Cabergoline protects dopaminergic neurons against rotenone-induced cell death in primary mesencephalic cell culture.

In the present study, primary mesencephalic cell cultures prepared from embryonic mouse mesencephala were used to investigate the neuroprotective effect of cabergoline, an ergoline D2 receptor agonist, against the pesticide and neurotoxin rotenone relevant to Parkinson disease (PD). Treatment of cultures with cabergoline alone significantly increased the number of tyrosine hydroxylase immunoreactive (THir) neurons and reduced the release of lactate dehydrogenase (LDH) into the culture medium compared to untreated controls. Against rotenone toxicity, cabergoline significantly rescued degenerating THir neurons, reduced the release of LDH into the culture medium and improved the morphology of surviving THir neurons. The neuroprotective effects afforded by cabergoline were independent of dopaminergic stimulation as blocking of dopamine receptors by the dopamine receptor antagonist sulpiride did not prevent them. Furthermore, rotenone-induced formation of reactive oxygen species (ROS) was significantly reduced by cabergoline. Although cabergoline increased the glutathione (GSH) content in the culture, the protective effect for dopaminergic neurons seemed not to be predominantly mediated by increasing GSH, as depletion of GSH by L-buthionine-(S,R)-sulfoximine (BSO), a GSH biosynthesis inhibitor, did not prevent cabergoline-mediated neuroprotection of THir neurons in rotenone-treated cultures. Moreover, cabergoline significantly increased the ATP/protein ratio in primary mesencephalic cell cultures when added alone or prior to rotenone treatment. These results indicate a neuroprotective effect of cabergoline for dopaminergic neurons against rotenone toxicity. This effect was independent of dopamine receptor stimulation and was at least partially mediated by reducing ROS production and increasing the ATP/protein ratio.

[Consultation hours for adolescent males: because men's health begins in adolescence]. / Jungensprechstunde : Weil Männergesundheit bei Jungengesundheit anfängt.

BACKGROUND: Young men are underrepresented in terms of offers concerning primary and secondary prevention in medicine. As a consequence, urologists often only see boys and young men from the perspective of missed prevention. AIM: What should an offer for boys and young men look like in a urologist's practice that focuses on the physical, social and sexual health of boys and young men? The author draws analogies for the establishment of consultation hours for young men in a urologist's practice based on her successful establishment of consultation hours for girls in a gynecologist's practice. RESULTS: Due to acceleration, boys also enter puberty early today. Because of their lack of knowledge about the changes in their body, they can be described as overnewsed and underinformed, despite their intense media consumption. This mixture of half-knowledge, coolness, sexual curiosity and lack of ability for predictive planning and action prevents boys and young men from having the knowledge they need to adequately and responsibly deal with their physical, social and sexual health care. CONCLUSION: If boys and young men had the opportunity to learn, appreciate, and protect their bodies at an early stage through competent preventive offers in the urologist's practice, then they would also experience less stress and powerlessness. In addition, it is almost certain that solid, fundamental understanding concerning their health will also lead to specific effects in male health competence. Only in this manner can young men be made ​​aware of the preventive services in a urological practice and can be a partner in other medically necessary decision-making processes.

Sexual behaviour and Chlamydia trachomatis infections in German female urban adolescents, 2004.

This ad-hoc observational study, conducted in the metropolitan area of Berlin during 2004, revealed that the prevalence of Chlamydia trachomatis (CT) infections in female urban adolescents self-presenting at their gynaecologist without (n=397) or with (n=124) symptoms of CT infection was 5.5% (95% CI 3.7-8.2%) and 9.7% (95% CI 5.6-16.2%), respectively. The prevalence of CT infection was significantly dependent on the number of lifetime sexual partners. Condom use was inconsistent, and lack of knowledge about CT infections and associated health risks predominated in this cohort. The data indicated a need for health education concerning CT to be targeted at female adolescents.

[Chlamydia trachomatis infections in teenagers]. / Chlamydia-trachomatis-Infektionen bei Teenagern.

Adolescents enter puberty early and many have sexual intercourse at a young age. That sexual intercourse can have side effects with life-long consequences is still a taboo field. In Germany, we do not have figures about the prevalence of the most frequently occurring sexually transmitted diseases in young people. Therefore the Medical Association for the Promotion of Women's Health (AGGF) initiated a prevalence study on infection with Chlamydia trachomatis (CT) in girls younger than 18 years in Berlin (n=266). After informed consent, information was given in 92 school classes. Thereafter in 30 offices of gynecologists the girls were offered a PCR test for the detection of CT free of charge. The results--10% of the 17-year-old girls had an acute chlamydial infection after an average of 19 months of sexual activity--suggest that in Germany there is a hidden epidemic among adolescents. Adolescents are not adequately informed about the risks of CT infection; medical counseling is both desired and effective.

2,9-Dimethyl-beta-carbolinium, a neurotoxin occurring in human brain, is a potent inducer of apoptosis as 1-methyl-4-phenylpyridinium.

The causes of neurodegeneration are not well understood. However, the role of environmental and endogenous toxins is receiving much attention. In this study, we compared the synthetic neurotoxin 1-methyl-4-phenyl-pyridinium with beta-carbolines occurring in human brain. Methylation of both nitrogens is necessary to convert a beta-carboline into a potent inhibitor of mitochondrial complex I. The respective beta-carboline, 2,9-dimethyl-beta-carbolinium ion is neurotoxic in rats. To investigate the underlying mechanisms, we incubated mouse neuroblastoma 2A cells with 2,9-dimethyl-beta-carbolinium ion, and compared the findings with effects of norharman, the precursor beta-carboline of methylated derivatives, and with 1-methyl-4-phenyl-pyridinium. 2,9-Dimethyl-beta-carbolinium ion caused a significant increase of reactive oxygen species (higher efficiency than 1-methyl-4-phenyl-pyridinium) and of mitochondrial membrane potential within the first minutes. After 60 min, the membrane potential dissipated. Concomitantly, the levels of glutathione increased in 2,9-dimethyl-beta-carbolinium ion but not in 1-methyl-4-phenyl-pyridinium treated cells. After 24 h effector caspases 3 and 7 were activated and the number of apoptotic cells increased as revealed by fluorescence-activated cell sorting cytometry. When incubated longer (48 h), cells underwent late apoptosis/secondary necrosis as shown by fluorescence-activated cell sorting analysis and confirmed qualitatively by an electron microscopy study. The effects of 2,9-dimethyl-beta-carbolinium ion on apoptotic changes were similar to those induced by 1-methyl-4-phenyl-pyridinium(,) while norharman showed only a weak potency at the very high doses. To investigate whether 2,9-dimethyl-beta-carbolinium ion is neurotoxic under in vivo conditions and whether only dopaminergic neurones are affected we conducted a dose-response study. Three weeks after injection of 2,9-dimethyl-beta-carbolinium ion in the substantia nigra we found a dose-dependent decrease of dopamine and its metabolites in the striatum of rats. The levels of 5-hydroxytryptamine were diminished although the decrease was less. The levels of noradrenaline increased after some doses. The findings strongly suggest an important role of endogenous beta-carbolines in neurodegeneration with apoptosis as the predominant mechanism.

Microarray analysis reveals distinct gene expression patterns in the mouse cortex following chronic neuroleptic and stimulant treatment: implications for body weight changes.

Atypical neuroleptics are associated with clinical significant weight gain, whereas stimulants are used as anorexiant drugs. The aim of this study was to examine gene expression changes in the mouse frontal cortex following chronic oral treatment with antipsychotics and a stimulant by microarray assessments. Twenty 10-12-week-old male C57BL6 mice received daily for 31 days either the typical neuroleptic haloperidol (1 mg/kg), the atypical neuroleptic clozapine (10 mg/kg) or the stimulant phenylpropanolamine (3 mg/kg). We identified a set of genes that was differently expressed between the neuroleptic-treated groups and the stimulant-treated group. Importantly, we found in the majority of gene alterations down-regulation in genes involved in ATP biosynthesis and lipid metabolism following the stimulant treatment, suggesting these genes as candidates that may regulate body weight. We also identified remarkable expression patterns of genes that encode signalling molecules (e.g. insulin, mitochondrial uncoupling protein 1) that are implicated in the control of food intake and are differently expressed in the neuroleptic groups.

Synergistic effect of alpha-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.

Coenzyme Q10 reduces the toxicity of rotenone in neuronal cultures by preserving the mitochondrial membrane potential.

Defects in mitochondrial energy metabolism due to respiratory chain disorders lead to a decrease in mitochondrial membrane potential (DeltaPsim) and induce apoptosis. Since coenzyme Q10 (CoQ10) plays a dual role as an antioxidant and bioenergetic agent in the respiratory chain, it has attracted increasing attention concerning the prevention of apoptosis in mitochondrial diseases. In this study the potential of CoQ10 to antagonize the apoptosis-inducing effects of the respiratory chain inhibitor rotenone was explored by video-enhanced microscopy in SH-SY5Y neuroblastoma cells. The cationic fluorescent dye JC-1 which exhibits potential-dependent accumulation in mitochondria was used as an indicator to monitor changes in DeltaPsim. The relative changes in fluorescence intensity after incubation with rotenone for 15 minutes were calculated. Pre-treatment with CoQ10 (10 or 100 microM) for 48 h led to a significant reduction of rotenone-induced loss of DeltaPsim. These results suggest, that cytoprotection by CoQ10 may be mediated by raising cellular resistance against the initiating steps of apoptosis, namely the decrease of DeltaPsim. Whether these data may provide new directions for the development of neuroprotective strategies has to be investigated in future studies.

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.

Practical importance of neuroprotection in Parkinson's disease.

Consensus could be reached that there is overwhelming evidence of preclinical neuroprotection. However, the evidence of neuroprotection/neurorescue under clinical conditions is limited. Lessons from clinical trials designed to show neuroprotection (selegiline, amantadine, dopamine agonists) demonstrate that with the drugs available neuroprotection/neurorescue has to start as early as possible. A PET-controlled clinical trial with ropinirole shows that there seems to be a good chance for neuroprotection in the early phase of Parkinson's disease in patients treated from the very beginning of the disease while there is no such benefit in patients with a late start of a neuroprotective therapeutic strategy. Also long-term clinical neuroprotection cannot be reached. Complicating factors to demonstrate clinical neuroprotection are discussed.