Cause of Parkinson's disease (PD) is still not understood. Motor symptoms are not observed at ear... more Cause of Parkinson's disease (PD) is still not understood. Motor symptoms are not observed at early stages of disease due to compensatory processes. Dysfunction of mitochondria was indicated already at preclinical PD. Selective toxin 6-OHDA was applied to kill dopaminergic neurons in substantia nigra and disturb neuronal transmission in striatum. Early phase of active degeneration and later stage, when surviving cells adapt to function normally, were analysed. 2D BN/SDS difference gel electrophoresis (DIGE) of mitochondrial proteome enabled to point out crucial processes involved at both time-points in dopaminergic structures. Marker proteins such as DPYSL2, HSP60, ATP1A3, EAAT2 indicated structural remodelling, cytoskeleton rearrangement, organelle trafficking, axon outgrowth and regeneration. Adaptations in dopaminergic and glutamatergic neurotransmission, recycling of synaptic vesicles, along with enlargement of mitochondria mass were proposed as causative for compensation. Changed expression of carbohydrates metabolism and oxidative phosphorylation proteins were described, including their protein-protein interactions and supercomplex assembly.
In Parkinson's disease (PD) motor symptoms are not observed until loss of 70% of dopaminergic neu... more In Parkinson's disease (PD) motor symptoms are not observed until loss of 70% of dopaminergic neurons in substantia nigra (SN), preventing early diagnosis. Mitochondrial dysfunction was indicated in neuropathological process already at early PD stages. Aging and oxidative stress, the main factors in PD pathogenesis, cause membrane stiffening, which could influence functioning of membrane-bound oxidative phosphorylation (OxPhos) complexes (Cxs) in mitochondria. In 6-OHDA rat model, medium-sized dopaminergic lesion was used to study mitochondrial membrane viscosity and changes at the level of OxPhos Cxs and their higher assembled states—supercomplexes (SCxs), during the early degeneration processes and after it. We observed loss of dopaminergic phenotype in SN and decreased dopamine level in striatum (STR) before actual death of neurons in SN. Behavioural deficits induced by lesion were reversed despite progressing neurode-generation. Along with degeneration process in STR, mitochondrial Cx I performance and amount decreased in almost all forms of SCxs. Also, progressing decrease of Cx IV performance in SCxs (I 1 III 2 IV 3–1 , I 1 IV 2–1) in STR was observed during degeneration. In SN, SCxs containing Cx I increased protein amount and a shifted individual Cx I 1 into superassembled states. Importantly, mitochondrial membrane viscosity changed in parallel with altered SCxs performance. We show for the first time changes at the level of mitochondrial membrane viscosity influencing SCxs function after dopaminergic system degeneration. It implicates that altered mitochondrial membrane viscosity could play an important role in regulation of mitochondria functioning and pathomechanisms of PD. The data obtained are also discussed in relation to compensatory processes observed.
Depression is a frequent comorbid disorder in Parkinson's disease (PD) which may precede appearan... more Depression is a frequent comorbid disorder in Parkinson's disease (PD) which may precede appearance of its motor symptoms by several years. Pathomechanisms underlying PD have been suggested to be responsible for the PD-related depression. The aim of the study was to examine the influence of a partial lesion of striatal dopaminergic terminals on the " depressive-like " behavior of rats in the forced swimming test (FS). 6-Hydroxydopamine (6-OHDA) was injected bilaterally into the ventro-lateral region of the caudate-putamen (CP) (3.75 µg/2.5 µl/side). The locomotor activity and behavior of rats in the FS were measured 2 and 4 weeks after the operation. The lesion extent was analyzed by biochemical and immunohistochemical methods. Two weeks after the operation, the 6-OHDA-treated rats displayed a prolonged immobility in the FS. This effect disappeared after 4 weeks. The locomotor activity was not influenced by 6-OHDA. Levels of dopamine, DOPAC and HVA were decreased in the nucleus accumbens (NAC) 2 weeks after 6-OHDA but were not changed in the CP, frontal cortex (FCX) and substantia nigra (SN). No significant effect of 6-OHDA on tyrosine hydroxylase-immunoreactivity in the CP and NAC were found. The present study indicates that a relatively small lesion of dopaminergic terminals in the ventral striatum, which does not produce any motor disturbances, may induce " depressive-like " symptoms.
In a previous study, a primary culture of midbrain cells was exposed to 9-methyl-b-carboline for ... more In a previous study, a primary culture of midbrain cells was exposed to 9-methyl-b-carboline for 48 h, which caused an increase in the number of tyrosine hydroxylase-positive cells. Quantitative RT-PCR revealed increased transcription of genes participating in the maturation of dopaminergic neurons. These in vitro findings prompted us to investigate the restorative actions of 9-methyl-b-car-boline in vivo. The compound was delivered for 14 days into the left cerebral ventricle of rats pretreated with the neurotoxin 1-methyl -4-phenyl-pyridinium ion (MPP +) for 28 days applying a dose which lowered dopamine by approximately 50%. Interestingly, 9-methyl-b-carboline reversed the dopamine-lowering effect of the neurotoxin in the left striatum. Stereological counts of tyrosine hydroxylase-immunoreactive cells in the substantia nigra revealed that the neurotoxin caused a decrease in the number of those cells. However, when treated subsequently with 9-methyl-b-carboline, the number reached normal values. In search of an explanation for the restorative activity, we analyzed the complexes that compose the respiratory chain in striatal mitochondria by 2-dimension gel electrophoresis followed by MALDI-TOF peptide mass fingerprinting. We found no changes in the overall composition of the complexes. However, the activity of complex I was increased by approximately 80% in mitochondria from rats treated with MPP + and 9-methyl-b-carboline compared to MPP + and saline and to sham-operated rats, as determined by measurements of nicotinamide adenine dinucleotide dehydrogenase activity. Microarray technology and single RT-PCR revealed the induction of neurotrophins: brain-derived neurotrophic factor, conserved dopamine neurotrophic factor, cerebellin 1 precursor protein, and ciliary neurotrophic factor. Selected western blots yielded consistent results. The findings demonstrate restorative effects of 9-methyl-b-carboline in an animal model of Parkinson's disease that improve the effectiveness of the respiratory chain and promote the transcription and expression of neurotrophin-related genes.
The pesticide paraquat (PQ) was found to be a suitable xenobiotic to model Parkinson's disease. T... more The pesticide paraquat (PQ) was found to be a suitable xenobiotic to model Parkinson's disease. The reactive oxygen species (ROS) production was suggested to be the main cause of PQ toxicity but very few evidences were found for its generation in the brain in vivo after ip administration. We compared the effects of PQ-induced ROS generation between the brain structures and the peripheral tissues using two different hydroxyl radical generation markers. Repeated but not single ip PQ administration increased the levels of ROS in the striatal homogenates but, when measured in the extracellular microdialysis filtrate, no change was observed. The increased dopamine release was detected in the striatum after the fourth PQ administration and its basal levels were decreased. A single treatment with the pesticide did not influence ROS production in the lungs or kidneys but repeated intoxication decreased its levels. These results suggest that repeated, systemic administration of a low dose of PQ triggers intracellular ROS formation in the brain and can cause slowly progressing degenerative processes , without the toxic effects in the peripheral tissues.
Paraquat is a toxin suggested to contribute to pathogenesis of Parkinson’s disease. The aim of th... more Paraquat is a toxin suggested to contribute to pathogenesis of Parkinson’s disease. The aim of the present study was to examine toxic influence of subchronic treatment with this pesticide (5 days, one injection per day, 2–3 days of withdrawal) on dopaminergic, serotonergic, noradrenergic and GABAergic neurons. Paraquat decreased the number of tyrosine hydroxylase-immunoreactive (TH-ir) neurons in the substantia nigra by 22% (measured 3 days after withdrawal). Two days after withdrawal the levels of the dopamine metabolites and dopamine turnover in the caudate–putamen, substantia nigra and prefrontal cortex were reduced by ca. 20–60%, and the binding of [3H]GBR 12,935 to dopamine transporter dropped by 25–40% in the caudate–putamen. Three days after paraquat withdrawal, the level of dopamine in the caudate–putamen was significantly increased, and earlier decreases in DOPAC and HVA in the substantia nigra, as well as [3H]GBR 12,935 binding in the caudate–putamen were reversed. Moreover, an increase in serotonin turnover in the caudate–putamen and prefrontal cortex, and noradrenaline level in the former structure was observed 2–3 days after paraquat withdrawal. Three days after the last paraquat injection 24–35% decreases in the proenkephalin mRNA levels and 5–7% reduction in glutamic acid decarboxylase (GAD)67 mRNA were found in the caudate–putamen. The present study suggests that subchronic paraquat administration triggers processes characteristic of early stages of dopaminergic neuron degeneration, and activates compensatory mechanisms involving dopaminergic, noradrenergic, serotonergic and GABAergic transmissions.
—A deficiency of the dopaminergic transmission in the mesocortical system has been suggested to c... more —A deficiency of the dopaminergic transmission in the mesocortical system has been suggested to contribute to cognitive disturbances in Parkinson's disease. Therefore, the aim of the present study was to examine whether the long-term administration of a commonly used herbicide, para-quat, which has already been found to induce a slowly progressing degeneration of the nigrostriatal neurons, influences mesocortical dopaminergic neurons in rats. Para-quat at a dose of 10 mg/kg i.p. was injected either acutely or once a week for 4, 8, 12 and 24 weeks. Acute treatment with this pesticide increased the level of homovanillic acid (HVA) and HVA/dopamine ratio in the prefrontal cortex. After 8 weeks of administration paraquat increased the number of stereologically counted tyrosine hydroxylase– immunoreactive (TH-ir) neurons and their staining intensity in the ventral tegmental area (VTA), which is a source of the mesocortical dopaminergic projection. At the same time, few TH-ir neurons appeared in different regions of the cerebral cortex: in the frontal, cingulate, retrosplenial and parietal cortices. Chronic paraquat administration did not influence the level of dopamine in the prefrontal cortex but increased the levels of its metabolites: 3,4-dihydroxyphe-nylacetic acid (after 8 –12 weeks), HVA (after 4 and 12 weeks) and HVA/dopamine ratio (4 weeks). After 24 weeks this pesticide reduced the number of TH-ir neurons in the VTA by 42% and of the Nissl-stained neurons by 26%, and induced shrinkage of this structure by ca. 25%. Moreover, TH-ir neurons in the cortex were no more visible after such a long period of administration and levels of dopamine metabolites returned to control values. The present results suggest that the long-term paraquat administration destroys dopaminergic neurons of the VTA. However, compensatory activation of the VTA neurons and cortex overcomes progressing degeneration and maintains cortical dopaminergic transmission.
Selective toxicity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a parkinsonism inducin... more Selective toxicity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a parkinsonism inducing compound, is well known to be related to an uptake of its active metabolite MPP + into dopaminergic neurons by dopamine transporter (DAT). The aim of the present study was to examine whether paraquat, a commonly used herbicide, which is an 1-methyl-4-phenyl-pyridinium ion (MPP +) analogue, affects DAT in vivo in rats. Paraquat administered at a dose of 10 mg/kg ip decreased the binding of [ 3 H]GBR 12,935 to DAT measured by quantitative autoradiography in the dorsal and ventral caudate-putamen, but not in the substantia nigra pars compacta. Moreover, this compound increased the level of 3-methoxytyramine (3-MT) and 3-MT/dopamine ratio in the anterior and posterior caudate-putamen measured by HPLC with electrochemical detection. No other alterations in the levels of dopamine and its metabolites were found in the caudate-putamen and substantia nigra. The present study seems to suggest that systemic paraquat administration affects striatal DAT and dopamine metabolism in the nigrostriatal neurons in rats which may be crucial for its neurotoxic effects on dopaminergic neurons.
The aim of the present study was to examine the influence of the long-term paraquat administratio... more The aim of the present study was to examine the influence of the long-term paraquat administration on the dopaminergic nigrostriatal system in rats. Paraquat was injected at a dose of 10 mg ⁄ kg i.p. for 4–24 weeks. We found that this pesticide reduced the number of tyrosine hydroxylase-immunoreactive neurons of the substantia nigra; after the 4-week treatment the reduction (17%, nonsignificant) was confined to the rostrocentral region of this structure but, after 24 weeks, had spread along its whole length and was % 37%. Moreover, it induced a biphasic effect on dopaminergic transmission. First, levels of dopamine, its metabolites and turnover were elevated (4–8 weeks) in the caudate–putamen, then all these parameters returned to control values (12 weeks) and dropped by 25–30% after 24 weeks. The binding of [ 3 H]GBR 12,935 to dopamine transporter in the caudate–putamen was decreased after 4–8 weeks, then returned to control values after 12 weeks but was again decreased after 24 weeks. Twenty-four-week paraquat administration also decreased the level of tyrosine hydroxylase (Western blot) in the caudate–putamen. In addition, paraquat activated serotonin and noradrenaline transmission during the first 12 weeks of treatment but no decreases in levels of these neurotransmitters were observed after 24 weeks. The above results seem to suggest that long-term paraquat administration produces a slowly progressing degeneration of nigrostriatal neurons, leading to delayed deficits in dopaminergic transmission, which may resemble early, presymptomatic, stages of Parkinson's disease.
We have examined the pattern of striatal messenger RNA expression of over 8000 genes in a rat mod... more We have examined the pattern of striatal messenger RNA expression of over 8000 genes in a rat model of levodopa (l-DOPA)-induced dyskinesia and Parkinson disease (PD). 6-Hydroxydopamine (6-OHDA)-lesioned rats were treated with l-DOPA or physiological saline for 22 days and repeatedly tested for antiakinetic response to l-DOPA and the development of abnormal involuntary movements (AIMs). In a comparison of rats that developed a dyskinetic motor response to rats that did not, we found striking differences in gene expression patterns. In rats that developed dyskinesia, GABA neurons had an increased transcriptional activity, and genes involved in Ca 2+ homeostasis, in Ca 2+-dependent signaling, and in structural and synaptic plasticity were upregulated. The gene expression patterns implied that the dyskinetic striatum had increased transcriptional, as well as synaptic activity, and decreased capacity for energy production. Some basic maintenance chores such as ribosome protein biosynthesis were downregulated, possibly a response to expended of ATP levels.
Cause of Parkinson's disease (PD) is still not understood. Motor symptoms... more Cause of Parkinson's disease (PD) is still not understood. Motor symptoms are not observed at early stages of disease due to compensatory processes. Dysfunction of mitochondria was indicated already at preclinical PD. Selective toxin 6-OHDA was applied to kill dopaminergic neurons in substantia nigra and disturb neuronal transmission in striatum. Early phase of active degeneration and later stage, when surviving cells adapted to function normally, were analysed. 2D BN/SDS difference gel electrophoresis (DIGE) of mitochondrial proteome enabled to point out crucial processes involved at both time-points in dopaminergic structures. Marker proteins such as DPYSL2, HSP60, ATP1A3, EAAT2 indicated structural remodelling, cytoskeleton rearrangement, organelle trafficking, axon outgrowth and regeneration. Adaptations in dopaminergic and glutamatergic neurotransmission, recycling of synaptic vesicles, along with enlargement of mitochondria mass were proposed as causative for compensation. Changed expression of carbohydrates metabolism and oxidative phosphorylation proteins were described, including their protein-protein interactions and supercomplex assembly.
Regarding the pathogenesis of Parkinson&a... more Regarding the pathogenesis of Parkinson's disease, a neurotoxin hypothesis was proposed following the discovery that 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) produces a Parkinson-like syndrome in humans and primates. Since then, researchers have searched for endogenous and exogenous compounds that are structurally similar to this neurotoxin. Such compounds include beta-carbolines, formed from tryptophan and its derivatives. beta-carbolines are present naturally in the human brain and cerebrospinal fluid. The present study examined the effect of bilateral, intranigral administration of 2,9-dimethyl-beta-carbolinium ion on muscle tone, electromyographic activity, dopamine metabolism in the striatum, and the number of tyrosine hydroxylase-immunoreactive neurons and volume of the substantia nigra in rats. We found that the beta-carbolinium ion (15 or 40 nmol per side) caused a significant decrease in the striatal levels of dopamine and its metabolites, which was accompanied by an enhancement of muscle tone and electromyographic activity. Stereological counting revealed that the beta-carbolinium caused a significant decrease in the total number of tyrosine hydroxylase-immunoreactive neurons and shrinkage of the substantia nigra. The findings suggest that the methylated beta-carbolinium ion produces a dose-dependent degeneration of nigrostriatal neurons, leading to deficits in dopaminergic neurotransmission and an increase of muscle resistance and electromyographic activity, a syndrome equivalent to muscle rigidity in Parkinson's disease.
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, 2016
In Parkinson's disease (PD) motor symptoms are no... more In Parkinson's disease (PD) motor symptoms are not observed until loss of 70% of dopaminergic neurons in substantia nigra (SN), preventing early diagnosis. Mitochondrial dysfunction was indicated in neuropathological process already at early PD stages. Aging and oxidative stress, the main factors in PD pathogenesis, cause membrane stiffening, which could influence functioning of membrane-bound oxidative phosphorylation (OxPhos) complexes (Cxs) in mitochondria. In 6-OHDA rat model, medium-sized dopaminergic lesion was used to study mitochondrial membrane viscosity and changes at the level of OxPhos Cxs and their higher assembled states-supercomplexes (SCxs), during the early degeneration processes and after it. We observed loss of dopaminergic phenotype in SN and decreased dopamine level in striatum (STR) before actual death of neurons in SN. Behavioural deficits induced by lesion were reversed despite progressing neurodegeneration. Along with degeneration process in STR, mitochondrial Cx I performance and amount decreased in almost all forms of SCxs. Also, progressing decrease of Cx IV performance in SCxs (I1III2IV3-1, I1IV2-1) in STR was observed during degeneration. In SN, SCxs containing Cx I increased protein amount and a shifted individual Cx I1 into superassembled states. Importantly, mitochondrial membrane viscosity changed in parallel with altered SCxs performance. We show for the first time changes at the level of mitochondrial membrane viscosity influencing SCxs function after dopaminergic system degeneration. It implicates that altered mitochondrial membrane viscosity could play an important role in regulation of mitochondria functioning and pathomechanisms of PD. The data obtained are also discussed in relation to compensatory processes observed.
In a previous study, a primary culture of midbrain cells was exposed to 9-methyl-beta-carboline f... more In a previous study, a primary culture of midbrain cells was exposed to 9-methyl-beta-carboline for 48 h, which caused an increase in the number of tyrosine hydroxylase-positive cells. Quantitative RT-PCR revealed increased transcription of genes participating in the maturation of dopaminergic neurons. These in vitro findings prompted us to investigate the restorative actions of 9-methyl-beta-carboline in vivo. The compound was delivered for 14 days into the left cerebral ventricle of rats pretreated with the neurotoxin 1-methyl-4-phenyl-pyridinium ion (MPP+) for 28 days applying a dose which lowered dopamine by approximately 50%. Interestingly, 9-methyl-beta-carboline reversed the dopamine-lowering effect of the neurotoxin in the left striatum. Stereological counts of tyrosine hydroxylase-immunoreactive cells in the substantia nigra revealed that the neurotoxin caused a decrease in the number of those cells. However, when treated subsequently with 9-methyl-beta-carboline, the numbe...
The aim of the present study was to examine the expression of synphilin-1, alpha-synuclein, and t... more The aim of the present study was to examine the expression of synphilin-1, alpha-synuclein, and tyrosine hydroxylase in human elderly brains and the incidence of Marinesco bodies (MBs, intranuclear inclusions) in the neuromelanin-containing substantia nigra neurons. The brains of twenty-two individuals without clinical signs and symptoms of parkinsonism and dementia and an additional two parkinsonian patients were dissected and subjected to histopathological examination and western blotting. Ubiquitin-positive and agr;-synuclein-negative MBs were found in 0.84-9.45% of the nigral neurons from brains of 15 healthy individuals and both parkinsonian patients. The frequency of pigmented nigral neurons containing MBs was positively correlated with age. The levels of tyrosine hydroxylase in the caudate nucleus and putamen decreased with age, and were inversely correlated with the MB frequency. The level of synphilin-1 in the caudate nucleus was positively correlated both with age and the ...
Cause of Parkinson's disease (PD) is still not understood. Motor symptoms are not observed at ear... more Cause of Parkinson's disease (PD) is still not understood. Motor symptoms are not observed at early stages of disease due to compensatory processes. Dysfunction of mitochondria was indicated already at preclinical PD. Selective toxin 6-OHDA was applied to kill dopaminergic neurons in substantia nigra and disturb neuronal transmission in striatum. Early phase of active degeneration and later stage, when surviving cells adapt to function normally, were analysed. 2D BN/SDS difference gel electrophoresis (DIGE) of mitochondrial proteome enabled to point out crucial processes involved at both time-points in dopaminergic structures. Marker proteins such as DPYSL2, HSP60, ATP1A3, EAAT2 indicated structural remodelling, cytoskeleton rearrangement, organelle trafficking, axon outgrowth and regeneration. Adaptations in dopaminergic and glutamatergic neurotransmission, recycling of synaptic vesicles, along with enlargement of mitochondria mass were proposed as causative for compensation. Changed expression of carbohydrates metabolism and oxidative phosphorylation proteins were described, including their protein-protein interactions and supercomplex assembly.
In Parkinson's disease (PD) motor symptoms are not observed until loss of 70% of dopaminergic neu... more In Parkinson's disease (PD) motor symptoms are not observed until loss of 70% of dopaminergic neurons in substantia nigra (SN), preventing early diagnosis. Mitochondrial dysfunction was indicated in neuropathological process already at early PD stages. Aging and oxidative stress, the main factors in PD pathogenesis, cause membrane stiffening, which could influence functioning of membrane-bound oxidative phosphorylation (OxPhos) complexes (Cxs) in mitochondria. In 6-OHDA rat model, medium-sized dopaminergic lesion was used to study mitochondrial membrane viscosity and changes at the level of OxPhos Cxs and their higher assembled states—supercomplexes (SCxs), during the early degeneration processes and after it. We observed loss of dopaminergic phenotype in SN and decreased dopamine level in striatum (STR) before actual death of neurons in SN. Behavioural deficits induced by lesion were reversed despite progressing neurode-generation. Along with degeneration process in STR, mitochondrial Cx I performance and amount decreased in almost all forms of SCxs. Also, progressing decrease of Cx IV performance in SCxs (I 1 III 2 IV 3–1 , I 1 IV 2–1) in STR was observed during degeneration. In SN, SCxs containing Cx I increased protein amount and a shifted individual Cx I 1 into superassembled states. Importantly, mitochondrial membrane viscosity changed in parallel with altered SCxs performance. We show for the first time changes at the level of mitochondrial membrane viscosity influencing SCxs function after dopaminergic system degeneration. It implicates that altered mitochondrial membrane viscosity could play an important role in regulation of mitochondria functioning and pathomechanisms of PD. The data obtained are also discussed in relation to compensatory processes observed.
Depression is a frequent comorbid disorder in Parkinson's disease (PD) which may precede appearan... more Depression is a frequent comorbid disorder in Parkinson's disease (PD) which may precede appearance of its motor symptoms by several years. Pathomechanisms underlying PD have been suggested to be responsible for the PD-related depression. The aim of the study was to examine the influence of a partial lesion of striatal dopaminergic terminals on the " depressive-like " behavior of rats in the forced swimming test (FS). 6-Hydroxydopamine (6-OHDA) was injected bilaterally into the ventro-lateral region of the caudate-putamen (CP) (3.75 µg/2.5 µl/side). The locomotor activity and behavior of rats in the FS were measured 2 and 4 weeks after the operation. The lesion extent was analyzed by biochemical and immunohistochemical methods. Two weeks after the operation, the 6-OHDA-treated rats displayed a prolonged immobility in the FS. This effect disappeared after 4 weeks. The locomotor activity was not influenced by 6-OHDA. Levels of dopamine, DOPAC and HVA were decreased in the nucleus accumbens (NAC) 2 weeks after 6-OHDA but were not changed in the CP, frontal cortex (FCX) and substantia nigra (SN). No significant effect of 6-OHDA on tyrosine hydroxylase-immunoreactivity in the CP and NAC were found. The present study indicates that a relatively small lesion of dopaminergic terminals in the ventral striatum, which does not produce any motor disturbances, may induce " depressive-like " symptoms.
In a previous study, a primary culture of midbrain cells was exposed to 9-methyl-b-carboline for ... more In a previous study, a primary culture of midbrain cells was exposed to 9-methyl-b-carboline for 48 h, which caused an increase in the number of tyrosine hydroxylase-positive cells. Quantitative RT-PCR revealed increased transcription of genes participating in the maturation of dopaminergic neurons. These in vitro findings prompted us to investigate the restorative actions of 9-methyl-b-car-boline in vivo. The compound was delivered for 14 days into the left cerebral ventricle of rats pretreated with the neurotoxin 1-methyl -4-phenyl-pyridinium ion (MPP +) for 28 days applying a dose which lowered dopamine by approximately 50%. Interestingly, 9-methyl-b-carboline reversed the dopamine-lowering effect of the neurotoxin in the left striatum. Stereological counts of tyrosine hydroxylase-immunoreactive cells in the substantia nigra revealed that the neurotoxin caused a decrease in the number of those cells. However, when treated subsequently with 9-methyl-b-carboline, the number reached normal values. In search of an explanation for the restorative activity, we analyzed the complexes that compose the respiratory chain in striatal mitochondria by 2-dimension gel electrophoresis followed by MALDI-TOF peptide mass fingerprinting. We found no changes in the overall composition of the complexes. However, the activity of complex I was increased by approximately 80% in mitochondria from rats treated with MPP + and 9-methyl-b-carboline compared to MPP + and saline and to sham-operated rats, as determined by measurements of nicotinamide adenine dinucleotide dehydrogenase activity. Microarray technology and single RT-PCR revealed the induction of neurotrophins: brain-derived neurotrophic factor, conserved dopamine neurotrophic factor, cerebellin 1 precursor protein, and ciliary neurotrophic factor. Selected western blots yielded consistent results. The findings demonstrate restorative effects of 9-methyl-b-carboline in an animal model of Parkinson's disease that improve the effectiveness of the respiratory chain and promote the transcription and expression of neurotrophin-related genes.
The pesticide paraquat (PQ) was found to be a suitable xenobiotic to model Parkinson's disease. T... more The pesticide paraquat (PQ) was found to be a suitable xenobiotic to model Parkinson's disease. The reactive oxygen species (ROS) production was suggested to be the main cause of PQ toxicity but very few evidences were found for its generation in the brain in vivo after ip administration. We compared the effects of PQ-induced ROS generation between the brain structures and the peripheral tissues using two different hydroxyl radical generation markers. Repeated but not single ip PQ administration increased the levels of ROS in the striatal homogenates but, when measured in the extracellular microdialysis filtrate, no change was observed. The increased dopamine release was detected in the striatum after the fourth PQ administration and its basal levels were decreased. A single treatment with the pesticide did not influence ROS production in the lungs or kidneys but repeated intoxication decreased its levels. These results suggest that repeated, systemic administration of a low dose of PQ triggers intracellular ROS formation in the brain and can cause slowly progressing degenerative processes , without the toxic effects in the peripheral tissues.
Paraquat is a toxin suggested to contribute to pathogenesis of Parkinson’s disease. The aim of th... more Paraquat is a toxin suggested to contribute to pathogenesis of Parkinson’s disease. The aim of the present study was to examine toxic influence of subchronic treatment with this pesticide (5 days, one injection per day, 2–3 days of withdrawal) on dopaminergic, serotonergic, noradrenergic and GABAergic neurons. Paraquat decreased the number of tyrosine hydroxylase-immunoreactive (TH-ir) neurons in the substantia nigra by 22% (measured 3 days after withdrawal). Two days after withdrawal the levels of the dopamine metabolites and dopamine turnover in the caudate–putamen, substantia nigra and prefrontal cortex were reduced by ca. 20–60%, and the binding of [3H]GBR 12,935 to dopamine transporter dropped by 25–40% in the caudate–putamen. Three days after paraquat withdrawal, the level of dopamine in the caudate–putamen was significantly increased, and earlier decreases in DOPAC and HVA in the substantia nigra, as well as [3H]GBR 12,935 binding in the caudate–putamen were reversed. Moreover, an increase in serotonin turnover in the caudate–putamen and prefrontal cortex, and noradrenaline level in the former structure was observed 2–3 days after paraquat withdrawal. Three days after the last paraquat injection 24–35% decreases in the proenkephalin mRNA levels and 5–7% reduction in glutamic acid decarboxylase (GAD)67 mRNA were found in the caudate–putamen. The present study suggests that subchronic paraquat administration triggers processes characteristic of early stages of dopaminergic neuron degeneration, and activates compensatory mechanisms involving dopaminergic, noradrenergic, serotonergic and GABAergic transmissions.
—A deficiency of the dopaminergic transmission in the mesocortical system has been suggested to c... more —A deficiency of the dopaminergic transmission in the mesocortical system has been suggested to contribute to cognitive disturbances in Parkinson's disease. Therefore, the aim of the present study was to examine whether the long-term administration of a commonly used herbicide, para-quat, which has already been found to induce a slowly progressing degeneration of the nigrostriatal neurons, influences mesocortical dopaminergic neurons in rats. Para-quat at a dose of 10 mg/kg i.p. was injected either acutely or once a week for 4, 8, 12 and 24 weeks. Acute treatment with this pesticide increased the level of homovanillic acid (HVA) and HVA/dopamine ratio in the prefrontal cortex. After 8 weeks of administration paraquat increased the number of stereologically counted tyrosine hydroxylase– immunoreactive (TH-ir) neurons and their staining intensity in the ventral tegmental area (VTA), which is a source of the mesocortical dopaminergic projection. At the same time, few TH-ir neurons appeared in different regions of the cerebral cortex: in the frontal, cingulate, retrosplenial and parietal cortices. Chronic paraquat administration did not influence the level of dopamine in the prefrontal cortex but increased the levels of its metabolites: 3,4-dihydroxyphe-nylacetic acid (after 8 –12 weeks), HVA (after 4 and 12 weeks) and HVA/dopamine ratio (4 weeks). After 24 weeks this pesticide reduced the number of TH-ir neurons in the VTA by 42% and of the Nissl-stained neurons by 26%, and induced shrinkage of this structure by ca. 25%. Moreover, TH-ir neurons in the cortex were no more visible after such a long period of administration and levels of dopamine metabolites returned to control values. The present results suggest that the long-term paraquat administration destroys dopaminergic neurons of the VTA. However, compensatory activation of the VTA neurons and cortex overcomes progressing degeneration and maintains cortical dopaminergic transmission.
Selective toxicity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a parkinsonism inducin... more Selective toxicity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a parkinsonism inducing compound, is well known to be related to an uptake of its active metabolite MPP + into dopaminergic neurons by dopamine transporter (DAT). The aim of the present study was to examine whether paraquat, a commonly used herbicide, which is an 1-methyl-4-phenyl-pyridinium ion (MPP +) analogue, affects DAT in vivo in rats. Paraquat administered at a dose of 10 mg/kg ip decreased the binding of [ 3 H]GBR 12,935 to DAT measured by quantitative autoradiography in the dorsal and ventral caudate-putamen, but not in the substantia nigra pars compacta. Moreover, this compound increased the level of 3-methoxytyramine (3-MT) and 3-MT/dopamine ratio in the anterior and posterior caudate-putamen measured by HPLC with electrochemical detection. No other alterations in the levels of dopamine and its metabolites were found in the caudate-putamen and substantia nigra. The present study seems to suggest that systemic paraquat administration affects striatal DAT and dopamine metabolism in the nigrostriatal neurons in rats which may be crucial for its neurotoxic effects on dopaminergic neurons.
The aim of the present study was to examine the influence of the long-term paraquat administratio... more The aim of the present study was to examine the influence of the long-term paraquat administration on the dopaminergic nigrostriatal system in rats. Paraquat was injected at a dose of 10 mg ⁄ kg i.p. for 4–24 weeks. We found that this pesticide reduced the number of tyrosine hydroxylase-immunoreactive neurons of the substantia nigra; after the 4-week treatment the reduction (17%, nonsignificant) was confined to the rostrocentral region of this structure but, after 24 weeks, had spread along its whole length and was % 37%. Moreover, it induced a biphasic effect on dopaminergic transmission. First, levels of dopamine, its metabolites and turnover were elevated (4–8 weeks) in the caudate–putamen, then all these parameters returned to control values (12 weeks) and dropped by 25–30% after 24 weeks. The binding of [ 3 H]GBR 12,935 to dopamine transporter in the caudate–putamen was decreased after 4–8 weeks, then returned to control values after 12 weeks but was again decreased after 24 weeks. Twenty-four-week paraquat administration also decreased the level of tyrosine hydroxylase (Western blot) in the caudate–putamen. In addition, paraquat activated serotonin and noradrenaline transmission during the first 12 weeks of treatment but no decreases in levels of these neurotransmitters were observed after 24 weeks. The above results seem to suggest that long-term paraquat administration produces a slowly progressing degeneration of nigrostriatal neurons, leading to delayed deficits in dopaminergic transmission, which may resemble early, presymptomatic, stages of Parkinson's disease.
We have examined the pattern of striatal messenger RNA expression of over 8000 genes in a rat mod... more We have examined the pattern of striatal messenger RNA expression of over 8000 genes in a rat model of levodopa (l-DOPA)-induced dyskinesia and Parkinson disease (PD). 6-Hydroxydopamine (6-OHDA)-lesioned rats were treated with l-DOPA or physiological saline for 22 days and repeatedly tested for antiakinetic response to l-DOPA and the development of abnormal involuntary movements (AIMs). In a comparison of rats that developed a dyskinetic motor response to rats that did not, we found striking differences in gene expression patterns. In rats that developed dyskinesia, GABA neurons had an increased transcriptional activity, and genes involved in Ca 2+ homeostasis, in Ca 2+-dependent signaling, and in structural and synaptic plasticity were upregulated. The gene expression patterns implied that the dyskinetic striatum had increased transcriptional, as well as synaptic activity, and decreased capacity for energy production. Some basic maintenance chores such as ribosome protein biosynthesis were downregulated, possibly a response to expended of ATP levels.
Cause of Parkinson's disease (PD) is still not understood. Motor symptoms... more Cause of Parkinson's disease (PD) is still not understood. Motor symptoms are not observed at early stages of disease due to compensatory processes. Dysfunction of mitochondria was indicated already at preclinical PD. Selective toxin 6-OHDA was applied to kill dopaminergic neurons in substantia nigra and disturb neuronal transmission in striatum. Early phase of active degeneration and later stage, when surviving cells adapted to function normally, were analysed. 2D BN/SDS difference gel electrophoresis (DIGE) of mitochondrial proteome enabled to point out crucial processes involved at both time-points in dopaminergic structures. Marker proteins such as DPYSL2, HSP60, ATP1A3, EAAT2 indicated structural remodelling, cytoskeleton rearrangement, organelle trafficking, axon outgrowth and regeneration. Adaptations in dopaminergic and glutamatergic neurotransmission, recycling of synaptic vesicles, along with enlargement of mitochondria mass were proposed as causative for compensation. Changed expression of carbohydrates metabolism and oxidative phosphorylation proteins were described, including their protein-protein interactions and supercomplex assembly.
Regarding the pathogenesis of Parkinson&a... more Regarding the pathogenesis of Parkinson's disease, a neurotoxin hypothesis was proposed following the discovery that 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) produces a Parkinson-like syndrome in humans and primates. Since then, researchers have searched for endogenous and exogenous compounds that are structurally similar to this neurotoxin. Such compounds include beta-carbolines, formed from tryptophan and its derivatives. beta-carbolines are present naturally in the human brain and cerebrospinal fluid. The present study examined the effect of bilateral, intranigral administration of 2,9-dimethyl-beta-carbolinium ion on muscle tone, electromyographic activity, dopamine metabolism in the striatum, and the number of tyrosine hydroxylase-immunoreactive neurons and volume of the substantia nigra in rats. We found that the beta-carbolinium ion (15 or 40 nmol per side) caused a significant decrease in the striatal levels of dopamine and its metabolites, which was accompanied by an enhancement of muscle tone and electromyographic activity. Stereological counting revealed that the beta-carbolinium caused a significant decrease in the total number of tyrosine hydroxylase-immunoreactive neurons and shrinkage of the substantia nigra. The findings suggest that the methylated beta-carbolinium ion produces a dose-dependent degeneration of nigrostriatal neurons, leading to deficits in dopaminergic neurotransmission and an increase of muscle resistance and electromyographic activity, a syndrome equivalent to muscle rigidity in Parkinson's disease.
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, 2016
In Parkinson's disease (PD) motor symptoms are no... more In Parkinson's disease (PD) motor symptoms are not observed until loss of 70% of dopaminergic neurons in substantia nigra (SN), preventing early diagnosis. Mitochondrial dysfunction was indicated in neuropathological process already at early PD stages. Aging and oxidative stress, the main factors in PD pathogenesis, cause membrane stiffening, which could influence functioning of membrane-bound oxidative phosphorylation (OxPhos) complexes (Cxs) in mitochondria. In 6-OHDA rat model, medium-sized dopaminergic lesion was used to study mitochondrial membrane viscosity and changes at the level of OxPhos Cxs and their higher assembled states-supercomplexes (SCxs), during the early degeneration processes and after it. We observed loss of dopaminergic phenotype in SN and decreased dopamine level in striatum (STR) before actual death of neurons in SN. Behavioural deficits induced by lesion were reversed despite progressing neurodegeneration. Along with degeneration process in STR, mitochondrial Cx I performance and amount decreased in almost all forms of SCxs. Also, progressing decrease of Cx IV performance in SCxs (I1III2IV3-1, I1IV2-1) in STR was observed during degeneration. In SN, SCxs containing Cx I increased protein amount and a shifted individual Cx I1 into superassembled states. Importantly, mitochondrial membrane viscosity changed in parallel with altered SCxs performance. We show for the first time changes at the level of mitochondrial membrane viscosity influencing SCxs function after dopaminergic system degeneration. It implicates that altered mitochondrial membrane viscosity could play an important role in regulation of mitochondria functioning and pathomechanisms of PD. The data obtained are also discussed in relation to compensatory processes observed.
In a previous study, a primary culture of midbrain cells was exposed to 9-methyl-beta-carboline f... more In a previous study, a primary culture of midbrain cells was exposed to 9-methyl-beta-carboline for 48 h, which caused an increase in the number of tyrosine hydroxylase-positive cells. Quantitative RT-PCR revealed increased transcription of genes participating in the maturation of dopaminergic neurons. These in vitro findings prompted us to investigate the restorative actions of 9-methyl-beta-carboline in vivo. The compound was delivered for 14 days into the left cerebral ventricle of rats pretreated with the neurotoxin 1-methyl-4-phenyl-pyridinium ion (MPP+) for 28 days applying a dose which lowered dopamine by approximately 50%. Interestingly, 9-methyl-beta-carboline reversed the dopamine-lowering effect of the neurotoxin in the left striatum. Stereological counts of tyrosine hydroxylase-immunoreactive cells in the substantia nigra revealed that the neurotoxin caused a decrease in the number of those cells. However, when treated subsequently with 9-methyl-beta-carboline, the numbe...
The aim of the present study was to examine the expression of synphilin-1, alpha-synuclein, and t... more The aim of the present study was to examine the expression of synphilin-1, alpha-synuclein, and tyrosine hydroxylase in human elderly brains and the incidence of Marinesco bodies (MBs, intranuclear inclusions) in the neuromelanin-containing substantia nigra neurons. The brains of twenty-two individuals without clinical signs and symptoms of parkinsonism and dementia and an additional two parkinsonian patients were dissected and subjected to histopathological examination and western blotting. Ubiquitin-positive and agr;-synuclein-negative MBs were found in 0.84-9.45% of the nigral neurons from brains of 15 healthy individuals and both parkinsonian patients. The frequency of pigmented nigral neurons containing MBs was positively correlated with age. The levels of tyrosine hydroxylase in the caudate nucleus and putamen decreased with age, and were inversely correlated with the MB frequency. The level of synphilin-1 in the caudate nucleus was positively correlated both with age and the ...
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Papers by Katarzyna Kuter
Selective toxin 6-OHDA was applied to kill dopaminergic neurons in substantia nigra and disturb neuronal transmission in striatum. Early phase of active degeneration and later stage, when surviving cells adapt to function normally, were analysed. 2D BN/SDS difference gel electrophoresis (DIGE) of mitochondrial proteome enabled to point out crucial processes involved at both time-points in dopaminergic structures. Marker proteins such as DPYSL2, HSP60, ATP1A3, EAAT2 indicated structural remodelling, cytoskeleton rearrangement, organelle trafficking, axon outgrowth and regeneration. Adaptations in dopaminergic and glutamatergic neurotransmission, recycling of synaptic vesicles, along with enlargement of mitochondria mass were proposed as causative for compensation. Changed expression of carbohydrates metabolism and oxidative phosphorylation proteins were described, including their protein-protein interactions and supercomplex assembly.
suggests that subchronic paraquat administration triggers processes characteristic of early stages of dopaminergic neuron degeneration, and activates compensatory mechanisms involving dopaminergic, noradrenergic, serotonergic and GABAergic transmissions.
Selective toxin 6-OHDA was applied to kill dopaminergic neurons in substantia nigra and disturb neuronal transmission in striatum. Early phase of active degeneration and later stage, when surviving cells adapt to function normally, were analysed. 2D BN/SDS difference gel electrophoresis (DIGE) of mitochondrial proteome enabled to point out crucial processes involved at both time-points in dopaminergic structures. Marker proteins such as DPYSL2, HSP60, ATP1A3, EAAT2 indicated structural remodelling, cytoskeleton rearrangement, organelle trafficking, axon outgrowth and regeneration. Adaptations in dopaminergic and glutamatergic neurotransmission, recycling of synaptic vesicles, along with enlargement of mitochondria mass were proposed as causative for compensation. Changed expression of carbohydrates metabolism and oxidative phosphorylation proteins were described, including their protein-protein interactions and supercomplex assembly.
suggests that subchronic paraquat administration triggers processes characteristic of early stages of dopaminergic neuron degeneration, and activates compensatory mechanisms involving dopaminergic, noradrenergic, serotonergic and GABAergic transmissions.