Showing papers in "Journal of Neural Transmission in 2000"

Membrane breakdown in acute and chronic neurodegeneration: focus on choline-containing phospholipids.

Abstract: Breakdown of cellular membranes is a characteristic feature of neuronal degeneration in acute (stroke) and chronic (senile dementia) neurological disorders. The present review summarizes recent experimental and clinical work which concentrated on changes of choline-containing phospholipids as indicators of neuronal membrane breakdown. Experimental studies identified glutamate release, calcium influx, and activation of cellular phospholipase A2 (PLA2) as important steps initiating membrane breakdown in cultured neurons or brain slices under hypoxic or ischemic conditions. Proton NMR studies have shown an elevation of choline-containing compounds in the brain of Alzheimer patients while neurochemical studies in post mortem-brain demonstrated increases of the catabolic metabolite, glycerophosphocholine, an indicator of PLA2 activation. In contrast, studies of cerebrospinal fluid, phosphorus NMR studies, and measurements of phospholipases in post mortem Alzheimer brain gave ambiguous results which may be explained by methodical limitations. The finding that, in experimental studies, choline was a rate-limiting factor for phospholipid biosynthesis has stimulated clinical studies aimed at counteracting phospholipid breakdown, e.g. by combinations of choline and cytidine. Future experimental approaches should clarify whether loss of membrane phospholipids is cause or consequence of the neurodegenerative disease process.

Tryptophan degradation and immune activation in Alzheimer's disease

Abstract: Alzheimer's disease (AD) is likely associated with systemic immune activation. During immune response, interferon-gamma stimu-lates indoleamine 2,3-dioxygenase (IDO) converting tryptophan to N-formylkynurenine followed by kynurenine in an ensuing step. Thus, IDO activity is estimated by the kynurenine per tryptophan quotient (Kyn/Trp). In 21 patients suffering from AD, in 20 controls of similar age, and in 49 blood donors we measured serum tryptophan and kynurenine concentrations by HPLC. Lower tryptophan concentrations were found in elderly control subjects compared to blood donors (62.1 vs. 73.0 μM, p < 0.005). Tryptophan concentrations tended to be still lower in AD patients (54.4 μM, p = 0.07) compared to elderly controls. Enhanced tryptophan degradation in patients was reflected by significantly increased Kyn/Trp (46.1 vs. 34.1 in elderly controls, p < 0.05). Correlations were found in patients between Kyn/Trp and concentrations of soluble immune markers in serum, i.e., neopterin, interleukin-2 receptor and tumor necrosis factor receptor (all p < 0.001). Increased Kyn/Trp was associated with reduced cognitive performance. Tryptophan degradation due to immune activation may exert impact on the pathogenesis of AD.

Caspase activities and tumor necrosis factor receptor R1 (p55) level are elevated in the substantia nigra from parkinsonian brain.

Abstract: The activities of caspase-1 and caspase-3 were measured by use of fluoropeptides as substrates for the first time in the brain (substantia nigra, caudate nucleus, putamen, cerebellum, and frontal cortex) from control and parkinsonian patients. The activities of caspases in the brain were significantly higher in the substantia nigra from parkinsonian patients than those in the brain from control patients (p < 0.01). However, the activities of caspases in the caudate nucleus, putamen, cerebellum, and frontal cortex showed no significant difference between parkinsonian and control patients. The tumor necrosis factor (TNF) receptor R1 (TNF-R1, p55) level was also elevated in the substantia nigra of the parkinsonian brain in comparison with that of controls (p < 0.05). Since both caspases and TNF-R1 may play important roles in apoptotic cell death through TNF-α-induced signaling pathway, our present data suggest the presence of a proapoptotic environment in the substantia nigra of parkinsonian brain, probably inducing vulnerability of neurons and glias towards a variety of noxious factors.

An assessment of the antioxidant and the antiamyloidogenic properties of melatonin: implications for Alzheimer's disease.

Abstract: Summary. This review summarizes recent advancements in our understanding of the potential role of the amyloid ‚ protein in Alzheimer’s disease. It also discusses the significance of amyloid ‚ in initiating the generation of partially reduced oxygen species and points out their role in damaging essential macromolecules in the CNS which leads to neuronal dysfunction and loss. Recently acquired experimental data links these destructive oxidative processes with some neurodegenerative aspects of Alzheimer’s disease. The experimental findings related to the free radical scavenging and antioxidative properties of melatonin are tabulated and its efficacy and the likely mechanisms involved in its ability to reduce neuronal damage mediated by oxygen-based reactive species in experimental models of Alzheimer’s disease are summarized. Besides the direct scavenging properties and indirect antioxidant actions of melatonin, its ability to protect neurons probably also stems from its antiamyloidogenic properties. Melatonin is also unique because of the ease with which it passes through the blood-brain barrier.

CSF levels of tau, beta-amyloid(1-42) and GAP-43 in frontotemporal dementia, other types of dementia and normal aging

Abstract: Cerebrospinal fluid (CSF) levels of tau, beta-amyloid(1-42) and growth-associated protein 43 (GAP-43) were studied in patients with frontotemporal dementia (FTD; n = 17), Alzheimer's disease (AD; n = 60), subcortical white-matter dementia (SWD; n = 24), Parkinson's disease (PD; n = 23) and dysthymia (n = 19) and in age-matched controls (n = 32). CSF-tau was significantly increased only in AD, and CSF-beta-amyloid(1-42) was significantly decreased in AD and SWD as compared to controls, and in AD compared to FTD. CSF-GAP-43 was significantly decreased only in PD. The GAP-43/tau ratio was decreased in all the patient groups except the dysthymia group compared to controls. A positive correlation was found between CSF-GAP-43 and CSF-tau in all groups. The results suggest normal levels of CSF-tau and CSF-beta-amyloid(1-42) in FTD, which will aid in the clinical separation of FTD from AD. In SWD, decreased levels of CSF-beta-amyloid(1-42) suggest concomitant involvement of vascular and amyloid protein mechanisms.

Cell death mechanisms in Parkinson's disease

Abstract: Objective While the causes of neuronal death in Parkinson's disease (PD) and other neurodegenerative disorders are still unknown, several mechanisms are under discussion: programmed vs passive cell death (apoptosis vs necrosis), mainly based on conflicting results on the rare presence or absence of DNA fragmentation in substantia nigra neurons using the in situ DNA-labeling (TUNEL) method Design/Methods In 4 cases of Parkinson's disease (PD), 2 cases of Dementia with Lewy bodies (DLB) and 3 age-matched controls, the TUNEL/ISEL method was used to detect DNA fragmentation in substantia nigra locus coeruleus and cerebral cortex [method by Gold et al (1994)] In addition, immunohistochemistry was performed for an array of apoptosis-related proteins, ie the recently described apoptosis specific protein cJun/AP1 (ASP), the proto-oncogenes c-Jun, c-Jun AP1, Bcl2, Bax, Bcl-x, p53, CD 95 (Fas/Apo-1), activated caspase 3, several heat shock proteins (α-B crystallin, ubiquitin), and α-synuclein Results None of the cases of PD, DLB, and controls showed convincing TUNEL-positivity nor morphologic signs of apoptosis in nigral, locus coeruleus or cortical neurons with or without Lewy bodies but variable numbers of TUNEL-positive astrocytes and microglial cells in substantia nigra of PD and DLB There were no significant differences in the expression of c-Jun, ASP, Bcl-2, Bax, and Bcl-x in substantia nigra neurons between PD, DLB, and controls nor between cortical and subcortical neurons with and without Lewy bodies No expression of p53, and activated caspase 3, or any of the examined stress proteins was seen in neurons, while reactive astroglia and microglia were decorated by antibodies to Bcl-2, Bax, α-B-crystallin and less, to Bcl-x and caspase 3 Lewy bodies, dystrophic neurites and axonal spheroids, all being negative for the applied apoptosis regulating proteins, showed strong expression of the examined stress proteins and of α-synuclein Conclusions These findings which are in line with previous results in Alzheimer's disease (Stadelmann et al, 1998) and Parkinson's disease (Banati et al, 1999) suggest that mechanisms distinct from classical apoptosis play a central role in the pathogenesis of PD and related neurodegenerative diseases Further studies are warranted to elucidate the intracellular cascade of events leading to cell death in these disorders showing slow progression over many years

Apoptosis and Alzheimer's disease.

Abstract: Cell death by apoptosis comprises a sequence of events leading to the activation of caspases. Caspases execute the fragmentation of the cellular protein and DNA, ultimately, leading to disintegration of the cell. Apoptosis is a tightly regulated physiological mechanism that is crucial during development and thereafter for the maintenance of the balance between cell division and cell death. In contrast to the rather smoothly operating cell death machinery of apoptosis, necrosis is caused by insults leading to the rapid disruption of cellular metabolism and the non-physiological disintegration of the cells. Frequently, toxic events or traumatic challenges trigger the rapid necrotic cell death. Apoptosis and necrosis can be discriminated by a number of morphological and biochemical characteristics. To describe the specific mechanisms of cell death occurring during neurodegenerative disorders, such as Alzheimer's disease (AD), many investigations, both in vivo and in vitro, have attempted to label the particular pathway of cell death either as apoptosis or as necrosis. The elucidation of the mechanism of cell death promises to identify novel pharmaceutical targets for the prevention and therapy of AD. Apoptotic and necrotic cells can be found in AD tissue, and both pathways can be mimicked employing a variety of models systems of AD-associated nerve cell degeneration. Certain genes that are linked to familial AD may render neurons more vulnerable to apoptosis, but it has to be stressed that the vast majority of AD cases are sporadic and not strictly genetically determined. Apoptosis and necrosis may overlap, may sequentially occur under certain conditions, and may not be detected unequivocally. In conclusion, on the basis of the presently available data it has to be stated that although many studies in vivo and in vitro favor apoptosis in AD, there is considerable evidence that a mixture of both events may contribute to neurodegeneration in AD and to its final pathology.

Risk factors for dementia, depression and psychosis in long-standing Parkinson's disease.

Abstract: Objectives. To study the relationships between clinical features of Parkinson's disease (PD) and the development of dementia, depression or psychosis in patients with long-standing disease. Background. The natural history of dementia and depression in PD, and its relation to psychosis in long standing PD, are unclear. Method. 172 consecutive patients (99 men and 73 women, mean age at symptoms onset 58.3 ± 13.2 years) with 5 years or more of PD (mean symptom duration of 11.8 ± 5.6 years) were studied. Clinical data were collected during the last office visit through physical examination, detailed history, review of patient charts and outside documents. Dementia and depression were diagnosed according to DSM-IV criteria, while psychosis was diagnosed if hallucinations or delusions were present. Chi-square and t tests were used to compare the patient characteristics among those with vs. those without mental complications of the disease at different disease stages. Logistic regression was used for the comparison of associations between the presence of dementia or depression (dependent variable) and age at onset of PD, duration of PD and disease staging (explanatory variables). Results. The study population consisted of 45 patients at Hoehn & Yahr (HY P = 0.006, Z = 3.22, respectively). These associations were significant also for the older age of PD onset (≥59 years n = 89) subgroup (p = 0.001, Z = 3.2 for dementia and p = 0.02, Z = 2.9 for depression), but not for younger onset cases (<59 years n = 83). Dementia was significantly associated with older age of PD onset (β = 0.04, p = 0.009) while depression was inversely associated with age of PD onset (β = −0.04, p = 0.02). The presence of dementia was also significantly associated with depression (β = 1.49, p = 0.0006). Dementia and depression were found to be independent explanatory variables for the development of psychosis (logistic regression, odds ratio (OR) = 26.0, p < 0.0001; OR = 10.2, p < 0.0001, respectively). In patients with younger age of PD onset, depression more than dementia was strongly correlated with the appearance of psychosis. Conclusion. Dementia in PD was related to older age of symptoms onset and old age. Depression was associated with dementia or early age of PD onset. Depression seemed to contribute to the appearance of psychosis even more than dementia, especially in patients with younger age of symptoms onset.

Vitamin D in schizophrenia, major depression and alcoholism.

Abstract: 25-Hydroxyvitamin D3, 1,25-dihydroxyvitamin D3, calcium, phosphate and parathyreoidal hormone levels were assessed in 34 patients with schizophrenia (DSM-III-R, 44% female, mean age 38.9 +/- 2.1 years), 30 patients with alcohol addiction (16% female, mean age 48.7 +/- 2.2 years), 25 patients with major depression (56% female, mean age 57.6+/- years) and 31 healthy controls. Only 25-hydroxyvitamin D3 and 1,25-dihydroxvitamin D3 levels were significantly lower in all groups of psychiatric patients than in normal controls, but not phosphate, calcium and parathyreoidal hormone levels. Significant differences in the vitamin D levels could not be found between the three psychiatric groups. These findings do not support the idea that vitamin D is specifically involved in the pathophysiology of depression. The difference in patients as compared to the healthy controls might be related to a different social background resulting in differing habits e.g. of nutrition.

Striatal [I-123]beta-CIT SPECT and prefrontal cognitive functions in Parkinson's disease

Abstract: Twenty non-demented patients with idiopathic Parkinson's disease (PD) underwent single photon emission computed tomography (SPECT) with [123I]beta-CIT to further investigate the contribution of nigrostriatal dysfunction to cognitive and motor deficits. Compared to matched controls PD patients showed normal verbal intelligence, short-term memory and phasic alertness. There were significant (p < 0.05) deficits in tests of verbal working memory (digit ordering, reading span), strategic memory (story recall) and executive functions (card sorting), indicating a "prefrontal" cognitive deficit. Significant (p < 0.05) correlations were observed between dopamine transporter (DAT) density in the putamen and motor deficits as well as between DAT density in both striatal compartments (head of the caudate nucleus and putamen) and prefrontal functioning. Age was a major contributing factor to both cognitive status and nigrostriatal integrity as measured by [123I]beta-CIT SPECT. These results support the view that the striatum is part of a neuronal network that is mediating prefrontal cognitive functions.

Pharmacological validation of a new animal model of alcoholism.

Abstract: A new animal model of alcoholism has been developed. Rats derived from this model show certain characteristics: (i) they have an incentive demand to consume alcohol, (ii) they exhibit relapse-like drinking even after a very long time of abstinence, (iii) they show tolerance to alcohol and have mild signs of physical withdrawal during the onset of abstinence, and (iv) during abstinence they also exhibit a psychological withdrawal syndrome consisting of enhanced anxiety-related behaviour and hyperreactivity to stressful situations. Anti-craving drugs such as acamprosate and naltrexone which proved to be effective in human alcoholics to prevent relapse were also effective in our animal model. Thus, both compounds suppressed the alcohol deprivation effect which is used as a measure for craving and relapse. It is concluded that this pharmacological validation of our model demonstrates the predictive value of our model and enables us to further characterize putative anti-craving drugs and neurobiological mechanisms of addictive behaviour.

Hyperhomocysteinemia in dementia.

Abstract: Hyperhomocysteinemia is a strong risk factor for atherosclerotic vascular disease, and elevated serum homocysteine is correlated with vitamin B deficiency. In this pilot study, significantly elevated homocysteine levels were found in patients with Alzheimer's disease as well as in patients with vascular dementia, probably indicating similar pathophysiological pathways. We found significant correlations between low folic acid concentrations as well as high homocysteine concentrations and cognitive decline. Supplementation with folic acid may be an inexpensive way to reduce elevated homocysteine levels in demented patients.

Adult treatment with methamphetamine transiently decreases dentate granule cell proliferation in the gerbil hippocampus.

Abstract: The objective of the present study was to examine whether acute treatment with the recreational drug methamphetamine influences adult granule cell proliferation in the dentate gyrus of the hippocampus. For that purpose, at the age of postnatal day 90 adult male gerbils (Meriones unguiculatus) received a single dose of either methamphetamine (25 mg/kg; i.p.) or saline. Proliferation of granule cells was identified by in-vivo labeling with 5-bromo-2'-desoxyuridine (BrdU) which was applied either simultaneously with methamphetamine or 36 h after administration of the drug. BrdU-labeled granule cell nuclei were identified in consecutive horizontal slices along the mid-septotemporal axis of the hippocampus and light-microscopically quantified 7 days after the BrdU-labeling. It was found that in both saline- and methamphetamine-treated animals there was a highly significant spatial septotemporal gradient in granule cell proliferation with numbers of BrdU-labeled cells gradually declining from the septal towards the temporal pole. The acute treatment with methamphetamine suppressed granule cell proliferation by about 28% and the septotemporal gradient of mitotic activity became significantly attenuated. It was further found that 36 h after the drug challenge granule cell proliferation rates had been restored almost to the control values along the whole septotemporal axis of the hippocampus. The present results are discussed with regard to (1) pharmacological regulation of neurogenesis in the hippocampus and (2) probable clues they may provide for both understanding the biological correlates of psychotic disorders and evolution of future concepts in neuropharmacological intervention.

No association between the alpha2-macroglobulin (A2M) deletion and Alzheimer's disease, and no change in A2M mRNA, protein, or protein expression.

Abstract: A polymorphism consisting of a deletion near the 5' splice site of exon 18 on the alpha2-macroglobulin (A2M) gene (A2M-2) has been suggested to be associated with Alzheimer's disease (AD) in family-based studies. We studied the A2M-2 allele together with the ApoE alleles in a large series on patients with AD (n = 449) and age-matched controls (n = 349). Neuropathologically confirmed diagnoses were available in 199 cases (94 AD and 107 control cases). We found no increase in A2M-2 genotype or allele frequencies in AD (27.5% and 14.6%) versus controls (26.4% and 14.9%). In contrast, a marked increase (p < 0.0001) in ApoE epsilon4 genotype or allele frequencies was found in AD (66.6% and 41.2%) as compared with controls (29.8% and 16.5%), suggesting sufficient statistical power in our sample. No relation was found between the A2M-2 and the ApoE epsilon4 allele. No change in A2M exon 17-18 mRNA size or sequence or A2M protein size was found in cases carrying the A2M-2 deletion, suggesting that there is no biological consequences of the A2M intronic deletion. No change in A2M protein level in cerebrospinal fluid was found in AD, suggesting that the A2M-2 allele does not effect the A2M protein expression in the brain. The lack of an association between the A2M-2 allele and AD in the present study, and the lack of abnormalities in the A2M mRNA or protein suggest that the A2M-2 allele is not associated with AD.

Antioxidant property of pramipexole independent of dopamine receptor activation in neuroprotection.

Abstract: Pramipexole and several other dopamine agonists have been recently demonstrated to have neuroprotective effects in vitro and in vivo. We report here that pramipexole can protect DAergic cell line MES 23.5 against dopamine (DA), 6-hydroxydopamine (6-OHDA), and hydrogen peroxide (H2O2)-induced cytotoxicity in vitro possibly through antioxidant effects, and such neuroprotection could not be blocked by selective D2 or D3 antagonists. Incubation with pramipexole (5-20 microM) in MES 23.5 cell cultures increased cellular levels of glutathione (GSH), and elevated glutathione peroxidase (GSH-Px) and catalase activities, but only marginally enhanced SOD activity. Pretreatment with D2 or D3 antagonists did not block the stimulating effects of pramipexole on the cellular levels of GSH, and on the activities of GSH-Px and catalase in MES 23.5 cells. These results indicate that pramipexole's neuroprotective effects are likely associated with its antioxidant property independent of D2/D3 receptor activation.

Standardized stimuli to assess drug craving and drug memory in addicts.

Abstract: Due to conditioning processes, originally neutral stimuli become drug-associated cues and can initiate drug craving Standardized stimuli are required to assess stimulus-induced activation of drug memory and craving in brain imaging and neurophysiology studies We developed substance-specific visual and olfactory stimuli for alcohol, tobacco, opiate and cannabis abuse and tested them in subjects with the respective addiction and in healthy volunteers Stimulus-related drug craving differed significantly between the diagnostic groups and indicated that the stimuli are suitable for craving studies

Involvement of other neurotransmitters in behaviors induced by the cannabinoid CB1 receptor antagonist SR 141716A in naive mice

Abstract: The receptor mechanisms by which the selective cannabinoid CB1 receptor antagonist/inverse agonist, SR 141716A [N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-3-pyrazole-carboxamide] produces scratching and head-twitch response (HTR) in naive mice were examined. Acute intraperitoneal administration of varying doses of SR 141716A produced both scratchings (ED50 = 3.9 mg/kg) and head-twitches (ED50 = 4.6 mg/kg) in a dose-dependent manner. A dose of 10 mg/kg SR 141716A was used to induce the cited behaviors for drug interaction studies. The selective 5-HT2A/C receptor antagonist, SR 46349B [trans-4-[(3Z)3-(2-dimethylaminoethyl) oxyimino-3-(2-fluorophenyl) propen-1-yl] phenol] potently and completely blocked the head-twitches produced by SR 141716A (ID50 = 0.08 mg/kg). The induced scratching behavior was partially (68%) and less potently (ID50 = 0.6 mg/kg) blocked by SR 46349B pretreatment. The AMPA/kainate receptor antagonist, CNQX [6-cyano-7-nitroquinoxaline-2,3-dione), partially attenuated (68–78%) the induced scratching and head-twitching behaviors. On the contrary, the selective NMDA antagonist, AP-3 [(±)-2-amino-3-phosphonopropionic acid), had no significant effect on these behaviors. The selective tachykinin NK1 antagonist, CP 94, 994 [(±)-(2S, 3S)-3-(2-methoxybenzylamino)-2-phenylpiperidine], also partially attenuated both the scratching (64%) and the head-twitching (76%) symptoms produced by SR 141716A. Since SR 141716A lacks affinity for the discussed receptors, it appears that the induction of the cited behaviors probably involve indirect activation of their respective neurotransmitter systems.

In-vivo measurements of regional acetylcholine esterase activity in degenerative dementia: comparison with blood flow and glucose metabolism

Abstract: Memory and attention are cognitive functions that depend heavily on the cholinergic system. Local activity of acetylcholine esterase (AChE) is an indicator of its integrity. Using a recently developed tracer for positron emission tomography (PET), C-11-labeled N-methyl-4-piperidyl-acetate (C-11-MP4A), we measured regional AChE activity in 4 non-demented subjects, 4 patients with dementia of Alzheimer type (DAT) and 1 patient with senile dementia of Lewy body type (SDLT), and compared the findings with measurements of blood flow (CBF) and glucose metabolism (CMRGlc). Initial tracer extraction was closely related to CBF. AChE activity was reduced significantly in all brain regions in demented subjects, whereas reduction of CMRGlc and CBF was more limited to temporo-parietal association areas. AChE activity in SDLT was in the lower range of values in DAT. Our results indicate that, compared to non-demented controls, there is a global reduction of cortical AChE activity in dementia.

Genetic analysis of immunomodulating factors in sporadic Parkinson's disease.

Abstract: Immunomodulating factors have been shown to play a role in the pathogenesis of Parkinson's disease (PD) by biochemical methods In order to investigate functionally important genes of the tumor necrosis factor alpha (TNFalpha) pathway we studied the frequency of DNA polymorphisms in the interleukin 6 (IL6), the TNFalpha, and the TNFalpha receptor 1 (TNFR1) genes in 264 sporadic German PD patients and in 183 age and sex matched German healthy controls Analyzing the TNFalpha-308 polymorphism we found heterozygous individuals carrying alleles 1 and 2 more frequently in patients with a relative risk of 156 (p = 0046, p(c) = 013, chi2 = 398) In contrast, the frequency of the B/2 haplotype described by the TNFR1-609 and TNFRI+36 polymorphisms was significantly decreased in our PD patients group (p = 00097, p(c) = 0048, chi2 = 669) with a relative risk reduced to 052 Our results suggest an involvement of immunomodulating factors in the pathogenesis of sporadic PD as revealed by a molecular genetic approach

Different allele distribution of a regulatory MAOA gene promoter polymorphism in antisocial and anxious-depressive alcoholics.

Abstract: Summary. Heritable factors account for approximately 40‐60% of the total variance of liability to alcohol dependence. The present study tested whether a novel functional polymorphism in the promotor region of the Xchromosomal monoamine oxidase A gene (MAOA) was related to antisocial and anxious-depressive traits in alcoholics. Due to the X-chromosomal localization of the MAOA gene, psychobiological traits were compared separately for both genders of 298 male and 66 female alcoholics. In males, 30 of 59 alcoholics with antisocial personality disorder carried the low-activity 3-repeat allele in contrast to only 7 of 31 anxious-depressive alcoholics (51% vs. 23%; p 5 0.02). Likewise, female anxious-depressive alcoholics showed a trend towards a low frequency of genotypes with the 3 repeat allele compared to female alcoholics without these symptoms (29% vs. 53%; p 5 0.09). Taken together, these findings suggest that the 3-repeat allele of the MAOA polymorphism contributes modestly to the dimension of overand underreactive behaviors as possible antecedents of alcoholism.

CSF copper concentrations, blood-brain barrier function, and coeruloplasmin synthesis during the treatment of Wilson's disease.

Abstract: During the treatment of four patients with cerebral manifestation of Wilson's disease, we measured the copper concentration in the cerebrospinal fluid (CSF) and serum, the serum coeruloplasmin concentration, the free copper concentration in the serum, and the albumin ratio CSF/serum (AR). These measurements were treated as indicators of the copper-related toxic effects on the brain and the blood-brain barrier (BBB). The half – life of the decrease in the CSF copper concentration during therapy was 23.5 ± 5.78 months (mean ± S.E.M.). The therapeutic – target – copper concentration in the CSF (mean normal concentration) is below 20 μg/l. The average length of therapy needed to normalize CSF – copper values in our patients with an average initial value of 76.25 μg/L was 47 month. During the first 10 month of treatment there was an increase in all cases of the measured disturbance in the blood-brain barrier (measured as the ratio of albumin in CSF to albumin in serum, AR). All patients showed an initial worsening of the neurological condition, on average after 1.75 ± 0.25 months. The maximal rise in AR, from the initial values, was on average 18.4 ± 5.08%; this maximum was reached after an average of 6.9 ± 1.5 months. The AR normalized during therapy, indicating a reduction in toxicity in the blood-brain barrier region. The extent of the AR increases in individual patients did not correlate significantly with CSF copper half-life, serum copper half-life, the initial half – life of the reduction in the ratio (copper in serum)/(coeruloplasmin in serum), the initial copper concentration in CSF or serum, the initial free copper concentration in serum, or the initial dose of penicillamine (within the first 2 months). We conclude that the normalization of the CSF copper concentration in patients with the cerebral manifestation of Wilson's disease is a slow process, even if therapy is sufficient. The initial worsening of the neurological condition which has often been reported may be reflected in the disturbance of blood-brain barrier function, which we have measured here for the first time (using the parameter of the albumin ratio CSF/serum). Based on repeated measurements of the AR during the course of treatment it seems that the brain toxicity of mobilized copper can be assessed and the therapy adjusted.

6-Hydroxydopamine toxicity towards human SH-SY5Y dopaminergic neuroblastoma cells: independent of mitochondrial energy metabolism.

Abstract: 6-Hydroxydopamine (6-OHDA) is widely used to generate animal models of Parkinson's disease. However, little is known about the intracellular events leading to cell death of dopaminergic neurones. Here we correlate indices of energy production and cell viability in human dopaminergic neuroblastoma SH-SY5Y cells after exposure to 6-OHDA. The toxin induces a time and dose-dependent decrease in cell survival with an IC50 value of 25 microM after 24 h. In contrast to the mitochondrial complex I inhibitor 1-methyl-4-phenylpyridinium (MPP+), 6-OHDA-induced reduction of cell viability is not associated with a decrease of intracellular ATP content, intracellular ATP/ADP ratio or NAD+ content. In addition, preventing or forcing glycolysis do not alter 6-OHDA toxicity. The antioxidant D-alpha-tocopherol can attenuate cell death induced by 6-OHDA. These results suggest that cell death induced by 6-OHDA is not due to an inhibition of mitochondrial energy supply, but probably involves production of free radicals.

Altered redox state of platelet coenzyme Q10 in Parkinson's disease.

Abstract: Background. The reduced form of coenzyme Q10 (CoQ10) acts as a lipophilic antioxidant and participates in electron and proton transport of the respiratory chain in the inner mitochondrial membrane. An alteration in CoQ10 redox state may thus reflect a change in membrane electron transport and the effectiveness of defense against toxic reactive oxygen species such as hydrogen peroxide and superoxide. In Parkinson's disease alterations in the activities of complex I have been reported in substantia nigra and platelets. Deficiency of mitochondrial enzyme activities could affect electron transport which might be reflected by the platelet CoQ10 redox state.

Platelet monoamine oxidase activity is related to MAOB intron 13 genotype.

Abstract: Monoamine oxidases (MAO) play a critical role in the degradation of endogenous and exogenous amines throughout the body. There are two distinct MAO isoforms, MAO-A and MAO-B, which both are encoded in genes on the X chromosome. Alterations in MAO-B activity have previously been connected with several neurological disorders. Platelet MAO (trbc-MAO) is exclusively of the B-type and the catalytic activity of this enzyme is under strong, yet unknown, genetic control. Specific trbc-MAO activity has been reported to be increased in certain neurodegenerative diseases and to correlate with personality traits such as sensation seeking and impulsiveness. In the present study, we investigated if trbc-MAO activity is associated with genotype at a variable region (A/G dimorphism) in intron 13 of the human gene encoding MAO-B. The MAOB intron 13 allele status and levels of trbc-MAO were determined for 55 Caucasian non-smoking males. Individuals with the "A-allele" displayed significantly lower enzyme activity than individuals with the "G-allele", i.e. 11.4 ± 0.6 nmol/1010 platelets/min compared with 13.5 ± 0.6 (mean ± SEM, p = 0.019). The present results suggest that the MAOB genotype may be involved in determining trbc-MAO activity.

Sexual differences and estrous cycle in methamphetamine-induced dopamine and serotonin depletions in the striatum of mice.

Abstract: Four consecutive doses (10 mg/kg) of methamphetamine, s.c., produced a substantial striatal dopamine depletion in both sexes of BALB/c and C57BL/6J mice. Male C57BL/6J mice exhibited greater dopamine depletions in the striatum compared to female C57BL/6J mice. In contrast, male and female BALB/c mice demonstrated an equivalent magnitude of striatal dopamine depletion. Regardless of sex, C57BL/6J mice demonstrated approximately 1.4 to 2.2 times greater dopamine depletions in the striatum compared to BALB/c mice. Moreover, methamphetamine caused 4 times greater serotonin depletions in male as opposed to female BALB/c mice while sparing either sex of the C57BL/6J mice. Furthermore, female mice of both strains appeared to have the greatest basal dopamine levels during proestrus and the lowest basal dopamine levels during diestrus. Likewise, female mice of both strains exhibited the lowest dopamine depletions in the striatum when the dosing regimen of methamphetamine started at proestrus whereas the greatest dopamine depletions in the striatum occurred when the regimen started during diestrus. These results suggest that sex hormones and other modulating factors may play a role in methamphetamine-induced dopamine and serotonin neurotoxicity.

Muscarinic agonists reduce tau phosphorylation in non-neuronal cells via GSK-3beta inhibition and in neurons.

Abstract: Muscarinic agonists alter the metabolism of amyloid precursor protein, leading to an increase in α-secretase cleavage and a decreased production of amyloidogenic peptides; suggesting that these compounds might modify the Alzheimer's disease process. A second therapeutic target in AD is the accumulation of stably phosphorylated tau into neurofibrillary tangles; an early event correlating with cognitive impairment. Glycogen synthase kinase-3 (GSK-3β) phosphorylates tau and is inhibited via protein kinase C (PKC). As certain muscarinic receptors are linked to PKC, we examined the effect of a range of agonists on GSK-3β phosphorylation of tau. In neurons a non-specific muscarinic agonist, carbachol, reduced tau phosphorylation. In non-neuronal cells expressing the m1 receptor a range of m1 agonists reduced transiently-expressed tau phosphorylation and altered its microtubule-binding properties. These findings link the two pathological process of AD – APP metabolism and tau phosphorylation – and suggest that muscarinic and other cholinergic compounds might have disease-modifying properties.

Vitamin E protects neurons against oxidative cell death in vitro more effectively than 17-β estradiol and induces the activity of the transcription factor NF-κB

Abstract: Antioxidants can function as powerful protectants for neurons in vitro. Here, the neuroprotective activity of lipophilic free radical scavengers synthetic (+/-) alpha-tocopherol (synthetic vitamin E) and natural (+) alpha-tocopherol (natural vitamin E) against oxidative stress was investigated and compared to the neuroprotective effect of the female sex hormone estradiol. Employing mouse clonal hippocampal HT22 cells and rat cerebellar granule neurons, we found that both types of alpha-tocopherol exerted a higher neuroprotective antioxidant activity than 17-beta estradiol. At concentrations as low as 100 nM, synthetic (+/-) alpha-tocopherol and natural (+) alpha-tocopherol protected neurons effectively against the oxidative cell death caused by the Alzheimer's disease-associated amyloid beta protein, hydrogen peroxide, and the excitatory amino acid glutamate. Moreover, vitamin E induced the activity of the redox-sensitive transcription factor NF-kappaB, which is involved in the control of nerve cell survival and, therefore, may play also a role in vitamin E-induced neuroprotection. These results may have implications regarding the prevention and treatment of oxidative stress-related degenerative disorders such as Alzheimer's disease.

Measuring the progression of idiopathic Parkinson's disease with [123I] beta-CIT SPECT.

Abstract: Idiopathic Parkinson's disease (PD) is the most common neurodegenerative disorder. An important step in diagnosing the dis-ease has been achieved with the development of the cocaine derivative [123I] β-CIT for single photon emission computed tomography (SPECT). The aim of this study was to demonstrate the disease progression by repeated measuring presynaptic dopamine transporter density and relating it to clinical data. Methods: The presynaptic dopamine transporter densitiy of 15 PD patients was measured two times with a mean interval of 15 months. All patients were clinically assessed at the time of the experiments according to the classification scheme of Hoehn and Yahr. 11 healthy volunteers were used as a control group. [123I] β-CIT was injected intravenously and measured with a triple-headed camera twenty hours later. The pictures were evaluated semiquantitatively by using the ratio of specific to non-displaceable binding. Results: Presynaptic dopamine transporter density differed significantly between controls and PD patients. A significant correlation between imaging data and clinical stages (H/Y I −27%, H/Y II −40%, H/Y III −58%) was observed for the patient group in the initial experiment. The subsequent decrease of dopamine transporter binding depended on the initial clinical stage (H/Y I −6.81%; H/Y II −6.05%; H/Y III −1.25%) of the patients, and regression analysis revealed that. 91.4% of the variance of the second measurement were predicted by the initial measurement. No correlations were found for age, gender and disease progression. All patients were treated with L-DOPA and those given a higher dose showed a more rapid decrease of dopamine transporter density. This result could be interpreted as an indication for in vivo neurotoxicity of high concentrations of L-DOPA. Conclusion: We conclude that combining [123I] β-CIT with SPECT imaging is not only a powerful tool for diagnosing PD patients, but may also be used to demonstrate neurodegeneration in vivo.

Animal models of addiction : models for therapeutic strategies?

Abstract: When having a continuous free choice in their home cages between water and alcohol- or drug-containing drinking solutions, rats first develop a controlled consumption of the psychotropic compound and, after several months, lose their control over drug taking. After a long period of abstinence, they reveal an excessive, compulsive drug intake. Adulteration of the drug-containing solutions reduces the doses taken by controlled consumers, but not those of the excessive drinkers, they can therefore be regarded as addicted. These animals show a pre-intake motor restlessness that may be related to craving. In two studies with putative anti-craving agents (the dopamine D2 receptor agonist lisuride and the D2 receptor antagonist flupentixol) we treated alcohol-addicted and non-addicted rats and observed the effects on alcohol taking, alcohol seeking and brain neurotransmission. These two investigations paralleled clinical studies, in both cases the results could be predicted correctly (“pro-craving” effect of both pharmaceutics). Differences between “symptomatic” and possible “causal” therapies are discussed, approaches towards a causal therapy according to an "imprinting"-model of an addition are suggested.

Haloperidol-induced neurotoxicity--possible implications for tardive dyskinesia.

Abstract: Tardive dyskinesia (TD) is one of the major side effects of long – term neuroleptic treatment. The pathophysiology of this disabling and commonly irreversible movement disorder is still obscure. The traditional concept of supersensitivity of striatal dopamine receptors as the mechanism involved in the development of TD is not satisfying, and current studies have focused on the role of neuroleptic – induced neuronal toxicity in the development of TD. We performed a series of experiments to gain a better understanding on the mechanisms involved in induction of TD. We have evaluated the direct neurotoxic effect of haloperidol (HP), a widely – used neuroleptic drug, and its three metabolites, in mouse neuronal cultures and in PC-12 cells.