Auswirkung der intrazerebrovenrikulären Baclofenapplikation auf den arteriellen Blutdruck der Ratte

Einleitung: In dieser Arbeit sollte die Auswirkung der intrazerebroventrikulären Baclofenapplikation auf den arteriellen Blutdruck der Ratte untersucht werden. Methoden: Männliche Wistar-Ratten wurden mit Chloralhydrat anästhesiert. Die Arteria femoralis wurde punktiert, die Versuchstiere in ein Stereotaxiegestell eingespannt und eine Injektionskanüle in den lateralen Ventrikel positioniert. In einem 2-stündigen Vorlauf wurde der Blutdruck kontinuierlich registriert. Nach der Injektion von 1,5 µg Baclofen bzw. dem äquivalenten Volumen an Ringerlösung wurden die Blutdruckveränderungen erneut ca. 2 Stunden aufgezeichnet. Ergebnisse: Baclofen bewirkt in den ersten 10-15 min. einen nicht signifikanten systolischen und diastolischen Blutdruckabfall. Die max. Senkung des systolischen Blutdruckes war um 10%, die des diastolischen Blutdruckes um 9% höher als in der Kontrollgruppe. Zusätzlich konnte auch eine Stabilisierung des arteriellen Blutdruckes in der Baclofengruppe festgestellt werden. Schlussfolgerung: Baclofen bewirkt eine nicht signifikante Senkung des systolischen und diastolischen Blutdruckes. Nebenbei waren die Versuchstiere in der Baclofengruppe weniger Blutdruckoszillationen ausgesetzt

The synthetic peptide P111-136 derived from the C-terminal domain of heparin affin regulatory peptide inhibits tumour growth of prostate cancer PC-3 cells

<p>Abstract</p> <p>Background</p> <p>Heparin affin regulatory peptide (HARP), also called pleiotrophin, is a heparin-binding, secreted factor that is overexpressed in several tumours and associated to tumour growth, angiogenesis and metastasis. The C-terminus part of HARP composed of amino acids 111 to 136 is particularly involved in its biological activities and we previously established that a synthetic peptide composed of the same amino acids (P111-136) was capable of inhibiting the biological activities of HARP. Here we evaluate the ability of P111-136 to inhibit <it>in vitro </it>and <it>in vivo </it>the growth of a human tumour cell line PC-3 which possess an HARP autocrine loop.</p> <p>Methods</p> <p>A total lysate of PC-3 cells was incubated with biotinylated P111-136 and pulled down for the presence of the HARP receptors in Western blot. <it>In vitro</it>, the P111-136 effect on HARP autocrine loop in PC-3 cells was determined by colony formation in soft agar. <it>In vivo</it>, PC-3 cells were inoculated in the flank of athymic nude mice. Animals were treated with P111-136 (5 mg/kg/day) for 25 days. Tumour volume was evaluated during the treatment. After the animal sacrifice, the tumour apoptosis and associated angiogenesis were evaluated by immunohistochemistry. <it>In vivo </it>anti-angiogenic effect was confirmed using a mouse Matrigel™ plug assay.</p> <p>Results</p> <p>Using pull down experiments, we identified the HARP receptors RPTPβ/ζ, ALK and nucleolin as P111-136 binding proteins. <it>In vitro</it>, P111-136 inhibits dose-dependently PC-3 cell colony formation. Treatment with P111-136 inhibits significantly the PC-3 tumour growth in the xenograft model as well as tumour angiogenesis. The angiostatic effect of P111-136 on HARP was also confirmed using an <it>in vivo </it>Matrigel™ plug assay in mice</p> <p>Conclusions</p> <p>Our results demonstrate that P111-136 strongly inhibits the mitogenic effect of HARP on <it>in vitro </it>and <it>in vivo </it>growth of PC-3 cells. This inhibition could be linked to a direct or indirect binding of this peptide to the HARP receptors (ALK, RPTPβ/ζ, nucleolin). <it>In vivo</it>, the P111-136 treatment significantly inhibits both the PC-3 tumour growth and the associated angiogenesis. Thus, P111-136 may be considered as an interesting pharmacological tool to interfere with tumour growth that has now to be evaluated in other cancer types.</p

Origin and Properties of Striatal Local Field Potential Responses to Cortical Stimulation: Temporal Regulation by Fast Inhibitory Connections

Evoked striatal field potentials are seldom used to study corticostriatal communication in vivo because little is known about their origin and significance. Here we show that striatal field responses evoked by stimulating the prelimbic cortex in mice are reduced by more than 90% after infusing the AMPA receptor antagonist CNQX close to the recording electrode. Moreover, the amplitude of local field responses and dPSPs recorded in striatal medium spiny neurons increase in parallel with increasing stimulating current intensity. Finally, the evoked striatal fields show several of the basic known properties of corticostriatal transmission, including paired pulse facilitation and topographical organization. As a case study, we characterized the effect of local GABAA receptor blockade on striatal field and multiunitary action potential responses to prelimbic cortex stimulation. Striatal activity was recorded through a 24 channel silicon probe at about 600 µm from a microdialysis probe. Intrastriatal administration of the GABAA receptor antagonist bicuculline increased by 65±7% the duration of the evoked field responses. Moreover, the associated action potential responses were markedly enhanced during bicuculline infusion. Bicuculline enhancement took place at all the striatal sites that showed a response to cortical stimulation before drug infusion, but sites showing no field response before bicuculline remained unresponsive during GABAA receptor blockade. Thus, the data demonstrate that fast inhibitory connections exert a marked temporal regulation of input-output transformations within spatially delimited striatal networks responding to a cortical input. Overall, we propose that evoked striatal fields may be a useful tool to study corticostriatal synaptic connectivity in relation to behavior

Significance of Input Correlations in Striatal Function

The striatum is the main input station of the basal ganglia and is strongly associated with motor and cognitive functions. Anatomical evidence suggests that individual striatal neurons are unlikely to share their inputs from the cortex. Using a biologically realistic large-scale network model of striatum and cortico-striatal projections, we provide a functional interpretation of the special anatomical structure of these projections. Specifically, we show that weak pairwise correlation within the pool of inputs to individual striatal neurons enhances the saliency of signal representation in the striatum. By contrast, correlations among the input pools of different striatal neurons render the signal representation less distinct from background activity. We suggest that for the network architecture of the striatum, there is a preferred cortico-striatal input configuration for optimal signal representation. It is further enhanced by the low-rate asynchronous background activity in striatum, supported by the balance between feedforward and feedback inhibitions in the striatal network. Thus, an appropriate combination of rates and correlations in the striatal input sets the stage for action selection presumably implemented in the basal ganglia

Rebound Discharge in Deep Cerebellar Nuclear Neurons In Vitro

Neurons of the deep cerebellar nuclei (DCN) play a critical role in defining the output of cerebellum in the course of encoding Purkinje cell inhibitory inputs. The earliest work performed with in vitro preparations established that DCN cells have the capacity to translate membrane hyperpolarizations into a rebound increase in firing frequency. The primary means of distinguishing between DCN neurons has been according to cell size and transmitter phenotype, but in some cases, differences in the firing properties of DCN cells maintained in vitro have been reported. In particular, it was shown that large diameter cells in the rat DCN exhibit two phenotypes of rebound discharge in vitro that may eventually help define their functional roles in cerebellar output. A transient burst and weak burst phenotype can be distinguished based on the frequency and pattern of rebound discharge immediately following a hyperpolarizing stimulus. Work to date indicates that the difference in excitability arises from at least the degree of activation of T-type Ca2+ current during the immediate phase of rebound firing and Ca2+-dependent K+ channels that underlie afterhyperpolarizations. Both phenotypes can be detected following stimulation of Purkinje cell inhibitory inputs under conditions that preserve resting membrane potential and natural ionic gradients. In this paper, we review the evidence supporting the existence of different rebound phenotypes in DCN cells and the ion channel expression patterns that underlie their generation

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Distinct roles of presynaptic dopamine receptors in the differential modulation of the intrinsic synapses of medium-spiny neurons in the nucleus accumbens

Background: In both schizophrenia and addiction, pathological changes in dopamine release appear to induce alterations in the circuitry of the nucleus accumbens that affect coordinated thought and motivation. Dopamine acts principally on medium-spiny GABA neurons, which comprise 95% of accumbens neurons and give rise to the majority of inhibitory synapses in the nucleus. To examine dopamine action at single medium-spiny neuron synapses, we imaged Ca2+ levels in their presynaptic varicosities in the acute brain slice using two-photon microscopy. Results: Presynaptic Ca2+ rises were differentially modulated by dopamine. The D1/D5 selective agonist SKF81297 was exclusively facilitatory. The D2/D3 selective agonist quinpirole was predominantly inhibitory, but in some instances it was facilitatory. Studies using D2 and D3 receptor knockout mice revealed that quinpirole inhibition was either D2 or D3 receptor-mediated, while facilitation was mainly D3 receptor-mediated. Subsets of varicosities responded to both D1 and D2 agonists, showing that there was significant co-expression of these receptor families in single medium-spiny neurons. Neighboring presynaptic varicosities showed strikingly heterogeneous responses to DA agonists, suggesting that DA receptors may be differentially trafficked to individual varicosities on the same medium-spiny neuron axon. Conclusion: Dopamine receptors are present on the presynaptic varicosities of medium-spiny neurons, where they potently control GABAergic synaptic transmission. While there is significant coexpression of D1 and D2 family dopamine receptors in individual neurons, at the subcellular level, these receptors appear to be heterogeneously distributed, potentially explaining the considerable controversy regarding dopamine action in the striatum, and in particular the degree of dopamine receptor segregation on these neurons. Assuming that post-receptor signaling is restricted to the microdomains of medium-spiny neuron varicosities, the heterogeneous distribution of dopamine receptors on individual varicosities is likely to encode patterns in striatal information processing

Auswirkungen einer Blockade des Angiotensin Converting Enzyms durch Enalapril auf die Aktivierung von Endothelzellen und Leukozyten bei systemischer Entzündung induziert durch Lipopolysaccharide

In dieser Studie untersuchte man die Auswirkungen eines ACE-Inhibitors Enalapril in einer LPS induzierten, TNF-Alpha vermittelten systemischen Entzündung und betrachtete, ob eine Verminderung der erhöhten Adhäsionsmoleküle während einer Sepsis durch Enalapril gesenkt werden könnte. 30 männliche Probanden, die ein Alter von durchschnittlich 31 plus/minus 5 (SD) und einen Body Maß Index von 22 plus/minus 2 (SD) hatten, wurden in einer randomisierten, doppelblind placebo-kontrollierten Studie per Zufall in drei parallele Gruppen (A, B, C) unterteilt. Die Probanden waren einschließlich normaler Laborwerte gesund und dies wurde durch eine Voruntersuchung gesichert. Gruppe A erhielt sechs Tage ein Placebo, Gruppe B fünf Tage ein Placebo und am 6. Tag (Studientag) 20 mg Enalapril und Gruppe C sechs Tage 20 mg Enalapril. Man konnte anhand von gemessenen Parametern, wie zum Beispiel cE-Selektin, cICAM-1, cVCAM-1, TNF- und zelluläre Parameter, keine signifikante Veränderung durch Enalapril feststellen. Dies bedeutet, dass eine kurzfristige Hemmung der ACE-Aktivität durch Enalapril in dieser Dosierung keinen positiven Einfluss auf die LPS induzierte, TNF-Alpha vermittelte Aktivierung von Endothel, Leukozyten und der Adhäsionsmoleküle während einer Endotoxinämie hat

Einfluss der SIV-Infektion und einer antiretroviralen Therapie auf die Expression von vesikulären Transmitterproteinen im Striatum von Rhesus Affen

Seit dem Ausbruch der AIDS-Pandemie sind komplexe kognitive und sensomotorische neurologische Komplikationen im Zuge einer HIV-Infektion bekannt. Sie werden als HAND (HIV-associated neurocoginitve diseases) zusammengefasst und stellen trotz antiretroviraler Therapien nach wie vor ein relevantes gesundheitliches und sozioökonomisches Problem dar. Prävention und Therapie von HAND sind nicht zufriedenstellend gelöst. Neuroinflammation im ZNS wird als wichtiger pathogenetischer Faktor in der Entwicklung von HAND angesehen. Regionen-spezifische Veränderungen in cerebralen Transmittersystemen sind ein weiterer Faktor HAND-assoziierter neurologischer Dysfunktionen. Das Striatum gilt als besonders vulnerable Region. Ziel der vorliegenden Arbeit war es zu untersuchen, wie sich die klassischen Transmittersysteme im Striatum im Zuge einer SIV-Infektion des Rhesus-Makaken und deren antiretroviraler Therapie transient oder permanent verändern. Insbesondere sollte geklärt werden, inwieweit die vesikulären Transportproteine der klassischen Transmittersyteme im Striatum von der SIV-Infektion betroffen sind und ob, wie in anderen ZNS-Regionen beobachtet, dissoziierte oder konkordante Veränderungen entsprechender transmittersynthetisierender Enzyme auftreten. Des Weiteren sollte geklärt werden, wie sich die Veränderungen striataler Transmitterenzyme und vesikulärer Transporterproteine zur neuroinflammatorischen Signatur mikroglialer und astrozytärer Reaktionen im Zuge der SIV-Infektion und deren antiretroviralen Therapie verhalten. Zur Klärung dieser Fragen wurden immunhistochemische Analysen von striatalem Gewebe aus vier Versuchsgruppen des SIV-Modells durchgeführt: 1. Nicht-infizierte Kontrollgruppe, 2. SIV-infizierte, nicht an AIDS erkrankte Gruppe von Rhesus Makaken (SIV/-AIDS), 3. SIV-infiziert, an AIDS erkrankt (SIV/+AIDS), 4. SIV-infiziert, an AIDS erkrankt und anschließend antiretroviral behandelt (SIV/+AIDS/+ddG). Das entsprechende striatale Gewebe stand im Rahmen des durch die Volkswagen-Stiftung geförderten Kooperationsprojekte