摘要:

AbstractA glycerol‐containing analog of ganglioside, with sialic acid attached to a diglyceride‐like structure possessing two ether‐linked alkyl chains, was prepared synthetically and applied exogenously to three culture systems; neuro‐2A neuroblastoma cells, PC12 cells and dorsal root ganglia. This resulted in pronounced stimulation of neunte outgrowth in all three, demonstrating that sialo‐lipids(s) lacking ceramide and possessing sialic acid as the sole carbohydrate are able to promote neuritogenesis in approximately the same manner as naturally occurring gangliosides.

ISSN:0736-5748    

DOI:10.1016/0736-5748(88)90015-9

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractNeocortex explants obtained from 6‐day‐old rat pups and cultured in a serum‐free medium from 5 hr to 13 daysin vitro(DIV) show preservation of cytoarchitectural characteristics. Major changes in the size of the explants and their layers occur during the first 2 DIV. A radial arrangement of neurons within layer 2‐3‐4, which becomes apparent between 2 and 10 DIV, suggests an advance in maturation in culture. In contrast to the situationin vivo, a distinct layer 4 cannot be consistently identified. During the first 2 DIV, a transposition of cells into the pial direction can be seen. Individual degenerated cells are spotted especially in layer 5. The presence of these cells amidst healthy neurons suggests that their death has a functional cause. Neurons at the ventricular border of layer 6 become relatively large in comparison with other neurons. Within the cultured tissue there is a marked increase in GFA reactivity compared to the situationin vivo. The described results clearly indicate that in these cultured expiants, both similarities and differences are of interest for studies on the formation of neuronal circuitry within the cerebral cortex.

ISSN:0736-5748    

DOI:10.1016/0736-5748(88)90016-0

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractOntogenetic changes of the total activity and the subcellular distribution of Ca2+‐activated, phospholipid‐dependent protein kinase (protein kinase C) were investigated in the cat visual cortex.Following homogenization of the tissue in Ca2+‐free buffer and separation of membrane‐bound and soluble protein kinase C, the enzyme was partially purified by diethylaminoethyl‐cellulose chromatography. Total, membrane‐bound and soluble enzyme activity were determined by measuring the phosphate incorporation into lysine‐rich histone, a substrate for protein kinase C.It was found that the total activity level, while being low in the first 4 weeks, increased rapidly to peak values at 5 weeks of age and declined slightly thereafter. Although at all developmental stages most of the enzyme was recovered in the soluble fraction, the membrane‐bound activity exhibited a considerable increase at 5 weeks of age, reflecting a relative shift of protein kinase C from the cytosol to the membranes.The increase and redistribution of protein kinase C activity coincide in time with the developmental phase during which the visual cortex is particularly susceptible to undergo use‐dependent modifications. This finding is compatible with the hypothesis that protein kinase C‐mediated phosphorylation processes are involved in activity‐dependent modifications of neuronal transmission.

ISSN:0736-5748    

DOI:10.1016/0736-5748(88)90017-2

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe density of [3H]dihydroalprenolol binding to β‐adrenergic receptors in the visual structures (visual cortex, superior colliculus and lateral geniculate nucleus) of rats raised under a normal 12 hr light‐dark cycle was compared to those of rats visually deprived at different postnatal ages. Unilateral eyelid suture from postnatal days 10 or 16 to 3 months resulted in an increased [3H]dihydroalprenolol bilateral binding in the lateral geniculate nucleus compared to control animals. Monocular deprivation from postnatal days 25, 40, 60 and 90 had no effect on the density of [3H]dihydroalprenolol binding. After re‐opening of the eyelid, which was sutured on postnatal day 10, at postnatal day 25 no changes in β‐adrenergic receptor binding in the lateral geniculate nucleus of the adult animal could be detected. After re‐opening of the sutured eyelid on day 90, followed by examination of the adrenoceptor density 4 weeks later, the [3H]dihydroalprenolol binding in both lateral geniculate nuclei remained elevated as was also found in corresponding regions of monocular deprived animals.Binocular visual deprivation from postnatal day 10 until the age of 3 months had no effect on [3H]dihydroalprenolol binding in the visual centres in comparison to corresponding control animals.The data suggest that there exists a critical period for the ontogenetic development of β‐adrenergic receptors binding in the visual system of rats during which permanent alterations of receptor binding can be induced by monocular but not binocular visual deprivation.

ISSN:0736-5748    

DOI:10.1016/0736-5748(88)90018-4

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractIn this work we have studied the organization of the serotonergic system in new‐hatched snails and the developmental changes that occur postnatally. The serotonergic system of the newhatched snail is not completely developed. Tracts previously described in the adult were already present at hatching; however immunoreactivity of these tracts was somewhat less intense than that in adults, but, their location was practically the same.At hatch the pro‐ and postcerebral serotonergic plexi were poorly developed, while the mesocerebral one was nearly absent. The procerebral plexus occupied only the caudal half of the procerebral neuropile. Growth cone profiles were found in all plexi.The paired giant dorsal serotonergic neurons were the only stained neurons constantly found at hatching; they were symmetrically located. The paired medium‐sized neurons were not found in all brains examined. Sometimes only one of them was present at hatching; it was located either in the right or in the left ganglion.The small neurons were absent in most cases. They gradually appeared during the first three postnatal months. Following hatching the procerebral plexus had undergone an intense growth. By the third postnatal month it innervated completely the procerebral neuropile. At hatching the area innervated by the procerebral plexus was 4500 μm2, by the third month this area was about 58,000 μm2and in the adult was 80,000 μm2.The postnatal development of the procerebral serotonergic plexus proceeds through two different modalities of neuritic growth: expansive growth is mediated by centrifugal elongation of terminal branches while the increase in fiber density within the plexus results from lateral sprouting. This growth probably depends on dynamic interactions with afferent fibers proceeding from the tentacular sensory organs.

ISSN:0736-5748    

DOI:10.1016/0736-5748(88)90019-6

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe ontogeny of a dopamine and cyclic adenosine‐3′:5′‐monophosphate‐regulated phosphoprotein with an apparent molecular weight of 32 kilodaltons (DARPP‐32) has been studied in the central nervous system of the prenatal, newborn and adult mouse.DARPP‐32‐immunoreactive somata were first identified at day 12 of gestation, in the primary olfactory cortex and in the ventrolateral medulla oblongata. On day 14 of gestation, neurons containing DARPP‐32‐like immunoreactivity became apparent in the caudate nucleus, olfactory tubercle, nucleus accumbens, frontoparietal cortex and the ventral medulla oblongata. During the period up to and including birth, the number of cell bodies and fibres in all these areas increased markedly. In addition, DARPP‐32‐positive neurons became visible in the olfactory nucleus, the arcuate nucleus, and DARPP‐32‐positive cells appeared in the choroid plexus of the lateral, third and fourth ventricles. DARPP‐32‐containing fibres could be seen in the median eminence, the ventrolateral thalamus, and in the striatonigral projection, descending in the internal capsule to ramify extensively in the substantia nigra. Only in the cerebellum and suprachiasmatic nucleus did the development of DARPP‐32‐like immunoreactivity occur postnatally.The development of tyrosine hydroxylase, the rate‐limiting enzyme for catecholamine synthesis, was simultaneously examined. The arrival of the tyrosine hydroxylase‐containing projection to the caudate nucleus, the olfactory tubercle and the nucleus accumbens apparently occurred 1–2 days after the appearance of DARPP‐32‐immunoreactive cells within these regions. In the ventral and ventrolateral medulla oblongata, and the primary olfactory cortex, no tyrosine hydroxylase innervation was seen near the DARPP‐32‐positive neurons at days 12–14. The organization of the DARPP‐32‐containing somata of the caudate nucleus into aggregates of 5–15 neurons was partly paralleled spatially by an increased density of tyrosine hydroxylase‐positive fibres.Many DARPP‐32‐immunoreactive cells in the immature mouse brain are present by the day of birth, particularly in the areas known to receive a dopaminergic innervation. The development of these presumptive dopaminoceptive DARPP‐32‐containing neurons does not seem to be dependent on the presence, however, of a dopaminergic input, since in all regions examined DARPP‐32‐LI preceded the appearance of tyrosine hydroxylase‐like immunoreactivity by at least 1–2 days. Indeed, the results suggest that the existence of DARPP‐32‐like immunoreactivity in cell bodies and dendrites may be a pre‐requisite for the formation or subsequent stabilization of dopaminergic synapses.

ISSN:0736-5748    

DOI:10.1016/0736-5748(88)90020-2

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe effect of the neurotrophic factor NGF on the expression of two genes involved in the accumulation of amyloid deposits in neurodegenerative disorders was studied in a clonal cell line, PC12. Use of hybridization methods showed that NGF increased the cellular pool of the mRNA of the prion protein, a macromolecule known to generate fibrillary aggregates in the brain of scrapie‐infected animals. Maximal levels of prion mRNA were obtained after 7 days of treatment, but a significant increase was already detectable after 48 hr of exposure to NGF. In contrast, the factor did not increase the cellular content of the transcripts coding for the precursor of the β‐amyloid peptide (APP), which participates in the formation of neuritic plaques in human brains affected by Alzheimer's disease. However, NGF caused a drop in the molecular weight of that mRNA. This change, which is likely to result from a loss of 100–200 bp, was already detected after 24 hr of treatment. These results indicate that NGF induces in target neuronal cells a quantitative and a qualitative modification of the transcription products encoding two different amyloid precursor proteins.

ISSN:0736-5748    

DOI:10.1016/0736-5748(88)90021-4

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThis study reports the production of myelin‐like membranes in oligodendrocyte subcultures derived from 20‐day‐old primary glial cell cultures of newborn rat brain. These multi‐layered structures show a variable number of membrane turns; up to 10 concentric lamellae are found in 3‐ to 4‐week‐old subcultures. When they are compacted, alternate dense and intraperiodic lines with a periodicity of 11.2 nm are noticeable. The most typical myelin proteins were detected straight on the multi‐lammellar structures by a gold immunocytochemical method. Subcellular fractions containing these myelin‐like structures were isolated by ultracentrifugation on a discontinuous sucrose gradient. They were analysed by sodium dodecylsulfate‐polyacrylamide gel electrophoresis and immunoblotting; UDP‐galactose: ceramide galactosyltransferase and 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase activities were also measured.The results indicate that the multi‐layered membrane profiles have many characteristics of the myelin foundin vivo; nevertheless some differences were still apparent. Our data support the concept of the cultured oligodendrocytes expressing the intrinsic myeltnogenic properties and possessing a basic developmental program of myelination, apparently in the absence of stimuli coming from other brain cells.

ISSN:0736-5748    

DOI:10.1016/0736-5748(88)90022-6

出版商:Wiley    

年代:2003

数据来源: WILEY