16 research outputs found

    Occurrence and dietary intake of food processing contaminants (FPCs) in Catalonia, Spain

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    Altres ajuts: Agència Catalana de Seguretat Alimentària (ACSA), Department de Salut, Generalitat de Catalunya.Food processing contaminants (FPCs) form a wide group of chemicals that are generated during different cooking practices. This study was aimed at determining the levels of a number of FPCs (i.e., acrylamide, furans, monochloropropanediols (MCPDs) and glycidyl esters (GEs)) in foodstuffs purchased in Catalonia (Spain), and assessing the human exposure for different population groups. The dietary intake of acrylamide for the adult population was estimated in 2.91 μg/day, while that of furan, 2-methylfurans and 3-methylfurans was 4.32, 7.35 and 0.439 μg/day, respectively. Finally, the exposure to 3-MCPD, 2-MCPD, 3-MCPD esters, 2-MCPD esters and GEs through food consumption was estimated in 0.657, 0.529, 10.7, 5.15 and 8.81 μg/day, respectively. The risk assessment showed that there is a health concern for developing neoplastic effects derived from the intake of acrylamide for all the population groups. In addition, toddlers and infants would exceed the threshold values of 3-MCDP and GEs. The global analysis of these results indicates that a special attention should be paid to the youngest population groups in Catalonia, reinforcing the need of conducting periodical monitoring studies and developing policy measures, especially focused on foodstuffs highly consumed by toddlers, infants and children

    The db/db Mouse : a Useful Model for the Study of Diabetic Retinal Neurodegeneration

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    Background: To characterize the sequential events that are taking place in retinal neurodegeneration in a murine model of spontaneous type 2 diabetes (db/db mouse). Methods: C57BLKsJ-db/db mice were used as spontaneous type 2 diabetic animal model, and C57BLKsJ-db/+ mice served as the control group. To assess the chronological sequence of the abnormalities the analysis was performed at different ages (8, 16 and 24 weeks). The retinas were evaluated in terms of morphological and functional abnormalities [electroretinography (ERG)]. Histological markers of neurodegeneration (glial activation and apoptosis) were evaluated by immunohistochemistry. In addition glutamate levels and glutamate/aspartate transporter (GLAST) expression were assessed. Furthermore, to define gene expression changes associated with early diabetic retinopathy a transcriptome analyses was performed at 8 week. Furthermore, an additional interventional study to lower blood glucose levels was performed. Results: Glial activation was higher in diabetic than in non diabetic mice in all the stages (p<0.01). In addition, a progressive loss of ganglion cells and a significant reduction of neuroretinal thickness were also observed in diabetic mice. All these histological hallmarks of neurodegeneration were less pronounced at week 8 than at week 16 and 24. Significant ERG abnormalities were present in diabetic mice at weeks 16 and 24 but not at week 8. Moreover, we observed a progressive accumulation of glutamate in diabetic mice associated with an early downregulation of GLAST. Morphological and ERG abnormalities were abrogated by lowering blood glucose levels. Finally, a dysregulation of several genes related to neurotransmission and oxidative stress such as UCP2 were found at week 8. Conclusions: Our results suggest that db/db mouse reproduce the features of the neurodegenerative process that occurs in the human diabetic eye. Therefore, it seems an appropriate model for investigating the underlying mechanisms of diabetes-induced retinal neurodegeneration and for testing neuroprotective drugs

    Topical Administration of Somatostatin Prevents Retinal Neurodegeneration in Experimental Diabetes

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    Retinal neurodegeneration is an early event in the pathogenesis of diabetic retinopathy (DR). Somatostatin (SST) is an endogenous neuroprotective peptide that is downregulated in the diabetic eye. The aim of the study was to test the usefulness of topical administration of SST in preventing retinal neurodegeneration. For this purpose, rats with streptozotocin-induced diabetes mellitus (STZ-DM) were treated with either SST eye drops or vehicle for 15 days. Nondiabetic rats treated with vehicle served as a control group. Functional abnormalities were assessed by electroretinography (ERG), and neurodegeneration was assessed by measuring glial activation and the apoptotic rate. In addition, proapoptotic (FasL, Bid, and activation of caspase-8 and caspase-3) and survival signaling pathways (BclxL) were examined. Intraretinal concentrations of glutamate and its main transporter glutamate/aspartate transporter (GLAST) were also determined. Treatment with SST eye drops prevented ERG abnormalities, glial activation, apoptosis, and the misbalance between proapoptotic and survival signaling detected in STZ-DM rats. In addition, SST eye drops inhibited glutamate accumulation in the retina and GLAST downregulation induced by diabetes mellitus. We conclude that topical administration of SST has a potent effect in preventing retinal neurodegeneration induced by diabetes mellitus. In addition, our findings open up a new preventive pharmacological strategy targeted to early stages of DR

    Neurodegeneration as an early event in the pathogenesis of diabetic retinopathy: therapeutic implications

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    La Retinopatía Diabética (RD) es la complicación más común de la diabetes y una de las principales causas de ceguera. La RD se ha considerado clásicamente como una enfermedad microcirculatoria de la retina. No obstante, antes de que las anormalidades microcirculatorias se puedan detectar en un examen oftalmoscópico, la neurodegeneración ya está presente. Esto significa que la neurodegeneración es un acontecimiento temprano en la patogenia de la RD. Por tanto, existe la necesidad de tener buenos modelos animales donde se puedan testar fármacos potencialmente neuroprotectores y entender sus mecanismos de acción. En el primer capítulo de la tesis el objetivo fue caracterizar los acontecimientos secuenciales que tienen lugar en la neurodegeneración retiniana en un modelo murino de diabetes tipo 2, el ratón db/db. Se encontró un incremento progresivo con la edad de los marcadores de neurodegeneración (activación glial y apoptosis) en todas las etapas estudiadas. Se observaron anormalidades electroretinográficas en ratones de 16 y 24 pero no a 8 semanas de edad. Además, se observó una acumulación progresiva de glutamato en ratones diabéticos asociada con la disminución de su transportador GLAST. Todas estas anormalidades fueron abolidas al reducir los niveles de glucosa en sangre. Finalmente, a 8 semanas de edad, se encontraron alteraciones en la expresión de varios genes relacionados con la neurotransmisión y el estrés oxidativo como por ejemplo UCP2. Estos resultados sugieren que el ratón db/db reproduce las características del proceso neurodegenerativo que tiene lugar en el ojo diabético humano. Por tanto éste es un modelo apropiado para investigar los mecanismos subyacentes de la neurodegeneración retiniana inducida por la diabetes y para testar fármacos neuroprotectores. En el segundo capítulo se evalúan los efectos potenciales del ácido fenofíbrico (el metabolito activo del fenofibrato) en la prevención de la neurodegeneración retiniana que presenta el ratón db/db. El tratamiento oral durante una semana resultó en la reducción de la activación glial y de la apoptosis en comparación con los ratones tratados con vehículo. Las anormalidades funcionales mejoraron y el tratamiento con ácido fenofíbrico también previno la disminución de GLAST producida por la diabetes. Estos resultados sugieren que la neuroprotección es uno de los mecanismos subyacentes por los cuales el ácido fenofíbrico ejerce sus acciones beneficiosas en la retinopatía diabética. El tercer capítulo se centra en GLP-1 y sus efectos neuroprotectores en la retina. Se ha demostrado que GLP-1 ejerce efectos neuroprotecotres en el sistema nervioso central. El objetivo fue examinar la expresión y contenido de GLP-1R en retinas humanas y de ratón db/db, determinar los efectos neuroprotectores en la retina después de un tratamiento sistémico y otro tópico ocular (colirio) y examinar los mecanismos neuroprotectores subyacentes. Se encontró abundante expresión de GLP-1R en las retinas humanas y de ratón db/db. Además, se demostró que la administración sistémica de agonistas de GLP-1R (liraglutide) previene la neurodegeneración en la retina (activación glial, apoptosis neuronal y anormalidades electroretinográficas). Este efecto puede ser atribuido a una reducción significativa de glutamato extracelular y a un incremento de las vías de señalización pro-supervivencia. Se encontró un nivel similar de neuroprotección usando administración tópica ocular de GLP-1 nativo y de otros agonistas de GLP-1R (liraglutide, lixisenatide y exenatide). Cabe destacar que esta acción neuroprotectora fue observada sin reducción en los niveles de glucosa en sangre. Estos resultados sugieren que la activación de GLP-1R por si misma previene la neurodegeneración en la retina inducida por la diabetes.Diabetic retinopathy (DR) is the most common complication of diabetes and one of the leading causes of preventable blindness. DR has been classically considered to be a microcirculatory disease of the retina. However, before any microcirculatory abnormalities can be detected under ophthalmoscopic examination, retinal neurodegeneration is already present. This is to say that retinal neurodegeneration is an early event in the pathogenesis of diabetic retinopathy. There is a need to have a good animal model where potentially neuroprotective drugs could be tested on and understand their mechanisms of action. In the first chapter of this thesis the main aim was to characterize the sequential events that take place in retinal neurodegeneration in a murine model of spontaneous type 2 diabetes, the db/db mouse. We found progressively increased levels of the histological markers of neurodegeneration (glial activation and apoptosis) at all stages studied worsening with age. Significant electroretinographic abnormalities were present in diabetic mice at weeks 16 and 24 but not at week 8. Moreover it was observed a progressive accumulation of glutamate in diabetic mice associated with an early downregulation of its transporter GLAST. All this abnormalities were abrogated by lowering blood glucose levels. Finally, a dysregulation of several genes related to neurotransmission and oxidative stress such as UCP2 were found at week 8. All these results suggest that db/db mouse reproduce the features of the neurodegenerative process that occurs in the human diabetic eye. Therefore it is an appropriate model for investigating the underlying mechanisms of diabetes induced retinal neurodegeneration and for testing neuroprotective drugs. In the second chapter the potential effects of fenofibric acid (FA) (the active metabolite of fenofibrate) in preventing retinal neurodegeneration in the db/db mouse are evaluated. Oral treatment for one week resulted in a reduction of glial activation and apoptosis in comparison to vehicle-treated mice. Functional abnormalities were ameliorated and FA treatment also prevented GLAST downregulation induced by diabetes. Our results suggest that neuroprotection is one of the underlying mechanisms by which FA exerts its beneficial actions in diabetic retinopathy. The third chapter is focused on GLP-1 and its neuroprotective effects in the retina. GLP-1 has been demonstrated to have neuroprotective effects in the central nervous system. We sought to examine the expression and content of GLP-1R in human and db/db mice retinas, to determine the retinal neuroprotective effects of systemic and topical administration of GLP-1R agonists in db/db mice and, to examine the underlying neuroprotective mechanisms. We found abundant expression of GLP-1R in the human retina and retinas from db/db mice. Moreover, it has been demonstrated that systemic administration of GLP-1R agonists (liraglutide) prevents retinal neurodegeneration (glial activation, neural apoptosis and electroretinographical abnormalities). This effect can be attributed to a significant reduction of extracellular glutamate and to an increase of prosurvival signalling pathways. We have found a similar neuroprotective effect using topical administration of native GLP-1 and several GLP-1R agonists (liraglutide, lixisenatide and exenatide). Notably, this neuroprotective action was observed without any reduction in blood glucose levels. These results suggest that GLP-1R activation itself prevents diabetes induced retinal neurodegeneration

    Neurodegeneration as an early event in the pathogenesis of diabetic retinopathy: therapeutic implications

    Get PDF
    La Retinopatía Diabética (RD) es la complicación más común de la diabetes y una de las principales causas de ceguera. La RD se ha considerado clásicamente como una enfermedad microcirculatoria de la retina. No obstante, antes de que las anormalidades microcirculatorias se puedan detectar en un examen oftalmoscópico, la neurodegeneración ya está presente. Esto significa que la neurodegeneración es un acontecimiento temprano en la patogenia de la RD. Por tanto, existe la necesidad de tener buenos modelos animales donde se puedan testar fármacos potencialmente neuroprotectores y entender sus mecanismos de acción. En el primer capítulo de la tesis el objetivo fue caracterizar los acontecimientos secuenciales que tienen lugar en la neurodegeneración retiniana en un modelo murino de diabetes tipo 2, el ratón db/db. Se encontró un incremento progresivo con la edad de los marcadores de neurodegeneración (activación glial y apoptosis) en todas las etapas estudiadas. Se observaron anormalidades electroretinográficas en ratones de 16 y 24 pero no a 8 semanas de edad. Además, se observó una acumulación progresiva de glutamato en ratones diabéticos asociada con la disminución de su transportador GLAST. Todas estas anormalidades fueron abolidas al reducir los niveles de glucosa en sangre. Finalmente, a 8 semanas de edad, se encontraron alteraciones en la expresión de varios genes relacionados con la neurotransmisión y el estrés oxidativo como por ejemplo UCP2. Estos resultados sugieren que el ratón db/db reproduce las características del proceso neurodegenerativo que tiene lugar en el ojo diabético humano. Por tanto éste es un modelo apropiado para investigar los mecanismos subyacentes de la neurodegeneración retiniana inducida por la diabetes y para testar fármacos neuroprotectores. En el segundo capítulo se evalúan los efectos potenciales del ácido fenofíbrico (el metabolito activo del fenofibrato) en la prevención de la neurodegeneración retiniana que presenta el ratón db/db. El tratamiento oral durante una semana resultó en la reducción de la activación glial y de la apoptosis en comparación con los ratones tratados con vehículo. Las anormalidades funcionales mejoraron y el tratamiento con ácido fenofíbrico también previno la disminución de GLAST producida por la diabetes. Estos resultados sugieren que la neuroprotección es uno de los mecanismos subyacentes por los cuales el ácido fenofíbrico ejerce sus acciones beneficiosas en la retinopatía diabética. El tercer capítulo se centra en GLP-1 y sus efectos neuroprotectores en la retina. Se ha demostrado que GLP-1 ejerce efectos neuroprotecotres en el sistema nervioso central. El objetivo fue examinar la expresión y contenido de GLP-1R en retinas humanas y de ratón db/db, determinar los efectos neuroprotectores en la retina después de un tratamiento sistémico y otro tópico ocular (colirio) y examinar los mecanismos neuroprotectores subyacentes. Se encontró abundante expresión de GLP-1R en las retinas humanas y de ratón db/db. Además, se demostró que la administración sistémica de agonistas de GLP-1R (liraglutide) previene la neurodegeneración en la retina (activación glial, apoptosis neuronal y anormalidades electroretinográficas). Este efecto puede ser atribuido a una reducción significativa de glutamato extracelular y a un incremento de las vías de señalización pro-supervivencia. Se encontró un nivel similar de neuroprotección usando administración tópica ocular de GLP-1 nativo y de otros agonistas de GLP-1R (liraglutide, lixisenatide y exenatide). Cabe destacar que esta acción neuroprotectora fue observada sin reducción en los niveles de glucosa en sangre. Estos resultados sugieren que la activación de GLP-1R por si misma previene la neurodegeneración en la retina inducida por la diabetes.Diabetic retinopathy (DR) is the most common complication of diabetes and one of the leading causes of preventable blindness. DR has been classically considered to be a microcirculatory disease of the retina. However, before any microcirculatory abnormalities can be detected under ophthalmoscopic examination, retinal neurodegeneration is already present. This is to say that retinal neurodegeneration is an early event in the pathogenesis of diabetic retinopathy. There is a need to have a good animal model where potentially neuroprotective drugs could be tested on and understand their mechanisms of action. In the first chapter of this thesis the main aim was to characterize the sequential events that take place in retinal neurodegeneration in a murine model of spontaneous type 2 diabetes, the db/db mouse. We found progressively increased levels of the histological markers of neurodegeneration (glial activation and apoptosis) at all stages studied worsening with age. Significant electroretinographic abnormalities were present in diabetic mice at weeks 16 and 24 but not at week 8. Moreover it was observed a progressive accumulation of glutamate in diabetic mice associated with an early downregulation of its transporter GLAST. All this abnormalities were abrogated by lowering blood glucose levels. Finally, a dysregulation of several genes related to neurotransmission and oxidative stress such as UCP2 were found at week 8. All these results suggest that db/db mouse reproduce the features of the neurodegenerative process that occurs in the human diabetic eye. Therefore it is an appropriate model for investigating the underlying mechanisms of diabetes induced retinal neurodegeneration and for testing neuroprotective drugs. In the second chapter the potential effects of fenofibric acid (FA) (the active metabolite of fenofibrate) in preventing retinal neurodegeneration in the db/db mouse are evaluated. Oral treatment for one week resulted in a reduction of glial activation and apoptosis in comparison to vehicle-treated mice. Functional abnormalities were ameliorated and FA treatment also prevented GLAST downregulation induced by diabetes. Our results suggest that neuroprotection is one of the underlying mechanisms by which FA exerts its beneficial actions in diabetic retinopathy. The third chapter is focused on GLP-1 and its neuroprotective effects in the retina. GLP-1 has been demonstrated to have neuroprotective effects in the central nervous system. We sought to examine the expression and content of GLP-1R in human and db/db mice retinas, to determine the retinal neuroprotective effects of systemic and topical administration of GLP-1R agonists in db/db mice and, to examine the underlying neuroprotective mechanisms. We found abundant expression of GLP-1R in the human retina and retinas from db/db mice. Moreover, it has been demonstrated that systemic administration of GLP-1R agonists (liraglutide) prevents retinal neurodegeneration (glial activation, neural apoptosis and electroretinographical abnormalities). This effect can be attributed to a significant reduction of extracellular glutamate and to an increase of prosurvival signalling pathways. We have found a similar neuroprotective effect using topical administration of native GLP-1 and several GLP-1R agonists (liraglutide, lixisenatide and exenatide). Notably, this neuroprotective action was observed without any reduction in blood glucose levels. These results suggest that GLP-1R activation itself prevents diabetes induced retinal neurodegeneration

    Topical Administration of Somatostatin Prevents Retinal Neurodegeneration in Experimental Diabetes

    No full text
    Retinal neurodegeneration is an early event in the pathogenesis of diabetic retinopathy (DR). Somatostatin (SST) is an endogenous neuroprotective peptide that is downregulated in the diabetic eye. The aim of the study was to test the usefulness of topical administration of SST in preventing retinal neurodegeneration. For this purpose, rats with streptozotocin-induced diabetes mellitus (STZ-DM) were treated with either SST eye drops or vehicle for 15 days. Nondiabetic rats treated with vehicle served as a control group. Functional abnormalities were assessed by electroretinography (ERG), and neurodegeneration was assessed by measuring glial activation and the apoptotic rate. In addition, proapoptotic (FasL, Bid, and activation of caspase-8 and caspase-3) and survival signaling pathways (BclxL) were examined. Intraretinal concentrations of glutamate and its main transporter glutamate/aspartate transporter (GLAST) were also determined. Treatment with SST eye drops prevented ERG abnormalities, glial activation, apoptosis, and the misbalance between proapoptotic and survival signaling detected in STZ-DM rats. In addition, SST eye drops inhibited glutamate accumulation in the retina and GLAST downregulation induced by diabetes mellitus. We conclude that topical administration of SST has a potent effect in preventing retinal neurodegeneration induced by diabetes mellitus. In addition, our findings open up a new preventive pharmacological strategy targeted to early stages of DR

    Gene enrichment analysis of genes differentially expressed in retinas of diabetic mice.

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    <p>Only the six most significant gene ontology (GO) terms in each category are shown (MF, molecular function; BP, biological process; CC, cellular compartment).</p

    Glial activation.

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    <p>A) Comparison of GFAP immunofluorescence (green) between representative samples from a diabetic (upper panel) and a non-diabetic mouse (lower panel) at 8 weeks, 16 and 24 weeks. In the diabetic retina, the Müller cells’ endfeet show abundant GFAP immunofluorescence and the radial processes stain intensely throughout both the inner and outer retina. Nuclei were labeled with DAPI (blue). ONL: outer nuclear layer; INL: inner nuclear layer; GCL: ganglion cell layer. B) Quantification of glial activation based on extent of GFAP staining.</p

    Images demonstrating the progressive loss of cells in retinal ganglion layer (GCL).

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    <p>A) Hematoxylin and eosin stained central retina in a representative case of a diabetic mouse (upper panel) and a non-diabetic mouse (lower panel) of 8, 16 and 24 weeks old. In the diabetic retina a loss of cells in GCL was observed. B) Cell number in GCL in control and diabetic mice in central retina. C) Comparison of TUNEL immunofluorescence (green) between representative samples from a diabetic (upper panel) and a non-diabetic mouse (lower panel) at 8 weeks, 16 and 24 weeks. Nuclei were labeled with Hoechst (blue). D) Percentage of TUNEL positive cells in the GCL in non-diabetic and diabetic mice at 8, 16 and 24 weeks (upper panel). ONL: outer nuclear layer; OPL: outer plexiform layer; INL: inner nuclear layer; IPL: inner plexiform layer; GCL: ganglion cell layer. Results are expressed as mean ± SD. White bars: non-diabetic mice; Black bars: diabetic mice. *p<0.05, **p<0.001 between non-diabetic and diabetic mice.</p
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