摘要:

AbstractGrafting of fetal rabbit brain fragments into the brains of newborn mice results in the successful establishment and migration of xenogenic astrocytes in the majority of recipients. This can be demonstrated by the use of Tp‐GFAP1 monoclonal antibody which binds with rabbit, but not with murine glial fibrillary acidic protein. In the first phase, donor astrocytes are found in more than 80% of recipients 3 and 4 weeks after grafting. In the second phase, there is a decline and disappearance of donor astrocytes by the tenth week. We have recently demonstrated that the decline and disappearance of donor astrocytes was coincident with infiltration of T cells into the brain, compatible with T‐cell‐mediated graft rejection. In the present studies, we wished to characterize the types of host cells responding during the period of graft success, in the first 4 weeks after transplantation. It was found that responses by microglia, macrophages, and astrocytes occurred promptly and were sustained throughout this period. Host responses occurred at the graft site and at sites of migration. Examination of sham transplanted control mice revealed responses by the same types of cells. No expression of donor Ia antigen was observed, and the expression of Ia antigen by the host was variable and of low magnitude. T cells were rarely present in transplanted brains during this period.Taken together with previous findings, the present studies demonstrate a clear difference in the host response in the brain at the time when xenogenic astrocytes migrate and survive compared to the period when they disappear. The biphasic nature of the model should facilitate studies to examine mechanisms of brain graft rejection as well as the design of protocols to prevent reje

ISSN:0360-4012    

DOI:10.1002/jnr.490300302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractPeripheral benzodiazepine (PBD) receptors are localized on the mitochondrial membrane and are highly expressed in brain tumors compared to normal brain. To elucidate the biological role of the PBD receptor on mitochondria, we examined the effect of PBDs on mitochondrial morphology in C6 and T98G glioma cells using rhodamine 123 and quantitative electron microscopy. In cells incubated in serum‐free medium alone, mitochondria were distributed in a filamentous pattern throughout the cytoplasm. By contrast, the mitochondria aggregated in the perinuclear region in PK11195 or Ro5‐4864 (10 nM) treated cells. Quantitative electron micrography revealed a 250% increased in the number of mitochondria with elongated cristae and a fivefold increase in dividing mitochondria in PK11195‐treated cells compared with cells incubated in serum‐free medium alone. PBD treatment also resulted in vacuolation within the matrix and mitochondrial swelling. These data suggest that PBDs influence mitochondrial morphology and induce mitochondrial replication in cultured gliom

ISSN:0360-4012    

DOI:10.1002/jnr.490300303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractHuman leptomeningeal cells grown in culture were immortalized via transfection with an SV40 large T antigen gene construct under the control of the Rous sarcoma virus promoter. This cell line, designated LTAg2B, maintained the polygonal morphology characteristic of primary cultures, and stained positively in early passage for cytokeratin, a specific marker for arachnoid cells of the leptomeninges. Additional immunofluorescent staining revealed that these cells express vimentin and desmoplakin as well; these antigens have been found together only in normal arachnoid tissue and in meningiomas, which are the neoplastic derivatives of leptomeningeal cells. Significantly, LTAg2B cells demonstrate a greatly increased life span and growth rate relative to primary cultures. The establishment of this cell line should thus facilitate studies on the cellular and molecular biology of leptomeningeal cells, as well as elucidate their roles in certain pathological situations involving the leptomeninges, such as meningitis and meningioma tumor formation.

ISSN:0360-4012    

DOI:10.1002/jnr.490300304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractWe have shown that ethanol exposure during embryogenesis affects a variety of parameters of neuronal growth. In this study we examined the direct effects of ethanol exposure on developing neuroblasts in culture. Neuroblast‐enriched cultures derived from 3‐day‐old whole chick embryos were grown in the presence of ethanol at doses ranging from 12.5 to 50 mM from culture day 3–14. Cholinergic and GABAergic phenotypic expression were both significantly reduced following ethanol exposure as assessed by the activities of choline acetyltransferase and glutamate decarboxylase, respectively. Morphometric analysis of the growth patterns showed significant differences between control and ethanol‐treated cultures. Control cultures exhibited the characteristic pattern of growth consisting of neuronal aggregation with neuritic arborization, i.e., neuritic bundles and fasciculation. Cultures grown in ethanol from culture day 3 consisted of aggregates that measured significantly greater in size than those observed in control cultures. In addition, in ethanol‐treated cultures, the primary pattern of neuritic bundles was replaced by a complex network of individual neurites radiating from the central aggregate, forming a defined “neuritic field.” Morphometric analysis revealed that both neurite number and neurite length were significantly reduced in ethanol‐treated cultures. The biochemical data confirm earlier reports from this laboratory suggesting that ethanol exposure during early embryogenesis alters the normal neuronal pattern of phenotypic expression. In addition, we have presented evidence in this study that ethanol alters the morphological growth patterns of developing neurons. Although ethanol does not alter the ability of these cells to aggregate, there is a significant alteration in neuritic outgrowth. We conclude that the alterations in the growth patterns induced by ethanol hinder full neurotransmitter phen

ISSN:0360-4012    

DOI:10.1002/jnr.490300305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractBasic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) have been described to exert neuronotrophic effects on central nervous system neurons in culture. To study the selectivity of trophic actions of these growth factors, neurotransmitter‐identified populations of embryonic rat mesencephalon were used. At 20 days in vitro, EGF (3 ng/ml) promoted survival and neurite outgrowth from these neurons. The neuritogenic effect of bFGF (3 ng/ml) was, however, more robust. Quantitative analysis with the neurofilament monoclonal antibody RT97 and ELISA confirmed the differential response, bFGF being 2–2.5 times more effective at all concentrations tested (ED100:3–10 ng/ml for both EGF and bFGF). At 10 days in vitro, EGF displayed no trophic activity — even at 30 ng/ml. Treatment of mesencephalic cultures with EGF (3 ng/ml) for 20 days stimulated [3H]dopamine and [14C]GABA uptakes about 4‐fold. While bFGF (3 ng/ml) also stimulated GABA uptake some 4‐fold, dopamine uptake was increased almost 20‐fold. Thus, EGF is also capable of enhancing the transmitter traits of selected central neuronal populations; however, the actions of bFGF appear to preferentially address dopam

ISSN:0360-4012    

DOI:10.1002/jnr.490300306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe present study sought to establish the cellular basis for the catecholaminergic (i.e., noradrenaline and dopamine) modulation of neurons in the horizontal limb of the diagonal band of Broca (HDB) in the rat brain. The light and electron microscopic localization of antigenic sites for a polyclonal antibody directed against the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH), were examined in the HDB using a double‐bridged, peroxidase‐antiperoxidase method. By light microscopy, numerous punctate, varicose processes with intense TH‐immunoreactivity (TH‐I) were detected in the HDB. Additionally, a few small, bipolar, or multipolar TH‐immunoreactive neurons were observed.Ultrastructural analysis of single sections revealed that the TH‐labeled processes were axons and axon terminals. Axons (n = 134) with TH‐I were primarily unmyelinated. Terminals with TH‐I (n = 169) were 0.3–1.4 μm in diameter and contained many small, clear vesicles and 0–5 larger dense‐core vesicles. The types of associations (i.e., asymmetric synapses, symmetric synapses, and appositions which lacked a membrane specialization in the plane of section analyzed) formed by the TH‐labeled terminals were quantitatively evaluated. The TH‐labeled terminals: (1) formed associations with unlabeled perikarya and dendrites (134 out of 169), (2) were closely apposed without glial intervention to unlabeled and TH‐labeled terminals (11 out of 169), or (3) had no neuronal associations in the plane of section analyzed (24 out of 169). The relatively rare (n = 4) associations with unlabeled perikarya were mostly characterized by symmetric synaptic specializations. The majority of the TH‐labeled terminals were associated with the shafts of small dendrites (66% of 134). Moreover, most of the associations on dendrites and dendritic spines were further characterized by asymmetric synaptic specializations; however, many were also appositions without any apparent glial intervention in the plane of section analyzed. Additionally, the TH‐labeled terminals were often associated with only one dendrite, which, in the same plane of section, was sparsely innervated by other terminals. Astrocytic processes usually surrounded the portions of the terminals and dendrites not involved in the region of association.The TH‐immunoreactive perikarya were small (7–12 μm), ovoid, and had an indented nucleus with some heterochromatin. Their scant cytoplasm contained mitochondria, Golgi complexes, and endoplasmic reticulum. A few immunoreactive dendrites, presumably derived from the local neurons, were also detected. Both TH‐immunoreactive perikarya and dendrites were associated primarily with unlabeled terminals, although a few terminals with TH‐I also contacted them.These results provide ultrastructural evidence showing that in the HDB many TH‐immunoreactive processes are terminals that form direct synapses on unlabeled and a few TH‐labeled neurons and more rarely are in apposition with other unlabeled and labeled terminals. Thus they may provide a cellular substrate for both pre‐ and postsynaptic modulation of septal function by norepinephrine and do

ISSN:0360-4012    

DOI:10.1002/jnr.490300307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractCortical focal ischemia in the rat was induced by middle cerebral artery occlusion (MCAo) together with permanent occlusion of the ipsilateral common carotid artery (CCAo) and a temporary (1 hr) occlusion of the contralateral CCA. By using a defined cortical tissue sampling procedure at 3, 6, 24, 72, 96, and 120 hr after the MCAo + CCAo, patterns of edema and ion (Na+, K+, and Ca++) changes in a primary and three peri‐ischemic cortical areas are described. Ionic imbalances and edema formation have distinct patterns, are time dependent, and are different when comparing primary and peri‐ischemic areas. Calcium increases to “neurotoxic” levels appear temporally independent of edema formation, reaching magnitudes 20 times greater than basal levels in the pri‐mary infarct area. Na+increases correlate with increases in water, while K+losses do not appear to be directly related to edema formation or Na+and Ca++increases. K+losses are only significant in the primary infarct area. Rats treated with GM1 ganglioside (10 mg/kg, i.m.) daily showed significant reductions in edema, Na+and Ca++increases. These ganglioside effects were evident as early as 24 hr after the ischemic injury. Ca++increases, which was maximal at 72 hr after the ischemic injury, was reduced by greater than 50% in GM1‐treated animals. The mechanism by which GM1 is an effective neuroprotective agent may be evidenced by its effects on Ca++influx/efflux processe

ISSN:0360-4012    

DOI:10.1002/jnr.490300308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractBy means of dual immunohistochemical labeling on the same brain section examined with a light microscope, the present study reports the presence with serotonin (5‐hydroxytryptamine; 5‐HT) of gamma‐aminobutyric acid (GABA), substance P (SP), thyro‐tropin‐releasing hormone (TRH), leucin‐enkephalin (LEU‐enk), or methionin‐enkephalin (MET‐enk), within the same neuron in the nuclei raphe magnus, raphe obscurus, and raphe pallidus of the rat. On the one hand, peptides or GABA are detected with specific rabbit antibodies by indirect peroxidase labeling using peroxidase‐conjugated Fab fragments, and on the other, 5‐HT is detected with a rabbit antibody against the BSA‐serotonin conjugate by radio‐immunocytochemistry using [125I]‐labeled protein A. The possible coexistence of TRH and SP in these neurons is also investigated by using peroxidase labeling and radio‐immunocytochemical detection, respectively.In the whole caudal raphe nuclei the proportion of each coexisting peptide with 5‐HT appears in decreasing order as: TRH>SP>MET‐enk # LEU‐enk>GABA. In all instances the level of coexistence differs considerably in B1–B2 vs. B3 cell groups. No SP/TRH dually labeled cells have ever been found in any of the serotonergic nuclei of the caudal raphe.Given the evidence that these raphe nuclei project possibly to the spinal cord, these data constitute an anatomical substrate for the several distinct physiological functions presumably subserved by 5‐HT in the cord, namely the modulation of noci

ISSN:0360-4012    

DOI:10.1002/jnr.490300309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractWe report procedures that allow one to develop and maintain cultures highly enriched in rat neopallial type‐2 astrocytes. Even after four weeks such cultures consist of more than 90% type‐2 astrocytes, ˜ −5% O‐2A progenitors and fewer than 2% type‐1 astrocytes. Their survival for more than 5 days requires the addition of conditioned medium from type‐1 astrocyte cultures. The type‐2 astrocytes have an intense glutamine synthetase activity whose basal level is sevenfold higher than in type‐1 astrocytes. The glutamine synthetase activities of both the type‐2 and type‐1 astrocytes are increased after exposure to cortisol. Thus, type‐2 astrocytes express the two quint‐essential astrocytic features: glial fibrillary acidic protein (previously reported by others) a

ISSN:0360-4012    

DOI:10.1002/jnr.490300310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe myelination‐related enzyme 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase (CNP), a relatively abundant protein in the CNS possesses the C‐terminal isoprenylation consensus domain found in a small family that includes therasoncoproteins and their relatives, some G‐proteins, and nuclear lamins. We found that CNP, like these other proteins, is modified post‐translationally by an isoprenoid derived from mevalonic acid. It appears that only the smaller of the two CNP isoforms (CNP1) is isoprenylated, but similar modification of CNP2 cannot be excluded. Inhibition of isoprenoid synthesis by Lovastatin blocks the binding of newly synthesized CNP to cell membranes; binding is restored upon addition of mevalonate to the culture medium. This shows that isoprenylation is permissive for the well‐known avid association of

ISSN:0360-4012    

DOI:10.1002/jnr.490300311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY