RESUMEN
Linolenic acid undergoes rapid metabolism in the brain of 21-day-old rats. Radioactivity is rapidly transferred from linolenic acid to the C20 (n--3) fatty acids while that in docosapentaenoic acid (22 : 5 n--3) and docosahexaenoic acid (22 : 6 n--3) gradually increases. A greater proportion of the radioactivity is associated with the polyunsaturated and less with saturated and monounsaturated fatty acids in essential fatty acid-deprived rats relative to controls.
Asunto(s)
Encéfalo/metabolismo , Ácidos Grasos Esenciales/deficiencia , Ácidos Linolénicos/metabolismo , Animales , Encéfalo/crecimiento & desarrollo , Femenino , Inyecciones Espinales , Ácidos Linolénicos/administración & dosificación , Masculino , Fosfolípidos/metabolismo , RatasRESUMEN
Essential fatty acid (EFA) deficiency was induced by feeding pregnant rats a fat-free diet 10--12 days after impregnation and maintaining the offspring on this diet until 120 days of age. EFA-deficiency rats demonstrated marked alterations in the fatty acid composition of ethanolamine phosphoglycerides (EPG's) from myelin subfractions. A decrease in the fatty acids of the linoleic (n-6) and linolenic (n-3) families was accompanied by an increase in the non-essential fatty acids of the oleic (n-9) family. These alterations decreased the unsaturation index of heavy myelin by 23% and that of light myelin by 10%. The EPG fatty acid composition of heavy myelin from control animals contained a higher percentage of polyunsaturated fatty acids than the light myelin which contained more monounsaturated fatty acids. These differences may be a reflection of distinct anatomical locations or functional properties of the subfractions. The differences between light and heavy myelin EPG fatty acids were not maintained during EFA deficiency. Morphologically, 1 mum thick sections revealed vacuoles within the optic nerve of EFA-deficient rats. Ultrastructurally these vacuoles were identified as fibers undergoing Wallerian degeneration and fibers demonstrating intramyelinic splitting. No qualitative changes were found in oligodendrocytes, astrocytes or vascular elements within EFA-deficient optic nerve. EFA deficiency did not alter the diameter of fibers within the optic nerve. These results show that although there is no apparent decrease in the degree of myelination within the optic nerve, morphological changes do occur in fibers of EFA-deficient optic nerve concomitantly with alterations in the EPG fatty acids of myelin subfractions.
Asunto(s)
Química Encefálica , Ácidos Grasos Esenciales/análisis , Ácidos Grasos Esenciales/deficiencia , Vaina de Mielina/análisis , Animales , Microscopía Electrónica , Nervio Óptico/análisis , Nervio Óptico/ultraestructura , RatasRESUMEN
Acetylcholinesterases in the muscle homogenates of hamsters receiving ACTH intraperitoneally for six weeks were reduced as compared to the activities in the control samples. In polyacrylamide disc gel electrophoresis of the ACTH-treated muscles some acetylcholinesterase bands were absent. These observations may be significant in explaining the ACTH-induced improvement in myasthenia gravis patients and in the pathophysiology of steroid myopathy.
Asunto(s)
Acetilcolinesterasa/metabolismo , Hormona Adrenocorticotrópica/farmacología , Esterasas/metabolismo , Músculos/enzimología , Animales , Cricetinae , Electroforesis en Gel de Poliacrilamida , HistocitoquímicaAsunto(s)
Acetilcolinesterasa/metabolismo , Encéfalo/enzimología , Isoenzimas/metabolismo , Isoflurofato/farmacología , Animales , Técnicas In Vitro , Inyecciones , Isoflurofato/administración & dosificación , Masculino , Microsomas/metabolismo , Terminaciones Nerviosas/enzimología , Proteínas del Tejido Nervioso/biosíntesis , Ratas , Sinaptosomas/ultraestructura , Factores de TiempoRESUMEN
Astrocytes and neuronal and oligodendroglial perikarya isolated by the method of Norton and Poduslo (1970) were examined by transmission and scanning electron microscopy and inverted phase contrast microscopy. The viability of the cells, as determined by the eosin exclusion method, was also determined. The three cell fractions showed only slight cross-contamination, but the astrocyte fraction contained significant amount of small debris. The ultrastructural appearance of the cells indicated that much of the in situ properties were retained, with bundles of fibrils preserved in astrocytes with well-defined plasma membranes. Oligodendroglial perikarya were found to be the best preserved of the cell types. The viability studies indicated that about 90% of the cells excluded eosin. Scanning electron microscopy revealed the neuronal cell surface to be rough and studded with knob-like bodies. Oligodendrocytes tended to aggregate and demonstrated a much smoother surface than the neurons.