摘要:

AbstractThe developmental evolution of 5‐HT1Areceptor binding sites was examined in the rat CNS during the early postnatal period using quantitative autoradiography and binding assays with3H‐8‐OH‐DPAT as the selective ligand. A progressive increase in the density of 5‐HT1Asites was observed in the hippocampus, septum and cerebral cortex, up to adult levels which were reached around the third postnatal week. In contrast, complex biphasic (increase then decrease) changes were noted in other structures (for instance the nucleus of the lateral lemniscus) and even a progressive decrease in the density of 5‐HT1Asites took place in the cerebellum during the first two postnatal weeks. The transient expression of 5‐HT1Areceptor binding sites in a structure such as the cerebellum which develops exclusively for the postnatal period further supports that 5‐HT might play a trophic role during maturation of the CNS.

ISSN:0736-5748    

DOI:10.1016/0736-5748(87)90027-X

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractAstroblasts from brain of newborn rat can survive and even proliferate to some extent in a chemically defined medium containing no other growth factor than insulin, providing they are grown first in the presence of fetal calf serum for at least 4 days (Weibelet al., 1984,Int. J. devl Neurosci,2,355–366). We found that thrombin is a potent mitogen for these cells,in vitro. The mitogenic activity of thrombin for astroblasts can be compared to that of the astroglial growth factor 2 (AGF2), also known as basic fibroblast growth factor (bFGF), which was, up to now, the most active factor on astroblasts. However, in contrast to the bFGF, thrombin does not modify significantly the morphology of the cells and their synthesis of glutamine synthetase, an astroglial marker in rat brain. Some other proteases are also able to stimulate the proliferation of astroblasts, but to a lesser extent than thrombin. Thrombin does not stimulate the proliferation of oligodendroblasts from newborn rat and of neuroblasts from 13‐day‐old rat embryo. These results suggest that in the central nervous system thrombin might play a role in the induction of astrocyte proliferation after brain injury.

ISSN:0736-5748    

DOI:10.1016/0736-5748(87)90028-1

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractCorticosterone (1 μg/g) was administered to the pregnant rat mother at 17, 18 and 19 days of gestation. The pups were killed at birth or at 6 or 12 days of age and the morphological and biochemical development of the brain, with special emphasis in the cerebellum was studied. The brain and cerebellar weight was slightly diminished in the corticosterone treated animals. Corticosterone produced changes in the pattern of development of the cerebellar layers, causing an accelerated decrement of the external granular layer at 12 days of life. The total protein content of the cerebellum was increased in the hormone treated pups at birth, 6 and 12 postnatal days. Newborn corticosterone treated animals showed a decreased DNA content, but this phenomenon was completely reversed at 12 days. It was concluded that corticosterone given to the pregnant mother influences the time pattern of the development of the brain and the cerebellum.

ISSN:0736-5748    

DOI:10.1016/0736-5748(87)90029-3

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractQuantitative effects of nerve growth factor (NGF) on the sympathetic, Remak and ciliary ganglia in chicken embryos were investigated. Purified mouse βNGF was injected (80 μg per day for three or four consecutive days) into the yolk sac at different stages (starting on days 6, 8, 10 and 13) of embryonic development. Ganglia were taken for fixation and embedding one day after the last NGF injection. The number of neurons belonging to the different size classes was determined by a computer aided stereological method based on unfolding of cell diameter frequencies. The volume of sympathetic ganglia was increased at all stages with a maximum of 8‐fold occurring on day 10. The ganglion of Remak showed a 3‐fold volume increase up to embryonic days 10 and 12. Ciliary ganglia did not exhibit any differences in volume or neuron size between the controls and the embryos injected with NGF. The number of neurons was increased in younger sympathetic and Remak ganglia in response to NGF, as was the recruitment of neurons to the larger size classes.

ISSN:0736-5748    

DOI:10.1016/0736-5748(87)90030-X

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractChicken embryos on days 6–13 of incubation received injections of purified βNGF (80 μ/ day) for 3 or 4 days and were then killed. Sensory ganglia were fixed and taken for embedding and sectioning. A stereological method based on unfolding of cell‐diameter frequencies was used to determine the number of neurons of different size in the spinal, trigeminal and nodose ganglia. The total volume of the ganglia was also determined. NGF induced increases in diameter of the neural crest‐derived dorsomedial (DM) neurons in spinal and trigeminal ganglia. Injected NGF did not influence ventrolateral (VL) neurons of neural crest origin in the spinal ganglia nor the ventrolateral neurons of placodal origin in the trigeminal ganglion. The volumes of spinal and trigeminal ganglia increased by 50 and 100%, respectively. The volume of the nodose ganglion and the total number and size of the placodal nodose neurons were unaffected by NGF. The results demonstrate a clear difference in the response to NGFin vivobetween smaller and larger sensory neurons.

ISSN:0736-5748    

DOI:10.1016/0736-5748(87)90031-1

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractC6 rat glioma cells respond to glia maturation factor (GMF) with characteristic morphological alterations. Observed under phase‐contrast microscopy, the cells changed from a rounded morphology in random formation to a spindle‐shaped appearance in parallel arrays. Observed under scanning electron microscopy, GMF led to a decrease in the number of microvilli and cell surface knobs. Transmission electron microscopy demonstrated the appearance of numerous microtubules aligned with the long axis of the cells after GMF stimulation. The change in cell shape and histotypic pattern was inhibited by vinblastin, further implicating the involvement of microtubules. Immunofluorescence using anti‐α‐tubulin revealed a well‐defined cytoskeletal system in GMF‐stimulated cells but not in the control cells. Finally, an increase in tubulin was confirmed with enzyme‐linked immunosorbent assay (ELISA) on extracts from these cultures. The findings indicate that morphological alterations induced by GMF are associated with changes in the quantity and arrangement of microtubules.

ISSN:0736-5748    

DOI:10.1016/0736-5748(87)90032-3

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractWe are interested in identifying the target cells for norepinephrine in cerebral cortex and in characterizing the effects of norepinephrine on these target cells. Norepinephrine inhibits the incorporation of tritiated glucose into glycogen in rat cerebral cortex in dissociated cell culture. To identify which cells store glycogen in these cultures we combined glycogen cytochemistry with glial flbrillary acidic protein immunocytochemistry. Using this technique we show that cytochemically detectable glycogen is restricted to a small subset of astrocytes as well as an unidentified cell type which does not contain glial fibrillary acidic protein.These results demonstrate that only a minority of astrocytes in cortical cultures accumulate glycogen. Therefore cortical astrocytes are differentiated with respect to glycogen accumulation, an important metabolic function. We do not know if glycogen accumulation in astrocytes is a constitutive or facultative property. In either case the subset of astrocytes which accumulates glycogen might be one of the major cellular targets for norepinephrine in cerebral cortex.

ISSN:0736-5748    

DOI:10.1016/0736-5748(87)90033-5

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractBy means of immunohistochemical techniques we have investigated the presence of dipeptidyl aminopeptidase IV immunoreactivity in brain material derived from human fetuses, new‐borns and aged persons. It was revealed that the enzyme protein is abundantly present in the immature human CNS. On the contrary the adult human brain contains much less dipeptidyl aminopeptidase immunoreactivity. It is speculated that the enzyme might play an important role in neuronal proliferation and/or differentiation especially with regard to its possible action on certain neuronotrophic peptides (IGF II, growth hormone).

ISSN:0736-5748    

DOI:10.1016/0736-5748(87)90034-7

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe optic nerves from a goat fetus affected with β‐mannosidosis and a control fetus were analysed morphologically in order to investigate developmental aspects of β‐mannosidosis‐associated myelin deficits. In the affected fetus, the number of myelinated axons per unit area was about 25% of the control values. Histograms of axonal diameter indicated that a greater percentage of the myelinated and unmyelinated axons were of larger caliber in the affected fetus than in the control fetus and that very few small axons were myelinated in the affected animal. The mean values of myelin sheath thickness in the affected and control animals did not differ significantly. Ultrastructural analysis revealed a decreased proportion of oligodendrocytes and an increased proportion of astrocytes in the affected fetus.These results indicate that the pathogenetic process leading to cellular abnormalities and myelin deficits in β‐mannosidosis has been initiated prior to 124 days gestation, during an early stage of myelination in the goat optic nerve. The decrease in number of oligodendrocytes suggests that early cell death and/or change in oligodendrocyte proliferation contribute to the myelin deficit. Analysis of the prenatal development of lesions will help clarify the pathogenesis of dysmyelinogenesis in β‐mannosidosis.

ISSN:0736-5748    

DOI:10.1016/0736-5748(87)90035-9

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractDose‐dependent actions of triiodothyronine were studied in serum‐containing primary cultures of embryonal rat forebrain cells. Triiodothyronine at concentrations exceeding the normal medium concentration by 2 and 5 nM failed to cause significant changes in the development of CAT‐activity and GFAP‐immunoreactivity. In the presence of additional 10 and 20 nM T3, however, CAT‐activity was increased and GFAP‐immunoreactivity was decreased in comparison to cultures maintained with ‘normal’ (10% FCS‐containing) media.

ISSN:0736-5748    

DOI:10.1016/0736-5748(87)90036-0

出版商:Wiley    

年代:2003

数据来源: WILEY