Search results for "Prague"
showing 10 items of 652 documents
Acute intermittent nicotine treatment produces a reduction in the total number of FGF-2 immunoreactive astroglial cells in the substantia nigra of th…
2004
To understand the morphological substrate of the nicotine effect on nigral FGF-2 expression, a stereological analysis of FGF-2 immunoreactive neuronal and glial profiles has been performed in the substantia nigra of the rat after acute intermittent nicotine treatment. The major finding of this paper is the demonstration that this type of nicotine treatment produces a significant reduction in the total number of nuclear FGF-2 immunoreactive astroglial profiles in the substantia nigra. A parallel analysis of nigral FGF-1 and FGF-5 immunoreactivities showed no effect of this type of nicotine treatment. The results may be explained by an inhibition of FGF-2 synthesis in a subpopulation of nigra…
Regulation of Oxygen Distribution in Tissues by Endothelial Nitric Oxide
2009
Nitric oxide (NO) decreases cellular oxygen (O 2 ) consumption by competitively inhibiting cytochrome c oxidase. Here, we show that endogenously released endothelial NO, either basal or stimulated, can modulate O 2 consumption both throughout the thickness of conductance vessels and in the microcirculation. Furthermore, we have shown that such modulation regulates O 2 distribution to the surrounding tissues. We have demonstrated these effects by measuring O 2 consumption in blood vessels in a hypoxic chamber and O 2 distribution in the microcirculation using the fluorescent oxygen-probe Ru(phen) 3 2+ . Removal of NO by physical or pharmacological means, or in eNOS −/− mice, abolishes this …
The unilateral nigral lesion induces dramatic bilateral modification on rat brain monoamine neurochemistry
2009
6-Hydroxydopamine (6-OHDA) is a neurotoxic compound commonly used to induce dopamine (DA) depletion in the nigrostriatal system, mimicking Parkinson's disease (PD) in animals. The aim of the present study was to evaluate the 7-day effect of unilateral nigral lesion on rat brain monoamine neurochemistry. Five brain regions were examined: the brain stem, cerebellum, hippocampus, striatum, and cortex. 6-OHDA-unilateral lesion dramatically modified DA, serotonin (5-HT) and their metabolites contents in both sides of the different brain nuclei. Furthermore, unilateral 6-OHDA lesion reduced DA and 5-HT contents and produced a robust inversion of their turnover in the nonlesioned side compared to …
Functional and neurochemical changes of the gastrointestinal tract in a rodent model of Parkinson's disease.
2009
Patients with Parkinson’s disease develop motor disturbances often accompanied by peripheral autonomic dysfunctions, including gastrointestinal disorders, such as dysphagia, gastric stasis and constipation. While the mechanisms subserving enteric autonomic dysfunctions are not clearly understood, they may involve the enteric dopaminergic and/or nitrergic systems. In the present study, we demonstrate that rats with unilateral 6-hydroxydopamine lesion of nigrostriatal dopaminergic neurons develop a marked inhibition of propulsive activity compared to sham-operated controls, as indicated by a 60% reduction of daily fecal output at the 4th week of observation. Immunohistochemical data revealed …
Elevation of striatal urate in experimental models of Parkinson's disease: a compensatory mechanism triggered by dopaminergic nigrostriatal degenerat…
2014
Epidemiological studies have indicated an inverse association between high uricemia and incidence of Parkinson's disease (PD). To investigate the link between endogenous urate and neurotoxic changes involving the dopaminergic nigrostriatal system, this study evaluated the modifications in the striatal urate levels in two models of PD. To this end, a partial dopaminergic degeneration was induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in mice, while a severe dopaminergic degeneration was elicited by unilateral medial forebrain bundle infusion of 6-hydroxydopamine (6-OHDA) in rats. Urate levels were measured by in vivo microdialysis at 7 or 14 days from toxin exposure. The resu…
Cardiac effects of isoliquiritigenin
1997
The effects of isoliquiritigenin on force of contraction (Fc), L-type Ca2+ current (I(Ca)) and intracellular Ca2+ concentration ([Ca2+]i) were investigated in rat ventricular heart muscle. Isoliquiritigenin increased Fc and I(Ca) and, after longer exposure times, resting tension and [Ca2+]i. The effect of isoliquiritigenin (100 microM) on I(Ca) was diminished by Rp-cAMPS (30 microM). 1H-[1,2,4]oxa- diazolo[4,3-a]quinoxalin-1-one (50 microM) did not influence the effects of isoliquiritigenin on Fc and I(Ca). The positive inotropic effects of isoprenaline and forskolin, but not of 3-isobutyl-1-methylxanthine, were potentiated by isoliquiritigenin (100 microM). In the presence of milrinone (10…
Inhibition by Fendiline of the Transient Outward Current in Rat Ventricular Cardiomyocytes
1999
The effects of fendiline on the transient outward current (Ito) were investigated in rat ventricular cardiomyocytes. Extracellularly applied fendiline reduced peak and steady-state current amplitude of Ito; the inactivation of Ito was accelerated by the drug, which reflects onset of block. The described effects were concentration dependent: half-maximal effects were achieved at approximately 3 microM fendiline. Intracellularly applied fendiline (3 microM) did not affect Ito within 5 min. The steady-state current amplitude of Ito was more efficiently suppressed by the drug at 22 +/- 1 degrees C than at 36 +/- 1 degrees C. The recovery of Ito was analyzed by the application of twin depolarizi…
Mechanism of Block by 4-Aminopyridine of the Transient Outward Current in Rat Ventricular Cardiomyocytes
1998
The effects of 4-aminopyridine (4-AP) on the transient outward current (I to ) were investigated in rat ventricular cardiomyocytes at different values of intracellular pH (pH i ) and extracellular pH (pH o ). The 4-AP was administered either extracellularly (bath application) or intracellularly (diffusion from the intrapipette solution). The 4-AP diminished I to given either from inside or outside the cell membrane. The block by extracellularly applied 4-AP (4-AP o ) of the peak amplitude of I to was decreased by external acidification but increased by external alkalinization: conversely. the block by 4-AP o was decreased by internal alkalinization but increased by internal acidification. I…
Voltage-Dependent Effects of Barnidipine in Rat Vascular Smooth Muscle
2003
The effects of the dihydropyridine nifedipine and its more lipophilic congener, barnidipine, were investigated in smooth muscle preparations from the rat in resting and depolarizing conditions. Both drugs relaxed precontracted aortic rings more potently in depolarizing conditions, barnidipine being more potent than nifedipine. Currents through Ca 2+ channels in rat vascular smooth muscle cells (A7r5) and in isolated rat cardiomyocytes were reduced more potently by both drugs at a holding potential of-40 mV than at -80 mV. However, barnidipine and nifedipine were more effective in reducing the current in A7r5 cells than in cardiomyocytes. The IC 50 obtained in aortic rings and in A7r5 cells …
The Role of Tumor Volume in ‘Reoxygenation’ upon Cyclophosphamide Treatment
1995
The effect of cyclophosphamide (CP) injection (60 mg/kg i.p., single dose) on volume growth and tissue oxygenation (pO2 distribution) was investigated in rat DS-sarcomas. CP was administered 4 days after subcutaneous (s.c.) tumor implantation (volume approximately 0.35 ml). Polarographic pO2 measurements were performed in the subcutis at the hind foot dorsum and in tumors 72 h after CP administration. The oxygenation status of these tissues was compared with that of saline-treated controls. CP-injection caused a mean growth delay of 11 days in DS-sarcomas and had no impact on the oxygenation status of the subcutis. In contrast, in s.c. growing DS-sarcomas the pO2 distribution improved signi…