<p>The blood-brain barrier regulates the transport into the brain and protects the central nerve system (CNS) from toxics substances. However some areas of the brain, called circumventricular organs (CVO), lack the blood-brain barrier. One of these is area postrema (AP), which is located in the brainstem immediately adjacent to the nucleus tractus solitarius (NTS). These two areas together regulate autonomic behaviours such as food intake, and also make up the vomiting center.</p><p>The hormones leptin and ghrelin, which regulate food intake, are too big to pass the blood-brain barrier, but have receptors in NTS.</p><p>In this study we used immunohistochemistry to obtain a detailed map of the different components of the blood-brain barrier in AP and NTS.</p><p>The results suggest that there is a barrier that prevents diffusion of substances from AP into NTS. However, there seems to be some vessels in NTS that have a weaker or no barrier characteristics. These vessels could provide an entrance for peripheral substances to neurons in NTS.</p>

The blood-brain barrier regulates the transport into the brain and protects the central nerve system (CNS) from toxics substances. However some areas of the brain, called circumventricular organs (CVO), lack the blood-brain barrier. One of these is area postrema (AP), which is located in the brainstem immediately adjacent to the nucleus tractus solitarius (NTS). These two areas together regulate autonomic behaviours such as food intake, and also make up the vomiting center. The hormones leptin and ghrelin, which regulate food intake, are too big to pass the blood-brain barrier, but have receptors in NTS. In this study we used immunohistochemistry to obtain a detailed map of the different components of the blood-brain barrier in AP and NTS. The results suggest that there is a barrier that prevents diffusion of substances from AP into NTS. However, there seems to be some vessels in NTS that have a weaker or no barrier characteristics. These vessels could provide an entrance for peripheral substances to neurons in NTS.

Dados pré-clínicos e clínicos indicam que o canabidiol (CBD), um composto não-psicotomimético presente na planta Cannabis sativa, induz efeitos tipo-antipsicóticos. No entanto, poucos estudos em animais de laboratório investigaram as propriedades antipsicóticas do tratamento repetido com CBD. As alterações comportamentais induzidas pelo tratamento repetido com antagonistas dos receptores glutamatérgicos do tipo N-metil-D-aspartato (NMDA) têm sido propostas como um modelo animal de esquizofrenia. Evidências sugerem que uma hipofunção dos receptores NMDA estaria envolvida nos sintomas positivos, bem como nos sintomas negativos e cognitivos da esquizofrenia. Assim, no presente estudo, nós avaliamos se o tratamento repetido com CBD atenuaria as alterações comportamentais e moleculares induzidas pela administração crônica de um desses antagonistas, o MK-801. Camundongos C57BL/6J receberam injeções intraperitoneais diárias de MK-801 (0,1, 0,5 ou 1 mg/kg) durante 14, 21 ou 28 dias. Vinte e quatro horas após a última injeção, os animais foram submetidos ao teste de inibição pelo pré-pulso (PPI). Posteriormente, foi avaliado se o tratamento repetido com CBD (15, 30 e 60 mg/kg) atenuaria o prejuízo no teste de PPI induzido pelo MK-801 (1 mg/kg; por 28 dias). O tratamento com CBD iniciou-se no sexto dia após o início da administração de MK-801 e continuou até o final do tratamento. Nós também avaliamos se o tratamento com CBD atenuaria as alterações comportamentais induzidas pelo MK-801 nos testes de interação social e reconhecimento de objeto. Imediatamente após os testes comportamentais, os cérebros dos animais foram removidos e processados para posterior avaliação de alterações moleculares. Foram avaliadas as alterações na expressão das proteínas FosB/FosB e parvalbumina, um marcador de atividade neuronal e uma proteína de ligação ao cálcio expressa em uma subclasse de interneurônios GABAérgicos, respectivamente. Alterações na expressão do RNAm para o gene da subunidade obrigatória GluN1 do receptor NMDA (GRN1) também foram avaliadas. Adicionalmente, um número crescente de estudos indica que condições neuroinflamatórias e células gliais, como microglia e astrócitos, parecem estar envolvidas na patogênese da esquizofrenia. E, devido ao fato que o CBD, além de suas propriedades antipsicóticas, também induz efeitos anti-inflamatórios e neuroprotetores, nós também avaliamos possíveis alterações na expressão de NeuN (um marcador neuronal), Iba-1 (um marcador de microglia) e GFAP (um marcador de astrócitos) induzidas pelos tratamentos. Os efeitos do CBD foram comparados àqueles induzidos pelo antipsicótico atípico clozapina. A administração de MK-801, na dose de 1 mg/kg, por 28 dias induziu um prejuízo no teste de PPI, um efeito atenuado pelo tratamento repetido com CBD (30 e 60 mg/kg). Adicionalmente, o CBD também foi capaz de atenuar os prejuízos nos testes de interação social e reconhecimento de objeto induzidos pelo MK-801. Além das alterações comportamentais, o tratamento repetido com MK-801 aumentou a expressão da proteína FosB/FosB e diminuiu a expressão da parvalbumina no córtex pré-frontal medial (CPFm). Uma diminuição da expressão do mRNA para GRN1 no hipocampo também foi observada. O tratamento com MK-801 resultou ainda em aumento no número de astrócitos GFAP-positivos no CPFm e na porcentagem de células microgliais Iba-1-positivas apresentando um fenótipo reativo no CPFm e hipocampo dorsal, mas sem alterar o número total de células Iba-1-positivas. Nenhuma alteração no número de células NeuN-positivas foi observada. Assim como para as alterações comportamentais, as alterações moleculares induzidas pelo MK-801 também foram atenuadas pelo CBD. Entretanto, o CBD por si só não induziu qualquer efeito. Além disso, os efeitos do CBD foram semelhantes àqueles induzidos pelo tratamento repetido com clozapina. Estes resultados indicam que o tratamento repetido com o CBD, semelhante à clozapina, atenuou as alterações comportamentais tipo-esquizofrenia e as alterações moleculares observadas após a administração repetida de um antagonista dos receptores NMDA. Estes dados reforçam a proposta de que o CBD possui propriedades antipsicóticas. Embora os possíveis mecanismos de ação envolvidos nesses efeitos não estejam completamente elucidados, eles poderiam envolver as propriedades antiinflamatórias e neuroprotetoras do CBD. Além disso, nossos dados suportam a visão de que a inibição da microglia ativada pode ser benéfica para a melhora dos sintomas da esquizofrenia / Preclinical and clinical data suggest that cannabidiol (CBD), a major non-psychotomimetic compound from Cannabis sativa, induces antipsychotic-like effects. However, the antipsychotic properties of repeated CBD treatment have been poorly investigated. Behavioral changes induced by repeated treatment with glutamate NMDA receptor antagonists have been proposed as an animal model of schizophrenia-like symptoms. Evidence suggests that NMDA receptor hypofunction could be involved, in addition to the positive, also to the negative symptoms and cognitive deficits found in schizophrenia patients. In the present study we evaluated if repeated treatment with CBD would attenuate the behavioral and molecular changes induced by chronic administration of one of these antagonists, MK-801. Male C57BL/6J mice received daily intraperitoneal injections of MK-801 (0.1, 0.5 or 1 mg/kg) for 14, 21 or 28 days. Twenty-four hours after the last injection animals were submitted to the prepulse inhibition (PPI) test. After that, we investigated if repeated treatment with CBD (15, 30 and 60 mg/kg) would attenuate the PPI impairment induced by chronic treatment with MK-801 (1 mg/kg; 28 days). We also evaluate if the repeated CBD treatment would attenuate the MK-801-induced behavioral changes in social interaction and novel object recognition tests. CBD treatment began on the 6th day after the start of MK-801 administration and continued until the end of the treatment. Immediately after the behavioral tests, the mice brains were removed and processed to evaluate molecular changes. We measured changes in FosB/FosB and parvalbumin expression, a marker of neuronal activity and a calcium-binding protein expressed in a subclass of GABAergic interneurons, respectively. Changes in the mRNA expression of the NMDA receptor GluN1 subunit gene (GRN1) were also evaluated. Additionally, an increasing number of data has linked schizophrenia with neuroinflammatory conditions, and glial cells, such as microglia and astrocytes, have become increasingly attractive as candidates accounting for the pathogenesis of schizophrenia. And besides its antipsychotic properties, CBD also induces anti-inflammatory and neuroprotective effects. Thus, we also evaluated changes in NeuN (a neuronal marker), Iba-1 (a microglia marker) and GFAP (an astrocyte marker) expression in the medial prefrontal cortex (mPFC), dorsal striatum, nucleus accumbens core and shell, and dorsal hippocampus by immunohistochemistry. CBD effects were compared to those induced by the atypical antipsychotic clozapine. MK-801 administration at the dose of 1 mg/kg for 28 days impaired PPI responses. Chronic treatment with CBD (30 and 60 mg/kg) attenuated MK801-induced PPI impairment. CBD treatment also attenuated the impairment in social interaction and NOR tests induced by MK-801 treatment. Besides behavioral disruption, MK-801 treatment increased FosB/FosB expression and decreased parvalbumin expression in the mPFC. A decreased mRNA level of GRN1 in the hippocampus was also observed. Repeated MK-801 treatment also increased the number of GFAP-positive astrocytes in the mPFC and increased the percentage of Iba-1-positive microglia cells with a reactive phenotype in the mPFC and dorsal hippocampus without changing the number of Iba-1-positive cells. In addition, no change in the number of NeuN-positive cells was observed. All the molecular changes were attenuated by CBD. CBD by itself did not induce any effect. Moreover, CBD effects were similar to those induced by repeated clozapine treatment. These results indicate that repeated treatment with CBD, similar to clozapine, reverses the psychotomimetic-like effects and attenuates molecular changes observed after chronic administration of an NMDA receptor antagonist. These data reinforce the proposal that CBD may induce antipsychotic-like effects. Although the possible mechanism of action of these effects is still unknown, it may involve CBD anti-inflammatory and neuroprotective properties. Furthermore, our data support the view that inhibition of microglial activation may improve schizophrenia symptoms

Dados pré-clínicos e clínicos indicam que o canabidiol (CBD), um composto não-psicotomimético presente na planta Cannabis sativa, induz efeitos tipo-antipsicóticos. No entanto, poucos estudos em animais de laboratório investigaram as propriedades antipsicóticas do tratamento repetido com CBD. As alterações comportamentais induzidas pelo tratamento repetido com antagonistas dos receptores glutamatérgicos do tipo N-metil-D-aspartato (NMDA) têm sido propostas como um modelo animal de esquizofrenia. Evidências sugerem que uma hipofunção dos receptores NMDA estaria envolvida nos sintomas positivos, bem como nos sintomas negativos e cognitivos da esquizofrenia. Assim, no presente estudo, nós avaliamos se o tratamento repetido com CBD atenuaria as alterações comportamentais e moleculares induzidas pela administração crônica de um desses antagonistas, o MK-801. Camundongos C57BL/6J receberam injeções intraperitoneais diárias de MK-801 (0,1, 0,5 ou 1 mg/kg) durante 14, 21 ou 28 dias. Vinte e quatro horas após a última injeção, os animais foram submetidos ao teste de inibição pelo pré-pulso (PPI). Posteriormente, foi avaliado se o tratamento repetido com CBD (15, 30 e 60 mg/kg) atenuaria o prejuízo no teste de PPI induzido pelo MK-801 (1 mg/kg; por 28 dias). O tratamento com CBD iniciou-se no sexto dia após o início da administração de MK-801 e continuou até o final do tratamento. Nós também avaliamos se o tratamento com CBD atenuaria as alterações comportamentais induzidas pelo MK-801 nos testes de interação social e reconhecimento de objeto. Imediatamente após os testes comportamentais, os cérebros dos animais foram removidos e processados para posterior avaliação de alterações moleculares. Foram avaliadas as alterações na expressão das proteínas FosB/FosB e parvalbumina, um marcador de atividade neuronal e uma proteína de ligação ao cálcio expressa em uma subclasse de interneurônios GABAérgicos, respectivamente. Alterações na expressão do RNAm para o gene da subunidade obrigatória GluN1 do receptor NMDA (GRN1) também foram avaliadas. Adicionalmente, um número crescente de estudos indica que condições neuroinflamatórias e células gliais, como microglia e astrócitos, parecem estar envolvidas na patogênese da esquizofrenia. E, devido ao fato que o CBD, além de suas propriedades antipsicóticas, também induz efeitos anti-inflamatórios e neuroprotetores, nós também avaliamos possíveis alterações na expressão de NeuN (um marcador neuronal), Iba-1 (um marcador de microglia) e GFAP (um marcador de astrócitos) induzidas pelos tratamentos. Os efeitos do CBD foram comparados àqueles induzidos pelo antipsicótico atípico clozapina. A administração de MK-801, na dose de 1 mg/kg, por 28 dias induziu um prejuízo no teste de PPI, um efeito atenuado pelo tratamento repetido com CBD (30 e 60 mg/kg). Adicionalmente, o CBD também foi capaz de atenuar os prejuízos nos testes de interação social e reconhecimento de objeto induzidos pelo MK-801. Além das alterações comportamentais, o tratamento repetido com MK-801 aumentou a expressão da proteína FosB/FosB e diminuiu a expressão da parvalbumina no córtex pré-frontal medial (CPFm). Uma diminuição da expressão do mRNA para GRN1 no hipocampo também foi observada. O tratamento com MK-801 resultou ainda em aumento no número de astrócitos GFAP-positivos no CPFm e na porcentagem de células microgliais Iba-1-positivas apresentando um fenótipo reativo no CPFm e hipocampo dorsal, mas sem alterar o número total de células Iba-1-positivas. Nenhuma alteração no número de células NeuN-positivas foi observada. Assim como para as alterações comportamentais, as alterações moleculares induzidas pelo MK-801 também foram atenuadas pelo CBD. Entretanto, o CBD por si só não induziu qualquer efeito. Além disso, os efeitos do CBD foram semelhantes àqueles induzidos pelo tratamento repetido com clozapina. Estes resultados indicam que o tratamento repetido com o CBD, semelhante à clozapina, atenuou as alterações comportamentais tipo-esquizofrenia e as alterações moleculares observadas após a administração repetida de um antagonista dos receptores NMDA. Estes dados reforçam a proposta de que o CBD possui propriedades antipsicóticas. Embora os possíveis mecanismos de ação envolvidos nesses efeitos não estejam completamente elucidados, eles poderiam envolver as propriedades antiinflamatórias e neuroprotetoras do CBD. Além disso, nossos dados suportam a visão de que a inibição da microglia ativada pode ser benéfica para a melhora dos sintomas da esquizofrenia / Preclinical and clinical data suggest that cannabidiol (CBD), a major non-psychotomimetic compound from Cannabis sativa, induces antipsychotic-like effects. However, the antipsychotic properties of repeated CBD treatment have been poorly investigated. Behavioral changes induced by repeated treatment with glutamate NMDA receptor antagonists have been proposed as an animal model of schizophrenia-like symptoms. Evidence suggests that NMDA receptor hypofunction could be involved, in addition to the positive, also to the negative symptoms and cognitive deficits found in schizophrenia patients. In the present study we evaluated if repeated treatment with CBD would attenuate the behavioral and molecular changes induced by chronic administration of one of these antagonists, MK-801. Male C57BL/6J mice received daily intraperitoneal injections of MK-801 (0.1, 0.5 or 1 mg/kg) for 14, 21 or 28 days. Twenty-four hours after the last injection animals were submitted to the prepulse inhibition (PPI) test. After that, we investigated if repeated treatment with CBD (15, 30 and 60 mg/kg) would attenuate the PPI impairment induced by chronic treatment with MK-801 (1 mg/kg; 28 days). We also evaluate if the repeated CBD treatment would attenuate the MK-801-induced behavioral changes in social interaction and novel object recognition tests. CBD treatment began on the 6th day after the start of MK-801 administration and continued until the end of the treatment. Immediately after the behavioral tests, the mice brains were removed and processed to evaluate molecular changes. We measured changes in FosB/FosB and parvalbumin expression, a marker of neuronal activity and a calcium-binding protein expressed in a subclass of GABAergic interneurons, respectively. Changes in the mRNA expression of the NMDA receptor GluN1 subunit gene (GRN1) were also evaluated. Additionally, an increasing number of data has linked schizophrenia with neuroinflammatory conditions, and glial cells, such as microglia and astrocytes, have become increasingly attractive as candidates accounting for the pathogenesis of schizophrenia. And besides its antipsychotic properties, CBD also induces anti-inflammatory and neuroprotective effects. Thus, we also evaluated changes in NeuN (a neuronal marker), Iba-1 (a microglia marker) and GFAP (an astrocyte marker) expression in the medial prefrontal cortex (mPFC), dorsal striatum, nucleus accumbens core and shell, and dorsal hippocampus by immunohistochemistry. CBD effects were compared to those induced by the atypical antipsychotic clozapine. MK-801 administration at the dose of 1 mg/kg for 28 days impaired PPI responses. Chronic treatment with CBD (30 and 60 mg/kg) attenuated MK801-induced PPI impairment. CBD treatment also attenuated the impairment in social interaction and NOR tests induced by MK-801 treatment. Besides behavioral disruption, MK-801 treatment increased FosB/FosB expression and decreased parvalbumin expression in the mPFC. A decreased mRNA level of GRN1 in the hippocampus was also observed. Repeated MK-801 treatment also increased the number of GFAP-positive astrocytes in the mPFC and increased the percentage of Iba-1-positive microglia cells with a reactive phenotype in the mPFC and dorsal hippocampus without changing the number of Iba-1-positive cells. In addition, no change in the number of NeuN-positive cells was observed. All the molecular changes were attenuated by CBD. CBD by itself did not induce any effect. Moreover, CBD effects were similar to those induced by repeated clozapine treatment. These results indicate that repeated treatment with CBD, similar to clozapine, reverses the psychotomimetic-like effects and attenuates molecular changes observed after chronic administration of an NMDA receptor antagonist. These data reinforce the proposal that CBD may induce antipsychotic-like effects. Although the possible mechanism of action of these effects is still unknown, it may involve CBD anti-inflammatory and neuroprotective properties. Furthermore, our data support the view that inhibition of microglial activation may improve schizophrenia symptoms

The topic of the thesis is the mechanisms of cellular volume regulation in the rat retina. Müller cells as main macroglial cells of the retina are supposed to play important roles in the regulation of the retinal ion- and osmohomeostasis and, thus, in the regulation of the extracellular space volume. In the first part of the thesis, signaling pathways were determined which are involved in the regulation of the volume of Müller glial cells and bipolar cells, the main second-order cells of the retina, in the healthy rat retina. The topic of the second part of the thesis is the evaluation of gliotic alterations of Müller cells in a transgenic rat model of retinal degeneration (CMV-PKD21/703 HA rats), in order to obtain indications for a pathogenic role of reactive glial cells in the development of retinal degeneration and edema. Various methods were used including immunohistochemical stainings, real-time RT-PCR, patch-clamp recordings, and cell swelling experiments. The data suggest that both neurons and reactive Müller cells may contribute to formation of retinal edema. In contrast to Müller cells, bipolar cells are apparently not capable to regulate the extracellular space volume in the healthy retina. However, reactive Müller cells are impaired in their capability to regulate retinal water and ion homeostasis. Impaired regulation of the extracellular space volume may result in neuronal hyperexcitation and degeneration.

The topic of the thesis is the mechanisms of cellular volume regulation in the rat retina. Müller cells as main macroglial cells of the retina are supposed to play important roles in the regulation of the retinal ion- and osmohomeostasis and, thus, in the regulation of the extracellular space volume. In the first part of the thesis, signaling pathways were determined which are involved in the regulation of the volume of Müller glial cells and bipolar cells, the main second-order cells of the retina, in the healthy rat retina. The topic of the second part of the thesis is the evaluation of gliotic alterations of Müller cells in a transgenic rat model of retinal degeneration (CMV-PKD21/703 HA rats), in order to obtain indications for a pathogenic role of reactive glial cells in the development of retinal degeneration and edema. Various methods were used including immunohistochemical stainings, real-time RT-PCR, patch-clamp recordings, and cell swelling experiments. The data suggest that both neurons and reactive Müller cells may contribute to formation of retinal edema. In contrast to Müller cells, bipolar cells are apparently not capable to regulate the extracellular space volume in the healthy retina. However, reactive Müller cells are impaired in their capability to regulate retinal water and ion homeostasis. Impaired regulation of the extracellular space volume may result in neuronal hyperexcitation and degeneration.

<p>The ß-carbolines norharman and harman structurally resemble the synthetic compound 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) that is known for its ability to damage neuromelanin-containing dopaminergic neurons of the substantia nigra and thereby induce parkinsonism. MPTP is, however, not normally present in the environment whereas the ß-carbolines are present in cooked food and tobacco smoke. </p><p>In this thesis it was demonstrated that norharman and harman had affinity to melanin and were retained in neuromelanin-containing neurons of frogs up to 30 days post-injection (the longest survival time examined). It was also demonstrated that norharman induced neurodegeneration, activation of glia cells and motor impairment in mice. Furthermore, this compound induced ER stress and cell death in PC12 cells. An in vitro model of dopamine melanin-loaded PC12 cells was developed in order to study the effect of melanin on norharman-induced toxicity. In this model, melanin seemed to attenuate toxicity induced by low concentrations of norharman. After exposure to the highest concentration of norharman, melanin clusters were disaggregated and there was an increased expression of stress proteins and caspases-3, known to be involved in apoptosis.</p><p>The polycyclic aromatic hydrocarbon, 7,12-dimethylbenz[<i>a</i>]anthracene was demonstrated to have a CYP1A1-dependent localization in endothelial cells in the choroid plexus, in the veins in the leptomeninges and in the cerebral veins of mice pre-treated with CYP1-inducers. </p><p>These results demonstrate that the distribution of environmental compounds could be influenced by the presence of neuromelanin and expression of CYP enzymes in the brain and that norharman may induce neurotoxic effects in vivo and in vitro.</p>

The ß-carbolines norharman and harman structurally resemble the synthetic compound 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) that is known for its ability to damage neuromelanin-containing dopaminergic neurons of the substantia nigra and thereby induce parkinsonism. MPTP is, however, not normally present in the environment whereas the ß-carbolines are present in cooked food and tobacco smoke. In this thesis it was demonstrated that norharman and harman had affinity to melanin and were retained in neuromelanin-containing neurons of frogs up to 30 days post-injection (the longest survival time examined). It was also demonstrated that norharman induced neurodegeneration, activation of glia cells and motor impairment in mice. Furthermore, this compound induced ER stress and cell death in PC12 cells. An in vitro model of dopamine melanin-loaded PC12 cells was developed in order to study the effect of melanin on norharman-induced toxicity. In this model, melanin seemed to attenuate toxicity induced by low concentrations of norharman. After exposure to the highest concentration of norharman, melanin clusters were disaggregated and there was an increased expression of stress proteins and caspases-3, known to be involved in apoptosis. The polycyclic aromatic hydrocarbon, 7,12-dimethylbenz[a]anthracene was demonstrated to have a CYP1A1-dependent localization in endothelial cells in the choroid plexus, in the veins in the leptomeninges and in the cerebral veins of mice pre-treated with CYP1-inducers. These results demonstrate that the distribution of environmental compounds could be influenced by the presence of neuromelanin and expression of CYP enzymes in the brain and that norharman may induce neurotoxic effects in vivo and in vitro.

Die Dissertation befasst sich mit der Untersuchung der Ko-Expression des GFAP- und des PLP-Promotors in Müllerzellen der Netzhaut transgener Mäuse. Die verwendete Mauslinie ist tripel-transgen für den GFAP- und den PLP-Promotor sowie für einen ROSA26-Reporter. Durch die Quantifizierung der EYFP-Expression in Müllerzellen konnte gezeigt werden, dass es nach akuter ischämischer Schädigung sowie einer angeborenen retinalen Degeneration in Müllerzellen zu einer Aktivierung des oligodendrozytären PLP-Promotors kommt. Weiterhin wurde festgestellt, dass die Aktivierung des Transkriptionsfaktors Sox-9, der sowohl für die Entwicklung der Müllerzellen als auch für die Oligodendrogenese von entscheidender Rolle ist, mit dieser Promotoraktivierung korreliert. Diese Ergebnisse implizieren, dass Müllerzellen im Rahmen ihrer Stammzelleigenschaften in der Lage sind, auf embryonale Entwicklungsprozesse, die auch die oligodendrozytäre Zellreihe beinhalten, zurückgreifen zu können.

Die Dissertation befasst sich mit der Untersuchung der Ko-Expression des GFAP- und des PLP-Promotors in Müllerzellen der Netzhaut transgener Mäuse. Die verwendete Mauslinie ist tripel-transgen für den GFAP- und den PLP-Promotor sowie für einen ROSA26-Reporter. Durch die Quantifizierung der EYFP-Expression in Müllerzellen konnte gezeigt werden, dass es nach akuter ischämischer Schädigung sowie einer angeborenen retinalen Degeneration in Müllerzellen zu einer Aktivierung des oligodendrozytären PLP-Promotors kommt. Weiterhin wurde festgestellt, dass die Aktivierung des Transkriptionsfaktors Sox-9, der sowohl für die Entwicklung der Müllerzellen als auch für die Oligodendrogenese von entscheidender Rolle ist, mit dieser Promotoraktivierung korreliert. Diese Ergebnisse implizieren, dass Müllerzellen im Rahmen ihrer Stammzelleigenschaften in der Lage sind, auf embryonale Entwicklungsprozesse, die auch die oligodendrozytäre Zellreihe beinhalten, zurückgreifen zu können.:Inhaltsverzeichnis ....................................................................................................................... 3 Bibliographische Darstellung ..................................................................................................... 5 Abkürzungsverzeichnis und Erläuterungen ................................................................................ 6 1 Einleitung ............................................................................................................................ 8 1.1 Die Retina als Teil des Auges ................................................................................................. 8 1.1.1 Aufbau .............................................................................................................................. 8 1.2 Die gliale Müllerzelle ............................................................................................................ 12 1.2.1 Definition und Morphologie der Müllerzellen ............................................................... 12 1.2.2 Funktion .......................................................................................................................... 13 1.2.3 Ursprung und Ontogenese der Müllerzelle ..................................................................... 14 1.3 Erkrankungen der Netzhaut .................................................................................................. 15 1.3.1 Akute Läsionen ............................................................................................................... 15 1.3.2 Chronische Erkrankungen der Netzhaut ......................................................................... 15 1.3.3 Die Rolle der Müllerzelle in der erkrankten Retina ....................................................... 16 1.4 Mausgenetik .......................................................................................................................... 18 1.4.1 Das Cre-loxP-System ..................................................................................................... 18 1.5 Pax-6 und Sox-9: Transkriptionsfaktoren spezifizieren das Zellschicksal ........................... 24 1.5.1 Die PAX-Familie ............................................................................................................ 24 1.5.2 SOX-9-Gene ................................................................................................................... 25 2 Ziele .................................................................................................................................. 26 3 Material und Methoden ..................................................................................................... 27 3.1 Material ................................................................................................................................. 27 3.1.1 Chemikalien .................................................................................................................... 27 3.1.2 Antikörper ....................................................................................................................... 27 3.1.3 Größenstandards ............................................................................................................. 28 3.1.4 Mauslinien ...................................................................................................................... 29 3.1.5 Geräte ............................................................................................................................. 31 3.2 Methoden .............................................................................................................................. 31 3.2.1 Genotypisierung transgener Mäuse ................................................................................ 31 3.2.2 Akute retinale Läsion durch Anlegen eines erhöhten Augeninnendrucks („high intraocular pressure“, HIOP) .......................................................................................... 37 3.2.3 Herstellung und Fixierung der retinalen Gewebsproben ................................................ 37 3.2.4 Immunhistochemische Färbungen .................................................................................. 38 3.2.5 Mikroskopische Auswertung .......................................................................................... 39 3.2.6 Datenverarbeitung und Statistik ..................................................................................... 41 4 Ergebnisse ......................................................................................................................... 42 4.1 Technische Aspekte: Vergleich der Quantifizierung in Ganzpräparate und Querschnitte ... 42 4.1.1 Vergleich der Abbildungen ............................................................................................ 42 4.1.2 Auszählung Retina-Ganzpräparate ................................................................................. 43 4.1.3 Auszählung der Zellen in Querschnitten der Netzhaut ................................................... 45 4.1.4 Vergleich der Quantifizierung von Ganzpräparaten und Querschnitten ........................ 46 4.1.5 Quantifizierung ............................................................................................................... 48 4.2 Analyse der Reporterexpression in der Retina tripel-transgener Mäuse ............................... 49 4.2.1 Quantitative Auswertung GS-positiver Müllerzellen ..................................................... 49 4.2.2 Quantitative Auswertung EYFP-positiver Müllerzellen ................................................ 51 4.2.3 Auswertung des prozentualen Anteils der EYFP-positiven Müllerzellen ...................... 53 4.3 Auswertung der Transkriptionsfaktorexpression von Pax-6 und Sox-9 ............................... 56 4.3.1 Auswertung der Pax-6-positiven Müllerzellen ............................................................... 57 4.3.2 Auswertung der Sox-9-positiven Müllerzellen .............................................................. 60 5 Diskussion ......................................................................................................................... 63 5.1 Die GFAP-Expression in der Müllerzellgliose ..................................................................... 63 5.2 Auswertung und Vergleich der retinalen Ganzpräparate und Querschnitte ......................... 64 5.3 Die Untersuchung der Promotoraktivität nach retinaler Ischämie ........................................ 65 5.4 Die Untersuchung der Promotoraktivität bei angeborener retinaler Degeneration ............... 66 5.5 Die Rolle der Transkriptionsfaktoren Pax-6 und Sox-9 ........................................................ 68 5.5.1 Pax-6 ............................................................................................................................... 68 5.5.2 Sox-9 ............................................................................................................................... 69 5.6 Einordnung der Ergebnisse in die Zellbiologie der Müllerzelle ........................................... 72 6 Zusammenfassung ............................................................................................................. 74 7 Literaturverzeichnis .......................................................................................................... 77 8 Lebenslauf ......................................................................................................................... 83 9 Danksagung ....................................................................................................................... 84 10 Eigenständigkeitserklärung ............................................................................................... 85