The intestinal transport of nutrients exhibits distinct diurnal rhythmicity, and the enterocytes harbor a circadian clock. However, temporal regulation of the genes involved in colonic ion transport, i.e., ion transporters and channels operating in absorption and secretion, remains poorly understood. To address this issue, we assessed the 24-h profiles of expression of genes encoding the sodium pump (subunits Atp1a1 and Atp1b1), channels (α-, β-, and γ-subunits of Enac and Cftr), transporters (Dra, Ae1, Nkcc1, Kcc1, and Nhe3), and the Na(+)/H(+) exchanger (NHE) regulatory factor (Nherf1) in rat colonic mucosa. Furthermore, we investigated temporal changes in the spatial localization of the clock genes Per1, Per2, and Bmal1 and the genes encoding ion transporters and channels along the crypt axis. In rats fed ad libitum, the expression of Atp1a1, γEnac, Dra, Ae1, Nhe3, and Nherf1 showed circadian variation with maximal expression at circadian time 12, i.e., at the beginning of the subjective night. The peak γEnac expression coincided with the rise in plasma aldosterone. Restricted feeding phase advanced the expression of Dra, Ae1, Nherf, and γEnac and decreased expression of Atp1a1. The genes Atp1b1, Cftr, αEnac, βEnac, Nkcc1, and Kcc1 did not show any diurnal variations in mRNA levels. A low-salt diet upregulated the expression of βEnac and γEnac during the subjective night but did not affect expression of αEnac. Similarly, colonic electrogenic Na(+) transport was much higher during the subjective night than the subjective day. These findings indicate that the transporters and channels operating in NaCl absorption undergo diurnal regulation and suggest a role of an intestinal clock in the coordination of colonic NaCl absorption.

• MeSH
• aldosteron krev   MeSH
• cirkadiánní proteiny Period genetika   MeSH
• cirkadiánní rytmus genetika   MeSH
• elektrolyty farmakokinetika   MeSH
• enterocyty metabolismus   MeSH
• intestinální absorpce genetika   MeSH
• iontové kanály genetika   MeSH
• kolon cytologie   fyziologie   MeSH
• krysa rodu rattus MeSH
• kuchyňská sůl farmakokinetika   MeSH
• potkani Wistar MeSH
• přijímání potravy genetika   MeSH
• stanovení celkové genové exprese MeSH
• střevní sliznice metabolismus   MeSH
• transportní proteiny genetika   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Increased colonic Cl- secretion was supposed to be a causative factor of diarrhea in inflammatory bowel diseases. Surprisingly, hyporesponsiveness to Cl- secretagogues was later described in inflamed colon. Our aim was to evaluate changes in secretory responses to cholinergic agonist carbachol in distal and proximal colon during colitis development, regarding secretory activity of enteric nervous system (ENS) and prostaglandins. Increased responsiveness to carbachol was observed in both distal and proximal colon after 3 days of 2 % dextran sodium sulfate (DSS) administration. It was measured in the presence of mucosal Ba2+ to emphasize Cl- secretion. The described increase was abolished by combined inhibitory effect of tetrodotoxin (TTX) and indomethacin. Indomethacin also significantly reduced TTXsensitive current. On the 7th day of colitis development responsiveness to carbachol decreased in distal colon (compared to untreated mice), but did not change in proximal colon. TTXsensitive current did not change during colitis development, but indomethacin-sensitive current was significantly increased the 7th day. Decreased and deformed current responses to serosal Ba2+ were observed during colitis induction, but only in proximal colon. We conclude that besides inhibitory effect of DSS on distal colon responsiveness, there is an early stimulatory effect that manifests in both distal and proximal colon.

• MeSH
• karbachol MeSH
• kolitida chemicky indukované   patologie   MeSH
• kolon patofyziologie   patologie   účinky léků   MeSH
• myši inbrední BALB C MeSH
• myši MeSH
• prostaglandiny fyziologie   MeSH
• síran dextranu aplikace a dávkování   farmakologie   MeSH
• střevní nervový systém patofyziologie   MeSH
• střevní sliznice patofyziologie   patologie   účinky léků   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH

Energy depletion during ischemia leads to disturbed ionic homeostasis and accumulation of neuroactive substances in the extracellular space, subsequently leading to volume changes in astrocytes. Confocal microscopy combined with 3D reconstruction was used to quantify ischemia-induced astrocyte volume changes in cortical slices of GFAP/EGFP transgenic mice. Twenty-minutes of oxygen-glucose deprivation (OGD) or oxygen-glucose deprivation combined with acidification (OGD(pH 6.8)) revealed the presence of two distinct astrocytic populations, the first showing a large volume increase (HR astrocytes) and the second displaying a small volume increase (LR astrocytes). In addition, changes in resting membrane potential (V(m)), measured by the patch-clamp technique, supported the existence of two astrocytic populations responding differently to ischemia. Although one group markedly depolarized during OGD or OGD(pH 6.8), only small changes in V(m) toward more negative values were observed in the second group. Conversely, acidification (ACF(pH 6.8)) led to a uniform volume decrease in all astrocytes, accompanied by only a small depolarization. Interestingly, two differently responding populations were not detected during acidification. Differences in the expression of inwardly rectifying potassium channels (Kir4.1), glial fibrillary acidic protein (GFAP), and taurine levels in cortical astrocytes were detected using immunohistochemical methods. We conclude that two distinct populations of astrocytes are present in the cortex of GFAP/EGFP mice, based on volume and V(m) changes during exposure to OGD or OGD(pH 6.8). Immunohistochemical analysis suggests that the diverse expression of Kir4.1 channels and GFAP as well as differences in the accumulation of taurine might contribute to the distinct ability of astrocytes to regulate their volume. 2008 Wiley-Liss, Inc.

• MeSH
• astrocyty fyziologie   klasifikace   patologie   MeSH
• draslíkové kanály dovnitř usměrňující metabolismus   MeSH
• elektrická stimulace MeSH
• financování organizované MeSH
• gliový fibrilární kyselý protein genetika   MeSH
• glukosa nedostatek   MeSH
• hypoxie MeSH
• ischemie patologie   MeSH
• koncentrace vodíkových iontů MeSH
• konfokální mikroskopie MeSH
• membránové potenciály fyziologie   MeSH
• metoda terčíkového zámku MeSH
• modely nemocí na zvířatech MeSH
• mozková kůra patologie   MeSH
• myši transgenní MeSH
• myši MeSH
• proteiny nervové tkáně metabolismus   MeSH
• taurin metabolismus   MeSH
• velikost buňky MeSH
• zelené fluorescenční proteiny genetika   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH

Although the gastrointestinal tract is a rich source of melatonin and possesses numerous melatonin-binding sites, the role of melatonin in this tissue has not yet been fully elucidated. In this work we focused on the role of melatonin in the modulation of ion transport in rat distal colon. Whereas melatonin had no effect on colonic secretion or caused only infrequent and small changes in the short circuit current (Isc) due to its solvent ethanol, this mediator significantly modulated the secretion elicited by some secretagogues. Out of the five substances tested (prostaglandin E(2); 5-hydroxytryptamine; bethanechol; histamine; sodium nitroprusside) melatonin inhibited the effect of prostaglandin E(2) (PGE(2)) and sodium nitroprusside (SNP). Melatonin concentration-dependently decreased PGE(2)-evoked Isc and this inhibitory effect was more obvious from the mucosal side. The basal level of cAMP in colonic mucosa was not influenced by melatonin, but this drug prevented a PGE(2)-induced increase in the level of cAMP. The neurotoxin tetrodotoxin blocked the inhibitory effect of melatonin on SNP-induced Isc. Our data suggests that melatonin takes part in the modulation of colonic ion transport. The modulatory effect of melatonin on PGE(2)-induced Isc occurs directly at the level of the epithelium, whereas the effect on SNP-induced Isc is indirect and located in tetrodotoxin-sensitive enteric neurons.

• MeSH
• AMP cyklický fyziologie   MeSH
• dinoproston farmakologie   MeSH
• financování organizované MeSH
• iontový transport účinky léků   MeSH
• kolon sekrece   účinky léků   MeSH
• krysa rodu rattus MeSH
• melatonin farmakologie   MeSH
• nitroprusid farmakologie   MeSH
• potkani Wistar MeSH
• receptor melatoninový MT1 fyziologie   účinky léků   MeSH
• tetrodotoxin farmakologie   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH

Neuronal activity and many pathological states in the CNS are accompanied by transient astrocytic swelling, which affects excitability, extrasynaptic transmission, and neuron-glia interactions. By using three-dimensional confocal morphometry (3DCM), we quantified the morphometric parameters of astrocytes in intact tissue. In experiments performed in brain cortex slices from transgenic GFAP/EGFP mice, we applied 3DCM to study the dynamic changes in astrocyte morphology during hypotonic stress. Our morphometric analysis showed that the effect of a 10-min application of hypotonic solution (200 mmol/kg) on the swelling of different cell compartments was dependent on the extent of the swelling of the total astrocyte volume. If the swelling of the whole cell, i.e., soma and processes, was less than approximately 10%, there were no differences between the swelling of the soma and the processes. However, if the swelling of the total cell volume was greater than 10%, the swelling of the processes was greater than the swelling of the soma. Analyzing the effect of hypotonic solution on the morphology of these astrocytes revealed that the total cell volume increased; however, certain cell compartments were distinguished in which the volume increased, whereas in other compartments cell volume decreased or apparently did not change, and the structure of some compartments was altered. Our data show that astrocytes in brain slices undergoing hypotonic stress display cell volume regulation as well as transient changes in morphology.

• MeSH
• astrocyty ultrastruktura   MeSH
• financování organizované MeSH
• gliový fibrilární kyselý protein genetika   MeSH
• hypotonické roztoky MeSH
• konfokální mikroskopie MeSH
• mozek ultrastruktura   MeSH
• myši transgenní MeSH
• myši MeSH
• orgánové kultury - kultivační techniky MeSH
• počítačové zpracování obrazu MeSH
• promotorové oblasti (genetika) MeSH
• zelené fluorescenční proteiny genetika   MeSH
• zobrazování trojrozměrné MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH

• Publikační typ
• abstrakty MeSH

• MeSH
• finanční podpora výzkumu jako téma MeSH
• Publikační typ
• abstrakty MeSH

• Publikační typ
• abstrakty MeSH