摘要:

AbstractNerve growth factor (NGF) plays a trophic and tropic role in the development of vertebrate sympathetic and sensory ganglia; however, the precise nature of the NGF effect(s) is not understood. Study of NGF‐responsive human neuroblastoma cell lines allows characterization of NGF‐induced neunte outgrowth in cells not dependent on NGF for survival. The human neuroblastoma line SK‐N‐SH did not significantly extend neuntes in response to NGF, but did show an increase in cell number. By contrast, a clone of the line, SH‐IN, extended neuntes in response to NGF or dibutyryl cyclic AMP, and showed inhibition of cell proliferation. Thus, cells capable of morphological differentiation in response to NGF can be cloned from neuroblastoma cell lines in which the majority of the cells fail to extend neurites even in the presence of NGF.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90063-4

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractNeurons in mixed primary embryonic CNS cultures degenerate secondary to their detachment from the substratum. The present study demonstrates that in primary cultures of postnatal cerebellum, detachment of neurons can be prevented by antiproliferative drugs which inhibit the growth of astroglia. Several types of proteinase inhibitors did not affect the process of detachment. However, among several types of glycosaminoglycans, heparan sulfate and to a lesser degree heparin, could reversibly inhibit neuron detachment without causing morphological changes of astroglia. The enzymes heparitinase and heparinase caused neuron detachment but only within the first 24–48 hr after plating and not in older cultures. We conclude: (1) cerebellar interneurons in culture are not dependent on astroglia for their survival; (2) astroglia are most probably responsible for neuron detachment via a membrane associated activity and (3) heparan sulfate‐like glycosaminoglycans are important in neuronsubstratum attachment.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90064-6

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractMyelin‐basic protein (MBP)‐like immunoreactivity was studied during development from postnatal day 1 to day 21 as a marker for the myelination process in the rat brain. Using monoclonal MBP antibodies, the caudo‐rostral successive progression of MBP immunoreactivity was mapped in 1‐, 7‐, 14‐, and 21‐day‐old animals using fluorescence microscopy of both coronal and sagittal sections. At 1 day of age, MBP‐immunoreactive single fibers were seen in the lower brain stem, especially in formatio reticularis, whereas the rest of the brain was negative. In 1‐week‐old animals, MBP‐positive fibers extended all the way into frontal cortex, but still in sparse arrays of single fibers with the largest number at the brain stem level. The 2‐week stage showed a dramatic increase in the number of MBP‐immunoreactive fibers. At the brain stem level, MBP‐positive fiber plexuses were mixed with MBP‐positive longitudinal axonal pathways. In cerebellar cortex, positive fibers began to radiate out from the white matter into the grey matter. A dense network of MBP‐positive fibers was located in thalamus, and dense fluorescent fiber bundles were seen in capsula interna piercing through striatum. In cerebral cortex positive radiating fibers were considerably more numerous than at the previous stage. At the age of 3 weeks, MBP‐immunoreactive fibers could be seen in networks and bundles in all parts of the brain. In the brain stem, a dense plexus of positive fibers filled formatio reticularis. In cortex cerebelli and cortex cerebri, a high density of radiating positive fibers was found. In striatum, a sparse distribution of single fibers was found in the neuropil surrounding the now strongly positive bundles of capsula interna.MBP‐like immunoreactivity was followed during postnatal rat brain development and seemed to serve as a good indicator of progression of the myelinization process. With the excellent signal‐to‐noise ratio and the detailed morphological description of the distribution of MBP‐like immunoreactivity, the present report can serve as a reference for studies of pathological disturbances of myelination in CNS as they relate to mechanical, chemical or hormonal perturbations.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90065-8

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe role of the electrogenic Na+‐K+pump in the determination of the level of the resting membrane potential in cultured chick limb muscle was investigated. Transmembrane resting potential and ouabain‐sensitive86Rb‐uptake were measured in myotubes at different ages in culture from 2 to 10 daysin vitro. Inhibition of the Na+‐K+pump with ouabain prevented the developmental increase in membrane potential which normally follows fusion of myotubes (day 2–3). In mature myotubes, ouabain caused a dose‐related decrease in both membrane potential and86Rb‐uptake, with values for EC50and maximal effect being nearly the same on both variables. The decrease in membrane potential by ouabain, up to 20 mV maximum, occurred within 2–5 sec and was not accompanied by detectable changes in input resistance. Membrane potential was also reduced by a decrease in temperature of the recording medium and removal of extracellular K+, both of which reduce Na+‐K+pump activity. We also found that the relation between membrane potential and extracellular K+concentration was completely attenuated by ouabain in the physiological range (2–10 mM). We conclude that the electrogenic Na+‐K+pump plays an important role in the determination of the resting membrane potential of chick myotubes and that regulation of its level is not entirely explained by the diffusion potential hypothesis.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90066-X

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractExpression of the three opioid receptor subtypes mu, delta and kappa in aggregating cell cultures prepared from embryonic guinea pig or rat brains was compared with thein vivoexpression of the receptors in the brain of developing and adult animals of the same species. At the day of culturing, one third of the receptors in the brain of guinea pig embryos were of the kappa type. In culture, however, the aggregating brain cells acquired within 14 days a high percentage (75%) of kappa receptors. As only 28% of the receptors in the adult guinea pig brain are of this subtype, an attempt was made to further analyse the specificity of this developmental process.In guinea pig, the 2‐fold increase in kappa receptors in culture was accompanied with a decline in both the percentage and the density (per protein) of mu and delta subtypes. In contrast, a marked increase in delta receptors was observed in rat whole brain, forebrain or hindbrain cultures. Thus, the developmental pattern of the three receptor subtypes in rat brain cultures, but not in guinea pig, was similar to thatin vivo. These and additional experiments suggest that at the developmental stage taken to prepare the cultures, neurons expressing opioid receptors were already programmed in the rat but not in guinea pig brain.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90067-1

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractIn order to investigate the membrane activities underlying development of neural cells, a histochemical localization of Ca2+‐ATPase, Mg2+‐ATPase and alkaline phosphatase (AlPase) activities in the rat cerebellar cortex during postnatal development was carried out. In the developing cerebellar cortex, ATPase activity was mainly associated with the plasma membranes of Purkinje and granular cells. This activity appeared in the immature Purkinje cells at birth and was proportionally increased throughout postnatal development. It was observed that the ATPase activity of migratory granular cells during a critical period from 3 and 15 postnatal days was increased in a funicular pattern in the developing cerebellar cortex. Conversely, peak AlPase activity in the developing cerebellar cortex was localized in the proliferative external granular cells until 7 postnatal days. Apparently, these phosphatase activities were not present in Bergmann glial fibers during the course of granular cell migration. The present findings were taken to indicate that neuronal cells in the cerebellar cortex have acquired a membrane‐bound ATPase which can participate in Ca2+transport or ATP metabolism during the course of early postnatal development.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90068-3

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractRecent evidence indicates that the insulin‐like family of peptides may act as endogenous trophic factors in the central nervous system. To further examine this possibility we have investigated the effects of three insulin‐like peptides on thein vitrogrowth of fetal hypothalamic cell lines. Two virally transformed rat hypothalamic cell lines which have been developed in our laboratory (A‐6 and F‐12) were used. Cells were plated at varying densities and cultured in the presence or absence of either insulin‐like growth factor I (IGF‐I), insulin, or multiplication stimulating activity (MSA or IGF‐II), in serum‐free medium for 1 wk. Cell growth was assessed by counting or by measuring cellular incorporation of3H‐thymidine. Of the three peptides tested IGF‐I was the most potent in eliciting cell growth. Insulin also stimulated growth of both cell lines, but was 100 times less potent for A‐6 cells while it was equipotent with IGF‐I in F‐12 cells. MSA had no effect on either cell line. Both IGF‐I and insulin showed dose‐response effects in increasing cell growth. We also found that the two cell lines had the greatest response to IGF‐I at low cell densities. Finally, time‐course experiments suggested that a continued presence of the peptide is essential for the growth‐promoting effects. We conclude that IGF‐I is a potent growth factor for virally transformed cell lines derived from the rat fetal hypothalamus. Since both IGF‐I immunoreactivity and IGF‐I receptors have been located in this diencephalic area these results suggest that IGF‐I may constitute a mitogenic signal for hypothalamic cells during neurogenesis.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90069-5

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractMalic enzyme activity in the soluble fraction of neonate brains from mothers fed with propylthiouracil (0.015% w/v) in drinking water from day 12 of the gestation period was significantly lowered (P<0.01) as compared to the offspring of normal mothers. Supplementation of triiodothyronine to the neonates from experimental mothers restored the malic enzyme activity to normal levels. However, administration of triiodothyronine to adult control rats did not influence malic enzyme activity in the brains of these animals. Our data suggest that during the initial critical period of brain maturation, malic enzyme is under the control of thyroid hormones. The response of malic enzyme towards thyroid hormones is lost once the brain has matured.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90070-1

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractNeural cell adhesion molecule (NCAM) is a glycoprotein found in neurons, glial cells and muscle cells. In this report we describe the polypeptide composition and amount of soluble NCAM in brain, cerebrospinal fluid (CSF) and plasma in rats of various ages. One‐two percent of total NCAM in rat brain was shown to be buffer‐soluble. Soluble NCAM in brain, extracted at pH 7.2, constituted an increasing relative proportion of total NCAM during development, whereas the concentration of soluble NCAM in both CSF and plasma decreased in the same period. By radioiodination of brain extracts, CSF, and plasma, soluble NCAM was found to be composed of up to five polypeptides with molecular weights (Mr) of 200,000, 170,000, 150,000, 115,000 and 80,000. The relative composition did not vary significantly with age. The major forms in brain were the polypeptides with Mr of 200,000 and 115,000, whereas in CSF all forms seemed to appear in equal amounts. In plasma the 200,000 and the 170,000 Mr polypeptides were not observed and here the major forms were the 150,000 and 115,000 Mr polypeptides.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90071-3

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractNeurite promoting activities (NPFs) are essential factors in neuronal differentiation. Some of them are associated with proteins of the extracellular matrix (ECM). C6 cells, a rat glioma cell line, release NPF activities into the cell culture medium. We used antibodies against ECM‐proteins for enrichment and partial characterization of these activities. Results show that, (1) C6 cells express and release laminin; (2) the C6‐laminin consists of 260 kD chains only and is therefore different from typical basal lamina laminin (220 and 440 kD chains), but comparable to other laminins of glial origin (chains in the 200 kD range only); (3) C6‐laminin partially purified by affinity chromatography shows NPF‐activity; (4) laminin concentration in C6 cell‐conditioned medium is not sufficient to account for the total neurite promoting activity of the medium, and (5) in addition to laminin C6 cells express and release fibronectin and possibly type IV collagen.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90072-5

出版商:Wiley    

年代:2003

数据来源: WILEY