Rol de la neuroglia en el trastorno del espectro autista / Role of neuroglia in autism spectrum disorder

RESUMEN: El trastorno del espectro autista (TEA) se caracteriza por presentar déficits persistentes en la comunicación y en la interacción social. Además, patrones de comportamiento, intereses o actividades de tipo restrictivo o repetitivo. Su etiología es compleja y heterogenia, y los mecanismos neurobiológicos que dan lugar al fenotipo clínico aún no se conocen por completo. Las investigaciones apuntan a factores genéticos y ambientales que afectan el cerebro en desarrollo. Estos avances coinciden con un aumento en la comprensión de las funciones fisiológicas y el potencial patológico de la neuroglia en el sistema nervioso central (SNC) que llevó a la noción de la contribución fundamental de estas células en el TEA. Así, el objetivo de este artículo fue revisar brevemente los factores de riesgo clave asociados al TEA y luego, explorar la contribución de la neuroglia en este trastorno. Se destaca el rol de los astrocitos, los microglocitos y los oligodendrocitos en el control homeostático del SNC, en la regulación inmunitaria del cerebro y en la mielinización axonal, así como el mal funcionamiento y las alteraciones morfológicas de estas células en los cerebros autistas.

SUMMARY: Autism spectrum disorder (ASD) is characterized by persistent deficits in communication and social interaction, as well as restrictive or repetitive activities or interests. Its etiology is complex and heterogeneous, and the neurobiological mechanisms that give rise to the clinical phenotype are not yet fully understood. Research points to genetic and environmental factors that affect the developing brain. These advances are consistent with an enhanced understanding of the physiological functions and pathological potential of neuroglia in the central nervous system (CNS) which supports the conclusion of the contribution of these cells in ASD. Therefore, the objective of this article was to briefly review the key risk factors associated with ASD and then explore the contribution of glia in this disorder. The role of astrocytes, microgliocytes and oligodendrocytes in the homeostatic control of the CNS in the immune regulation of the brain and in axonal myelination, as well as malfunction and morphological alterations of these cells in autistic brains are emphasized.

Altered oligodendrocytes in spinal enlargements of streptozotocin diabetic rats / Oligodendrocitos alterados en la intumescencia espinal de ratas diabéticas con estreptozotocina

SUMMARY: Disturbances of sensory and motor nerve conduction velocity in the spinal cord as well as degenerated myelin sheaths are observed in diabetic patients and animal models. Indeed, oligodendrocytes (OLs), which are important neuroglial cells, generate myelin in the central nervous system. Spinal enlargement, including cervical and lumbar enlargements, innervates all limbs. Thus, the purposes of this study were to examine and compare the ultrastructural alterations of OLs in spinal enlargements of streptozotocin (STZ)- induced diabetic rats and controls. Thirteen male Sprague-Dawley rats were induced with STZ in citrate buffer and six control rats were injected with the same buffer solution. All rats were sacrificed after inductions at four (short-term DM) and twenty-four weeks (long-term DM). The selected spinal enlargements were processed for transmission electron microscopy. The OL alterations in both the cervical and lumbar enlargements were apparently the same. In short-term DM, the nuclei of OLs became swelled with chromatin clumping. Cytoplasmic organelles were moderately damaged. In long-term DM, OLs contained shrinkage nuclei with thick heterochromatin clumping. Severely degenerated mitochondria with disrupted cristae and broken membranes were observed. Moreover, distended and fragmented rough endoplasmic reticulum were observed, and large clear areas were present in the cytoplasm. Additionally, the loosening, splitting, and destruction of myelin lamellae were found. This study can provide important preliminary information about the alteration of OLs in the spinal cords of diabetic patients, which might be involve in the impairments of sensory and motor conduction velocities in these individuals.

RESUMEN: En pacientes diabéticos y modelos animales se observan alteraciones de la velocidad de conducción nerviosa sensorial y motora en la médula espinal, así como vainas de mielina degeneradas. De hecho, los oligodendrocitos (OL), que son importantes células neurogliales, generan mielina en el sistema nervioso central. La intumescencia espinal, a nivel cervical y lumbar, inerva los miembros. Por lo tanto, los propósitos de este estudio fueron examinar y comparar las alteraciones ultraestructurales de los OL en la intumescencia espinal de ratas diabéticas inducidas por estreptozotocina (STZ) y controles. Se indujeron trece ratas macho Sprague-Dawley con STZ en tampón citrato y se inyectaron seis ratas de control con la misma solución tampón. Todas las ratas se sacrificaron después de la inducción a las cuatro (DM a corto plazo) y a las veinticuatro semanas (DM a largo plazo). Las ampliaciones de la columna seleccionadas se procesaron para microscopía electrónica de transmisión. Las alteraciones de OL en las intumescencias cervical y lumbar eran aparentemente las mismas. En la DM a corto plazo, los núcleos de los OL se hincharon con la acumulación de cromatina. Los orgánulos citoplasmáticos sufrieron daños moderados. En la DM a largo plazo, los OL contenían núcleos de contracción con aglutinación de heterocromatina gruesa. Se observaron mitocondrias severamente degeneradas con crestas y membranas rotas. Además, se observó un retículo endoplásmico rugoso distendido y fragmentado, y estaban presentes grandes áreas claras en el citoplasma. Además, se encontraron el aflojamiento, la división y la destrucción de las laminillas de mielina. Este estudio puede proporcionar información preliminar importante sobre la alteración de los OL en la médula espinal de los pacientes diabéticos, que podría estar involucrada en las alteraciones de las velocidades de conducción sensorial y motora en estos individuos.

Gangliogliomas: A report of five cases.

Gangliogliomas are rare tumors of the Central Nervous System. Five gangliogliomas were diagnosed out of 1560 brain tumours surgically resected out in a period of 5 years accounting for 0. 32%. We have tried to discuss in detail the pathological features of these tumours and have mentioned the clinical and radiological features associated with them. All the slides, tissue blocks and pathology reports of the surgical specimens of gangliglioma were reviewed and the clinical and radiological data reviewed. The ages of the patients ranged from 7-65 years with 4 males and 1 female. The tumors were located in the lateral ventricle (a rare site), temporal, parietal and the frontal lobes with duration of seizures varying from 1-9 years. The tumors were diagnosed by the presence of a dual population of neoplastic ganglionic and glial components. The glial components consisted of pilocytic astrocytes (l case), fibrillary astrocytes (2 cases), oligodendrocytes (1 case) and anaplastic astrocytes and oligodendrocytes (1 case). There was one-grade I GG, three-Grade II GGs and one-grade III GG. Astrocytes were the commonest glial component of GGs, either pilocytic or fibrillary. Oligodendrocytes as the glial component of GGs was seen in 2 cases one of which was anaplastic and this is a rare finding.

Progressive multifocal leukoencephalopathy in a child with acquired immunodeficiency syndrome (AIDS)

Progressive multifocal leukoencephalopathy is a rare viral-induced demyelinating disease associated to immunodeficiency. A 10-year-old boy with AIDS is reported, who developed subacute cerebellar signs and symptoms with multiple cranial nerve involvement and dementia. A computed tomography scan revealed a focal nonenhancing area of low attenuation in the cerebellum. On magnetic resonance imaging high signal lesions in T2 weighted sequences were shown. The biopsy of one of those lesions showed the typical histological findings of progressive multifocal leukoencephalopathy. It seems important to consider this diagnosis in children with AIDS who present with progressive neurological features.