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At least 19 recordsLinked to original sources
PubMed1981

Net sulfatide synthesis, galactosylceramide sulfotransferase and arylsulfatase A activity in the developing cerebrum and cerebellum of normal mice and myelin-deficient jimpy mice.

Net sulfatide synthesis, galactosylceramide sulfotransferase (EC 2.8.2.11) and arylsulfatase A (EC 3.1.6.1) activities were measured in two brain regions, cerebrum and cerebellum, of normal and jimpy mice during postnatal development. In normally myelinating mice, two phases of increasing rates of net sulfatide synthesis were observed, the first coinciding with oligodendrocyte proliferation and the second with myelination. Net sulfatide synthesis was quantitatively higher in the cerebellum than in the cerebrum. In both brain regions, the developmental patterns of net sulfatide synthesis were related to the activity patterns of both galactosylceramide sulfotransferase and arylsulfatase A. In jimpy mice, a neurological mutant showing hypomyelination in brain, the first phase of net sulfatide synthesis was preserved in both brain regions and galactosylceramide sulfotransferase and arylsulfatase A activities were normal up to 12 days. However, during the phase in which myelination occurred in controls, the net sulfatide synthesis in both brain regions of jimpy mice was zero or even negative. The sulfatide deficit was larger in the cerebellum than in the cerebrum. In both mutant brain parts, galactosylceramide sulfotransferase activity increased up to 12 days showing about 50% of the maximal activities observed in normal brain regions. Thereafter up to 15 days, enzyme activity decreased to about 25% of that of controls and remained low in both brain regions. The developmental patterns and the activities of arylsulfatase A were, however, normal in the cerebrum and cerebellum of jimpy mice. These results suggest that the enzyme activities and the developmental patterns of galactosylceramide sulfotransferase and arylsulfatase A as measured in vitro reflect to a high degree their functional activity in vivo. Furthermore, sulfatide degradation by arylsulfatase A seems to be important in regulating net sulfatide synthesis during normal and impaired myelination.

Animals↗
PubMed1979

Brain sulfatide and non-lipid sulfate metabolism in leucodystrophic (jimpy) mice.

In leucodystrophic (jimpy mutant) mice there is a marked depletion of brain sulfatide as compared to normal ilttermates. Subcellular fractionation showed decreased sulfatide concentrations in microsomal and synaptosomal fractions prepared from jimpy brains. The in vivo incorporation of 35SO4 into sulfatide of myelin, microsomal, mitochondrial and synaptosomal fractions was significantly inhibited in the jimpy mutant. In addition, the incorporation of 35SO1 into non-lipid brain membrane components (sulfated glycoproteins and mucopolysaccarides) was also decreased in jimpy mice. These results suggest that the jimpy mutation produces widespread alterations in brain sulfatide metabolism and also affects the metabolism of non-lipid membrane components of brain.

Animals↗
PubMed1976

Pituicytes in normal and Jimpy Mice.

Neural lobes of control and "Jimpy" mice were examined electron microscopically. The ultrastructure and incidence of pituicytes was examined following reports of reductions in astrocyte and oligodendrocyte populations in areas of the CNS of Jimpy mice. The failure to demonstrate any modification of structure or numbers of the pituicytes in the affected animals suggests that the pituicytes are not as closely related to the satellite cells of the CNS as has previously been proposed.

Animals↗
PubMed1996

The microglial reaction in spinal cords of jimpy mice is related to apoptotic oligodendrocytes.

Jimpy is a shortened life-span murine mutant whose genetic disorder results in a severe hypomyelination in the central neruons system associated with a variety of glial abnormalities, including oligodendrocyte death. In this study, we report that oligodendrocyte death in jimpy occurs through an apoptotic mechanism, as demonstrated by in situ labeling of nuclear DNA fragmentation. Compared to those of normal littermates, the spinal cords of jimpy mice showed a significantly higher number of apoptotic cells. Our observations also corroborate that specific glial cell death in jimpy is restricted to oligodendrocytes, as evidenced by double labeling for DNA fragmentation and MBP immunocytochemistry. Cells labeled for DNA fragmentation were always negative for astroglial or microglial markers. Apoptotic oligodendrocytes were not aggregated into clusters and were ubiquitously distributed throughout the jimpy spinal cord, although were more numerous in white matter than in gray matter. We found no physical association between astrocytes and dying cells in jimpy. Microglial cells, however, were found closely attached to and even surrounding apoptotic cells. The possible role of microglial cells in relation to apoptotsis is discussed.

Animals↗
PubMed1986

Oligodendrocyte production and myelin recovery in heterozygous jimpy mice: an autoradiographic study.

Jimpy is a genetic disorder of mouse resulting in hypomyelination. In this study oligodendrocyte proliferation was examined in heterozygous carriers of the jimpy gene. The incorporation of [3H]-thymidine into DNA is increased in jimpy heterozygotes compared to controls. An autoradiographic analysis indicated that oligodendrocytes are the predominant neuroglial cell type being produced in the brain at the ages studied in both heterozygotes and control animals. In addition, the total number of labeled oligodendrocytes was increased in the heterozygote animals compared to controls. These results, taken together, indicate that the rate of oligodendrocyte production is greater in jimpy heterozygotes than in control animals. We have previously shown that young jimpy heterozygotes have a reduced myelin content and older heterozygotes do not. The increased rate of oligodendrocyte production, demonstrated in this study, is most likely responsible for the increasing myelin content in the heterozygote. Further study of the cellular interactions which trigger oligodendrocyte production and myelin recovery in the jimpy heterozygote may be relevant to remyelination in other disease states, including those affecting humans.

Animals↗
PubMed1980

Immunohistochemical localization of the myelin basic protein and of the glial fibrillary acidic protein: comparative study in normal, quaking and jimpy mice.

The topographical distribution of myelin basic protein (MBP) and of glial fibrillary acidic protein (GFA) have been compared in the CNS of 18-day-old normal, quaking, and jimpy mice using indirect immunofluorescence. Comparison was made in brain and spinal cord sections. MBP was strongly decreased in quaking and jimpy mice in all parts of the CNS. A pronounced gliosis was observed in jimpy mice with occurrence of numerous hypertrophied astrocytes. To a lesser extent, an astrocytic reaction was also observed in quaking CNS.

Animals↗
PubMed1984

Difference between the thyroid gland of normal and hypomyelinated jimpy mice--a light microscopic study.

A light microscopic quantitative analysis was performed on normal and jimpy male mice for studying the difference between the structures of the thyroid glands of the two animals. The results of this analysis showed that the thyroid gland of the normal mice consisted of numerous homogenous round follicles with cuboidal follicular cells, separated by thin interlobular and interfollicular connective tissue and a few adipose tissue. The thyroid gland of jimpy mice consisted of a few, small follicles surrounded by columnar follicular cells and intraepithelial capillaries, separated by thick connective tissue and abundant adipose tissue. The number of thyroid follicles are significantly less in the jimpy mice than in the normal mice. Another striking difference is that almost every follicular cell surrounding the follicular lumen of jimpy mice is accompanied by an intraepithelial capillary. In addition, the ratio of the number of intraepithelial capillaries to the number of the thyroid follicular cells are significantly higher in the jimpy mice than in the normal mice. The S-follicles or ultimobranchial cysts of the thyroid gland are well developed in the jimpy mice. The parafollicular cells are normal in appearance. Morphological evidence suggested that the thyroid follicular cells of the jimpy mice are very active in the transport, synthesis and release of thyroglobulin, and secretion of thyroid hormones. But owing to the significantly decreased number of thyroid follicles, the inadequate secretion of the thyroid hormones result in the hypothyroidism and the hypomyelination of the jimpy mice.

Animals↗
PubMed1986

Appearance of hematogenous cells in the white matter of myelin-deficient Jimpy mice.

Various cells from the monocyte-macrophage line, a few neutrophils and some lymphocytes were found in the non-myelinated white matter of Jimpy mice, though there was no vascular injury to the brain parenchyma. Some of the lymphocytes appearing in the white matter were in close contact with macrophages, and occasionally with young oligodendrocytes. Such lymphocytes were mainly of the small type with few cell organelles in a scanty cytoplasm, though a few were of the medium type with a moderate amount of cell organelles in an enriched cytoplasm. Macrophages in the non-myelinated white matter displayed a highly heterogeneous cytoplasm. In particular, "cytoplasmic compartments" in macrophages displayed specific structures differing from the inclusion bodies generally seen in phagocytic cells. The contents of such "cytoplasmic compartments" were rather similar to parts of the macrophage's own cytoplasm, though they were isolated from the cytoplasm by a membrane and gaps. Our findings would seem to support the previous presumption that inherited myelin deficiency in Jimpy mice is induced by a T-cell mediated autoimmune response.

Animals↗
PubMed1985

Astrocytal changes in the white matter of Jimpy mice: immunohistochemistry using antisera to glial fibrillary acidic protein.

Immunohistochemistry using antisera to glial fibrillary acidic protein (GFAP) was performed to observe astrocytal changes in the white matter of myelin-deficient Jimpy mice. In wild-type controls, astrocytes stained with the GFAP immunoreaction appeared in the cerebellar medulla by postnatal day 3 and in the corpus callosum by postnatal day 6. The immunoreactivity gradually intensified with age to reach a peak of the GFAP level around postnatal day 12. With the progress of myelinogenesis, GFAP positive astrocytes decreased in number and became sparse in the white matter. On the other hand, the white matter of Jimpy mutant mice revealed intensified GFAP immunoreactivity, corresponding to a numerical increase in astrocytes and an enlargement of their cytoplasm. This condition continued from postnatal day 12 up to the end of life. Such astrocytes made up a dense framework with thickened processes in the non-myelinated white matter, where oligodendrocytes were few. Under the electron microscope, an accumulation of gliofilaments and glycogen particles was apparent in the enriched astrocytal cytoplasm. Immunostaining was observed not only on gliofilament bundles but also rough endoplasmic reticulum and cytoplasmic matrix. The present results demonstrate that astrocytal hypertrophy and hyperplasia occur in the entire white matter of Jimpy mice.

Animals↗
PubMed1978

Proteins from sciatic-nerve myelin in quaking and jimpy mice.

Myelin from two neurological mutants in mice was isolated from sciatic nerves and its protein composition analysed. In Quaking mice, two intrinsic myelin proteins P1 and P2 were drastically decreased, whereas the major myelin protein P0 was unaffected. A normal protein composition was found in sciatic myelin from Jimpy mice.

Animals↗
PubMed1991

Developmental expression of glial fibrillary acidic protein and glutamine synthetase mRNAs in normal and jimpy mice.

Astrogliosis is a prominent feature in the CNS of the dysmyelinating mutant, jimpy. In the following study the expression of the glial markers, glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS) mRNAs were examined the cerebra of normal and jimpy mice. The relative abundance of GFAP and GS mRNAs increased rapidly in the CNS of normal mice during the first two postnatal weeks. During the third week the content of GFAP and GS mRNA remained constant. The pattern of developmental accumulation of these transcripts in jimpy animals was distinctly different. Levels of GFAP transcripts in 6- and 10-day-old jimpy animals were essentially the same as controls. In 14-day-old animals, however, the content of GFAP mRNA in jimpy had increased dramatically, and was 3-fold greater than that found in normal animals. The levels of GFAP message remained significantly elevated above control values for the life of the animals, approximately 22-24 days. In contrast, no significant difference in GS mRNA content was detected between control and jimpy brain tissue. The results of this study indicated that increased accumulation of GFAP mRNA was significant component of reactive gliosis and that the mechanisms responsible for the induction of GFAP were dissociated from those that regulate GS expression.

Aging↗
PubMed1988

Localization of glial cell antigens in the brains of young normal mice and the dysmyelinating mutant mice, jimpy and shiverer.

Tissue sections from the brains of normal, jimpy, and shiverer mice were immunostained by the peroxidase antiperoxidase method for carbonic anhydrase (CA) and the putative astrocytic "markers" glutamine synthetase (GS) and glial fibrillary acidic protein (GFAP). The cells in normal gray matter that immunostained with anti-CA and anti-GS were similar to one another in size and process elaboration. In the normal gray matter there were relatively few GFAP-positive astrocytes. When present, these cells resembled the CA- and GS-positive cells; however, the GFAP appeared to be concentrated in the astroglial processes, as distinguished from the cell bodies. Glial cell processes, immunostained for CA or GS, surrounded blood vessels and unstained neurons in the normal gray matter. The glial cells in shiverer gray matter were similar to those in the normal gray matter. When stained for GS or GFAP, the glial cells in the jimpy gray matter appeared to be somewhat hypertrophied, and when the glial cells in this mutant were stained for CA, the nuclei appeared to be swollen. It was concluded that some of the CA-positive cells in the gray matter of the normal and of each mutant mouse brain could be astrocytes. The patterns of immunostaining in the white matter emphasized the different complements of glial cells in the mutants. In the normal and shiverer mouse corpus callosum, CA, in particular, was detected only in the oligodendrocytes, their processes, and myelin. However, the data concerning the jimpy mouse suggested that the few CA-positive cells in the corpus callosum of that mutant could be astrocytes.

Animals↗
PubMed1987

An AG----GG transition at a splice site in the myelin proteolipid protein gene in jimpy mice results in the removal of an exon.

The myelin proteolipid protein gene was characterized in jimpy mice to identify the specific mutation that produces dysmyelination, oligodendrocyte cell death, and death of the animal by 30 days of age. Exon 5 and flanking intron segments were isolated from jimpy proteolipid protein genomic clones and sequenced. A single nucleotide difference was noted between the normal and jimpy proteolipid protein genes: the conversion of an AG/GT to a GG/GT in the splice acceptor signal preceding exon 5, which apparently destroys the splice signal. Thus, exon 5 of the mouse myelin proteolipid protein gene is skipped during the processing of mRNA, producing a shortened proteolipid protein mRNA.

Animals↗
PubMed1975

Oligodendroglial cell development in jimpy mice and controls. An electron-microscopic study in the optic nerve.

Glial development was studied in the optic nerve of 1- to 28-day-old Jimpy mice and controls. Abnormalities were found in oligodelopment and axons were not affected. These consisted in (a) Increased numbers of glioblastic cells containing lipids and increased occurrence of glial cell death in the premyelination stage; (b) Decreased numbers of maturing oligodendrocytes (i.e. young and active oligodendrocytes) in the period of early myelination; (c) An occurrence of abnormal oligodendroglial cells containing lipids and multimembranous tubes in the period of advanced myelination. The decreased number of maturing oligodendrocytes in the premyelination stage indicates that the lack of myelin in Jimpy mice may be secondary to a disturbance in the differentiation of the oligodendroglial cell line. The occurrence of abnormal, lipid-containing glioblasts and oligodendrocytes may be an expression of a defect in metabolism leading to an abnormality in the association of myelin proteins and myelin lipids.

Animals↗
PubMed1981

Radioautographic evidence for the protracted proliferation of glial cells in the central nervous system of jimpy mice.

Proliferation of glial cells has been studied in the central nervous system of jimpy mice and control littermates with [3H]thymidine radioautography. It was found that the proliferation of glial precursors was protracted in the 3 regions studied: spinal cord, cerebellum and corpus callosum. The difference between jimpy and littermates became obvious in each of these regions at the onset of myelination. It is concluded that the maturation of the oligodendrocyte is the target of the mutation. The protracted proliferation of glioblasts is a consequence of the absence of stable interactions with the axons.

Aging↗
PubMed1984

Studies on myelin basic protein-specific protein methylase I in various dysmyelinating mutant mice.

Jimpy mice are dysmyelinating mutants characterized by producing near normal levels of myelin basic protein (MBP) in the brain but failing to incorporate these proteins into the myelin sheath. In this study, the activity of MBP-specific protein-arginine N-methyltransferase (protein methylase I) was studied in the brains of normal and jimpy mice of different ages. The enzyme activity varied little with age in normal mice but in 18 and 21 days-old homozygous jimpy mice the activity was reduced by 50% and 75% respectively from the level of their normal littermates. Interestingly, however, heterozygous jimpy mice who are phenotypically normal and quaking mice (a similar dysmyelinating mutant) showed unaltered enzyme levels.

Age Factors↗
PubMed1995

Microglial cell reaction in the gray and white matter in spinal cords from jimpy mice. An enzyme histochemical study at the light and electron microscope level.

Jimpy is a genetic disorder which results in a severe hypomyelination in the central nervous system associated with a variety of astroglial and oligodendroglial abnormalities. In this study, we examined the morphology and distribution of microglial cells in spinal cord sections from jimpy and normal mice at 10-12 and 20-22 days postnatal using a specific microglial marker, the nucleoside diphosphatase staining. Compared to those of normal littermates, the spinal cords of jimpy mice showed an intense microglial cell reaction in white and gray matter, as revealed by quantitative analysis and light and electron microscope study. Microglial reactivity was apparent in all spinal cord areas, although it was more pronounced in white than in gray matter. The mean microglial densities in the jimpy white matter were about threefold (10-12 days) and fivefold (20-22 days) higher than in the normal, whereas in the gray matter, microglial density in jimpy was about 60% higher than in normal at both ages. Morphologically, microglial cells in the normal spinal cord showed a ramified appearance, similar in size and ramification pattern to those reported in other normal CNS areas. In contrast, microglial cells in the jimpy spinal cord showed a reactive morphology, characterized by a shortening and coarsening of their cell processes, swelling of their cell body and accumulation of lipid inclusions. Reactive microglial cells were found in close association with axons and oligodendroglial cells. The possible role of microglial cells in hypomyelination is discussed.

Acid Anhydride Hydrolases↗