Inibição do receptor de glutamato do tipo NMDA em um modelo de hipóxia-isquemia prenatal: avaliação morfofuncional do cerebelo / Inhibition of glutamate NMDA receptor in a prenatal hipoxia-ischemia model: morphofunctional analises of cerebellum

Lesões sistêmicas peri e pré-natais alteram o desenvolvimento do SNC, levando a problemas cognitivos e motores em crianças que podem perdurar por toda a vida. Um tipo particular de lesão é a hipóxia-isquemia (HI), caracterizada pela interrupção momentânea ou permanente do fluxo sanguíneo. Um dos mecanismos propostos para as lesões decorrentes da HI é a excitotoxicidade glutamatérgica. O uso de inibidores da neurotransmissão glutamatérgica tem sido estudados em diversos modelos de HI. Neste trabalho, avaliamos os efeitos morfofuncionais da administração de um antagonista não-competitivo do receptor de glutamato NMDA sobre o desenvolvimento do cerebelo. Ratas no 18º dia de gestação foram anestesiadas, os cornos uterinos expostos e as 4 artérias uterinas obstruídas por 45 minutos (Grupo H). Animais controle tiveram os úteros expostos, sem a obstrução (Grupo S). Após a cirurgia a gestação prosseguiu. Somente animais nascidos a termo foram utilizados. Um dia após o nascimento, metade de cada ninhada foi designada para receber MK801, 0,3mg/kg/dia, (grupos SM e HM) e a outra metade recebeu solução salina (grupos SS e HS), por 5 dias. Após anestesia e perfusão-fixação com paraformaldeído 4% aos 9, 23, 30 e 60 dias pós-natais, cortes parassagitais do cerebelo foram obtidos em criótomo e submetidos à imunohistoquímica para calbindina, GFAP, GLAST, PDGFRα e MBP. A partir de 45 dias de vida, os animais foram testados em vários de testes comportamentais: labirinto em cruz elevado (LCE), campo vazado (CV), ROTAROD, teste de caminhada sobre barras (ladder test) e teste do comprimento da passada (stride length). Aos 9 dias, a espessura da árvore dendrítica era menor nos animais SM, HS/HM, demonstrando efeitos deletérios tanto do MK801 quanto da HI. Menor número de células PDGFRα+ foi observado nos animais HS/HM, sem efeitos da administração de MK801. Aos 23 dias, maior número de células PDGFRα+ foi observado nos animais HM comparado aos outros 3 grupos, indicando efeito ...

Peri and prenatal systemic lesions alter CNS development leading to motor and cognitive problems in children that might persist throughout life. A particular kind of injury, the hypoxic ischemic (HI), is characterized by a permanent or temporary blockage of blood flow. One of the proposed mechanisms downstream from a HI event is called glutamatergic excitotoxicity. The administration of glutamate inhibitors has been studied in HI models for several years. In this work, we evaluated the effects of administration of a non-competitive antagonist of glutamate receptor, NMDA, on cerebellar development and behavioral tests of HI animals. Pregnant rats in the 18th gestational day were anesthetized, the uterine horns were exposed and the four uterine arteries were clamped for 45 minutes (group H). Sham controls had the uterine horns exposed, but no arteries were clamped (group S). Gestation proceeded after surgery. Only full term animals were used. One day after birth half the animals was assigned to receive either SALINE (groups SS and HS) or MK801 (groups SM and HM). Animals were anesthetized and perfused with 4% paraformaldehyde at 9, 23, 30 and 60 days of age. Parasagittal cerebellar sections were submitted to Calbindin, GFAP, GLAST, PDGFRα and MBP immunohistochemistry. Beginning at P45 animals were subjected to a battery of behavioral tests: elevated plus maze (EPM), hole board (HB), ROTAROD, ladder test and stride length. At P9 the dendritic tree of Purkinje cells were thinner in SM, HS/HM animals, indicating that both HI and MK801 are deleterious regarding this Purkinje cell differentiation. A lower number of PDGFRα+ cells was observed in HS/HM animals, with no effects of MK801 administration. At P23 a greater number of PDGFRα+ cells was found in HM animals when compared to the other 3 groups, demonstrating a neuroprotector effect of MK801. A lower number of myelinated fibers (MBP+) was observed in HS animals at P9, and MK801 administration reverse this ...

Phenytoin-induced Toxicity in the Postnatal Developing Cerebellum of Wistar Rats, Effect of Calotropis procera on Histomorphometric Parameters / Toxicidad Inducida por Fenitoína en el Desarrollo Postnatal del Cerebelo de Ratas Wistar, Efecto de Calotropis procera sobre los Parámetros Histomorfométricos

The role of methanolic leaf extracts of Calotropis procera in phenytoin-induced toxicity on histomorphometric variables in the postnatal developing cerebellum of Wistar rat was studied. Pregnant rats were treated orally with 50 mg/kg phenytoin in pre and post natal life and 300 mg/kg methanolic leaf extract of Calotropis procera 1 hour prior to phenytoin administration. 200 mg/kg vitamin C (standard antioxidant) was also administered orally 1 hour prior to phenytoin treatment. The control animals received water. Standard diet of rat pellets and water were provided ad libitum. At the end of the experiment, the offspring of days 1, 7, 14, 21, 28 and 50 post partum, five per group were sacrificed by cervical dislocation. The cerebellum of all groups were dissected out and processed for histomorphometric studies. The results showed in the developing cerebellum of phenytoin treated animals, a delayed cell maturation in the external granular layer, reduction of the molecular layer, astrocytic gliosis and loss of Purkinje cells on day 50 postpartum. Administration of extracts of Calotropis procera and vitamin C though reversed these changes when compared with the phenytoin treated group, but not significantly when compared with the control. In conclusion, supplementation with methanolic extracts of Calotropis procera reduced the rate at which phenytoin induced toxicity in the postnatal developing cerebellum of Wistar rat.

Fue estudiado el rol de los extractos metanólicos de las hojas de Calotropis procera en la toxicidad inducida por fenitoína sobre las variables histomorfométricas en el desarrollo postnatal del cerebelo de ratas Wistar. Ratas preñadas fueron tratadas por vía oral con 50 mg/kg de fenitoína durante la vida pre y post natal. Además, fue administrado, por vía oral, una hora antes del tratamiento con fenitoína 300 mg/kg de extracto metanólico de las hojas de Calotropis procera y 200 mg/kg de vitamina C (antioxidante estándar). Los animales control recibieron agua. Una dieta estándar de pellets para rata y agua se proporcionaron ad libitum. Al final del experimento, 5 crías por grupo de 1, 7, 14, 21, 28 y 50 días post parto, fueron sacrificadas por dislocación cervical. El cerebelo de todos los animales de los diferentes grupos fueron disecados y procesados para el estudio histomorfométrico. Los resultados mostraron en el desarrollo del cerebelo de los animales tratados con fenitoína un retraso en la maduración de células en la capa granular externa, reducción de la capa molecular, gliosis astrocitaria y pérdida de las células de Purkinje en el día 50 post parto. La administración de extractos de Calotropis procera y vitamina C, aunque invirtieron estos cambios, en comparación con los grupos tratados con fenitoína, no fueron significativos en comparación con el control. En conclusión, la suplementación con extractos metanólicos de Calotropis procera redujo la velocidad a la que la fenitoína induce toxicidad en el desarrollo postnatal del cerebelo de ratas Wistar.

Effects of postnatal exposure to static magnetic field on the development of the cerebellar granule cells

Many studies were performed to evaluate the effects of static magnetic fields [SMFs] on the processes of proliferation and migration of cerebellar cells to their final postnatal destinations. Granule cells are the most abundant interneurons in the cerebellum. Progenitors of these neurons actively proliferate during the first 2 postnatal weeks in external granular layer [EGL]. The granule cells in the EGL migrate inwards to form the internal granular layer [IGL], and the EGL disappears. So the postnatal development of the cerebellum depends on their postnatal proliferation and migration which is vulnerable to any micro-environmental insult. to evaluated the light and electron microscopic changes occurred to the cerebellar granule cells of the pups after postnatal exposure to SMF [20 mT]. Postnatal exposure to SMFs showed that there was a significant thinning in the EGL at the beginning of the study at postnatal thy 4, this significant decrease in thickness progressed in the first week. At two weeks when normally the EGL starts to disappear, it showed persistent increase in its thickness indicating delayed migration. At all ages of exposed group [P], EGL contained many apoptotic cells and some degenerated cells. IGL showed significant decrease in its cellular density till the postnatal day 15 concomitant with the period of delayed migration in the EGL. At the postnatal days 22, the cells in IGL began to regain its near normal cellular density but the IGL showed disarrangement of its crowded granule cells with absence of appearance of regular glomeruli among them with appearance of some degenerated cells among the granule cells. Many cells of the IGL also showed areas of cytoplasmic vacuolation. Postnatal exposure to SMFs produces some delay in the development and appearance of more apoptotic cells. But some of these changes in different stages of the postnatal development of the cerebellar cortex began to be less apparent with advancement of age

Aplicações da ultra-sonografia tridimensional na avaliação do cerebelo fetal / Three-dimensional ultrasonography in the evaluation of the fetal cerebellum

Nos últimos anos a ultra-sonografia tridimensional tem-se tornado um método de imagem de grande importância no diagnóstico em obstetrícia. Um de seus benefícios seria a maior sensibilidade, em relação ao ultra-som bidimensional, no diagnóstico de algumas malformações fetais. As potenciais aplicações desse novo método seriam uma maior acurácia na medida do volume de órgãos fetais, a possibilidade de rever volumes na ausência da paciente, a possibilidade de utilizar diferentes planos para avaliar determinada estrutura anatômica e a capacidade de transmissão de volumes para centros de referência. A avaliação ultra-sonográfica do cerebelo fetal é de extrema importância, pois, comprovadamente, alterações no seu desenvolvimento estão correlacionadas com alterações do crescimento fetal e anomalias congênitas. O objetivo desta atualização é demonstrar os métodos VOCAL™ e 3D XI™ na avaliação do cerebelo fetal, seus potenciais benefícios e o que há de mais atual na literatura a respeito deste assunto.

For the last years three-dimensional ultrasonography has become an imaging diagnosis method of great importance in obstetrics. One of its advantages would be the higher sensitivity compared with two-dimensional ultrasound in the diagnosis of some fetal malformations. The potential applications of this new method would be an improved accuracy in the measurement of fetal organs, the possibility of reviewing volumes in the absence of the patient, and using different planes to assess specific anatomical structures, as well as the capacity to transfer data files to remote reference centers. Ultrasonographic evaluation of fetal cerebellum is particularly important, since developmental alterations are correlated with the fetal growth alterations and congenital anomalies. The objective of this updating is to demonstrate the VOCAL™ and 3D XI™ methods in the evaluation of the fetal cerebellum, their potential benefits, and the latest information in the literature about this subject.

Morphometric evidences for regional variation in potential of neural plasticity

RESUMEN: Aunque la plasticidad neural muestra la capacidad del sistema nervioso para cambiar su estructura y función, lo cual es un hecho bien documentado, pocos estudios han mostrado la variación regional, dentro de la estructura del sistema nervioso central para sufrir cambios plásticos. A través de disecciones parasagitales, secuenciadas de medial a lateral, se estudió el grosor de la capa molecular, en el límite de la cisura primaria de hemisferio izquierdo del cerebelo, de ratas, con el propósito de evaluar las diferencias regionales en plasticidad. A pesar de la homogeneidad de la histología cerebelar, el estudio mostró que hay una diferencia interlobular significativa entre el grosor de la capa molecular en el límite de la fisura prima. Agregado a ello, fue revelado que los cambios de grosor tienen una tendencia significativa dentro de cada límite. La heterogeneidad cuantitativa de la arquitectura cerebelar, tal como la variación en el grosor cortical, puede proveer algunas evidencias que muestran que regiones diferentes de un corte homogéneo, aún de límites y áreas adyacentes dentro del mismo, pueden tener diferentes potenciales para plasticidad.

Neuroprotective effect of dexamethasone on the morphology of the Irradiated post natal developing cerebellum of wistar rat (Rattus norvegicus)

RESUMEN: Se estudió el efecto neuroprotector de la dexametasona, sobre el cerebelo post-natal en desarrollo irradiado de ratas Wistar. 75 neonatos de 1 día de edad fueron separados en 3 grupos; el grupo control no recibió ni drogas ni irradiación, un grupo irradiado y el otro irradiado con aplicación de dexametasona. Esta droga fue administrada una hora antes de la exposición de 5Gray (5Gy) de rayos gamma. El tejido cerebelar de cada grupo con 5, 9, 14, 21 y 25 días fueron procesados para estudios histológicos e histomorfométricos. El resultado del estudio demostró que la sola irradiación redujo significativamente el grosor de la capa granular externa, en los grupos con 5 y 14 día,s con un p0,05; la capa molecular en los ejemplares de 5, 9, 14 y 21 días con un p0,05 y la capa granular en las ratas de 5,9,14 y 25 días, con un p0,05. Cuando se combinó la dexametasona con irradiación, se observó un grosor significativamente diferente en la capa granular externa, en especímenes con 5, 9 y 14 días; en la capa molecular en los animales de 5, 14 y 21 días y en la capa granular en los que tenían 5 y 14 días, al compararlos con el grupo irradiado, con un p>0,05. El diámetro de las células de Purkinje (capa de Purkinje) aunque fue significativamente reducido en el grupo irradiado de 14 y 21 días, no fue significativamente diferente cuandos se administró dexametasona a los animales irradiados de 5, 9, 14, 21 y 25 días con un p0,05. Histológicamente, las células de la capa molecular, en el grupo irradiado de 9 y 14 días, fueron marcadamente gliosadas comparadas con las medianamente marcadas en los grupos control e irradiados-dexametasona. Hubo distorsión de la monocapa de Purkinje, con algunas células encontradas en la capa molecular o en la capa de Purkinje, en el grupo irradiado de 5, 9, 14 y 25 días. De los resultados de este estudio, se puede afirmar que la administración de 0,005 ml de dexametasona intraperitonealmente, una hora antes de una exposición a una irradiación, parece proteger el desarrollo del cerebelo de la rata, de lesiones producidas por irradiación.

Neurotoxicological effects of Methyl Mercury on developing cerebellum of albino rats: histological and immunohistochemical study

Mercury exists in the environment in three major forms: organic, inorganic and elemental. Organic methyl mercury is the most widely distributed and toxic form of mercury. It is used extensively in agriculture and industry. It is also bioaccumulated in sea food and fresh water fish. The central nervous system is a critical organ for mercury exposure. The aim of the present work was to study the possible neurotoxicological effects of low- level exposure to methyl mercury on the developing cerebellum of albino rats during the pre- and early postnatal periods. The study was carried out on twenty pregnant female albino rats. Ten pregnant rats constituted the control group. The remaining ten pregnant rats were given methyl mercury orally in a dose of 2 mg/kg body weight daily during late gestational period starting from day 12 and continued for 21 days after birth i.e. until weaning. Control rats were given an equivalent volume [2 ml] of physiological saline orally by gastric gavage for the same experimental duration. Control and methyl mercury-exposed rat pups were sacrificed following weaning [21 postnatal days] by decapitation after ether anesthesia. The cerebellum of each rat pup was prepared for histological study [light microscopic examination using haematoxylin and eosin stain, and electron microscopic examination using the transmission electron microscope], and immunohistochemical study using antibodies against glial fibrillary acidic protein [GFAP]. The present study revealed that there were marked histological and immunohistochemical changes in the neurons and neuroglial cells of the cerebellum of rat pups following exposure of their mothers to low-level of methyl mercury. It was concluded that methyl mercury is a potent neurotoxic substance causing severe damaging changes in the developing cerebellum

Deterioro cerebeloso inducido por aislamiento social temprano: estudio morfológico e inmunocitoquímico / Cerebellar impairment induced by early social isolation: a morphological and immunocytochemical study

En el presente trabajo se utiliza el modelo de aislamiento social en animales a objeto de estudiar el efecto que produce las experiencias tempranas adversas sobre el desarrollo morfofuncional de la corteza cerebelosa. Se utilizaron 103 ratas de la cepa Sprague-Dawley de 18 días de vida, las cuales fueron sepradas en dos grupos de estudio: (a) control (SC; 3- 4 ratas por jaula y (b) aislado (IC); estas últimas se colocaron en comportamientos individuales hasta los 32 días de edad (P32). En esta etapa, el 50 por ciento de los animales IC y SC fueron sacrificadas para su estudio neural; el resto de las ratas del grupo IC fue retirado de sus compartimientos individuales y reubicados en su entorno social normal hasta el día P62, realizándose el análisis neural respectivo. En ambas fases ontogenéticas (P32 y P62) se estudió el desarrollo dendrítico y la expresión de calbindina-D28k (CBD) en células de Purkinje vermianas. Los resultados obtenidos mostraron que la deprivación social y sensoriomotriz temprana altera el crecimiento dendríco en estrecha relación con una disminución del contenido intracelular de CBD. Además, la interacción social post-deprivación sólo logró recuperar la expresión de CBD, permaneciendo el deterioro estructural. Estos resultados indican que las experiencias postnatales adversas alteran el desarrollo morfológico y funcional de las neuronas de Purkinje vermianas cuando se emplea el modelo de aislamiento social

Effects of pre-and postnatal lead toxicity on cerebellar development in rabbit offsprings

The aim of this study was to investigate the effect of lead on the postnatal development of cerebellum in rabbit off springs. Pregnant rabbits were divided into a control group and an experimental group. The experimental group received lead acetate in a dose of 15 mg /kg B.W. by intragastric intubation. Lead administration was continued to the rabbit offspring. Exposure to lead resulted in an increase in the thickness of the external granular layer in comparison to control group. This layer disappeared at 3 months control rabbits while it was still present in exposed animals of the same age. Also the molecular layer of exposed animals was affected where it became decreased in thickness. Moreover administration of lead affected the Purkinje cells where they became decreased in size with indistinct Nissl granules, marked shortening of dendrites and focal loss of them. Lead, also, resulted in decreased thickness and density of the internal granular layer. Moreover, there were oedema, cavitations and foci of calcification. From the previous findings, it could be concluded that lead has degenerative changes on the cerebellar development

Efeitos da desnutriçäo protéica durante os períodos pré e pós natal no desenvolvimento cerebelar / Effects of protein undernutrition during the pre and post natal period of the cerebellum development

Estudou-se os efeitos da desnutriçao protéica nao severa, durante os períodos pré e pós natal, no desenvolvimento das camadas corticais cerebelares. Observou-se que a desnutriçao protéica afeta o processo de migraçao celular da camada granular externa, bem como induz atraso na formaçao da camada molecular. Após 60 dias ocorreu recuperaçao histológica do cerebelo em todos animais experimentais.