摘要:

AbstractCultures of astroglia from C3H/HeJ mice, which are resistant to bacterial cell wall polysaccharide (LPS), initiated from embryos of Theiler stage 14 (9 days of gestation) up to Theiler stage 25 (17 days of gestation) as well as newborn animals, when subjected to nutritional deprivation, i.e. non‐feeding of cultures, form large numbers of macrophage‐like cells. These cells express Mac‐1, Mac‐3, F4/80 and Fc antigens. The cells are negative for GFAP, positive for vimentin, express Ia antigen and take up DiL‐Ac‐LDL. They are positive to non‐specific esterase, secrete lysozyme and are phagocytic. Their morphology and ultrastructure closely resemble those of macrophages. Cultures initiated from neuroepithelium of Theiler stage 13 (8.5 days of gestation), before vascularization, when subjected to nutritional deprivation, also produce macrophage‐like cells. Using spleen colony assay and methyl cellulose cultures, we were unable to detect the presence of hemopoietic (macrophage) precursor cells in astroglia cultures. This supports the hypothesis that the macrophage‐like cells are of neuroectodermal origin and probably correspond to resident microglia of the CNS. Using nutritionally deprived astroglia cultures, a procedure was developed for isolation of macrophage‐like cells and production of highly enriched macrophage‐like (microglia) cultures.

ISSN:0736-5748    

DOI:10.1016/0736-5748(91)90067-V

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractUsing the percutaneous electrical stimulation of the brain and spinal cord, we have determined central motor pathway conduction velocities in a group of 19 healthy fullterm newborns (average post‐conceptional age 39.8 weeks) and in 19 infants between 2 months and 8 years of age. The newborns were examined during the first postnatal week. The percutaneous stimulation of the motor cortex and of the cervical and lumbar enlargements of the spinal cord was made by means of bipolar electrodes. The evoked compound muscle action potentials were recorded by bipolar surface electrodes fixed on the skin overlying the thenar eminence muscles and the tibialis anterior muscle.In fullterm newborns, the responses of lower limb muscles to cortical stimulation were more difficult to obtain than those of upper limb muscles. Conduction velocities of central motor fibres along the spinal cord (between vertebrae C7and L4) were around 10 m/sec in fullterm newborns and 38 m/sec at the age of 4 years. These values are considerably lower than those described for adult man (48–60 m/sec). The adult values are established around the age of 8 years.

ISSN:0736-5748    

DOI:10.1016/0736-5748(91)90068-W

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractIn order to study the absolute refractory period of a given group of nerve fibres during development we measured absolute refractory periods and conduction velocities of motor fibres and the most excitable fibres in the human ulnar nerve of newborns, children and adults. In each group of nerve fibres absolute refractory period was not correlated to conduction velocity (i.e. fibre diameters) and was rather constant during development. However, absolute refractory period of the most excitable fibres was smaller than absolute refractory period of motor fibres independently of the subject's age. Thus, it appears that already at birth, absolute refractory period is characteristic for a given group of nerve fibres.

ISSN:0736-5748    

DOI:10.1016/0736-5748(91)90069-X

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe male rat's corpus callosum is significantly larger than the female's. This dimorphism depends in part on the early presence of testosterone, since postnatal administration of testosterone to female pups enlarges their callosa in adulthood to the size of males. However, castrating males on day 1 is ineffective in reducing (demasculinizing) the size of their callosa as adults. We then addressed the question as to whether testosterone acts prior to day 1 to enlarge the callosa of males. To investigate this hypothesis pregnant rats were administered a non‐steroidal androgen blocker, flutamide, during the last 5 days of pregnancy, while controls received vehicle only. Male pups from flutamide litters were castrated on day 3 to prevent postnatal recovery following clearance of flutamide, while others received sham surgery. Callosal sex differences were found between males and females of control litters, but not between males and females from flutamide litters. The absence of sex effects among flutamide litters was a consequence of small callosal size in flutamide‐castrated males as compared to control males. We concluded that the prenatal production of testosterone in the male rat pup contributes to sexual dimorphism in the callosa of adult rats.

ISSN:0736-5748    

DOI:10.1016/0736-5748(91)90070-3

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractIt has been shown that the endogenous compound, acetyl‐L‐carnitine (ALCAR), acts in the brain as a metabolic cofactor in the synthesis of acetylcholine. In these studies, ALCAR was injected into the brain of developing rats every other day for the first three weeks after birth in order to assess its effect on forebrain cholinergic neurons. The results showed that intracerebroventricular (icv) administration of ALCAR causes an increase of choline acetyltransferase (ChAT) activity and of nerve growth factor receptor expression in the striatum. Biological assays of brain tissues revealed that the level of nerve growth factor (NGF) in the hippocampus also increases. The ability of brain cholinergic tissues to respond to exogenous administration of ALCAR is discussed.

ISSN:0736-5748    

DOI:10.1016/0736-5748(91)90071-S

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractSubstance P (SP) and the mRNA coding for its precursor peptide, preprotachykinin (PPT), were measured in medullary raphe nuclei (MRN) and neostriatum (NS) over development in order to determine (1) whether PPT mRNA levels correlate with peptide development, and (2) whether changes in PPT mRNA might help to account for the apparent decline in SP seen immunohistochemically in certain brain areas postnatally. Total RNA was quantified in dissected tissue pieces using the sensitive orcinol reaction. When MRN PPT mRNA levels measured by Northern blot analysis were adjusted to total RNA levels, PPT mRNA per MRN increased over development with a profile similar to that seen for SP peptide. Moreover, both peptide and mRNA levels exhibited a similar decline after postnatal day 15. Therefore, developmental regulation of SP biosynthesis in the MRN may, in part, explain previous evidence documenting a postnatal decline in SP there.In the NS, SP peptide and PPT mRNA increased with a similar profile from E18 through the first post‐natal week. Thereafter, SP increased less rapidly than its mRNA, indicating incongruities in prohormone message and processed peptide in the NS.

ISSN:0736-5748    

DOI:10.1016/0736-5748(91)90072-T

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractIn situhybridization was used to study expression of β‐nerve growth factor receptor (NGF‐R) mRNA in the early human fetus. In 8‐ to 12‐week old fetuses, high labelling was found over motoneurons along the entire length of the lateral motor column. High levels of NGF‐R mRNA were also seen over most developing nerve cell bodies in both the dorsomedial and ventrolateral part of the dorsal root ganglia. Lower, but clearly specific labelling was detected over a subpopulation of cells in Auerbach's plexus in the intestines. Evidence for a non‐neuronal expression of NGF‐R mRNA came from labelling over a subpopulation of cells in glomeruli of the kidney in a 12‐week old human embryo. Myoblasts in skeletal muscle anlagen were labelled as well as cells along peripheral nerve. The wide‐spread expression of NGF‐R mRNA in the human fetus suggests that the NGF‐R is important for development of a variety of different tissues of both neuronal and non‐neuronal origin.

ISSN:0736-5748    

DOI:10.1016/0736-5748(91)90073-U

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThis study has examined the development of immunoreactive myelin basic protein and transferrin in primary glial cell cultures. Cultures were initiated from control and experimental Sprague‐Dawley rats 1–2 days postnatally. Experimental treatment involved exposure to 5% (w/v) ethanol in a liquid diet during the last two weeks of gestation. Prenatal alcohol administration delayed the expression of myelin basic protein and transferrin during the first three weeks postnatally. Other oligodendroglial and astroglial markers were little affected, if at all, by fetal alcohol exposure.

ISSN:0736-5748    

DOI:10.1016/0736-5748(91)90074-V

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe role of taurine and β‐alanine was analyzed in kitten cerebellar cultures. Since in contrast to mouse, cats (and primates including man) cannot synthesize sufficient taurine to maintain their body pools, we considered the cat an ideal species for the analysis of the role of taurine during early postnatal cerebellar development under controlled conditions. Unexpectedly, we found that the presence of taurine was toxic to neurons but that compounds, considered to be competitors for the β‐amino acid uptake system,supportcell survival and cell functionin vitro, the opposite of the results found in mice. This could be explained by the finding that only minute amounts of [3H]taurine were taken up by both cat neurons and glial cells under optimal culture conditions but that in the presence of the taurine analogues β‐alanine and guanidinoethane sulfonic acid (GES) significant amounts of taurine were found in all cell types. These differences between mouse cerebellar cells and cat cerebellar cellsin vitrosuggest that a reevaluation of the mechanisms that control taurine function in cats and primates is warranted.

ISSN:0736-5748    

DOI:10.1016/0736-5748(91)90075-W

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractStudies on tubulin gene expression in brains from three different species, viz rat, mouse and chick, varying with respect to their periods of synaptogenesis, show that the rise and fall in the level of tubulin during synaptogenesis is closely parallel to that of tubulin mRNA. In all three species, the onset of synaptogenesis is accompanied by a dramatic rise in the level of tubulin which continues till the midphase and then declines to adult level by the end of synaptogenesis. The chick α‐ and β‐tubulin coding region probes, pT1 and pT2, which have a 80–90% homology with rat/mouse sequences, were employed to determine the overall levels of α‐ and β‐tubulin mRNA in all samples. Quantitation of tubulin mRNA by dot hybridization revealed a closely parallel change in the levels of both α‐ and β‐tubulin mRNA. In analogy with that of tubulin, the mRNA levels in rat and mouse brain increased progressively from birth till postnatal day 5 and that in the chick brain increased from day 7 till day 11 of embryonic development. In all three cases, the peak levels of tubulin mRNA corresponded closely with the midphase of synaptogenesis and declined almost to adult levels by the end of synaptogenesis. The sudden decline in the level of tubulin as well as its mRNA during the middle of synaptogenesis suggests that the repression of tubulin gene expression is neither due to cessation of cell division nor cell differentiation. Instead, it is likely to be due to the autoregulatory property of tubulin which leads to rapid turnover of its own mRNA when a sufficient level of intracellular tubulin accumulates during the midphase of synaptogenesis.

ISSN:0736-5748    

DOI:10.1016/0736-5748(91)90076-X

出版商:Wiley    

年代:2003

数据来源: WILEY