摘要:

AbstractAn electroporation technique was employed to study the effect of oncogenes H‐rasand c‐mycafter their short‐term expression in the rat pheochromocytoma PC12 cells. It was found that within 6 days after electroporation the mutant T24 H‐ras1 gene induced differentiation of PC12 cells whereas the c‐mycblocked NGF‐induced differentiation. The induction of differentiation by the T24 H‐rasgene may suggest a physiological role of therasgene in cell differentiation as well as in cell proliferation.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90039-7

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractHistochemical, biochemical and immunologic analysis of cytochromecoxidase (COX) in skeletal muscle, heart and kidney during human fetal development was performed. COX histochemical activity was present only in few muscle fibres from the 11th to the 20th week of gestation. At the same developmental stage intrafusal muscle fibres, heart and kidney already showed strong activity. At the 28th week of gestation muscular COX activity was present in about 90% of the fibres. Tissue biochemical analysis confirmed these histochemical findings. Histochemical and biochemical findings compared to the immunocytochemical results and ELISA indicate that COX activity parallels the progressive synthesis of the enzyme in each tissue.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90040-3

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe anticonvulsants phenobarbital and diphenylhydantoin administered early in life to mice resulted in significant and long‐lasting ultrastructural damage, including abnormalities of mitochondria, myelin sheaths and lamellar inclusion bodies inside identified cells throughout the cortical layers of the cerebellum in treated vs control mice. The magnitude, distribution and duration of damage was age and treatment specific. No differences were detected in density of parallel fiber processes nor in synapse density within the molecular layer. Neuron profiles containing damaged organelles were not homogeneously distributed but made up only a small fraction of the total cell population examined. In our experiments, there was an overall within‐animal correlation explaining 45% of the magnitude of damage in different cerebellar regions, but between synaptically connected cells, specifically mossy fiber axon varicosities and granule cell dendrite profiles, the subset population ratio of damaged‐to‐total mitochondria was highly significantly correlated (70–90%;P<0.001). We hypothesized that some correlated transneuronal degeneration and death in the central nervous system may have a transynaptically regulated component that first appears as correlated damage between synaptically connected cells, perhaps regardless of the degree of toxicity. The orderly cytoarchitecture and cell connections of the cerebellar cortex can be used to study these patterns of degeneration.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90041-5

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractDevelopment of the serotonergic system in the brain and frontal ganglion of theManducaembryo between 35 and 100% of development was studied immunocytochemically with an antiserum to serotonin (5‐HT). Serotonin immunoreactivity was initially detectable at 40–45% development in short fibers in the head region, prior to differentiation of the brain. Immunoreactive cell bodies were first seen in the brain at 60% development, located in the protocerebrum and tritocerebrum. Thick fiber tracts crossing the midline (commissures) could also be observed at this early stage. As development of the embryo progressed, eight immunoreactive cell groups, containing a total of about 38–40 cells and four commissures with terminal arborizations appeared successively in the brain. From 75 to 100% development, no obvious changes occurred in the number or distribution of cells and the brain exhibited the same pattern of 5‐HT immunoreactive cells, fiber tracts and arborizations as in last instar larvae ofManduca. However, an increase in the size of the cells in both the brain and frontal ganglion was noted between 75 and 80% development, followed by a decrease by 100% development. The frontal ganglion was found to contain three 5‐HT immunoreactive cells, which appeared to send bilateral projections into the frontal connectives and the recurrent nerve. During embryonic development, the dendritic arborizations of these frontal ganglion cells increased, while the amount of 5‐HT immunoreactivity in the cell bodies decreased. Thus, the serotonergic system first appears in theManducaembryo at an early stage of development, similar to the situation in other insects as well as vertebrates. By the end of the embryonic period, the same number of serotonergic neurons are present in the brain as in larval and adultManduca, suggesting that once formed, these cells persist through postembryonic development and metamorphosis.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90042-7

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe distribution of serotonin (5‐HT) immunoreactive cells and their projections was mapped in the ganglia of the ventral nerve cord of the tobacco hornworm,Manduca sexta, during embryonic development, using an antiserum to 5‐HT. Immunoreactive cells were first seen at 60% development. By 75% of embryonic development, a total of 94 immunoreactive cells were found in the ventral ganglia, including the suboesophageal ganglion. This number decreased to 80 neurons by 100% of development. About 50% of these cells were arranged in the abdominal ganglia and the rest were located in both the suboesophageal and thoracic ganglia. The suboesophageal ganglion exhibited immunoreactive segmentai interneurons in areas corresponding to the mandibular, maxillary and labial neuromeres. Two pairs of immunoreactive interneurons were also observed to occur bilaterally in each of the thoracic and abdominal ganglia, with the exception of the prothoracic ganglion. This ganglion contained three pairs of bilaterally arranged immunoreactive neurons as early as 60% of embryonic development. Serotonin immunoreactivity was also found in a number of efferent neurons in the mandibular and labial neuromeres of the suboesophageal ganglion and in the prothoracic, mesothoracic and posterior abdominal ganglia. The occurrence of 5‐HT in these efferent neurons suggests an involvement of serotonin in foreand hindgut function via its effect on the visceral muscles. Immunoreactive lateral longitudinal fibers extended along the entire length of the ventral nerve cord together with dense segmentai arborizations. The latter had regressed by the time the embryo was fully developed. This regression of the arborizations in the ganglia at the end of embryonic development indicates that a reorganization of 5‐HT innervation occurs to support new larval functions. The time of appearance of 5‐HT immunoreactive cells and fibers suggests that serotonin may play a role in the development of the ventral nerve cord.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90043-9

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe developing serotonergic system of the tobacco hornworm,Manduca sexta, has been studied immunocytochemically in whole mount preparations of brain‐retrocerebral complexes. The distribution of serotonin‐immunoreactive cell bodies, fibers and terminal fields has been analysed during larval and larval‐pupal development using a specific rabbit antiserum against serotonin‐hemocyanin conjugates. The serotonergic system was conserved from the fourth to the fifth larval stadium, with minimal changes occurring until the onset of pupal development. At this time, alterations in the distribution of serotonin‐immunoreactive cells and processes were observed, including the apparent disappearance of some cell bodies and terminals. Nevertheless, the overall appearance of this system in the pupal brain was not significantly different from that in the larva. The larval pattern was characterized by eight bilateral groups of cell bodies which sent thick bridges of fibers across the midline, a feature strikingly similar to the serotonergic system in vertebrate embryos. In addition, three bilateral immunoreactive fields of arborization were observed around and ventral to these cell groups, together with regions of serotonin immunoreactivity in the medial and lateral protocerebral lobes. The central body, larval antennal centers, larval accessory lobes and the tritocerebrum were also immunoreactive. Fibrous networks of serotonergic processes were usually observed around nerves emanating from the brain, including the connectives from the brain to the corpus cardiacum and corpus allatum. Smaller varicosities were observed in the interior of these neurohemal and glandular organs and a network of 5‐HT fibers was occasionally found around the corpus cardiacum and corpus allatum. The possible relationship of serotonin to cerebral neuroendocrine functions during the postembryonic development ofM. sextais discussed.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90044-0

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractDevelopmental changes in norepinephrine (NE), dopamine (DA) and epinephrine (E) contents of the rat metencephalon, mesencephalon and diencephalon, have been measured by high performance liquid chromatography with electrochemical detection, from fetal stages (E15 or E17 to E21) to postnatal days (P0 to P30) and compared to the adult levels. The data show a biphasic pattern in NE changes of the three brain areas, with a first increase in the late prenatal period, followed by a further development from PO to P18, thus reaching the adult levels. A similar pattern of development is found for the mesencephalic and diencephalic DA contents. The E levels of the diencephalon are very low in comparison to the NE and DA concentrations, but present a gradual increase from E17 to P18. The results correlate with the development of catecholamine systems in brain area as measured by other methodological approaches.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90045-2

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractSex differences have been reported in the size of the adult corpus callosum in both humans and rodents. This experiment investigated whether sex and/or different prenatal treatment conditions would influence commissural size at birth. Male and female 3‐day‐old Long Evans rats were selected from one of three prenatal treatment histories: prenatal alcohol‐exposed (35% ethanol‐derived calories, 35% EDC), nutritional control (0% ethanol‐derived calories, 0% EDC) or standard control (lab chow). Midline sagittal areas of the corpus callosum and the anterior commissure were determined for these subjects. Male control subjects had significantly larger callosal areas than females. Prenatal alcohol exposure significantly abolished this sexual dimorphism, with 35% EDC males having a significantly smaller callosal area than males from both control groups. This effect was independent of prenatal treatment differences in body or brain size. There were no significant sex differences in the midline sagittal area of the anterior commissure, nor were there any apparent effects of prenatal treatment on this measure. These results indicate that sex differences in the size of the corpus callosum are present at birth. Since a difference in myelination cannot account for this difference in area, there may be a sex difference in the number of fibers or in the average fiber size. Additionally, the effects of prenatal alcohol exposure on male, but not female, offspring suggest that this alcohol‐related birth defect is hormonally mediated.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90046-4

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractProjection patterns of dorsal root ganglion afferents within organotypic expiants of fetal mouse spinal cord were examined histologically using a horseradish peroxidase staining method. All expiants were also examined electrophysiologically and showed spontaneous and evoked bioelectric discharges, which were evenly distributed across the cord explants. Explants chronically grown in a serum‐free medium containing the monosialoganglioside GM1 failed to develop dorsal cord selectivity as was previously observed when a mixture of gangliosides was used. It therefore appears that not all gangliosides can induce selectivity in this model.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90047-6

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractGanglioside profiles in spinal cord from 13‐day mouse fetuses, 21‐day postnatal and adult mice were compared with those harvested from organotypic cross‐sections of fetal mouse spinal cord grown for 28 daysin vitroin a serum‐free medium. All the major species of gangliosides reported for brain were present both in thein vivotissue and cultured spinal cord, though not necessarily at each developmental stage examined. Fresh tissues showed increases and decreases in various gangliosides as have been reported for higher brain centers at similar stages of development in mammals and birds. However, qualitative and quantitative differences exist between fresh spinal cord and cultured cord explants as well as between galactose‐grown and galactose‐free cultures. Spinal cord explants grown in the presence of galactose showed measurable amounts of GM2 and GM3 which were not detected in the control‐defined medium‐grown cultures. The differences between the two culture groups may be related to interneuronal connectivity patterns.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90048-8

出版商:Wiley    

年代:2003

数据来源: WILEY