuclein interactions with Rab proteins are due to mutant alpha-synuclein as demonstrated in Rab pull-down assays with recombinant of wildtype and mutant A30P human alpha-synuclein. Since Rab3a, Rab5, and Rab8 are important proteins involved in synaptic vesicle trafficking and exocytosis at the synapse, vesicle endocytosis, and trans-Golgi transport, respectively, it can be suggested that these functions are impaired in Tg mice. This rationale is consistent with previous data showing that short-term hippocampal synaptic plasticity is altered and that alpha-synuclein accumulates in the cytoplasm of neurons in Tg mice.

Active, phosphorylation-dependent mitogen-activated protein kinase (MAPK/ERK), stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), and p38 kinase expression in Parkinson's disease and Dementia with Lewy bodies

The expression of mitogen-activated protein kinases, extracellular signal-regulated kinases (MAPK/ERK), stress-activated protein kinases, c-Jun N-terminal kinases (SAPK/JNK), and p38 kinases is examined in Parkinson disease (PD), in Dementia with Lewy bodies (DLB), covering common and pure forms, and in age-matched controls. The study is geared to gaining understanding about the involvement of these kinases in the pathogenesis of Lewy bodies (LBs) and associated tau deposits in Alzheimer changes in the common form of DLB. Active, phosphorylation dependent MAPK (MAPK-P) is found as granular cytoplasmic inclusions in a subset of cortical neurons bearing abnormal tau deposits in common forms of DLB. Phosphorylated p-38 (p-38-P) decorates neurons with neurofibrillary tangles and dystrophic neurites of senile plaques in common forms of DLB. Phosphorylated SAPK/JNK (SAPK/JNK-P) expression occurs in cortical neurons with neurofibrillary tangles in the common form of DLB. Lewy bodies (LBs) in the brain stem of PD and DLB are stained with anti-ERK-2 antibodies, but they are not recognized by MAPK-P, SAPK/JNK-P and p-38-P. Yet MAPK-P, p-38-P and SAPK/JNK-P immunoreactivity is found in cytoplasmic granules in the vicinity of LBs or in association with irregular-shaped or diffuse alpha-synuclein deposits in a small percentage of neurons, not containing phosphorylated tau, of the brain stem in PD and DLB. MAPK-P, p-38-P and SAPK-P are not expressed in cortical LBs or in cortical neurons with alpha-synuclein-only inclusions in DLB. MAPK-P, p-38-P and SAPK/JNK-P are not expressed in alpha-synuclein-positive neurites (Lewy neurites) in PD and DLB as revealed by double-labeling immunohistochemistry. These results show that MAPKs are differentially regulated in neurons with alpha-synuclein-related inclusions and in neurons with abnormal tau deposits in DLB. Moreover, different kinase expression in brain stem and cortical LBs suggest a pathogenesis of brain stem and cortical LBs in LB diseases. Finally, no relationship has been observed between MAPK-P, p-38-P and SAPK/JNK-P expression and increased nuclear DNA vulnerability, as revealed with the method of in situ end-labeling of nuclear DNA fragmentation, and active, cleaved caspase-3 expression in neurons and glial cells in the substantia nigra in PD and DLB.

Low concentrations of 1-methyl-4-phenylpyridinium ion induce caspase-mediated apoptosis in human SH-SY5Y neuroblastoma cells

There is growing evidence that apoptotic mechanisms underlie the neurodegeneration leading to Parkinson's disease. 1-Methyl-4-phenylpyridinium ion (MPP(+)), the active metabolite of the parkinsonism-inducing drug MPTP, induced apoptosis in cultures of human SH-SY5Y neuroblastoma cells. Nuclear fragmentation, DNA laddering, and a 20% decrease in viability were seen after a 4-day incubation with 5 microM MPP(+). Cell viability decreased by 40% at 100 microM MPP(+), but the degree of apoptosis was not correlatively increased. The MPP(+)-induced apoptosis was completely prevented by the broad caspase inhibitor zVAD.fmk but not by the caspase-8 inhibitor IETD.fmk. Furthermore, MPP(+) had no effect on the levels of Fas or Fas-L, suggesting lack of activation of the Fas-L/Fas/caspase-8 pathway of apoptosis. There was no evidence of mitochondrial dysfunction at 5 microM MPP(+): No differences were seen in transmembrane potential or in cytochrome c release from controls. At 100 microM MPP(+), the mitochondrial potential decreased, and cytoplasmic cytochrome c and caspase-9 activation increased slightly. At both low and high concentrations of MPP(+), VDVADase and DEVDase activities increased. We conclude that MPP(+) can induce caspase-mediated apoptosis, which is prevented by caspase inhibition, at concentrations lower than those needed to trigger mitochondrial dysfunction and closer to those found in the brains of MPTP-treated animals.

Brain-derived neurotrophic factor reduces cortical cell death by ischemia after middle cerebral artery occlusion in the rat

Stroke is the major cause of adult brain dysfunction. In an experimental approach to evaluate the possible beneficial effects of administration of neurotrophic factors in stroke, we have used a model of distal middle cerebral artery (MCA) occlusion in adult rats. In this model, we found: (1) a permanent reduction of brain-derived neurotrophic factor (BDNF) and its full-length receptor, TrkB, in the infarcted core; (2) a transient increase in BDNF immunoreactivity in the internal region of the border of the infarct (penumbra area) at 12 h after MCA occlusion; (3) increased truncated TrkB immunoreactivity in astrocytes surrounding the area of the infarction; and (4) increased full-length TrkB immunoreactivity in scattered neurons, distant from the infarct, in ipsilateral and contralateral cortices at 24 and 48 h after MCA occlusion. We next studied the regulation of TrkB expression by BDNF, after ischemia, and its neuroprotective effects in vivo. In control non-ischemic rats, grafting of mock- or BDNF-transfected fibroblasts (F3A-MT or F3N-BDNF cell lines, respectively) in the medial part of the somatosensory cortex increased truncated TrkB immunoreactivity in neighboring astrocytes. Grafting alone also increased full-length TrkB in the vicinity of the mock graft (at 24 and 48 h) and the BDNF-grafted graft (at 4 days). Interestingly, ischemic animals grafted with the mock-transfected cell line did not show any further regulation of TrkB receptors. However, ischemic animals grafted with the BDNF cell line showed an up-regulation of full-length TrkB expression in neurons located in the internal border of the infarct. Analysis of nuclear DNA fragmentation in situ, combined with microtubule-associated protein 2 immunohistochemistry, revealed that most cells dying in the borders of the infarct (penumbra area) at 48 h following MCA occlusion were neurons. No differences in the infarct size were found between MCA occluded, mock-transfected MCA-occluded, and BDNF-transfected MCA-occluded rats. Moreover, cell death was similar in nongrafted and mock-grafted rats subjected to MCA occlusion. However, the number of cells with nuclear DNA breaks was significantly reduced in the penumbra area close to the BDNF graft in ischemic rats. Thus, our results show that BDNF specifically up-regulates its full-length TrkB receptor in cortical neurons of the penumbra area and prevents their death in an in vivo model of focal ischemia.

Lymphocyte populations in Parkinson's disease and in rat models of parkinsonism

To assess the involvement of the immune system in Parkinson's disease we studied the phenotype of circulating lymphocytes in 30 untreated and 34 treated patients. We found a numeric decrease in helper T cells (higher in CD4(+)CD45RA(+) than in CD4(+)CD29(+)) and B cells, and a rise in activated, CD4(+)CD25(+) lymphocytes that was correlated with lymphocyte depletion. All these alterations were independent of levodopa treatment. In addition, we performed striatal dopamine depletion in rats with either MPP(+) or 6-OHDA, showing that MPP(+) but not 6-OHDA can increase CD4(+)CD25(+) lymphocytes. Thus, mechanisms other than dopamine deficit may explain the immune activation in Parkinson's disease.

Fas and Fas-L expression in Huntington's disease and Parkinson's disease

The Fas/Fas-L signalling system plays a role in the control of cell death and the survival of lymphocytes, in the regulation of the immune system, and in the progression of autoimmune diseases. Studies in the nervous system have shown Fas/Fas-L activation in multiple sclerosis and in various paradigms leading to neuronal death. Enhanced Fas and Fas-L expression has also been documented in astrocytomas and glioma cell lines. However, little is known about the possible implication of Fas/Fas-L signals in primary human neurodegenerative diseases. In an attempt to gain understanding of the mechanisms commanding cell death and neurone loss in Huntington's disease (HD) and Parkinson's disease (PD), Fas and Fas-L expression has been examined in the brains of patients with HD and PD with Western blotting and immunohistochemistry. Fas and Fas-L expression levels are reduced in the caudate and putamen, but not in the parietal cortex, in HD, as revealed in Western blots. Moreover, Fas and Fas-L immunoreactivity is reduced in striatal neurones in HD. Fas and Fas-L immunoreactivity is also decreased in neurones of the substantia nigra pars compacta in PD. Reduced Fas and Fas-L expression is observed equally in Lewy body-bearing and non-Lewy body-bearing neurones. Yet increased Fas and Fas-L immunoreactivity occurs in normal astrocytes in control brains and in reactive astrocytes in diseased brains. The meaning of increased Fas and Fas-L expression in astrocytes is still unclear. However, the present results suggest that Fas/Fas-L signals are minimized in sensitive neurones in HD and PD.

Molecular cloning, expression, and chromosomal localization of a ubiquitously expressed human 6-phosphofructo-2-kinase/ fructose-2, 6-bisphosphatase gene (PFKFB3)

We report the identification of a human 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase gene (PFKFB3) isolated from a human fetal brain cDNA library. The gene was localized to 10p15-->p14 by fluorescence in situ hybridization. The entire cDNA (4,322 bp) codes for a polypeptide of 520 amino acid residues (molecular weight, 59.571 kDa). Structural analysis showed the presence of a kinase domain located at the amino terminus and a bisphosphatase domain at the carboxy terminus, characteristic of previously described 6-phosphofructo-2-kinase/fructose 2, 6-bisphosphatase isozymes. In addition, a phosphorylation site for cAMP-dependent protein kinase was found at the carboxy terminus. Northern blot analysis showed the presence of a unique 4.8-kb mRNA expressed in the different tissues studied. In mammalian COS-1 cells, this cDNA drives the expression of an active isozyme. Taken together, these results identify the presence of a gene coding for a human 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase isozyme which is ubiquitously expressed.

MPP(+)-induced mitochondrial dysfunction is potentiated by dopamine

MPP(+), the major metabolite of the Parkinsonism-inducing compound MPTP, responsible for the destruction of the nigrostriatal pathway in primates and rodents, has been assayed in isolated rat liver mitochondria in the presence of physiological concentrations of dopamine or analogous concentrations of melanin-dopamine. 5 microM MPP(+) in the presence of 70 microM dopamine or melanin-dopamine, but not alone, decreased the heat production and oxygen consumption of a mitochondrial suspension activated with succinate and ADP. Both dopamine and oxidized dopamine plus MPP(+) also decreased the mitochondrial reductive power measured with MTT. Mitochondrial swelling was observed, associated with an increase in membrane mitochondrial potential, as a synergistic effect between low concentrations of MPP(+) and dopamine. It is suggested that cytosolic dopamine, by itself or via its autooxidation products, may play a relevant role in the mitochondrial toxicity of MPP(+). A failure in the regulation of the storage/release of dopamine could aggravate a mitochondrial damage and trigger the neurodegenerative process underlying MPTP toxicity and Parkinson's disease.

6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase expression in rat brain during development

This study reports the expression of the ubiquitous 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase gene (PFKFB3) (PFK-2/FBPase-2) in different stages of rat brain development. Northern blot and RT-PCR analysis demonstrated that ubiquitous PFK-2/FBPase-2 is expressed in rat brain from embryonic to adult life and shows a transient increase 1 day before birth, coincident with the maximum concentration of Fru-2,6-P(2) and PFK-2 activity. The levels of brain PFK-2/FBPase-2 gene expression as well as the enzymatic activity and the concentration of Fru-2,6-P(2) appear to be remarkably constant during adult life, without significant differences in the brain hippocampus, cortex, cerebellum or striatum areas.

Increased survival of dopaminergic neurons in striatal grafts of fetal ventral mesencephalic cells exposed to neurotrophin-3 or glial cell line-derived neurotrophic factor

The transplantation of fetal mesencephalic cell suspensions into the brain striatal system is an emerging treatment for Parkinson's disease. However, one objection to this procedure is the relatively poor survival of implanted cells. The ability of neurotrophic factors to regulate developmental neuron survival and differentiation suggests they could be used to enhance the success of cerebral grafts. We studied the effects of neurotrophin-3 (NT-3) or glial cell line-derived neurotrophic factor (GDNF) on the survival of dopaminergic neurons from rat fetal ventral mesencephalic cells (FMCs) implanted into the rat striatum. Two conditions were tested: (a) incubation of FMCs in media containing NT-3 and GDNF, prior to grafting, and (b) co-grafting of FMCs with cells engineered to overexpress high levels of NT-3 or GDNF. One week after grafting into the rat striatum, the survival of TH+ neurons was significantly increased by pretreatment of ventral mesencephalic cells with NT-3 or GDNF. Similarly, co-graft of ventral mesencephalic cells with NT-3- or GDNF-overexpressing cells, but not the mock-transfected control cell line, increased the survival of graft-derived dopaminergic neurons. Interestingly, we also found that co-grafting of GDNF-overexpressing cells was less effective than NT-3 at improving the survival of fetal dopaminergic neurons in the grafts, and that only GDNF induced intense TH immunostaining in fibers and nerve endings of the host tissue surrounding the implant. Thus, our results suggest that NT-3, by strongly enhancing survival, and GDNF, by promoting both survival and sprouting, may improve the efficiency of fetal transplants in the treatment of Parkinson's disease.

Exposure of foetal mesencephalic cells to bone morphogenetic protein-2 enhances the survival of dopaminergic neurones in rat striatal grafts

The transplantation of foetal mesencephalic cells (FMC) into the brain striatal system is an emerging treatment for Parkinson's disease, despite of the relatively poor survival of implanted cells. The ability of neurotrophic factors to regulate neurone survival and differentiation suggests they could be used to enhance the success of cerebral grafts. We analyzed the effect of pre-treatment of FMC suspensions with bone morphogenetic protein-2 (BMP-2) (50 ng/ml) prior to grafting into the striatum of 6-hydroxydopamine lesioned rats. The viability of a FMC suspension was enhanced in vitro by BMP-2. Four weeks after transplantation, the number of dopaminergic neurones was higher and their morphology more developed in grafts pre-treated with BMP-2, compared with non-pre-treated grafts and rats showed a significant reduction in the turning behaviour test. Thus, the pre-treatment of FMCs with BMP-2 should be considered, together with other neurotrophic factors, as a procedure for transplantational treatment of Parkinson's disease.

Caspase inhibition protects nigral neurons against 6-OHDA-induced retrograde degeneration

6-Hydroxydopamine (6-OHDA) administered intrastriatally to adult rats in a single injection causes neurodegeneration of the nigrostriatal pathway and loss of > 50% of dopamine neurons in substantia nigra pars compacta 30 days after administration. The death of nigral neurons occurs, at least partially, by a caspase-mediated mechanism. The nigral loss of dopaminergic neurons could be prevented by stereotaxical administration of zVAD.fmk, a caspase inhibitor, into the substantia nigra, indicating that 6-OHDA-induced nigrostriatal degeneration involves caspase activation. These results suggest that caspases are probably involved in neurodegenerative chronic processes such as Parkinson's disease and might be considered as possible targets in the treatment of such neurological disorders.

Degeneration and gliosis in rat retina and central nervous system following 3,3'-iminodipropionitrile exposure

3,3'-Iminodipropionitrile (IDPN) exposure causes a neurofilamentous axonopathy and olfactory, audiovestibular and visual toxicity. Many events relevant to these effects and the neurotoxic properties of nitriles as a class remain to be elucidated. We characterized the gliosis associated with the IDPN-induced retinal degeneration in comparison to other effects on the visual and central nervous systems. Gliosis was quantified using an ELISA for the intermediate filament protein, glial fibrillary acidic protein (GFAP). IDPN (0-400 mg kg-1 day-1x3 days, i.p.) caused corneal opacity and dose- and time-dependent increases in retinal GFAP, up to 26-28 fold of control values at 4 weeks post-exposure; a second peak occurred at 16 weeks. In contrast, GFAP peaked at 1 week in olfactory bulbs (OB), cingulate cortex and hippocampus. Cerebellum and striatum showed no gliosis. Retinal dopamine decreased within 2 weeks. Delayed GFAP increases occurred in superior and inferior colliculi. Retina and superior colliculi also showed increased [3H]PK-11195 binding. Histological analysis demonstrated progressive degeneration and gliosis in retina and colliculi. Taken together, the data indicate that primary and secondary degenerative events occur in the retina, and that this retinal degeneration induces GFAP increases in retina and superior colliculus. In addition, GFAP assays demonstrated that the retinal toxicity of IDPN is enhanced by CCl4 hepatotoxicity and blocked by methimazole inhibition of flavin-mono-oxygenases, similarly to its ototoxicity. GFAP assays also indicated that neither vestibulotoxic doses of crotononitrile nor olfatotoxic doses of dichlobenil damage the retina. The data support the use of GFAP assays for assessing the retinal toxicity of IDPN and other nitriles.

Bone morphogenetic protein-2 promotes dissociated effects on the number and differentiation of cultured ventral mesencephalic dopaminergic neurons

Bone morphogenetic proteins (BMPs) are a family of growth differentiation factors which induce bone formation from mesenchymal cells. These proteins are members of the transforming growth factor-beta super-family. The expression of BMPs in the nervous system as well as in other tissues has been reported. In this study, we show that the presence of BMP-2 resulted in a dose-dependent increase in the number of tyrosine hydroxylase-immunoreactive ventral mesencephalic cells after 7 days in serum-free medium cultures. A maximal response was elicited at 10 ng/mL. BMP-2 also increased the number of primary neurites and branch points as well as the length of the longest neurite in a dose-dependent manner, with a maximal effect at 1 ng/mL. In contrast, BMP-2 did not modify the number or the function of GABAergic neurons. On the other hand, we observed stimulation of proliferation and morphological changes in glial cells (astrocytes become more fibrous shaped) in the presence of a high BMP-2 concentration (100 ng/mL), but not with lower doses, suggesting that the neurotrophic effect in dopaminergic neurons is not mediated by astroglial cells. This is consistent with the fact that the BMP-2 effect on dopaminergic neurons was observed even when the cultures were treated with alpha-aminoadipic acid to exclude the presence of glial cells. In summary, our data indicate that BMP-2 is a potent neurotrophic factor for ventral mesencephalic dopaminergic cells in culture.

Intrastriatal grafts of fetal mesencephalic cell suspensions in MPP+-lesioned rats: a microdialysis study in vivo

The striatum of rats was lesioned by unilateral administration of MPP+. Two weeks later, a suspension of fetal mesencephalic cells (FMC), obtained from 14-day rat embryos, was injected into the lesioned striatum. Two weeks after grafting, the success of implantation and recovery of dopamine function were assessed by tyrosine hydroxylase immunocytochemistry (TH) and the measurement of striatal dopamine content. In addition, the extracellular concentrations of dopamine and dopamine metabolites were studied by microdialysis in vivo before and after perfusion of MPP+ to induce dopamine release from vesicular stores. TH+ cell bodies were seen in the lesioned grafted striata, indicating that fetal cells survived in these striata. In addition, there was a marked increase in TH-immunoreactivity in the neuronal fibers and terminals in the area surrounding the cell implant, suggesting a compensatory response of the host tissue which may involve fiber sprouting. Grafting induced a recovery in indices of dopamine function, including recovery in dopamine content, and basal and MPP+-induced dopamine release. Thus, grafts of FMC may provide a significant recovery of dopamine function in MPP+-lesioned striata.

7-Nitroindazole prevents dopamine depletion caused by low concentrations of MPP+ in rat striatal slices

A significant loss of dopamine was found in rat striatal slices incubated with 1-methyl-4-phenylpyridinium ion (MPP+) at a concentration of 2 microM or higher. The addition of 7-nitroindazole, a specific inhibitor of neuronal nitric oxide synthase (nNOS), prevented this effect on dopamine when the concentration of MPP+ was between 2-5 microM, but not at higher concentrations. This protection was reproduced with other less specific NOS-inhibitors, such as nitro-arginine and nitro-arginine methylester. 7-nitroindazole did not protect against the dopamine depletion caused by the non-specific mitochondrial chain blocker rotenone. Neither MPP- nor rotenone significantly increased the nitrite concentration in striatal slices, measured as an index of nitric oxide production. The basal production of nitric oxide may be enough to trigger the dopamine depletion at very low concentrations of MPP+, probably acting synergistically with cytosolic calcium increase. Higher concentrations of MPP+ are toxic by themselves without the mediation of nitric oxide. The inhibition of nNOS may protect against dopamine loss at early stages of a neurodegenerative process, and it could then be considered in the treatment or prevention of neurodegenerative human processes such as Parkinson's disease.

Evaluation of renographic and metabolic parameters in human kidney transplantation

BACKGROUND

The aim of this work is to demonstrate that the value of the mean transit time (MTT) obtained from the 99mTc-MAG3 renogram deconvolution is related to the levels of adenine nucleotides determined in cortical biopsies from transplanted kidneys.

METHODS

The functional state was estimated by means of the MTT and the initial height (H0) of the renal retention function obtained from the 99mTc-MAG3 renogram deconvolution and by the measure of adenine nucleotides obtained from biopsies. We studied 30 kidney graft recipients, 25 normal functioning grafts (NFG) and 5 with acute tubular necrosis (ATN).

RESULTS

The MTT is significantly longer for ATN (p < 0.001). The initial uptake values (H0) are significantly lower for ATN (p < 0.001). The sum of adenine nucleotides (SAN) is significantly greater for NFG than for ATN (p < 0.001). The values of the MTT seem to reflect the energy state of the cells in transplanted kidney.

CONCLUSION

The analysis of MTT may be indicative of the functional metabolic recovery and thus it may be predictive of the renal graft function at least in the same extent than the biochemical analysis of a cortical renal biopsy immediately after blood reperfusion of the tissue.

Early effects of basic fibroblast growth factor on foetal rat mesencephalic cell suspensions

Mesencephalic cell suspensions are used, experimentally but also clinically, to compensate for neurological deficiencies, by implantation into the striatum. Here, we have studied the metabolism of mesencephalic cell suspensions obtained from rat embryos by measuring heat dissipation, oxygen consumption, ATP and lactate production. The effect of basic fibroblast growth factor (bFGF) at a 50 ng/ml concentration on these parameters was studied in order to assess the effect of in vitro exposure of cell suspensions to this trophic factor. Heat production and oxygen consumption were low, as could be expected from an immature nervous tissue, and they further decreased after addition of bFGF. This trophic factor decreased the total ATP concentration and increased the lactate production. The viability of the cell suspensions was reduced by nearly a half, 2 h after the addition of bFGF, and numerous fragmented nuclei were observed. It seems that, in contrast to the neuroprotective effect of bFGF on mesencephalic cultures and nigrostriatal neurons, this factor could have an initial sorting effect in the development of mesencephalic structures.

MPP+ toxicity in rat striatal slices: relationship between non-selective effects and free radical production

Incubations of rat striatal slices have been used to assay MPP+ neurotoxicity. MPP+, at concentrations of 1 mM or higher, caused a marked increase in hydroxyl radicals, measured as malondialdehyde (MDA) accumulation, but not in nitric oxide production. At these doses, MPP+ showed an effect on dopamine terminals, causing a massive dopamine decrease, and on non-neuronal glial cells, where a marked reduction in glutamine synthetase activity was detected. At lower concentrations (25 mu M), the toxic effect on dopaminergic endings was maintained without increasing malondialdehyde concentrations or inhibiting glutamine synthetase activity. The effect on glutamine synthetase was prevented by the addition to the medium of 0.5% dimethyl sulfoxide, a hydroxyl-radical scavenger, but this did not protect the effect of dopamine depletion. We propose that non-selective effects of MPP+, at doses of 1 mM or higher, are mediated by extracellular overproduction of hydroxyl radicals. The main factor responsible for this overproduction would not be the released dopamine but rather the MPP+ itself through non selective inhibition of the mitochondrial respiratory chain or through a redox cycling that can trigger oxygen radical production.

Chronic effects of single intrastriatal injections of 6-hydroxydopamine or 1-methyl-4-phenylpyridinium studied by microdialysis in freely moving rats

Extracellular dopamine (DA) and its main cerebral metabolites, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), were measured by bilateral striatal microdialysis in rats at different times (2, 7, 15 and 60 days) after unilateral administration into the right striatum of 1-methyl-4-phenylpyridinium ion (MPP+) or 6-hydroxydopamine (6-OHDA). In both cases the decrease in extracellular dopamine did not exceed 40% of control values. The response of DOPAC and HVA depended on the treatment: MPP+ caused a marked acute decrease in the dopamine metabolites but allowed a progressive recovery that was very evident after 60 days; 6-OHDA caused a progressive decrease in the dopamine metabolites throughout the two months of the study. Tyrosine hydroxylase immunostaining revealed severe neuronal loss in substantia nigra two months after striatal administration of 6-OHDA, whereas no significant neuronal loss was found at the same time after MPP+ administration. A bilateral challenge infusion of MPP+ through the microdialysis probe was used to assess the dopaminergic capacity of both striata: at all the times studied there was a sharp depletion of DA on the non-lesioned side; both MPP(+)- and 6-OHDA-treated striata were unresponsive after a short time (2 days); after 2 months the response in MPP(+)-lesioned rats was similar on both sides, whereas 6-OHDA-lesioned striata were still unresponsive to MPP+. In rats, then, the effects of MPP+ could be partly reversed whereas the effects of 6-OHDA were not. These results suggest that neurotoxins causing striatal dopamine loss may act through different mechanisms, which could be significant for the etiopathogenic development of Parkinson's disease.

CSF somatostatin increase in patients with early parkinsonian syndrome

Somatostatin-like immunoreactivity levels (SLI) in cerebrospinal fluid (CSF) were determined in twenty-three patients with untreated parkinsonian syndrome (15 with Idiopathic Parkinson's disease (IPD) and 8 with other forms of parkinsonism) at the moment of clinical diagnosis (mean duration of disease 1.1 +/- 0.2 years), and in 26 subjects without neurological symptoms. None of the IPD patients had a diagnosis of dementia at the moment of inclusion in the study. CSF-SLI content was found to be significantly higher in patients with parkinsonian syndrome (107.9 +/- 9.8 pg/ml) than in control subjects (73.5 +/- 8.4 pg/ml). The increase was also significant when controls were compared with IPD patients. In addition, a positive correlation between SLI and homovanillic acid was found in CSF of all patients. A test of learning memory was used to evaluate the mental state of patients and a significant increase in CSF-somatostatin levels was observed in patients with Idiopathic Parkinson's disease and severe affectation of memory. These results indicate that in the early steps of untreated parkinsonian syndrome, somatostatin concentration in cerebrospinal fluid may increase, probably due to the neurodegenerative depletion of somatostatin from striatal or cortical neurons.

Cloning and expression of a catalytic core bovine brain 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase

A cDNA encoding the catalytic core of a novel brain 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase isoenzyme was isolated from a lambda gt10 bovine brain library. This brain cDNA begins and ends in an open reading frame encoding a peptide of 476 amino acids. This peptide contains both the catalytic kinase and bisphosphatase domains and has an overall 65% and 67% indentity with the bovine heart and liver isozymes, respectively, whereas the NH2 and COOH-termini are divergent. An active catalytic core brain bifunctional enzyme was expressed in E. coli using a T7 RNA polymerase-based expression system. These results support the presence of a distinct gene coding for the protein in bovine brain.

Effect of locally infused 2-chloroadenosine, an A1 receptor agonist, on spontaneous and evoked dopamine release in rat neostriatum

Adenosine has been shown to inhibit dopamine release from striatal slices and synaptosomes. Recently, a direct interaction between the adenosine A2 receptor and dopamine D2 receptor has been provided. Activation of striatal adenosine A1 receptors is known to partially inhibit the release of dopamine (DA), but some aspects of this mechanism remain unclear. We have studied the participation of adenosine A1 receptors in the control of DA release 'in vivo' in awake, freely moving rats using microdialysis. To this end, the effects of 2-chloroadenosine (2-CADO), a non-metabolizable adenosine A1 receptor agonist, were studied on basal and stimulated striatal DA release. Basal levels were found to be slightly decreased by a maximal concentration of 2-CADO without any changes in DA metabolites. Haloperidol stimulated DA release was fully counteracted by 2-CADO. However, high K+ (100 mM) or (+)-amphetamine stimulated DA release was not altered by 2-CADO. Altogether, these data suggest that adenosine acting through A1 receptors possibly localized on striatal dopaminergic nerve terminals can block an induced D2 receptor blockade, but not the releasing effects caused by (+)-amphetamine and high K+ concentration. It is postulated that the increase in DA release by haloperidol is mainly due to an increased firing rate of the DA neurons and that A1 receptor activation can block the DA release observed in response to the action potential activation of DA nerve terminals.

Cerebrospinal dopamine metabolites in rats after intrastriatal administration of 6-hydroxydopamine or 1-methyl-4-phenylpyridinium ion

Dopamine (DA) and its main cerebral metabolites, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were measured in striatum and cerebrospinal fluid (CSF) from cisterna magna in rats bilaterally lesioned by intrastriatal administration of 6-hydroxydopamine (6-OHDA) or 1-methyl-4-phenylpyridinium ion (MPP+). 6-OHDA caused a progressive lesion in striatum that is only moderately reflected in the decrease in dopamine metabolite concentration in CSF. MPP+ caused an acute but less selective lesion in the dopamine striatal system, as indicated by a significant reduction in striatal GABA content, followed by a slow recovery in dopamine striatal metabolism and content. The locomotor activity was dramatically reduced in both groups 48 hours after the treatment but remained significantly decreased after two months only in 6-OHDA lesioned animals. A positive correlation was found between HVA CSF concentration and striatal DA content in MPP+ lesioned rats, but not in 6-OHDA lesioned rats. It is concluded that the concentration of dopamine metabolites in CSF can be altered only after a severe striatal lesion: reduction of striatal dopamine content below 50% of normal values and involvement of neuronal or non-neuronal elements other than the dopaminergic system, similarly to the lesions caused by MPP+. These results may partly explain why CSF dopamine metabolites concentrations were significantly decreased both in advanced stages of parkinsonism and in other neurodegenerative disorders.

Cerebrospinal monoamine metabolites and amino acid content in patients with parkinsonian syndrome and rats lesioned with MPP+

Monoamine metabolites and amino acid concentration in cerebrospinal fluid (CSF) of 33 untreated patients with parkinsonian syndrome, and 20 control patients without specific neurological symptoms have been compared with those obtained in cerebrospinal fluid of rats intrastriatally lesioned with 1-methyl-4-phenylpyridinium ion (MPP+) and sham operated animals. Homovanillic acid content was found to be significantly lower in patients with severe parkinsonism (motor score of UPDRS > 24), but not in patients with mild symptoms (motor score < or = 24). A correlation between the loss of striatal dopamine and the decrease in cerebrospinal homovanillic acid has been established in rats treated with MPP+. The extrapolation of these results to those obtained from human patients could be important in assessing the degree of striatal dopamine loss shown by humans with parkinsonian syndrome at the moment of clinical diagnosis. No significant differences were found between the other monoamine metabolites analyzed and free amino acid content in human and rat CSF.

Dopaminergic function in rat brain after oral administration of calcium-channel blockers or haloperidol. A microdialysis study

Microdialysis technique was used to study the effects of both acute and repeated oral administration of calcium-channel blockers (flunarizine, cinnarizine, verapamil, nifedipine and nicardipine) in dopaminergic function in rat brain and to compare them to the effects of haloperidol. Acute flunarizine, nicardipine or haloperidol increased extracellular levels of dopamine (DA) or metabolites. After repeated (18 days) administration, nicardipine, nifedipine, verapamil or haloperidol increased and flunarizine decreased extracellular striatal levels of dopamine or metabolites. Chronic treatment with calcium-channel blockers or haloperidol failed to block K(+)-evoked release of dopamine. This suggests that the calcium-channel blockers used in this study do not influence calcium entry necessary for DA release. An acute challenge with haloperidol caused either no change or a decrease in extracellular levels of DA or metabolites after repeated administration of calcium-channel blockers or haloperidol. This is considered to be due to the lesser response of dopaminergic neurons because of treatment. A neuroleptic-like mechanism of action together with a decrease in firing activity and/or a reduced dopamine re-uptake of dopaminergic neurons are considered.

Sex-related effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine treatment may be related to differences in monoamine oxidase B

Effects of the parkinsonism inducing neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on striatal dopamine metabolism and the influence of sex on the recovery were investigated in adult (2-month-old) male and female C57/BL mice. We present here evidence that MPTP treatment (2 doses of 30 mg/kg i.p., each at 24 h interval) produced a similar reduction (-65% to -70%) of striatal dopamine in both sexes 24 h after the last injection of MPTP, and a greater loss of the metabolites in the female group. In contrast to the partial recovery observed in the male group, an increased dopamine loss occurred in the female group within 10 days following the last injection of MPTP. This impairment in recovery appears to be different to the one already observed in aged (24-month-old) male mice treated in similar conditions. As the neurotoxic effects of MPTP depend on its conversion to the 1-methyl-4-phenylpyridinium ion (MPP+) by monoamine oxidase B (MAO B), the presence of a different peripheral or central MAO B type in female mice could be in part responsible for these sex related effects. To investigate this possibility, MAO A and B activities were characterized in liver and brain of adult female control mice during the different steps of the oestrous cycle and compared to those of adult control male mice. Significant differences in MAO A and MAO B activities could be detected during the oestrous cycle and between the adult male and female groups. It is concluded that MAO B may be involved in the sex related effects of MPTP.

Stereotaxic administration of 1-methyl-4-phenylpyridinium ion (MPP+) decreases striatal fructose 2,6-bisphosphate in rats

The stereotaxic administration of 1-methyl-4-phenylpyridinium ion (MPP+) into the neostriatum of male rats caused a lesion that resulted in a large dose-dependent loss of striatal fructose 2,6-bisphosphate; initial values were restored 5 days after the treatment. This effect was not protected by systemic administration of MK-801 or by nitroarginine. The content of hexose 6-phosphates and ATP was also reduced by MPP+ treatment, whereas lactate was increased. Biochemical and histological results suggested that MPP+ caused a nonselective cell death, followed by a pronounced astroglial response, parallel to fructose 2,6-bisphosphate recovery. The stereotaxic administration of rotenone showed a different time effect on fructose 2,6-bisphosphate cerebral content, with a significantly faster recovery. These results indicate that cerebral fructose 2,6-bisphosphate may be a sensitive metabolite related to brain damage caused by potent neurotoxins such as MPP+. On the other hand, they show that MPP+ acts in the brain through a quick, strong cytotoxic mechanism, which probably involves mechanisms other than mitochondrial chain blockage.