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Mathias Zink

Publications and source records attributed to Mathias Zink.

17 recordsLinked to original sources
PubMed2006

IL-6 knockout mice exhibit resistance to stress-induced development of depression-like behaviors.

Cytokine-dependent mechanisms in the CNS have been implicated in the pathogenesis of depression. Interleukin-6 is upregulated in depressed patients and dowregulated by antidepressants. It is, however, unknown whether IL-6 is involved in the pathogenesis of depression. We subjected IL-6-deficient mice (IL-6(-/-)) to depression-related tests (learned helplessness, forced swimming, tail suspension, sucrose preference). We also investigated IL-6 in the hippocampus of stressed wild-type mice. IL-6(-/-) mice showed reduced despair in the forced swim, and tail suspension test, and enhanced hedonic behavior. Moreover, IL-6(-/-) mice exhibited resistance to helplessness. This resistance may be caused by the lack of IL-6, because stress increased IL-6 expression in wild-type hippocampi. This suggests that IL-6 is a component in molecular mechanisms in the pathogenesis of depression. IL-6(-/-) mice represent tools to study IL-6-dependent signaling pathways in the pathophysiology of depression in vivo. Moreover, these mice may support the screening of compounds for depression by altering cytokine-mediated signaling.

Animals↗
PubMed2006

[Optimizing the antipsychotic potency of olanzapine by augmentation--a critical review].

OBJECTIVE: Up to 40 % of patients with schizophrenic psychosis suffer from symptoms that are resistant to monotherapy with antipsychotic drugs. As a consequence, combined approaches are often used, especially based on clozapine and olanzapine. This review aims to provide a critical overview on olanzapine-augmentations. METHODS: A systematic database search including generic and trade names of antipsychotic substances as well as general items such as "augmentation" and "combination" was performed in Medline and BIOSIS (OVID) until May 2005. RESULTS: Amongst a number of 16 reports dealing with 9 different antipsychotic augmentation strategies (85 patients) only sulpiride was tested in a randomized manner. A significant part of the treatments achieved favourable results. In contrast, augmentations of olanzapine with antidepressants or mood stabilizers were evaluated in well-designed clinical trials (9 strategies, 10 publications, 837 patients). Improvements of positive and/or negative symptoms as well as depressed mood were reported. CONCLUSIONS: The empirical basis to combine olanzapine with antipsychotic substances has to be improved in order to evaluate benefits and risks. Augmentations with mood stabilizers were successful, for example on hostility, showing that randomized and placebo-controlled trials are feasible.

Anticonvulsants↗
PubMed2005

Antidepressants differentially affect expression of complexin I and II RNA in rat hippocampus.

Disturbance of synaptic transmission is currently viewed as an important pathophysiological mechanism and therapeutic target of mood disorders. Amongst other lines of evidence this theory is based on human post-mortem investigations showing differential expression of complexins. In order to discriminate between molecular correlates of the disease itself and effects of psychotropic drugs given to patients, we performed an animal trial using subchronic antidepressant treatment. Cohorts of adult male Sprague-Dawley rats were treated over a period of 14 days with intraperitoneal injections of either saline (0.9%, n=8), desipramine (15 mg/kg, n=7), fluoxetine (10 mg/kg, n=8), or tranylcypromine (10 mg/kg, n=5). Brain slices were used for in situ hybridizations with 35S labelled RNA probes of the genes complexin I, complexin II and syntaxin 1 A, the SNARE complex protein interacting with the complexins, and assessed semi-quantitatively for region-specific expression levels. Expression of complexin I was induced only in habenular nuclei after treatment with fluoxetine. In contrast, complexin II was significantly induced by desipramine and tranylcypromine, but not fluoxetine, in several brain regions. All treatment groups, but most significantly fluoxetine-treated animals, showed higher expression levels of syntaxin 1A. Antidepressants differentially affect expression levels of complexin I and more prominently complexin II and syntaxin 1A. The induction of complexin II and syntaxin 1A might strengthen the synaptic transmission at axo-dendritic or axo-axonal synapses. Previous post-mortem findings reporting on downregulation of complexins cannot be explained as mere effects of psychotropic drug treatment.

Adaptor Proteins, Vesicular Transport↗
PubMed2005

Mice with genetically altered glucocorticoid receptor expression show altered sensitivity for stress-induced depressive reactions.

Altered glucocorticoid receptor (GR) signaling is a postulated mechanism for the pathogenesis of major depression. To mimic the human situation of altered GR function claimed for depression, we generated mouse strains that underexpress or overexpress GR, but maintain the regulatory genetic context controlling the GR gene. To achieve this goal, we used the following: (1) GR-heterozygous mutant mice (GR+/-) with a 50% GR gene dose reduction, and (2) mice overexpressing GR by a yeast artificial chromosome resulting in a twofold gene dose elevation. GR+/- mice exhibit normal baseline behaviors but demonstrate increased helplessness after stress exposure, a behavioral correlate of depression in mice. Similar to depressed patients, GR+/- mice have a disinhibited hypothalamic-pituitary-adrenal (HPA) system and a pathological dexamethasone/corticotropin-releasing hormone test. Thus, they represent a murine depression model with good face and construct validity. Overexpression of GR in mice evokes reduced helplessness after stress exposure, and an enhanced HPA system feedback regulation. Therefore, they may represent a model for a stress-resistant strain. These mouse models can now be used to study biological changes underlying the pathogenesis of depressive disorders. As a first potential molecular correlate for such changes, we identified a downregulation of BDNF protein content in the hippocampus of GR+/- mice, which is in agreement with the so-called neurotrophin hypothesis of depression.

Animals↗
PubMed2005

Ethanol induces GAD67 and VGAT in slice cultures of newborn rat cerebral cortex.

Exposure of the developing brain to ethanol disposes to the fetal alcohol syndrome, causing changes in the neurotransmitter systems of glutamate and gamma-amino butyric acid (GABA). However, expression of genes involved in GABA synthesis, vesicular and transmembrane transport has not been investigated so far. We exposed organotypic slice cultures of newborn rat cerebral cortex to ethanol (100 mM) for 4 days and observed a significant induction of the enzyme producing GABA (GAD67, +21%) and the vesicular transporter VGAT (+112%), whereas the expression of the transmembrane transporters did not differ from control conditions. In summary, ethanol exposure of the developing cortex induces GABAergic genes, which might facilitate the excitatory functions of GABA during development.

Amino Acid Transport Systems↗
PubMed2005

Augmentation of olanzapine in treatment-resistant schizophrenia.

OBJECTIVE: Up to 40% of patients with schizophrenic psychoses have symptoms that are resistant to monotherapy with antipsychotic drugs. In consequence, combinations of drugs are often used, especially based on the antipsychotic agents clozapine and olanzapine because of their broad receptor-interaction profile. The aim of this review was to provide a critical overview of the published results of olanzapine augmentation. METHODS: A systematic database search was performed of MEDLINE and BIOSIS (Ovid), looking for publications on augmented therapeutic approaches involving olanzapine. The search terms used were "augmentation," "combination," "schizophrenia," "olanzapine," and the names of other antipsychotic drugs and non-antipsychotic agents, including brand names, spanning publications from 1966 until the end of December 2004. RESULTS: Of 14 reports dealing with 8 different antipsychotic augmentation strategies (83 patients), only 1 trial, of sulpiride-olanzapine therapy, was performed in a randomized manner. Based on clinical observation, a significant number of the treatments led to favourable results. In contrast to adjuvant therapy with antipsychotic drugs, augmentation of olanzapine with glycine, antidepressants or mood stabilizers was evaluated in well-designed clinical trials (8 publications, 989 patients), with distinct improvements of positive and/or negative symptoms reported. CONCLUSIONS: The combination of olanzapine with antidopaminergic atypical antipsychotic agents seems to follow a neurobiological rationale. The augmentation trials with non-antipsychotic agents, for example, mood stabilizers, were successful and showed that randomized and placebo-controlled trials are feasible. Therefore, systematic evaluations of antipsychotic agents as adjuvant therapy are possible as well as necessary to determine the benefits and risks of any new treatment strategy.

Antipsychotic Agents↗
PubMed2004

Reduced expression of brain-derived neurotrophic factor in mice deficient for pituitary adenylate cyclase activating polypeptide type-I-receptor.

In vitro pituitary adenylate cyclase activating polypeptide (PACAP) induces the expression of brain-derived neurotrophic factor (BDNF) via its specific receptor PAC1. Since BDNF has been implicated in learning paradigms and mice lacking functional PAC1 have deficits in hippocampus-dependent associative learning, we investigated whether PAC1 mutants show alterations in hippocampal expression of BDNF and its receptor TrkB. Semi-quantitative in situ-hybridization using exon-specific BDNF-probes revealed significantly reduced expression of the exon-III and exon-V-specific transcripts within the hippocampal CA3 region in PAC1-deficient mice. A similar trend was observed for the exon-I-specific transcript. The expression of the exon-III-specific transcript was also reduced within the dentate gyrus, while Trk B-expression did not differ between genotypes. Our data demonstrate that even in vivo PAC1-mediated signaling seems to play a pivotal role for the transcriptional regulation of BDNF.

Animals↗
PubMed2004

Differential effects of long-term treatment with clozapine or haloperidol on GABAA receptor binding and GAD67 expression.

One of the most consistent findings in postmortem studies of schizophrenia is increased GABAA receptor binding and reduced glutamic acid decarboxylase (GAD67) expression. Due to long-term antipsychotic treatment before death, these findings may reflect not only the consequences of schizophrenia but also medication effects. To differentiate between these options, we used an animal model and evaluated long-term effects of typical (haloperidol) and atypical (clozapine) antipsychotic drugs on the GABAergic system. A total of 33 adult male rats were treated in three cohorts over a period of 6 months. One cohort of 11 animals received clozapine (45 mg/kg/day), another one received haloperidol (1.5 mg/kg/day) and a third one received pH-adapted minimal concentrations of HCl in the drinking water. Receptor autoradiography of the GABAA receptor ([3H]-muscimol binding) and in situ hybridization in adjacent sections with 35S-labeled cRNA probes of the y-aminobutyric acid (GABA)-producing enzyme, GAD67, was performed. While haloperidol increased GABAA receptor binding in striatum and nucleus accumbens (NA), it suppressed GABAA receptor binding in temporal (TEMPC) and parietal (PARC) cortex. Clozapine induced GABAA receptor binding in infralimbic cortex (ILC) and similar like haloperidol in anterior cingulate cortex (ACC), two regions of the limbic cortex. In addition, either drug increased gene expression of GAD67. It is concluded that antipsychotic drugs differentially alter the GABAergic system, strongly suggesting that drug effects are partially responsible for the up-regulation of GABAA receptor binding in certain brain regions as observed in postmortem brains of schizophrenic patients. However, the reduced GAD67 expression seen in postmortem brains does not appear to reflect drug effects, since our animal model demonstrated increased gene expression.

Animals↗
PubMed2004

Combination of amisulpride and olanzapine in treatment-resistant schizophrenic psychoses.

Treatment-resistant schizophrenia often leads to combined application of antipsychotic drugs. We report first experience with the combination of olanzapine and amisulpride. Improvement of psychopathological state and side effects could be achieved, and drug doses were lower than under monotherapy. We thus conclude that this approach represents a useful therapeutic option.

Adult↗
PubMed2004

[Ziprasidone-augmentation of clozapine].

OBJECTIVES: In cases of treatment-resistant schizophrenic psychoses combined application of atypical antipsychotic drugs is an often-used strategy. METHOD: We report the case of a 35-year old man with paranoid schizophrenia, whose symptoms turned out to be resistant to the application of olanzapine, risperidone and quetiapine. After switch to clozapine paranoid delusions remitted, but schizophrenic negative symptoms persisted and side effects limited the patient's compliance. Augmentation with ziprasidone allowed a reduction of the clozapine dose and ameliorated the affective deficits. RESULTS: Positive and negative symptoms were well controlled. In spite of a transient hyperprolactinaemia and sexual dysfunction the patient was highly content. DISCUSSION: The combined application of ziprasidone and clozapine follows a neurobiological rationale, seems able to reduce side effects, and should be further evaluated with respect to risk and benefit in prospective studies.

Adult↗
PubMed2004

Combination of clozapine and amisulpride in treatment-resistant schizophrenia--case reports and review of the literature.

BACKGROUND: The clinical outcome of patients suffering from schizophrenic psychoses has been considerably improved by atypical antipsychotics like clozapine and amisulpride. In patients whose symptomatology cannot be ameliorated by monotherapy, it might be necessary to combine two atypical antipsychotics. While clozapine interacts with a variety of neurotransmitter receptors, amisulpride predominantly binds with high affinity to D3/D2-dopamine receptors. Combination can be considered if a supplementary dopamine-receptor blockade is desired. METHODS: We report on the therapy of 15 patients using a combination regimen of amisulpride and clozapine. Data were collected from patient records. The case reports document previous treatment attempts, describe the reason for the combination therapy, and determine its effect. RESULTS: Major (six cases) or at least marked (eight cases) improvement of previously treatment-resistant positive and negative symptoms could be achieved by using a mean clozapine dose of 375 mg/day (serum level 0.38 mg/l) and an amisulpride dose of 527 mg/day. Additionally, by reducing the clozapine dose compared to monotherapy by 24 %, a significant reduction of side effects was observed. CONCLUSIONS: The combination of amisulpride with clozapine considerably enriches the therapeutic arsenal in cases of severe schizophrenic psychoses. Additional prospective studies are needed in order to systematically evaluate this new treatment strategy.

Adult↗
PubMed2004

Ethanol induces expression of the glutamate transporters EAAT1 and EAAT2 in organotypic cortical slice cultures.

BACKGROUND: Exposure of the developing brain to ethanol disposes the fetus to fetal alcohol syndrome and causes a number of changes in several neurochemical systems. In particular, the glutamatergic system is affected by ethanol. Thus, increased sensitivity of glutamate receptors and enhanced transmembrane transport of glutamate were found in primary astrocyte cultures. However, in these in vitro studies, changes in the expression of glutamate transporters were not detected. To further characterize the influence of chronic ethanol exposure on the developing brain, we assessed the transcriptional and translational regulation of glutamate transporters in a less artificial in vitro system. METHODS: We exposed postnatal rat cortical organotypic slice cultures to ethanol (100 mM) for 4 and 8 days. Expression of the excitatory amino acid transporters EAAT1 and EAAT2 was analyzed in comparison to untreated controls with semiquantitative reverse transcriptase-polymerase chain reaction. In addition, changes in protein expression were detected by Western blotting. RESULTS: In ethanol-exposed cortical slices, we observed more prominent fiber outgrowth and significantly increased gene expression (EAAT1: +35%, p = 0.029; EAAT2: +251%, p = 0.015). These findings could be verified on the protein level, because Western blot analysis revealed significantly higher levels of EAAT1 (+76%; p = 0.008) and EAAT2 (+104%; p = 0.018) in ethanol-treated slices compared with controls. CONCLUSIONS: Our results are in concert with earlier studies describing the induction of glutamate transport by ethanol. Enhanced expression of EAAT1 and EAAT2 after ethanol exposure can be viewed as a maladaptive process that disposes the developing brain to fetal alcohol syndrome.

Amino Acid Transport System X-AG↗
PubMed2003

Decreased gene expression of glial and neuronal glutamate transporters after chronic antipsychotic treatment in rat brain.

Post-mortem studies in schizophrenic patients revealed alterations in glutamate transporter gene expression. The question concerning a possible influence of chronic antipsychotic treatment on these gene expressions, however, remained open. In this study, 11 rats per group were treated with either haloperidol (1.5 mg/kg per day) or clozapine (45 mg/kg per day) over a period of 6 months in doses comparable to clinic application. Gene expression of glial glutamate transporter EAAT2 and the predominantly neuronal glutamate transporter EAAT3 were examined by in situ hybridization. Clozapine significantly downregulated EAAT2 in hippocampal CA1 and parietal cortex and EAAT3 in the cingulate cortex compared to the expression upon haloperidol treatment and controls. Additionally, clozapine decreased EAAT2 in temporal, cingulate and frontal cortex and downregulated EAAT3 in cingulate and infralimbic cortex, striatum and hippocampal CA1 and CA2 compared to controls. Haloperidol downregulated EAAT2 in cingulate and frontal cortex and reduced EAAT3 in nucleus accumbens, infralimbic cortex and hippocampal CA2. We hypothesize that glutamate transporter downregulation by neuroleptics increases glutamatergic action at the postsynaptic neuron and thereby may be related to beneficial antipsychotic effects and side effects.

Amino Acid Transport System X-AG↗
PubMed2003

Effects of long-term antipsychotic treatment on NMDA receptor binding and gene expression of subunits.

Postmortem studies in schizophrenic patients revealed alterations in NMDA receptor binding and gene expression of specific subunits. Because most of the patients had been treated with antipsychotics over long periods, medication effects might have influenced those findings. We treated animals with haloperidol and clozapine in clinical doses to investigate the effects of long-term antipsychotic treatment on NMDA receptor binding and gene expression of subunits. Rats were treated with either haloperidol (1.5 mg/kg/day) or clozapine (45 mg/kg/day) given in drinking water over a period of 6 months. Quantitative receptor autoradiography with [3H]-MK-801 was used to examine NMDA receptor binding. In situ hybridization was performed for additional gene expression studies of the NR1, NR2A, NR2B, NR2C, and NR2D subunits. [3H]-MK-801 binding was found to be increased after haloperidol treatment in the striatum and nucleus accumbens. Clozapine was shown to up-regulate NMDA receptor binding only in the nucleus accumbens. There were no alterations in gene expression of NMDA subunits in any of the three regions. However, the NR2A subunit was down-regulated in the hippocampus and prefrontal cortex by both drugs, whereas only clozapine induced a down-regulation of NR1 in the dorsolateral prefrontal cortex. NR2B, 2C, and 2D subunits did not differ between treatment groups and controls. Both altered NMDA receptor binding and subunit expression strengthen a hyperglutamatergic function after haloperidol treatment and may contribute to some of our postmortem findings in antipsychotically treated schizophrenic patients. Because the effects seen in different brain areas clearly vary between haloperidol and clozapine, they may also be responsible for some of the differences in efficacy and side effects.

Animals↗
PubMed2002

Electroconvulsive therapy in a patient receiving rivastigmine.

We report the case of an 81-year-old woman, suffering from a major depressive episode and incipient Alzheimer disease, whom we treated with ECT without interrupting therapy with the acetylcholinesterase inhibitor (ACHE-I) rivastigmine. After eight right unilateral ECT sessions, the patient remitted completely without any significant deterioration of memory and cognitive abilities or cholinergic side effects. This report demonstrates that ECT was safely used in one elderly and mildly demented person with continuous ACHE-I therapy. The hypothesis that this drug may indeed protect against unfavorable side effects of ECT should be further tested in clinical trials.

Aged↗