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Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) leading to demyelination and neurodegeneration. Life expectancy and age of onset in MS patients have been rising over the last decades, and previous studies have shown that age affects disease progression. Therefore, age appears as one of the most important factors in accumulating disability in MS patients. Indeed, the degeneration of oligodendrocytes (OGDs) and OGD precursors (OPCs) increases with age, in association with increased inflammatory activity of astrocytes and microglia. Similarly, age-related neuronal changes such as mitochondrial alterations, an increase in oxidative stress, and disrupted paranodal junctions can impact myelin integrity. Conversely, once myelination is complete, the long-term integrity of axons depends on OGD supply of energy. These alterations determine pathological myelin changes consisting of myelin outfolding, splitting, and accumulation of multilamellar fragments. Overall, these data demonstrate that old mature OGDs lose their ability to produce and maintain healthy myelin over time, to induce de novo myelination, and to remodel pre-existing myelinated axons that contribute to neural plasticity in the CNS. Furthermore, as observed in other tissues, aging induces a general decline in regenerative processes and, not surprisingly, progressively hinders remyelination in MS. In this context, this review will provide an overview of the current knowledge of age-related changes occurring in cells of the oligodendroglial lineage and how they impact myelin synthesis, axonal degeneration, and remyelination efficiency.

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RESUMO

RESUMEN El estudio focalizado en dilucidar el rol neuroprotector del ARA y del DHA a lo largo del ciclo vital ha cobrado cada vez más interés puesto que se continúan descubriendo mecanismos mediante los cuales estos ácidos grasos poliinsaturados de cadena larga (AGPICL) modulan el metabolismo. Tanto el ARA como el DHA se encuentran depositados en los lípidos de las membranas de las células que forman la materia gris y representan aproximadamente el 25% del contenido total de ácidos grasos cerebrales. El ARA y el DHA tienen efectos sobre el crecimiento y la diferenciación neuronal a través de la modulación de las propiedades físicas de la membrana, de la transducción de señales asociada a proteínas G y la modulación de la expresión génica, adquiriendo un rol relevante en la neuro-génesis y el desarrollo cerebral. Además, se les atribuye un rol neuroprotector en patologías neurodegenerativas como la enfermedad de Alzheimer y la enfermedad de Parkinson, pudiendo disminuir la disfunción mitocondrial, la neuro-inflamación y el estrés oxidativo, expresiones características de estas patologías. La presente revisión analiza y discute acerca del rol del ARA y del DHA en la neuro-protección y en la neurodegeneración a través de una visión integradora.

ABSTRACT The study focused on elucidating the neuro-protective effects of ARA and DHA throughout the life cycle has become of increasingly interest since the continue discovering of mechanisms by which these long-chain polyunsaturated fatty acids (LCPUFA) modulate the metabolism. Both ARA and DHA are deposited into the membrane lipids of the cells that form the gray matter of the brain and represent approximately 25% of the total content of cerebral fatty acids. ARA and DHA have effects on the growth and neuronal differentiation through the modulation of the physical properties of the membrane, the signal transduction associated to G proteins and by the modulation of gene expression, acquiring a relevant role in neurogenesis and brain development. In addition, it is attributed to these fatty acids a neuro-protective role in neurodegenerative pathologies such as Alzheimer's disease and Parkinson's disease by decreasing the mitochondrial dysfunction, neuroinflammation and oxidative stress, characteristic of these pathologies. This review analyzes and discusses the role of ARA and DHA in neuro-protection and neuro-degeneration through an integrative vision.

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