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The Role of Aquaporin 4 channels and Transient Receptor Potential Vanilloid 4 channels in astrocytic swelling
Heřmanová, Zuzana ; Anděrová, Miroslava (advisor) ; Machová Urdzíková, Lucia (referee)
Astrocytes posses a wide range of functions within the brain. In response to ischemic conditions they swell due to increased uptake of osmolytes and they are mainly responsible for cytotoxic edema formation. However, they are also able to regulate their volume by releasing osmolytes together with water via the process of regulatory volume decrease (RVD). The Aquaporin 4 (AQP4) channel and Transient receptor potential vanilloid 4 (TRPV4) channel are suspected to be strongly involved in these processes of astrocytic volume regulation. The goal of the present diploma thesis was to clarify the role of both channels in astrocytic swelling in situ. For our experiments we used a subpopulation of green fluorescent protein-labelled astrocytes from AQP4-deficient (AQP4-/- ), TRPV4-deficient (TRPV4-/- ) and control (Ctrl) mice. Cell volume alterations were induced in acute brain slices by hypoosmotic stress or by oxygen-glucose deprivation (OGD). Data were quantified using fluorescence intensity-based approach in the whole cells and in astrocytic endfeet. Our results indicate, that there is no difference in astrocytic swelling or cell volume recovery between astrocytes from AQP4-/- , TRPV4-/- and control mice when exposed to hypoosmotic stress. On the contrary, volume changes induced by OGD varied...
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The role of astrocytes in the formation of brain edema
Heřmanová, Zuzana ; Anděrová, Miroslava (advisor) ; Pačesová, Dominika (referee)
Brain edema is a cause of mortality accompanying number of pathologies such as ischemia, traumatic brain injury, tumors or liver and kidney failure. It is described as a process of osmotic and water flux alterations, which lead to cell volume changes and to an increase in intracranial pressure. Brain edema is usually classified into two types: vasogenic and cytotoxic. Development of vasogenic edema is connected to the blood brain barrier disruption. Water accumulates in the extracellular space and exerts pressure on the cellular compartments of the tissue. The cytotoxic type of edema is characterized by water accumulation within the cells. The process of cellular volume enlargement is termed cellular swelling. Cytotoxic swelling is usually connected to glial cells, namely astrocytes, as these cells represent a part of the blood brain barrier and thus they influence homeostasis inside the brain. Water flows across cytoplasmic membrane through a system of specialized channels - aquaporins. For the brain edema formation, aquaporin 4 is the most important. It is localized on astrocytic membranes and using aquaporin-null mice, it has been shown, that it participates in water clearance in physiological and pathological conditions. Since the water fluxes are passive, the driving force for edema formation...
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The role of AQP4 and TRPV4 channels in the ischemic brain edema: focusing on glial cells
Kročianová, Daniela ; Anděrová, Miroslava (advisor) ; Máčiková, Lucie (referee)
Cerebral ischemia, also known as stroke, is one of the most common causes of death. It is accompanied by the formation of edema, which can be characterized as an influx of water and osmolytes into the brain, causing volume alterations. We recognize two types of cerebral edema - vasogenic, characterized by the disruption of the blood-brain barrier (BBB) and increase of the extracellular volume, and cytotoxic, caused by the increase of the volume of cells, mainly glia. The major contributors to the formation of cytotoxic edema are the astrocytes, which, in physiological conditions, are responsible for the maintenance of the BBB and keeping the homeostasis of the brain and spinal cord or central nervous system. The mechanism responsible for the process of volume and osmotic changes are the transmembrane channels, mainly aquaporin 4 (AQP4) and transient receptor potential vanilloid 4 (TRPV4). AQP4 is the main pathway for water influx as well as efflux when the edema subsides. TRPV4 is likely responsible for the maintenance of the osmotic balance of the organism, although its precise role in the formation of the edema has not yet been fully elucidated. The main aim of this thesis was to categorize the types of cerebral ischemia and edema, and to describe the process of cerebral edema formation and the...
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The role of AQP4 and TRVP4 channels in the ischemic brain edema: focusing on glial cells.
Kročianová, Daniela ; Anděrová, Miroslava (advisor) ; Máčiková, Lucie (referee)
Cerebral ischemia, also known as stroke, is one of the most common causes of death. It is accompanied by the formation of edema, which can be characterized as an influx of water and osmolytes into the brain, causing volume alterations. We recognize two types of cerebral edema - vasogenic, characterized by the disruption of the blood-brain barrier (BBB) and increase of the extracellular volume, and cytotoxic, caused by the increase of the volume of cells, mainly glia. The major contributors to the formation of cytotoxic edema are the astrocytes, which, in physiological conditions, are responsible for the maintenance of the BBB and keeping the homeostasis of the brain and spinal cord or central nervous system. The mechanism responsible for the process of volume and osmotic changes are the transmembrane channels, mainly aquaporin 4 (AQP4) and transient receptor potential vanilloid 4 (TRPV4). AQP4 is the main pathway for water influx as well as efflux when the edema subsides. TRPV4 is likely responsible for the maintenance of the osmotic balance of the organism, although its precise role in the formation of the edema has not yet been fully elucidated. The main aim of this thesis was to categorize the types of cerebral ischemia and edema, and to describe the process of cerebral edema formation and the...
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The Role of Aquaporin 4 channels and Transient Receptor Potential Vanilloid 4 channels in astrocytic swelling
Heřmanová, Zuzana ; Anděrová, Miroslava (advisor) ; Machová Urdzíková, Lucia (referee)
Astrocytes posses a wide range of functions within the brain. In response to ischemic conditions they swell due to increased uptake of osmolytes and they are mainly responsible for cytotoxic edema formation. However, they are also able to regulate their volume by releasing osmolytes together with water via the process of regulatory volume decrease (RVD). The Aquaporin 4 (AQP4) channel and Transient receptor potential vanilloid 4 (TRPV4) channel are suspected to be strongly involved in these processes of astrocytic volume regulation. The goal of the present diploma thesis was to clarify the role of both channels in astrocytic swelling in situ. For our experiments we used a subpopulation of green fluorescent protein-labelled astrocytes from AQP4-deficient (AQP4-/- ), TRPV4-deficient (TRPV4-/- ) and control (Ctrl) mice. Cell volume alterations were induced in acute brain slices by hypoosmotic stress or by oxygen-glucose deprivation (OGD). Data were quantified using fluorescence intensity-based approach in the whole cells and in astrocytic endfeet. Our results indicate, that there is no difference in astrocytic swelling or cell volume recovery between astrocytes from AQP4-/- , TRPV4-/- and control mice when exposed to hypoosmotic stress. On the contrary, volume changes induced by OGD varied...
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The role of astrocytes in the formation of brain edema
Heřmanová, Zuzana ; Anděrová, Miroslava (advisor) ; Pačesová, Dominika (referee)
Brain edema is a cause of mortality accompanying number of pathologies such as ischemia, traumatic brain injury, tumors or liver and kidney failure. It is described as a process of osmotic and water flux alterations, which lead to cell volume changes and to an increase in intracranial pressure. Brain edema is usually classified into two types: vasogenic and cytotoxic. Development of vasogenic edema is connected to the blood brain barrier disruption. Water accumulates in the extracellular space and exerts pressure on the cellular compartments of the tissue. The cytotoxic type of edema is characterized by water accumulation within the cells. The process of cellular volume enlargement is termed cellular swelling. Cytotoxic swelling is usually connected to glial cells, namely astrocytes, as these cells represent a part of the blood brain barrier and thus they influence homeostasis inside the brain. Water flows across cytoplasmic membrane through a system of specialized channels - aquaporins. For the brain edema formation, aquaporin 4 is the most important. It is localized on astrocytic membranes and using aquaporin-null mice, it has been shown, that it participates in water clearance in physiological and pathological conditions. Since the water fluxes are passive, the driving force for edema formation...
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