Variaciones de las células de cuadrícula y de posicionamiento de la corteza entorrinal y del giro dentado de 6 humanos de 56 a 87 años / Variations of the grid and place cells in the entorhinal cortex and dentate gyrus of 6 individuals aged 56 to 87 years

Introducción: La relación entre la corteza entorrinal y el hipocampo ha sido estudiada por diferentes autores, que han destacado la importancia de las células de cuadrícula, las células de posicionamiento y la conexión trisináptica en los procesos que regulan: la persistencia de la memoria espacial, explícita y reciente, y su posible afección con el envejecimiento. Objetivo: Observar si existen diferencias en el tamaño y número de células de cuadrícula contenidas en la lámina iii de la corteza entorrinal y en la capa granular del giro dentado del hipocampo de pacientes mayores. Métodos: Realizamos estudios posmortem del cerebro de 6 sujetos de edades comprendidas entre los 56 y 87 años. Los cortes de cerebros que contenían el giro dentado del hipocampo y la corteza entorrinal adyacente se tiñeron con el método de Klüver-Barrera, después se midió, mediante el programa Image J, el área neuronal individual, el área neuronal total, así como el número de neuronas, contenidas en cuadrículas rectangulares a nivel de la lámina iii de la corteza entorrinal y la lámina ii del giro dentado y se llevó a cabo un análisis estadístico. Resultados: Se ha observado una reducción de la población celular de la capa piramidal externa de la corteza entorrinal, así como de las neuronas de la capa granular del giro dentado relacionada con el envejecimiento. Conclusión: Nuestros resultados indican que el envejecimiento produce una disminución en el tamaño y la densidad neuronal en las células de cuadrícula de la corteza entorrinal y de posicionamiento del giro dentado.(AU)

Introduction: The relationship between the entorhinal cortex and the hippocampus has been studied by different authors, who have highlighted the importance of grid cells, place cells, and the trisynaptic circuit in the processes that they regulate: the persistence of spatial, explicit, and recent memory and their possible impairment with ageing. Objective: We aimed to determine whether older age causes changes in the size and number of grid cells contained in layer III of the entorhinal cortex and in the granular layer of the dentate gyrus of the hippocampus. Methods: We conducted post-mortem studies of the brains of 6 individuals aged 56-87 years. The brain sections containing the dentate gyrus and the adjacent entorhinal cortex were stained according to the Klüver-Barrera method, then the Image J software was used to measure the individual neuronal area, the total neuronal area, and the number of neurons contained in rectangular areas in layer III of the entorhinal cortex and layer II of the dentate gyrus. Statistical analysis was subsequently performed. Results: We observed an age-related reduction in the cell population of the external pyramidal layer of the entorhinal cortex, and in the number of neurons in the granular layer of the dentate gyrus. Conclusion: Our results indicate that ageing causes a decrease in the size and density of grid cells of the entorhinal cortex and place cells of the dentate gyrus.(AU)

Changes in the choroid plexuses and brain barriers associated with high blood pressure and ageing.

INTRODUCTION: The choroid plexuses, blood vessels, and brain barriers are closely related both in terms of morphology and function. Hypertension causes changes in cerebral blood flow and in small vessels and capillaries of the brain. This review studies the effects of high blood pressure (HBP) on the choroid plexuses and brain barriers. DEVELOPMENT: The choroid plexuses (ChP) are structures located in the cerebral ventricles, and are highly conserved both phylogenetically and ontogenetically. The ChPs develop during embryogenesis, forming a functional barrier during the first weeks of gestation. They are composed of highly vascularised epithelial tissue covered by microvilli, and their main function is cerebrospinal fluid (CSF) production. The central nervous system (CNS) is protected by the blood-brain barrier (BBB) and the blood-CSF barrier (BCSFB). While the BBB is formed by endothelial cells of the microvasculature of the CNS, the BCSFB is formed by epithelial cells of the choroid plexuses. Chronic hypertension induces vascular remodelling. This prevents hyperperfusion at HBPs, but increases the risk of ischaemia at low blood pressures. In normotensive individuals, in contrast, cerebral circulation is self-regulated, blood flow remains constant, and the integrity of the BBB is preserved. CONCLUSIONS: HBP induces changes in the choroid plexuses that affect the stroma, blood vessels, and CSF production. HBP also exacerbates age-related ChP dysfunction and causes alterations in the brain barriers, which are more marked in the BCSFB than in the BBB. Brain barrier damage may be determined by quantifying blood S-100ß and TTRm levels.

Variaciones de los plexos coroideos y las barreras cerebrales en la hipertensión arterial y el envejecimiento / Changes in the choroid plexuses and brain barriers associated with high blood pressure and ageing

Introducción: Los plexos coroideos, los vasos sanguíneos y las barreras cerebrales están íntimamente relacionados tanto morfológica como funcionalmente. Por otro lado, la hipertensión produce cambios en el flujo sanguíneo y en los pequeños vasos y capilares cerebrales. El propósito de la presente revisión es estudiar los efectos de la hipertensión arterial sobre los plexos coroideos y las barreras cerebrales. Desarrollo: Los plexos coroideos (PC) son una estructura del cerebro situada en los ventrículos cerebrales, altamente conservada filogenética y ontogénicamente. Los PC se desarrollan temprano durante la embriogénesis y constituyen una barrera funcional en las primeras semanas de gestación. Están compuestos por tejido epitelial altamente vascularizado, cubiertos por microvellosidades y su función principal es la producción del líquido cefalorraquídeo (LCR). El sistema nervioso central se encuentra aislado y protegido por la barrera hematoencefálica (BHE) y por la barrera sangre-LCR (BSLCR). Mientras que la BHE se localiza al nivel de las células endoteliales en la microvasculatura del encéfalo, la BSLCR está formada por las células epiteliales de los plexos coroideos. La hipertensión arterial crónica induce una remodelación vascular para adaptarse a los valores elevados de presión arterial, con lo que se evita el riesgo de hiperperfusión ante presiones elevadas, pero se incrementa el riesgo de isquemia a presiones bajas; en cambio, en las personas normotensas la circulación cerebral se autorregula y el flujo sanguíneo permanece constante y se mantiene la integridad de la BHE. [...] (AU)

Introduction: The choroid plexuses, blood vessels, and brain barriers are closely related both in terms of morphology and function. Hypertension causes changes in cerebral blood flow and in small vessels and capillaries of the brain. This review studies the effects of high blood pressure (HBP) on the choroid plexuses and brain barriers. Development: The choroid plexuses (ChP) are structures located in the cerebral ventricles, and are highly conserved both phylogenetically and ontogenetically. The ChPs develop during embryogenesis, forming a functional barrier during the first weeks of gestation. They are composed of highly vascularised epithelial tissue covered by microvilli, and their main function is cerebrospinal fluid (CSF) production. The central nervous system (CNS) is protected by the blood-brain barrier (BBB) and the blood–CSF barrier (BCSFB). While the BBB is formed by endothelial cells of the microvasculature of the CNS, the BCSFB is formed by epithelial cells of the choroid plexuses. Chronic hypertension induces vascular remodelling. This prevents hyperperfusion at HBPs, but increases the risk of ischaemia at low blood pressures. In normotensive individuals, in contrast, cerebral circulation is self-regulated, blood flow remains constant, and the integrity of the BBB is preserved. Conclusions: HBP induces changes in the choroid plexuses that affect the stroma, blood vessels, and CSF production. HBP also exacerbates age-related ChP dysfunction and causes alterations in the brain barriers, which are more marked in the BCSFB than in the BBB. Brain barrier damage may be determined by quantifying blood S-100β and TTRm levels. (AU)

Variations of the grid and place cells in the entorhinal cortex and dentate gyrus of 6 individuals aged 56 to 87 years. / Variaciones de las células de cuadrícula y de posicionamiento de la corteza entorrinal y del giro dentado de 6 humanos de 56 a 87 años.

INTRODUCTION: The relationship between the entorhinal cortex and the hippocampus has been studied by different authors, who have highlighted the importance of grid cells, place cells, and the trisynaptic circuit in the processes that they regulate: the persistence of spatial, explicit, and recent memory and their possible impairment with ageing. OBJECTIVE: We aimed to determine whether older age causes changes in the size and number of grid cells contained in layer III of the entorhinal cortex and in the granular layer of the dentate gyrus of the hippocampus. METHODS: We conducted post-mortem studies of the brains of 6 individuals aged 56-87 years. The brain sections containing the dentate gyrus and the adjacent entorhinal cortex were stained according to the Klüver-Barrera method, then the Image J software was used to measure the individual neuronal area, the total neuronal area, and the number of neurons contained in rectangular areas in layer III of the entorhinal cortex and layer II of the dentate gyrus. Statistical analysis was subsequently performed. RESULTS: We observed an age-related reduction in the cell population of the external pyramidal layer of the entorhinal cortex, and in the number of neurons in the granular layer of the dentate gyrus. CONCLUSION: Our results indicate that ageing causes a decrease in the size and density of grid cells of the entorhinal cortex and place cells of the dentate gyrus.

Changes in the choroid plexuses and brain barriers associated with high blood pressure and ageing. / Variaciones de los plexos coroideos y las barreras cerebrales en la hipertensión arterial y el envejecimiento.

INTRODUCTION: The choroid plexuses, blood vessels, and brain barriers are closely related both in terms of morphology and function. Hypertension causes changes in cerebral blood flow and in small vessels and capillaries of the brain. This review studies the effects of high blood pressure (HBP) on the choroid plexuses and brain barriers. DEVELOPMENT: The choroid plexuses (ChP) are structures located in the cerebral ventricles, and are highly conserved both phylogenetically and ontogenetically. The ChPs develop during embryogenesis, forming a functional barrier during the first weeks of gestation. They are composed of highly vascularised epithelial tissue covered by microvilli, and their main function is cerebrospinal fluid (CSF) production. The central nervous system (CNS) is protected by the blood-brain barrier (BBB) and the blood-CSF barrier (BCSFB). While the BBB is formed by endothelial cells of the microvasculature of the CNS, the BCSFB is formed by epithelial cells of the choroid plexuses. Chronic hypertension induces vascular remodelling. This prevents hyperperfusion at HBPs, but increases the risk of ischaemia at low blood pressures. In normotensive individuals, in contrast, cerebral circulation is self-regulated, blood flow remains constant, and the integrity of the BBB is preserved. CONCLUSIONS: HBP induces changes in the choroid plexuses that affect the stroma, blood vessels, and CSF production. HBP also exacerbates age-related ChP dysfunction and causes alterations in the brain barriers, which are more marked in the BCSFB than in the BBB. Brain barrier damage may be determined by quantifying blood S-100ß and TTRm levels.