摘要:

AbstractThe course of postnatal development of noradrenaline (NA) and its unconjugated free metabolite 3‐methoxy‐4‐hydroxyphenylglycol (MHPG), as well as the influence on early chronic vasopressin treatment, were investigated in various brain regions of the hereditary vasopressin‐deficient (homozygous di/di) Brattleboro rat. In addition, the densities of the adrenergic receptor subtypes were measured in adult brain.Brain NA levels of di/di pups appeared enhanced already at 7 days of age when compared with data of heterozygous (+/di) controls. This was also seen in areas not known to receive a vasopressinergic input, e.g. the frontal cortex. Levels of MHPG also differed between genotypes, but changes were slight and either a decrease or increase, depending on age and region tested. Saturation analyses of α1‐, α2‐, and β‐adrenoceptor binding on crude membrane preparations of some brain regions revealed no differences in adulthood.Chronic treatment with vasopressin between 6 and 13 days of age reduced the enhanced NA brain levels throughout the brain of the di/di Brattleboro pups. The known vasopressin‐mediated enhancement of NA turnover in adult brain was also measurable in +/di pups of this neonatal period (MHPG/NA ratios), indicating the early maturation of the interaction of vasopressinergic and NAergic systems. However, the dose‐response in the di/di Brattleboro rat was biphasic with a decrease at a low dose of vasopressin.Since changes were found throughout the brain, it was concluded that vasopressin deficiency had altered the maturation of NA neurons of the locus coeruleus which may be due to the absence of a presumed inhibitory control of vasopressin on synthesis and storage mechanisms at the perikaryal level.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00023-A

出版商:Wiley    

年代:1999

数据来源: WILEY

摘要:

AbstractUnderin situconditions, the innermost (juxtaventricular) neuroepithelial layer of the embryonic brain wall develops into ependyma. No development of ependyma was usually observed, however, in transplanted embryonic brain wall. In our telencephalic transplants, however, cysts lined by epithelium resembling ependyma were observed, although only sporadically. We supposed that occasional foldings of the transplanted telencephalic wall enclosed the aforementioned cysts and so induced the formation of ependyma. This hypothesis was supported by the observation that ependyma developed frequently in a model system in which the telencephalic wall was folded artificially prior to transplantation.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00009-6

出版商:Wiley    

年代:1999

数据来源: WILEY

摘要:

AbstractThe effect of age on the adrenergic and peptidergic innervation of the lower oesophageal, pyloric and ileocaecal sphincters of the rat was investigated using immunohistochemical techniques. The distribution of nerve fibres containing the neuronal protein, growth associated protein‐43, was also studied to determine the integrity of the enteric nervous system during development and aging. The four age groups examined were 2–3 days, 6 weeks, 3 months and 25 months old rats.Using protein gene product 9.5 antibody (a non‐specific general neuronal marker), it was revealed that the myenteric ganglia in all sphincter regions were compactly arranged and were smaller in size at neonatal stage getting more spaced out and larger in size with age. There was no obvious change in the structure of the neuronal elements with age. In the lower oesophageal sphincter, calcitonin gene‐related peptide‐ and substance P‐like immunoreactive nerve fibres showed notable changes in density and fluorescence intensity with age, decreasing and increasing, respectively, with no obvious change in vasoactive intestinal polypeptide‐ and growth‐associated protein‐like immunoreactivity. A slight increase in dopamine‐β‐hydroxylase‐like immunoreactivity was seen in old age. In the pyloric sphincter, there was an increase in calcitonin gene‐related peptide‐ and substance P‐like immunoreactivity with a less notable increase in dopamine‐β‐hydroxylase‐like immunoreactivity. A decrease in vasoactive intestinal polypeptide‐ and growth‐associated protein‐43‐like immunoreactivity in the circular muscle of the sphincter was seen in old age. In the ileocaecal sphincter there was a marked increase in growth associated protein‐43‐, vasoactive intestinal polypeptide‐, dopamine‐β‐hydroxylase and substance P‐like immunoreactivity. There was a decrease in the density of calcitonin gene‐related peptide‐like immuno‐reactive nerve fibres in old age.In summary, two main conclusions can be drawn from the results of the present study. First, there was an age‐related differential change in the density of immunoreactive nerve fibres containing various neuroactive substances. This indicates a level of plasticity of the various enteric nerve types and may reflect the degree of importance of the different neurotransmitters in the physiological activities of the specific sphincter. Second, in all three sphincters of aged rats, the density of nerve fibres containing the markers for theexcitatoryneurotransmitters noradrenaline and substance P (although the precise role of substance P in ileocaecal sphincter is not known) was increased, while the density of nerve fibres containing theinhibitoryneurotransmitters calcitonin gene‐related peptide in the lower oesophageal and possibly ileocaecal sphincter, and vasoactive intestinal polypeptide in the pylorus were decreased. This is likely to underlie the physiological activity of the sphincters and may be associated with malfunction in old age. Investigations to determine the functional implications of these changes would be of great interest.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00005-2

出版商:Wiley    

年代:1999

数据来源: WILEY

摘要:

AbstractThe neural cell‐adhesion molecule, NCAM, contains an unusual homopolymer of sialic acid units, polysialic acid. This carbohydrate seems to be involved in neurite outgrowth, bundling and branching, processes which are important during reinnervation. In aged rats, reinnervation of denervated muscle fibres is incomplete. In this study, age‐related changes in the degree of polysialylation of NCAM re‐expressed after denervation were examined using a monoclonal antibody recognizing polysialic acid and a polyclonal antibody recognizing NCAM. The results show that, after denervation, the degree of polysialylation on NCAM was clearly reduced in rat soleus muscle of aged, compared to young, adult rats. This age‐related change in expression of polysialic acid probably influences the reinnervation process in aged muscle.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00003-Y

出版商:Wiley    

年代:1999

数据来源: WILEY

摘要:

AbstractUnilateral injection of 6‐hydroxydopamine (6‐OHDA) into the caudate nucleus of rat caused degeneration of dopaminergic terminals, evidenced by significant (P⊂0.05) elevation of spontaneous and drug‐induced motor behaviour, enhanced DA receptor binding and significant increase in the neuronal firing rate of caudate neurons, suggesting supersensitivity of dopaminergic receptors. Eight weeks following the transplantation of embryonic cell suspensions from caudate at the lesioned site, a significant restoration of the enhanced3H spiperone binding and neuronal activity of caudate neurons was observed in comparison with lesioned rats.These results clearly demonstrate that transplanted embryonic neuronal tissue at the lesioned site is capable of restoring the neuronal deficits caused by 6‐OHDA as evidenced by significant amelioration in neurochemical, behavioral and electrophysiological alterations.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00002-X

出版商:Wiley    

年代:1999

数据来源: WILEY

摘要:

AbstractTau microtubule‐associated protein is a neuron specific protein found primarily in axons and is developmentally regulated. The function of tau is in stabilization of microtubules, which is important in establishing and maintaining neuronal morphology. Axonal localization of tau involves a multistep process which is studied in differentiating primary neuronal culture. The initial step involves sorting and subcellular localization of its encoding mRNA into the proximal portion of the axon. Using the transfection assay into neuronal cells, we have demonstrated that sequences located in the 3′‐untranslated region include acis‐acting signal which is involved in tau mRNA targeting. In addition, using ultraviolet cross‐linking assay, two RNA‐binding proteins of 43 and 38 kDa were identified, that exhibit specific binding to a minimal sequence of 91 nucleotides located within the same functional region, which is involved in targeting. The 43 and 38‐kDa RNA‐binding proteins are present in cytoplasmic extracts, prepared from neuronal cells, and in isolated microtubule preparations. Our results support a novel model in whichcis‐acting signals, together with RNA‐binding proteins, are involved in the targeting of tau mRNA, that may ultimately lead to its axonal localization.

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)00001-W

出版商:Wiley    

年代:1999

数据来源: WILEY

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)90012-8

出版商:Wiley    

年代:2004

数据来源: WILEY

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)90013-6

出版商:Wiley    

年代:2004

数据来源: WILEY

ISSN:0736-5748    

DOI:10.1016/0736-5748(95)90014-4

出版商:Wiley    

年代:2004

数据来源: WILEY