Bral2 is a link protein stabilizing the binding between lecticans and hyaluronan in perineuronal nets and axonal coats (ACs) in specific brain regions. Using the real-time iontophoretic method and diffusion-weighted magnetic resonance, we determined the extracellular space (ECS) volume fraction (α), tortuosity (λ), and apparent diffusion coefficient of water (ADCW ) in the thalamic ventral posteromedial nucleus (VPM) and sensorimotor cortex of young adult (3-6 months) and aged (14-20 months) Bral2-deficient (Bral2-/- ) mice and age-matched wild-type (wt) controls. The results were correlated with an analysis of extracellular matrix composition. In the cortex, no changes between wt and Bral2-/- were detected, either in the young or aged mice. In the VPM of aged but not in young Bral2-/- mice, we observed a significant decrease in α and ADCW in comparison with age-matched controls. Bral2 deficiency led to a reduction of both aggrecan- and brevican-associated perineuronal nets and a complete disruption of brevican-based ACs in young as well as aged VPM. Our data suggest that aging is a critical point that reveals the effect of Bral2 deficiency on VPM diffusion. This effect is probably mediated through the enhanced age-related damage of neurons lacking protective ACs, or the exhausting of compensatory mechanisms maintaining unchanged diffusion parameters in young Bral2-/- animals. A decreased ECS volume in aged Bral2-/- mice may influence the diffusion of neuroactive substances, and thus extrasynaptic and also indirectly synaptic transmission in this important nucleus of the somatosensory pathway.

• MeSH
• agrekany metabolismus   MeSH
• analýza rozptylu MeSH
• difuzní magnetická rezonance MeSH
• extracelulární matrix - proteiny nedostatek   genetika   MeSH
• extracelulární prostor diagnostické zobrazování   genetika   MeSH
• gangliová stimulancia farmakologie   MeSH
• kvartérní amoniové sloučeniny farmakologie   MeSH
• messenger RNA MeSH
• myši inbrední C57BL MeSH
• myši transgenní MeSH
• myši MeSH
• neurony cytologie   účinky léků   MeSH
• novorozená zvířata MeSH
• proteiny nervové tkáně nedostatek   genetika   MeSH
• stárnutí fyziologie   MeSH
• techniky in vitro MeSH
• thalamus cytologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Brain edema accompanying ischemic or traumatic brain injuries, originates from a disruption of ionic/neurotransmitter homeostasis that leads to accumulation of K(+) and glutamate in the extracellular space. Their increased uptake, predominantly provided by astrocytes, is associated with water influx via aquaporin-4 (AQP4). As the removal of perivascular AQP4 via the deletion of α-syntrophin was shown to delay edema formation and K(+) clearance, we aimed to elucidate the impact of α-syntrophin knockout on volume changes in individual astrocytes in situ evoked by pathological stimuli using three dimensional confocal morphometry and changes in the extracellular space volume fraction (α) in situ and in vivo in the mouse cortex employing the real-time iontophoretic method. RT-qPCR profiling was used to reveal possible differences in the expression of ion channels/transporters that participate in maintaining ionic/neurotransmitter homeostasis. To visualize individual astrocytes in mice lacking α-syntrophin we crossbred GFAP/EGFP mice, in which the astrocytes are labeled by the enhanced green fluorescent protein under the human glial fibrillary acidic protein promoter, with α-syntrophin knockout mice. Three-dimensional confocal morphometry revealed that α-syntrophin deletion results in significantly smaller astrocyte swelling when induced by severe hypoosmotic stress, oxygen glucose deprivation (OGD) or 50 mM K(+). As for the mild stimuli, such as mild hypoosmotic or hyperosmotic stress or 10 mM K(+), α-syntrophin deletion had no effect on astrocyte swelling. Similarly, evaluation of relative α changes showed a significantly smaller decrease in α-syntrophin knockout mice only during severe pathological conditions, but not during mild stimuli. In summary, the deletion of α-syntrophin markedly alters astrocyte swelling during severe hypoosmotic stress, OGD or high K(+).

• MeSH
• akvaporin 4 genetika   metabolismus   MeSH
• astrocyty metabolismus   patologie   MeSH
• biologický transport MeSH
• draslík metabolismus   MeSH
• draslíkové kanály genetika   metabolismus   MeSH
• edém mozku genetika   metabolismus   patologie   MeSH
• glukosa nedostatek   MeSH
• konfokální mikroskopie MeSH
• membránové proteiny nedostatek   genetika   MeSH
• mikrotomie MeSH
• mozková kůra metabolismus   patologie   MeSH
• myši transgenní MeSH
• myši MeSH
• osmolární koncentrace MeSH
• osmotický tlak MeSH
• promotorové oblasti (genetika) MeSH
• proteiny nervové tkáně genetika   metabolismus   MeSH
• proteiny vázající vápník nedostatek   genetika   MeSH
• regulace genové exprese MeSH
• signální transdukce MeSH
• stereotaktické techniky MeSH
• svalové proteiny nedostatek   genetika   MeSH
• techniky tkáňových kultur MeSH
• zelené fluorescenční proteiny genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Aquaporin-4 (AQP4) is the primary cellular water channel in the brain and is abundantly expressed by astrocytes along the blood-brain barrier and brain-cerebrospinal fluid interfaces. Water transport via AQP4 contributes to the activity-dependent volume changes of the extracellular space (ECS), which affect extracellular solute concentrations and neuronal excitability. AQP4 is anchored by α-syntrophin (α-syn), the deletion of which leads to reduced AQP4 levels in perivascular and subpial membranes. We used the real-time iontophoretic method and/or diffusion-weighted magnetic resonance imaging to clarify the impact of α-syn deletion on astrocyte morphology and changes in extracellular diffusion associated with cell swelling in vitro and in vivo. In mice lacking α-syn, we found higher resting values of the apparent diffusion coefficient of water (ADCW) and the extracellular volume fraction (α). No significant differences in tortuosity (λ) or non-specific uptake (k'), were found between α-syn-negative (α-syn -/-) and α-syn-positive (α-syn +/+) mice. The deletion of α-syn resulted in a significantly smaller relative decrease in α observed during elevated K(+) (10 mM) and severe hypotonic stress (-100 mOsmol/l), but not during mild hypotonic stress (-50 mOsmol/l). After the induction of terminal ischemia/anoxia, the final values of ADCW as well as of the ECS volume fraction α indicate milder cell swelling in α-syn -/- in comparison with α-syn +/+ mice. Shortly after terminal ischemia/anoxia induction, the onset of a steep rise in the extracellular potassium concentration and an increase in λ was faster in α-syn -/- mice, but the final values did not differ between α-syn -/- and α-syn +/+ mice. This study reveals that water transport through AQP4 channels enhances and accelerates astrocyte swelling. The substantially altered ECS diffusion parameters will likely affect the movement of neuroactive substances and/or trophic factors, which in turn may modulate the extent of tissue damage and/or drug distribution.

• MeSH
• akvaporin 4 metabolismus   MeSH
• astrocyty metabolismus   MeSH
• delece genu * MeSH
• difuze MeSH
• draslík metabolismus   MeSH
• extracelulární prostor metabolismus   MeSH
• genotyp MeSH
• genový knockout MeSH
• ischemie genetika   MeSH
• membránové proteiny genetika   metabolismus   MeSH
• myši knockoutované MeSH
• myši MeSH
• osmotický tlak MeSH
• proteiny vázající vápník genetika   metabolismus   MeSH
• somatosenzorické korové centrum metabolismus   MeSH
• srdeční zástava genetika   metabolismus   MeSH
• svalové proteiny genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Bral1 is a link protein that stabilizes the binding between lecticans and hyaluronic acid and thus maintains the extracellular matrix assembly in the CNS. Bral1 is specifically located in the white matter around the nodes of Ranvier. Recent studies suggest its function in promoting saltatory neural conduction. This article reviews the current knowledge about the structure, expression and function of this link protein.

• MeSH
• extracelulární matrix metabolismus   MeSH
• lidé MeSH
• mozek cytologie   metabolismus   MeSH
• proteiny nervové tkáně chemie   metabolismus   MeSH
• regulace genové exprese MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

Focal cortical dysplasias (FCDs) of the brain are recognized as a frequent cause of intractable epilepsy. To contribute to the current understanding of the mechanisms of epileptogenesis in FCD, our study provides evidence that not only cellular alterations and synaptic transmission, but also changed diffusion properties of the extracellular space (ECS), induced by modified extracellular matrix (ECM) composition and astrogliosis, might be involved in the generation or spread of seizures in FCD. The composition of the ECM in FCD and non-malformed cortex (in 163 samples from 62 patients) was analyzed immunohistochemically and correlated with the corresponding ECS diffusion parameter values determined with the real-time iontophoretic method in freshly resected cortex (i.e. the ECS volume fraction and the geometrical factor tortuosity, describing the hindrances to diffusion in the ECS). The ECS in FCD was shown to differ from that in non-malformed cortex, mainly by the increased accumulation of certain ECM molecules (tenascin R, tenascin C, and versican) or by their reduced expression (brevican), and by the presence of an increased number of astrocytic processes. The consequent increase of ECS diffusion barriers observed in both FCD type I and II (and, at the same time, the enlargement of the ECS volume in FCD type II) may alter the diffusion of neuroactive substances through the ECS, which mediates one of the important modes of intercellular communication in the brain - extrasynaptic volume transmission. Thus, the changed ECM composition and altered ECS diffusion properties might represent additional factors contributing to epileptogenicity in FCD.

• MeSH
• astrocyty metabolismus   MeSH
• brevican analýza   MeSH
• difuze MeSH
• dítě MeSH
• dospělí MeSH
• extracelulární matrix chemie   metabolismus   MeSH
• extracelulární prostor chemie   metabolismus   MeSH
• iontoforéza metody   MeSH
• lidé středního věku MeSH
• lidé MeSH
• malformace mozkové kůry metabolismus   patologie   MeSH
• mladiství MeSH
• mladý dospělý MeSH
• nemoci mozku metabolismus   patologie   MeSH
• neokortex patologie   MeSH
• předškolní dítě MeSH
• tenascin analýza   MeSH
• versikany analýza   MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

To understand the structural alterations that underlie early and late changes in hippocampal diffusivity after hypoxia/ischemia (H/I), the changes in apparent diffusion coefficient of water (ADC(W)) were studied in 8-week-old rats after H/I using diffusion-weighted magnetic resonance imaging (DW-MRI). In the hippocampal CA1 region, ADC(W) analyses were performed during 6 months of reperfusion and compared with alterations in cell number/cell-type composition, glial morphology, and extracellular space (ECS) diffusion parameters obtained by the real-time iontophoretic method. In the early phases of reperfusion (1 to 3 days) neuronal cell death, glial proliferation, and developing gliosis were accompanied by an ADC(W) decrease and tortuosity increase. Interestingly, ECS volume fraction was decreased only first day after H/I. In the late phases of reperfusion (starting 1 month after H/I), when the CA1 region consisted mainly of microglia, astrocytes, and NG2-glia with markedly altered morphology, ADC(W), ECS volume fraction and tortuosity were increased. Three-dimensional confocal morphometry revealed enlarged astrocytes and shrunken NG2-glia, and in both the contribution of cell soma/processes to total cell volume was markedly increased/decreased. In summary, the ADC(W) increase in the CA1 region underlain by altered cellular composition and glial morphology suggests that considerable changes in extracellular signal transmission might occur in the late phases of reperfusion after H/I.

• MeSH
• astrocyty patologie   MeSH
• buněčná smrt MeSH
• časové faktory MeSH
• difuze MeSH
• difuzní magnetická rezonance MeSH
• extracelulární prostor metabolismus   MeSH
• glióza etiologie   patologie   MeSH
• hipokampální oblast CA1 patologie   patofyziologie   MeSH
• hypoxie komplikace   patologie   patofyziologie   MeSH
• imunohistochemie MeSH
• ischemie mozku komplikace   patologie   patofyziologie   MeSH
• konfokální mikroskopie MeSH
• krysa rodu rattus MeSH
• neuroglie patologie   MeSH
• počet buněk MeSH
• potkani Wistar MeSH
• proliferace buněk MeSH
• reperfuze MeSH
• tělesná voda metabolismus   MeSH
• zobrazování trojrozměrné MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH