Milacemide, the selective substrate and enzyme-activated specific inhibitor of monoamine oxidase B, increases dopamine but not serotonin in caudate nucleus of rhesus monkey

Treatment of healthy male rhesus monkeys with milacemide 2(n-pentylaminoacetamide hydrochloride, 100 mg/kg, 21 days), the specific enzyme-activated inhibitor of monoamine oxidase B, resulted in a significant increase of dopamine (DA) in the caudate nucleus. There was a concomitant reduction of dihydroxyphenylacetic acid (dopac) and homovanilic acid (HVA) in the same region. Although serotonin (5-HT) and its oxidatively deaminated metabolite, 5-hydroxyindoleacetic acid (5-HIAA) in the striatum, pons and hippocampus were unchanged, significant increases in frontal cortex, temporal cortex and visual cortex 5-HT were noted. However, noradrenaline (NA) was unchanged in the brain regions examined. The alteration in caudate nucleus dopamine metabolism, resulting from milacemide treatment can be explained by the observation that in this tissue the predominant form of monoamine oxidase (MAO) is type B. Thus, although DA is a substrate for both enzyme forms in monkey brain, similar to what has been reported in human brain, its inactivation is primarily dependent on MAO-B activity. The ability of milacemide to specifically inhibit MAO-B in the brain makes it a natural choice as adjuvant to l-dopa for the treatment of Parkinson's disease.

Non-surgical periodontal therapy influences salivary melatonin levels

OBJECTIVES

Melatonin is a hormone, which is involved in the control of the circadian rhythm, but also acts as an antioxidant and immune modulator. Previous studies reported decreased salivary and serum melatonin levels in periodontitis. This prospective cohort trial assessed the effect of non-surgical periodontal therapy on melatonin levels.

METHODS

Salivary and serum samples of 60 participants (30 patients suffering from a severe generalized form of periodontitis, 30 healthy controls) were collected at baseline and 19 samples of periodontitis patients after treatment. Salivary and serum melatonin levels were determined by a commercially available ELISA kit and serum C-reactive protein (CRP) by a routine laboratory test.

RESULTS

At baseline, periodontitis patients showed significantly increased serum CRP values and significantly decreased salivary melatonin levels compared to the control group. Clinical periodontal parameters significantly correlated with salivary melatonin levels and serum CRP. Periodontal therapy resulted in a recovery of the decreased salivary melatonin levels and a negative correlation was detected for the changes of salivary melatonin and the inflammatory parameter bleeding on probing. Serum melatonin levels showed no significant differences.

CONCLUSIONS

Salivary melatonin levels recovered after periodontal therapy and correlated with a decrease of local periodontal inflammation. This may imply the local involvement of melatonin in the pathogenesis of periodontitis due to its antioxidant abilities. However, the exact role of melatonin in periodontal disease remains to be investigated in future trials.

CLINICAL RELEVANCE

The present results suggest salivary melatonin as a risk indicator for the severity of periodontal disease.

Role of alpha adrenoceptors in the nucleus accumbens in the control of accumbal noradrenaline efflux: a microdialysis study with freely moving rats

Microdialysis technique was used to study the effects of the locally applied alpha adrenoceptor agonist phenylephrine and antagonist phentolamine on the basal noradrenaline efflux as well as on the noradrenaline uptake inhibitor desipramine-elicited noradrenaline efflux in the nucleus accumbens (NAc) of freely moving rats. Tetrodotoxin reduced basal noradrenaline efflux by 72%, whereas desipramine increased it by 204%. Phenylephrine reduced the basal noradrenaline efflux by 32% and phentolamine blocked this effect. Phentolamine elevated the basal noradrenaline efflux by 150% and phenylephrine counteracted this effect. The desipramine-elicited noradrenaline efflux was not affected by phenylephrine, but enhanced by phentolamine. Desipramine counteracted the effects of phenylephrine and potentiated those of phentolamine. These results indicate that the accumbal noradrenaline efflux is under inhibitory control of alpha adrenoceptors that are suggested to be presynaptically located on adrenergic nerve terminals in the NAc. Furthermore, this study suggests that the conformational state of alpha adrenoceptors varies across the available amount of noradrenaline. The clinical impact of these data is discussed.

Glutamate-induced cell death and formation of radicals can be reduced by lisuride in mesencephalic primary cell culture

Oxidative stress evoked by excitotoxicity is considered an important factor for the loss of dopaminergic neurons in Parkinson's disease. In vitro, protective effects of the dopamine agonist lisuride on complex I inhibition in primary dopaminergic cell culture have been reported. However, little is known about the effects of lisuride on glutamate-induced radical formation. Here, effects of lisuride on the formation of nitric oxide (NO) and superoxide radicals following glutamate exposure were studied on primary cell cultures prepared from mouse mesencephala. Glutamate treatment resulted in doubling of NO and superoxide radical formation, increased dopaminergic cell degeneration and extensively altered neuronal appearance. Pretreatment with lisuride significantly lowered the levels of either reactive species and increased the survival of dopaminergic neurons compared to glutamate-treated cultures. Moreover, the beneficial effect of lisuride could be completely inhibited by the D2/D3 receptor antagonist sulpiride when co-treated in cultures.

Synergistic effect of α-dihydroergocryptine and L-dopa or dopamine on dopaminergic neurons in primary culture

There is an ongoing controversy about potential toxicity of L-3,4-dihydroxyphenylalanine (L-dopa) to dopaminergic neurons in Parkinson's disease (PD). Neuroimaging data suggest that L-dopa accelerates the loss of dopamine nerve terminals, especially at higher doses. The disputed aspect of toxicity and the frequently observed motor complications accompanying L-dopa therapy have led to an increased use of dopamine agonists during the past two decades. Reports describing their neuroprotective potential to dopaminergic neurons have attracted much attention. Here, we describe the novel finding that the combination of a dopamine (DA) agonist, alpha-dihydroergocryptine (DHEC), with L-dopa or DA exerts a synergistic stimulatory effect on dopaminergic neurons in primary culture, while each substance alone had no or less effect. DA receptor stimulation plays a decisive role. The synergistic effect suggests that a combinatory therapy can be beneficial to slow the degeneration of dopaminergic neurons.

Oxidative stress to dopaminergic neurons as models of Parkinson's disease

The effects of exogenous toxins (MPP(+), rotenone) and potentially neurotoxic properties of levodopa (L-DOPA) on the survival rate of dopaminergic neurons in dissociated primary culture are presented. Dopamine agonists show a capacity to counteract MPP(+)-toxicity. Moreover, a preserving potential of the antioxidant and bioenergetic coenzyme Q(10) (CoQ(10)) on the activities of tyrosine hydroxylase (TH), complexes I and II of the respiratory chain, and hexokinase activity in striatal slice cultures against MPP(+) is demonstrated.

Ginsenosides Rb1 and Rg1 effects on survival and neurite growth of MPP+-affected mesencephalic dopaminergic cells

Ginsenosides Rb1 and Rg1 are the main active ingredients of Panax ginseng C.A. Meyer (Araliaceae). They appear to exert protection against ischaemia and anoxic damage in animal models, suggesting an antioxidative and cytoprotective role. In our study, primary cultures from embryonic mouse mesencephalon are applied to examine the effects of these two ginsenosides on neuritic growth of dopaminergic cells and their survival affected by 1-methyl-4-phenylpyridinium-iodide (MPP(+)). Ginsenoside Rb1 (at 10 microM) enhanced the survival of dopaminergic neurons by 19% compared to untreated control. MPP(+) (at 1 microM) significantly reduced the number of dopaminergic neurons and severely affected neuronal processes. Both ginsenosides counteracted these degenerations and significantly protected lengths and numbers of neurites of TH(+) cells. Both compounds however could not prevent the cell loss caused by MPP(+). Our study thus indicates partial neurotrophic and neuroprotective actions of ginsenosides Rb1 and Rg1 in dopaminergic cell culture.

Pergolide protects dopaminergic neurons in primary culture under stress conditions

Dopamine agonists are an important therapeutic strategy in the treatment of Parkinson's disease. They postpone the necessity for and reduce the required dose of L-3,4-dihydroxyphenylalanine (L-DOPA) medication thus protecting against the development of motor complications and potential oxidative stress due to L-DOPA metabolism. In primary cultures from mouse mesencephalon we show that pergolide, a preferential D(2) agonist enhanced the survival of healthy dopaminergic neurons at low concentrations of 0.001 microM. About 100 fold higher concentrations (0.1 microM) were necessary to partially reverse the toxic effects of 10 microM 1-methyl-4-phenylpyridinium (MPP(+)). Pergolide was equally effective in preventing the reduction of dopamine uptake induced by 200 microM L-DOPA. Furthermore, between 0.001-0.1 microM it also reduced lactate production thus promoting aerobic metabolism. The present findings suggest that pergolide protects dopaminergic neurons under conditions of elevated oxidative stress.

Synthetic neuromelanin is toxic to dopaminergic cell cultures

In the present study, primary cultures of mesencephalic dopaminergic cells were exposed to synthetic dopamine neuromelanin (NM) for 48 hrs at concentrations of 0, 1, 10, 20, 50 and 100 microg NM/ml medium. Differently prepared synthetic NM with or without incorporated iron and NM oxidatively damaged by hydrogen peroxide were used. All NMs affected cellular structures e.g. as swelling of neural processes, rounding of cells, and occasional inclusion of neuromelanin particles. Cell numbers were uniformly and dose dependently reduced. Exposure to MPP(+) and ferric iron led to cytotoxic changes which could be further aggravated by oxidatively damaged NM, suggesting cytotoxicity of soluble compounds of NM in predamaged neurons.

Protection of dopaminergic neurons in primary culture by lisuride

Dopamine agonists play an important role in the treatment of Parkinson's disease by reducing the administration of L-3,4-dihydroxyphenylalanine (L-DOPA). The enzymatic and non-enzymatic conversion of L-DOPA is suspected to increase oxidative stress, which leads to the degeneration of dopaminergic neurons in Parkinson's disease. In primary mouse mesencephalic cultures we show that the dopamine D1/D2 receptor agonist lisuride, in a concentration range of 0.001-1 microM, enhances the survival of dopaminergic neurons, protects against toxicity induced by L-DOPA or 1-methyl-4-phenylpyridinium ion (MPP+) and stimulates 3H-dopamine uptake. Lisuride also reduces anaerobic metabolism during incubation with L-DOPA. The present findings suggest that lisuride may have trophic/survival-promoting properties and potentially reduces oxidative stress.

Reduction of Menkes mRNA and copper in leukocytes of patients with primary adult-onset dystonia

Studies on postmortem tissue of patients with primary adult-onset dystonia revealed a significant increase in copper levels and a reduction of copper transporting Menkes protein of the lentiform nuclei. Here we demonstrate that patients with idiopathic adult-onset cervical dystonia (n = 14) have reduced Menkes mRNA copies and lower copper levels in leukocytes compared to controls (n = 17; U test, p < 0.05). Changes were less distinct in patients with blepharospasm. Therefore, disturbances of copper metabolism in focal dystonia may not be restricted to the basal ganglia.

The industrial chemical Tinuvin 123 does not induce dopaminergic neurotoxicity in C57Bl/6 mice

We have investigated the acute effects of systemic administration of Tinuvin 123 on nigro-striatal dopaminergic neurons in the C57Bl/6 mouse. Tinuvin 123 was administered subcutaneously (s.c.) twice, 16 h apart, at doses of 0, 2, 20 or 200 mg/kg body weight to a total of 48 male C57Bl/6 mice (12 animals/group). Seven days following the last dose the animals were decapitated and the brains removed. No deaths occurred during the study. There were no differences between the mean body weights of any of the experimental groups prior to or following Tinuvin 123 treatment. Animals treated s.c. with 2 mg/kg Tinuvin 123 exhibited no changes in striatal dopamine or metabolite concentrations compared with vehicle-treated animals. Higher doses of Tinuvin 123 (20 and 200 mg/kg) resulted in a moderate loss of striatal dopamine (31 and 38%) but concentrations of the dopamine metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid and the neurotransmitters serotonin, aspartate, gamma aminobutyric acid and glutamate were unchanged. The total number of tyrosine hydroxylase-immunoreactive neurons in the entire substantia nigra were equivalent in the vehicle- and Tinuvin 123-treated animals at all doses, thus no neuronal loss was demonstrated. In conclusion, this study demonstrates no evidence that systemic administered Tinuvin 123 induces dopaminergic neurotoxicity in C57Bl/6 mice.

Increased tissue copper and manganese content in the lentiform nucleus in primary adult-onset dystonia

We analyzed trace metals in frozen brain tissue of several subcortical nuclei from 3 patients with primary adult-onset dystonia and 10 control subjects. Copper levels were significantly increased in the globus pallidus and putamen of patients with dystonia A slight increase in manganese content was identified in the putamen and thalamus of patients with dystonia. Our findings show for the first time an accumulation of trace metals in the lentiform nuclei in patients with primary dystonia, which may play a pathogenetic role in primary dystonia and may explain recent ultrasound and magnetic resonance imaging findings.

Iron accumulation in the substantia nigra in rats visualized by ultrasound

In recent studies, we have found a marked increase in substantia nigra (SN) echogenicity in patients with Parkinson's disease (PD) using transcranial ultrasound. Because a substantial body of evidence has accumulated indicating a selective elevation of iron in the SN from patients with PD, we set out to test the hypothesis that trace metals like iron could lead to the observed increase of SN echogenicity in PD. Rat brains were scanned after stereotactic injection of iron in different concentrations into the SN and after injecting ferritin, zinc and 6-OHDA alone, and after the addition of desferrioxamine. The amount of iron in the SN was measured spectroscopically. For iron, and partly for 6-OHDA, in different concentrations, a dose-dependent increase of SN echogenicity could be visualized, corresponding to an increase of iron measured by spectroscopy. No increase of echogenicity was visualized after the injection of ferritin and the addition of desferrioxamine to 6-OHDA, though an increase of iron was measured by spectroscopy. Therefore, we conclude that iron not bound to these proteins may lead to an increase of echogenicity of the SN.

Inverse hierarchy of vimentin epitope expression in primary cultures of chicken and rat astrocytes: a double-immunofluorescence study

Vimentin contributes to the cytoskeleton of different cell-types, among them glial cells. We report here that different forms of this protein, distinguishable by the monoclonal antibodies Vim3B4 and V9, are species-specifically expressed in cultures of glial fibrillary acidic protein (GFAP) positive, primary astrocytes of the chicken and rat. Most cells in the cultures co-expressed GFAP and one of the two vimentin epitopes. The Vim3B4 positive epitope was present in chicken astrocytes, while the V9 positive was not. Inverse situation was found in the astrocytes of rat. In vitro age of the cells did not influence the hierarchy of vimentin epitope expression with respect to species-specificity. Our result shows that the different vimentin expression program of cultured astrocytes of the chicken and rat is preserved under in vitro conditions. The presented data support the concept of the species-specific regulation of vimentin forms in glial cells of the central nervous system.

Comparison of substance P concentration in acupuncture points in different tissues in dogs

Histologically, acupuncture points show neuronal innervation. One hundred seventy-seven tissue samples of acupuncture points and control points from 4 dogs were collected. Concentrations of substance P, a neurotransmitter, in the skin, muscle and subcutis of acupuncture points and control points were measured by means of enzyme immunoassay. The determined tissue concentrations of substance P (mean +/- SEM) in acupuncture points and control points were 1.81 +/- 0.13 and 1.51 +/- 0.1 ng/g in the muscle, 3.33 +/- 0.29 and 2.63 +/- 0.28 ng/g in the skin and 1.59 +/- 0.22 and 1.32 +/- 0.16 ng/g in the subcutis, respectively. The results indicate that there is a difference in the neurochemical profile between acupuncture points and control points.

Characteristics of fetal heart rate changes during the expulsive stage of bovine parturition in relation to fetal outcome

OBJECTIVE

To characterize fetal heart rate (FHR) patterns of nonacidotic (N-AC) and acidotic (AC) calves during the expulsive stage of parturition.

ANIMALS

32 calves born to heifers, either unassisted or by moderate traction.

PROCEDURE

Cardiotocograms (CTG) evaluated qualitatively (visual) and quantitatively by a moving window technique (width 10, shift 5 minutes) for baseline FHR, variability, and periodic alterations (accelerations and decelerations).

RESULTS

Significant differences were apparent between increase in baseline FHR of N-AC and AC calves; change in FHR (delta-FHR), taking into account individual FHR, is a more discriminating parameter. The predominant reaction to uterine contraction is a decrease in FHR; variable decelerations were the most common type in both groups, and late decelerations were seen only in AC calves. Additional characteristics of variable decelerations were more frequently seen in AC calves.

CONCLUSIONS

CTG parameters during expulsion can discriminate between AC and N-AC calves, but specific characteristics are not exclusively restricted to AC or N-AC calves.

CLINICAL RELEVANCE

CTG recordings during bovine parturition in cattle provide information on the fetal condition and can be used in the future to study the effects of medication and manipulations to the fetus.

Selegiline is neuroprotective in primary brain cultures treated with 1-methyl-4-phenylpyridinium

The ability of selegiline to protect against the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been attributed to the inhibition of the conversion of MPTP to 1-methyl-4-phenylpyridinium (MPP+), catalyzed by monoamine oxidase-B. Selegiline, however, has been found to rescue neurons in MPP(+)-treated mice after they have sustained lethal damage independently of monoamine oxidase-B inhibition. In our present study, we investigate whether selegiline can protect and/or rescue MPP(+)-injured dopaminergic neurons in co-cultures of mesencephalic and striatal cells of embryonic C57B1/6 mouse brains. Cells were exposed to selegiline (1, 10, 100 microM) in three different schemes: (i) in control cultures on the 8th day for 48 h; (ii) pretreatment: on the 8th day for 48 h, followed by administration of MPP+ (0.5 microM) on the 9th day for 24 h; (iii) delayed treatment: on the 9th day for 48 h, while MPP+ was administered on the 8th day and remained in culture during treatment with selegiline. In the delayed scheme, selegiline (1 microM) increased dopamine content, number of tyrosine hydroxylase immunoreactive cells and astrocytes in the cultures. We question whether selegiline protects cells injured by a toxic stressor via an astrocyte-mediated mechanism.

MPP+ selectively affects calcium homeostasis in mesencephalic cell cultures from embryonal C57/Bl6 mice

1-Methyl-4-phenylpyridinium (MPP+), the active metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) serves as a valuable tool in animal models of Parkinson's disease. Primary cell cultures of mesencephalon from C57/Bl6 mice were used to investigate the effects of various dopaminergic neurotoxins on the intracellular calcium metabolism. MPP+ was compared to its precursor MPTP and a structural analogue paraquat (methylviologen). Direct addition of these neurotoxins (10 microM) to fura-2-labeled cells did not change intracellular calcium concentrations in the presence of 1 mM extracellular calcium. When mesencephalic neurons were exposed to the compounds for 24 hours, only MPP+ led to an increase in calcium concentration in the absence and presence of extracellular calcium (36%, p < 0.05 and 47%, p < 0.01 versus control group). Intracellular calcium concentrations in cortical cultures devoid of dopaminergic cells were not changed by the above neurotoxins. Thus MPP+ is shown to selectively increase intracellular calcium concentrations in mesencephalic cultures.

A morphometric analysis of bipolar and multipolar TH-IR neurons treated with the neurotoxin MPP+ in co-cultures from mesencephalon and striatum of embryonic C57BL/6 mice

Mesencephalic cultures contain two morphologically different tyrosine hydroxylase (TH)-immunoreactive (IR) neurons, fusiform bipolar, and pyramidal multipolar, which project to different anatomical structures (ventral striatum and neostriatum). The possibility of functional difference of these cells in Parkinson's disease led us study the effect of 1-methyl-4-phenylpyridinium (MPP+) on them. Survival and morphology of the two groups was studied in dissociated co-cultures from mesencephalon and striatum of embryonic C57BL/6 mice. Cells were grown at first in serum containing medium and then in serum free medium supplemented with hormones. Cultures were exposed to different concentrations of MPP+ on day 9 and 13 for 24 hr. They were fixed and stained with an anti-TH antibody. 0.1-1.0 microM MPP+ caused a dramatic reduction of the total area of TH-IR neurons. At 0.1 microM MPP+ some area was reduced, at 0.5 microM it appeared similar to controls, and decreased further at 1.0 microM. The relation of soma to total area showed that the decrease of the neuronal size was mainly due to the degeneration of the neuronal processes. The length of neuronal tree as well as the number of terminal segments were reduced dose dependently when cells were treated with the toxin. Similar results were obtained for bipolar and multipolar neurons. A significant difference in the decrease in total area was observed between the two age groups when cells were treated with MPP+, as older cells appeared to be more sensitive. When other parameters were checked no apparent difference was present.

Long-term behavioural effects of TaClo (1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline) after subchronic treatment in rats

1-Trichloromethyl-1,2,3,4-tetrahydro-beta-carboline (TaClo), which shows a great structural similarity to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), when administered to rats lead to enhanced spontaneous locomotion when they were tested 4-9 days after subchronic injection at a daily dose of 0.2 mg/kg over a seven week period. However, 9 weeks after the end of the course of injections animals walked more slowly during 12 hours of nocturnal activity, and apomorphine-induced locomotion was decreased 12 weeks later. These results suggest that the drug may exert a progressive neurotoxic effect.

Selegiline enhances survival and neurite outgrowth of MPP(+)-treated dopaminergic neurons

Selegiline was added to co-cultures of mesencephalon and neostriatum of C57BL/6 mouse embryos according to three schemes: (i) before and (ii) after cells were exposed to the toxin 1-methyl-4-phenylpyridinium (MPP+), (iii) in control cultures. In all schemes, selegiline enhanced the morphological differentiation of dopaminergic neurons and with delayed treatment, significantly increased their survival. These results indicate that selegiline exhibits trophic-like actions and can rescue MPP(+)-injured dopaminergic neurons in cultures.

Iron, copper, zinc, magnesium, and calcium in postmortem brain tissue from schizophrenic patients

The regional distribution of iron, copper, zinc, magnesium, and calcium in postmortem brain of schizophrenic patients was compared with that of matched controls. In none of the brain regions investigated (caudate nucleus, hippocampus, amygdala, cortex, corpus mamillare, gyrus cinguli, and hypothalamus) were significant differences observed between these two groups. In the total group, region-specific differences were found for iron, copper, zinc, and calcium, but not for magnesium. Gender differences were observed only for zinc. There was no correlation between a neuroleptic-free period before death and the content of any of the metals investigated, except for a positive correlation between copper in the hippocampus and a neuroleptic-free period. The results of the present study suggest that there are no profound differences in the content of iron, copper, zinc, magnesium, and calcium in postmortem brains between controls and schizophrenic patients.

Effect of lipoic acid on redox state of coenzyme Q in mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and diethyldithiocarbamate

We investigated the effects of a combined treatment of male C57Bl/6 mice with diethyldithiocarbamate and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in the absence or presence of different forms of lipoic acid (Thioctacid TR; commonly used for treatment of diabetic polyneuropathies) on levels and redox states of alpha-tocopherol and coenzyme Q in vivo and on activities of various enzymes of energy metabolism ex vivo. Treatment of mice with diethyldithiocarbamate plus MPTP resulted in a decrease in dopamine (67%) and its major metabolites dihydroxyphenylacetic acid (38%) and homovanillic acid (37%) in striatum. alpha-Tocopherol levels were unaltered in striatum; however, the reduced forms of coenzyme Q were decreased in frontal cortex and hippocampus following diethyldithiocarbamate plus MPTP. In frontal cortex activity of NADH dehydrogenase was significantly inhibited by diethyldithiocarbamate plus MPTP ex vivo, suggesting that the neurotoxic metabolite of MPTP, 1-methyl-4-phenylpyridinium ion, is acting in brain regions other than striatum as well. Lipoic acid, administered 6 times, each at 90 min prior to MPTP, could not restore dopamine in striatum but in contrast maintained a normal ratio of the reduced form to the oxidized form of coenzyme Q, suggesting an interaction of lipoic acid with energy metabolism which seems, however, not only to be due to an activation of pyruvate dehydrogenase.

Functional changes in cocultures of mesencephalon and striatal neurons from embryonic C57/BL6 mice due to low concentrations of 1-methyl-4-phenylpyridinium (MPP+)

1-Methyl-4-phenylpyridinium (MPP+), the active metabolite of 1-Methyl-4-phenyl-1,2,3, 6-tetrahydropyridine (MPTP) is taken up into dopaminergic terminals and selectively destroys dopaminergic neurons, serving as a valuable tool in animal model of Parkinson's disease. Cocultures from ventral mesencephalon and neostriatum of embryonic C57/BL6 mouse brains were used to study the sensitivity of dopaminergic neurons to the toxic agent MPP+. Cultures were grown for 9 days in vitro and exposed to different concentrations of MPP+ for various times. Treatment with (0.1-1.0 microM) MPP+ for 24 hours decreased 3H-dopamine (3H-DA) uptake with an IC50 at 0.2 microM. Exposure of cells to 1 microM MPP+ over time decreased the 3H-DA uptake to 38% of controls within the first two hours of incubation and to 8% after 48 hours. Loss of tyrosine hydroxylase (TH) positive cells became evident at 0.1 microM MPP+ (80% of control) leading to maximal toxicity at 10 microM (20% of control). MPP+ reduced the dopamine content in the cultures in a dose dependent manner (IC50 at 0.1 microM) and failed to show reversibility in recovery studies. These findings provide evidence that exposure of MPP+ even at low concentrations and for short time in our coculture model results in irreversible toxicity for dopaminergic neurons.

Influence of labor and neonatal hypoxia on sympathoadrenal activation and methionine enkephalin release in calves

Labor and delivery stimulate increased release of catecholamines and endogenous opioid peptides in neonates. Catecholamines promote adaptation to the extrauterine environment after birth. Enkephalins are stored together with catecholamines in the adrenal medulla and have an inhibitory effect on catecholamine release. We investigated the influence of labor and neonatal hypoxia on epinephrine, norepinephrine, and met-enkephalin release in calves. Blood samples were taken from the umbilical artery before rupture of the umbilical cord and from the jugular vein repeatedly after birth. Highest plasma norepinephrine concentration was found in calves delivered at the end of gestation (term calves) before umbilical cord rupture. In calves delivered before the physiologic end of gestation (preterm calves), norepinephrine values increased after cord rupture, but remained lower than values in term calves. Epinephrine release followed a similar pattern, but norepinephrine was clearly predominant. In term calves, met-enkephalin values were significantly higher than values in preterm calves. In calves of both groups, met-enkephalin release increased after cord rupture. During birth, the increase in catecholamine release seems to take place earlier than that of enkephalins. Norepinephrine-dominated stimulation during expulsion of the calf might be followed by increasing enkephalinergic inhibition after cord rupture and onset of respiration. Reduced release of catecholamines and enkephalins in preterm calves may be connected with delayed adaptation to the extrauterine environment.

Effects of L-deprenyl and amantadine in an MPTP-model of parkinsonism

Mongolian gerbils of both sexes received a single daily dose of 40 mg/kg of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) over 4 consecutive days. On the fifth day the animals were treated with 15 mg/kg i.p. of L-deprenyl or amantadine or the combination of both drugs. At different time intervals (1, 2, 5 hours) the animals were sacrificed. In the caudate nuclei dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) were measured by an HPLC technique. MPTP affected the dopaminergic (HVA -25%) as well as the serotoninergic system (5-HT -54%, 5-HIAA -31%). L-deprenyl and amantadine accumulated DA and 5-HT in the MPTP affected caudates. Synergistic effects of the drug combination could be proven.

[Catecholamine and cortisol concentrations in plasma from cattle at parturition]

Cows with spontaneous parturition (n = 8) and cows with flumethasone (n = 3) or prostaglandin (n = 3) induced parturition were used in this study. Catecholamine concentrations from cows in the periparturient period were measured in order to evaluate the stress of birth on the dam and the calf. The plasma content of both norepinephrine and epinephrine in late pregnancy was not different from control values in the 3rd to 6th month of pregnancy (norepinephrine 3.27 +/- 0.99 nmol/l plasma and epinephrine 0.98 +/- 0.45 nmol/l plasma), though both parameters appear elevated in the pregnant group. Norepinephrine concentrations rose to a value of 4.50 nmol/l immediately after birth, whereas epinephrine levels did not show an increase post partum. In two neonates norepinephrine and epinephrine values were 2-3 times higher than in the dams and decreased to the values of the dams within 48 hours. Synthetic glucocorticoids can mimic the increase of cortisol, which leads to birth. Cortisol concentrations in the cows remained unaffected by induction of parturition by prostaglandins. Newborn calves showed values of about 330 nmol/l, which also declined within 48 hours to values similar to those measured in the dam (9-28 nmol/l). As stress and exogenous glucocorticoids may affect antibody production, the IgG-content of the colostrum was examined. Prostaglandin induction of birth did not alter the IgG-content of colostrum, but flumethasone produced a decrease of about 14.5%. It is therefore concluded that pre-term birth induction does not produce negative effects on the supply of IgG.

Transition metals, ferritin, glutathione, and ascorbic acid in parkinsonian brains

The regional distributions of iron, copper, zinc, magnesium, and calcium in parkinsonian brains were compared with those of matched controls. In mild Parkinson's disease (PD), there were no significant differences in the content of total iron between the two groups, whereas there was a significant increase in total iron and iron (III) in substantia nigra of severely affected patients. Although marked regional distributions of iron, magnesium, and calcium were present, there were no changes in magnesium, calcium, and copper in various brain areas of PD. The most notable finding was a shift in the iron (II)/iron (III) ratio in favor of iron (III) in substantia nigra and a significant increase in the iron (III)-binding, protein, ferritin. A significantly lower glutathione content was present in pooled samples of putamen, globus pallidus, substantia nigra, nucleus basalis of Meynert, amygdaloid nucleus, and frontal cortex of PD brains with severe damage to substantia nigra, whereas no significant changes were observed in clinicopathologically mild forms of PD. In all these regions, except the amygdaloid nucleus, ascorbic acid was not decreased. Reduced glutathione and the shift of the iron (II)/iron (III) ratio in favor of iron (III) suggest that these changes might contribute to pathophysiological processes underlying PD.

Tyrosine hydroxylase activity in caudate nucleus from Parkinson's disease: effects of iron and phosphorylating agents

Tyrosine hydroxylase (TH) activity of human postmortem brain tissues from controls and patients with Parkinson's disease (PD) was examined in the presence of Fe2+ and phosphorylation agents, such as cyclic AMP, exogenous protein kinase, calcium plus calmodulin (Ca2+-CaM), and ATP. TH activity from parkinsonian tissue was increased by 48% with statistical significance in the presence of exogenous protein kinase. Cyclic AMP alone had no effect, whereas Ca2+-CaM increased the activity by only 10%. The presence of acetylcholine resulted in a slight decrease in enzyme activity. Human TH was stimulated 13.17-fold in the presence of 1 mM Fe2+. For iron dependence, no significant differences could be shown for the Km values of TH in striata of PD, while the activity of TH was half of that of controls. Here stimulation with 1 mM Fe2+ raised the activity of TH 11-fold. Stimulation of rat, gerbil, pig, and human caudate nucleus TH with Fe2+ shows remarkable species differences. In particular, the sensitivity of human TH to stimulating processes is noteworthy. H2O2 decreases TH activity only at high concentrations. Species differences are noted for the combined incubation of Fe2+ and H2O2. In the gerbil caudate nucleus, H2O2 does not prevent the stimulating properties of Fe2+, while the pig shows a dose-dependent decline of TH activity. In conclusion, there are no significant changes in the stimulating properties of human caudate nucleus TH activity with Fe2+ in PD, while such differences are noted by using exogenous protein kinase. Furthermore, experimental evidence shows that TH activity declines at high concentrations of H2O2 only. Potentiation of this effect by Fe2+ seems to be species-dependent.

[Changes in organic acids in plasma and cerebrospinal fluid in cerebral infarct]

Seventeen patients with recent cerebral infarction were included in the study. The general condition of the patients was evaluated within 3 days after the incidence (rating 1) and 7-9 days after the incidence (rating 2) using a clinical rating scale for internal, psychiatric and neurological findings. The statistical evaluation showed a clinical improvement of the score of 32%. The extent of the brain lesions was determined by cranial computed tomography. Routine analysis of the cerebrospinal fluid included determination of protein, cell count, cell type, glucose, lactic acid, and hemoglobin. In addition, spinal fluid and serum concentration of pyruvic acid, citric acid, fumaric acid, alpha-ketoglutaric acid and alpha-keto-beta-methylvaleric acid (3-MKV) were determined at the two rating times. CSF and serum values of fumaric acid, 3-MKV and pyruvic acid correlated at rating 1, while at rating 2 a correlation existed only for fumaric acid. A trend analysis infarction - postinfarction period showed the concentration of all metabolites to decrease significantly. This is interpreted as a reconstitution of the initially disturbed blood brain barrier function.

[Metabolic changes in ischemic brain infarct]

Serum and cerebrospinal fluid (CSF) from 17 patients less than 3 days after brain infarction (measurement 1) and during recovery 7 +/- 2 days after infarction (measurement 2) were analysed for organic acids (energy metabolites, keto acids and amino acids). Clinical parameters improved by 32% over the period of assessment. Only serum pyruvate levels were elevated at both measurement times. Acute infarction was characterized by significant correspondence of serum and CSF concentrations for pyruvate and alpha-oxo-beta-methyl valeric acid which was lost during the recovery period. Amino acids of the L-system were roughly doubled (phenylalanine 7-fold in the CSF); increased concentrations were recorded for amino acids of the basic transport system, while amino acids of the A-system stayed unchanged (with the exception of alpha-amino butyric acid--20-fold in CSF). Except in the case of taurine, serum and CSF amino acid concentrations remained unchanged between the two measurement times. Mutual dependence of CSF and serum amino acid concentrations, existing initially for glycine, valine, leucine, tyrosine, as well as ornithine, lysine and histidine was lost in the recovery phase. This is interpreted as indication of a normalization of the blood-brain barrier.

Dopamine metabolism in human brain: effect of monoamine oxidase inhibition in vitro by (-)deprenyl and (+) and (-) tranylcypromine

The effects of the monoamine oxidase inhibitors (-)deprenyl and (+)-and (-)tranylcypromine on dopamine oxidation in human caudate have been investigated. Oxidation of dopamine has been found to exhibit both (-)deprenyl-sensitive and -insensitive components. The tranylcypromine isomers are both more sensitive towards dopamine than 5-hydroxytryptamine oxidation, (+) isomer being the more effective of the two. These results are discussed in terms of the in vivo action of the drugs and their therapeutic value.