摘要:

AbstractThe aim of this work was to study the topographic distribution and the morphological behaviour of nerve growth factor (NGF) primed spleen cells injected into the lateral ventricles of developing rat brain. Serial coronal brain sections showed that these transplanted cells acquire phenotypical characteristics similar to those of mast cells (MCs) and that they enhance local neovascularization. These results, together with the observation that these cells are located in proximity to the hippocampus, a brain tissue which contains one of the highest levels of NGF, provide a model for studying the relationship between NGF and MC differentiation and secretion.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90015-4

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe development of neuronal number, explant thickness and amount of protein was studied in several series of rat neocortex expiants, cultured up to 21 daysin vitro(DIV). In contrast to the dimensions of the explant, which rapidly stabilized, the amount of protein showed a prolonged increase with agein vitro. The number of neurons initially tended to decrease until a constant level was reached from 14 to 21 DIV. These findings are in good agreement with previously described cytoarchitectural characteristics. The present data also provided an opportunity to calculate the variance for various parameters within and between culture series obtained from different rats. Especially for the amount of protein, the variance between culture series appeared to be larger than within culture series. This difference was present already at the onset of culturing and persisted during developmentin vitro. Implications of these findings for experimental design are discussed.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90016-6

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractPregnant Long‐Evans rats were fed a liquid diet containing ethanol (30% of total calories) during days 3–19 of gestation. Controls were givenad libitumaccess to liquid diet lacking ethanol, or pair‐fed isocaloric amounts based on consumption by the animals in the ethanol group. Brain development of female offspring was evaluated by analysis of electron micrographs of caudate‐putamen and visual cortex. Numbers of presynaptic terminals and synaptic junctions (synaptic density) per unit area were compared for 14‐ and 28‐day‐old offspring of dams from the three treatment groups. Synaptic density of the caudate‐putamen and visual cortex was not affected by ethanol at 14 or 28 days. Although exposure to ethanol during a period comparable to the first two trimesters of human development with minimal or no undernutrition did not affect numerical density of synapses in visual cortex or caudateputamen, synaptogenesis of caudate‐putamen was altered in offspring of pair‐fed animals.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90017-8

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe interactions of nerve cells with their environment and other cells are specific to different stages of cellular differentiation. Neurite outgrowth was measured from cultured spinal cord neurons under the influence of different Ca2+concentrations. We used fluorodeoxyuridine (FuDr), an antimitotic agent which reduces significantly the proportion of non‐neuronal cells in spinal cord cell cultures, to examine the effects of non‐neuronal cells on neurite outgrowth. Spinal cord neurons responded to changes in their environment by means of two types of neurite outgrowth: sprouting and elongation. The concurrent presence of non‐neuronal cells led to increased sprouting of neurites in certain ionic environments, thus lending support to the idea that non‐neuronal cells release diffusible factors which influence sprouting and guide neurite outgrowth.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90018-X

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractIn order to study the influence of gender on the development of transmitter uptake by dopaminergic neurons, dissociated cell cultures were raised separately from male and female midbrains of gestational day 14 rats. It was ascertained by use of specific inhibitors and by autoradiography that the uptake of [3H]dopamine was restricted to neurons immunoreactive for tyrosine hydroxylase and that these neurons have dopaminergic properties. The uptake capacity was higher in male than in female dopaminergic neurons by a factor of 1.5. This sexual dimorphism in dopamine uptake was present in cultures of tissue removed before the perinatal rise of testosterone occurs in males and was present even in the absence of hormonal additives to the culture medium. It therefore appears to be independent of the presence of gonadal steroids. It occurred likewise in cultures raised with serum‐supplemented and serum‐free medium, which may indicate that glia are not decisive in generating these differences. In addition, sexual differences were found regarding hormone responsiveness. Whereas testosterone and dihydrotestosterone were ineffective, estradiol was seen to promote dopamine uptake in female but not in male neurons. The results would suggest that mesostriatal and/or mesolimbic dopaminergic systems assume an early role in the development of some sexual dimorphisms of the brain.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90019-1

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe effects of administration of capsaicin to developing and adult Sprague‐Dawley rats on substance P‐containing primary afferent and peripheral adrenergic nerves were analysed by histochemical and neurochemical techniques. In control rats a relatively dense innervation with substance Pimmunoreactive fibers was seen in the iris, while 10 weeks after a single neonatal injection of capsaicin (50 mg/kg s.c.) a moderate loss of substance P‐immunoreactive nerve fibers was observed. The substance P level was decreased by 60%, while the noradrenaline level,3H‐noradrenaline uptakein vitroand the noradrenaline nerve density were unaltered. Repeated injections of capsaicin (2 × 50 mg/kg, 3 × 20 mg/kgs.c.) for 5 weeks to developing rats led to a very marked decrease of the substance P level and an almost complete disappearance of substance P‐immunoreactive fibers in the iris, when analysed at 10 weeks of age. The noradrenaline level in the iris was significantly increased (+42%), while no significant changes in noradrenaline level were observed in heart auricula or superior cervical ganglion. The uptakein vitroof3H‐noradrenaline in irides and heart auriculae, as well as the noradrenaline terminal density in the dilator plate and surrounding blood vessels in the iris, were unaffected by repeated capsaicin treatment to developing rats. Capsaicin administration to adult rats (50 mg/kg s.c.), leading to a profound decrease in substance P, did not affect the noradrenaline levels at 24 hr after the injections. The results indicate that an extensive sensory denervation with capsaicin during development can induce an increase of noradrenaline levels in sympathetic nerve terminals in a target area (rat iris) with a rich SP‐ergic sensory innervation, although the sympathetic terminal density is not influenced. Furthermore the increase in noradrenaline seems to require an extensive loss of SP‐immunoreactive fibers and not solely a reduction of SP levels.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90020-8

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

Abstractα‐Melanocyte‐stimulating hormone (α‐MSH) accelerates the regrowth of peripheral nerve axons in the rat following their transection (Verhaagenet al., Expl Neurol.92, 451–454, 1986). The cellular mechanisms of this trophic response were investigated for several naturally occurring derivatives of α‐MSH using Nerve Growth Factor (NGF)‐stimulated quail sensory ganglion explantsin vitroin which both neurite outgrowth and non‐neuronal cell behaviour could be more reliably observed and quantified. Neurite outgrowth was determined with a semi‐quantitative scoring assay. Glial migration into the outgrowth was quantified using a monoclonal antibody, GTE‐52, which labels the nuclei of Schwann cells. Des‐acetyl α‐MSH caused a marginal increase in the neurite outgrowth density which was significant at concentrations of 0.04 and 0.1 μg/ml. The response to acetylated (N‐acetyl, N,O‐diacetyl) forms of α‐MSH was characterized by fascicle formation by neurites which resulted in an apparent decrease in the neurite score and by the outgrowth of non‐neuronal cells. Using monoclonal antibody GTE‐52, which recognizes a glial nuclear antigen, these cells were identified as Schwann cells. N‐Acetyl, but not des‐acetyl α‐MSH increased the number of GTE‐52‐labelled cells in the NGF‐stimulated neurite outgrowth and stimulated their migration in the absence of neurites when NGF was omitted from the culture medium. Exposure of growing explants to two polyclonal antibodies against α‐MSH resulted in an increased neurite outgrowth density. The results support the hypothesis that α‐MSH peptides stimulate peripheral nerve growth by modulating the neurite sprouting response and demonstrate that the nature of the neurotrophic response to naturally occurring melanotropins depends on the existence of acyl substitution at the N‐terminal amino acid residue. A possible role of endogenous melanotropin peptides in the regulation of sensory nerve growth is discussed.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90021-X

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractTadpoles at premetamorphic stages of development were used to compare the precocious responses of lumbar dorsal root ganglia (DRG) and hindlimb bud (tissues destined for growth) with the responses of tail DRG and tail muscle (tissues destined for resorption) following exogenous administration of triiodothyronine (T3) and thyroxine (T4). Responses to intraperitoneal (i.p.) hormone treatment were assessed at varying times by injection of [3H]leucine i.p. and determination of3H‐labeled protein in tissues after an additional 1.5 hr. Incorporation of [3H]leucine in lumbar DRG and hindlimb bud was markedly stimulated by either hormone. T3and T4effects were both maximal at 0.3 nmol/g body wt although, as examined in lumbar DRG, the response to T4was more rapid and of lesser magnitude than that to T3. By contrast, incorporation in tail DRG and tail muscle was significantly depressed in response to T3and was unaffected by T4. Co‐injection of T3and T4(either 1:1 or 1:6 as occurs during the peak surge of circulating thyroid hormones during metamorphic climax) did not produce an additive effect; the hindlimb bud response was reduced while the lumbar DRG, tail DRG and tail muscle responses to the individual hormones were virtually eliminated. The present data suggest that the responses of lumbar and tail sensory neurons to thyroid hormones parallel the responses of their peripheral target tissues.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90022-1

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractThe study reports the effects of daily subcutaneous injections of the biogenic polyamines putrescine, spermidine and spermine (10 mg/kg each) given for a short postnatal period, on growth and development of rats. Polyamine treatment, while only slightly enhancing normal body weight gain, prevented the weight loss caused by surgical injury of 5‐day‐old animals. The treatment resulted in earlier eyelid and ear opening and in earlier maturation of righting and gripping responses. Increased number of neurons in the superior cervical ganglion that is caused by polyamine treatment, could not be prevented by castration of newborn rats, thus excluding the testes as a site through which polyamines may exert their action. An apparent increase in immunohistochemically detectable nerve growth factor was evident in iris and submaxillary salivary gland of polyamine‐treated animals, but no change in epidermal growth factor immunohistochemistry was detected in the salivary gland. We conclude: (1) treatment of newborn rats with polyamines can accelerate somatic and neurobehavioral development; (2) further studies are required in order to verify and quantitate the effects of polyamines on growth factors, and (3) the results imply that exogenous polyamines may exert their growth‐promoting effects on a number of cell types when these cells experience periods of polyamine dependence.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90023-3

出版商:Wiley    

年代:2003

数据来源: WILEY

摘要:

AbstractGM1 gangliosides were added to the medium of cultured raphe neurons enriched in the serotonergic phenotype in order to study their influence on biochemical and morphological growth parameters of serotonergic neurons. After 2 days of culture in the presence of GM1, specific uptake of serotonin measured by scintillation counting exhibited a moderate but significant increase for a GM1 concentration of 5 × 10−8M. Morphological parameters of 5‐HT neurons were measured after immunocytochemical staining with specific serotonin antiserum and digitalization of immunoreactive cells. Eight parameters were studied; for concentrations of 5 × 10−8and 10−7M of GM1, the absolute neuritic field area and the total length of the segments were significantly increased, whereas the number of neuritic segments and their mean length were not modified. We conclude that GM1 ganglioside has a significant influence on the growth of serotonergic neurons. Moreover, electron microscopy showed, on treated cultures, a dramatic increase of the number of spicules all along the neuron's process, suggesting that GM1 could act by modifying the attachment of cells to their substrate. The possible molecular mechanisms of the action of GM1 are discussed.

ISSN:0736-5748    

DOI:10.1016/0736-5748(89)90024-5

出版商:Wiley    

年代:2003

数据来源: WILEY