摘要:

AbstractIntracellular Cl‐activity (aCli) and 5‐hydroxytryptamine (5‐HT)‐induced membrane currents of Retzius neurons in the central nervous system of the medicinal leech were measured using Cl‐sensitive microelectrodes and a two‐microelectrode voltage‐clamp technique. At the membrane of Retzius neurons Cl‐ions were not passively distributed. Under different conditions the chloride equilibrium potential (ECl, ‐60.1 mV for isotonic saline and ‐57.8 mV for a hypertonic saline) was negative with respect to the membrane potential (Em‐55 ± 3.8 and ‐47 ± 3.4 mV respectively). The endogenous neurohormone 5‐HT always polarized the membrane of Retzius neurons in the direction of ECl. When voltage‐clamping the membrane of Retzius neurons near the resting potential bothin situand in primary culture, application of 5‐HT produced an outward current (l5‐HT) and increase in membrane conductance. Current ‐ voltage relationships forl5‐HTshowed a slight outward rectification and reversal potentials of ‐61.6± 3.1 mVin situand ‐66± 3.1 mV in primary culture, both values being comparable to the Eclof Retzius neurons as measuredin situ. The results indicate that 5‐HT increases the Cl‐conductance of Retzius neurons, thereby hyperpolarizing the cell membrane and affecting both the excitability of the neuron and 5‐HT release from it. This could affec

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1993.tb00225.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe functional organization of long‐horizontal inhibitory connections was studied in cat visual cortical area 17, using a combination of electrophysiological recording and anatomical tracing in the same tissue. Orientation maps were obtained by recording multiunit activity from layer III at regular intervals (100–300μm) in a region of ‐1.3 mm2of cortex at a depth corresponding to the location of the basket cell axons reconstructed later. Before the physiological mapping, the neuronal tracer biocytin had been iontophoretically injected at one functionally characterized site. On the basis of light microscopic features a total of five biocytin‐labelled large basket axons, BC1 ‐ BC5, were reconstructed from series of horizontal sections of two cats. The parent somata and dendritic fields of three axons (BC1, BC4 and BC5) could also be reconstructed. The axonal field of basket cell BC1 had an overall lateral spread of 1.8 mm. The axons of basket cells BC4 and BC5 spanned a distance of 3.05 and 2.85 mm, respectively. The distribution pattern of histologically reconstructed recording sites and of five labelled basket cell axons were directly compared in the same sections. The results show that a single large basket cell provides input to regions representing the whole range of orientations, i.e. iso‐orientation (±30°), oblique orientation (±[30–60]°) and cross‐orientation (±[60–90]°) to that at the basket cell's soma. Furthermore, the differential effect mediated by the same large basket cell at sites of different orientation preference was numerically estimated for two basket cells (BC4 and BC5) whose preferred orientations could be determined on the basis of recording sites adjacent to their parent somata. We counted the number of axonal terminals of these basket cells at iso‐, oblique‐ and cross‐orientation sites and found no significant difference in the average density of terminals at sites of either orientation preference. The functional topography of large basket cell axons indicates that the same basket cell can mediate iso‐, oblique‐ and cross‐orientation inhibition at different sites. Hence, we assume that large basket cells serve a complex physiological role depending on the location of

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1993.tb00226.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe distribution of secretoneurin‐like immunoreactivity, a peptide derived from secretogranin II, was studied by means of immunocytochemistry and compared to the pattern of staining for substance P‐ and enkephalin‐like immunoreactivities in the human basal forebrain, with special reference to the basal ganglia. Secretoneurin‐like immunoreactivity was characterized by gel filtration and reversed‐phase high pressure liquid chromatography analysis. Chromatographic analysis revealed a single peak for secretoneurin‐like immunoreactivity. No secretoneurin‐immunopositive forms of high molecular weight were found. Secretoneurin‐like immunoreactivity appeared mainly in dot‐ and fibre‐like structures. In addition, a band‐like terminal staining (woolly fibres) that has been shown by others for substance P‐ and enkephalin‐like immunoreactivities, was also observed for secretoneurin‐like immunoreactivity. Medium‐sized cells were found arranged in clusters or singly within the caudate and putamen. In the basal ganglia, a high density of secretoneurin‐like immunoreactivity was found in the internal segment of the globus pallidus, the ventral pallidum and in the pars reticulata of the substantia nigra. In these areas the immunostaining appeared mainly as woolly fibres. The bed nucleus of the stria terminalis and medial amygdala displayed a high density of fine beaded secretoneurin‐like immunoreactive fibres, sometimes forming pericellular contacts. The nucleus basalis of Meynert was highly innervated by secretoneurin‐like immunoreactive fibres, mainly in the form of woolly fibres. In general, a large overlap was found between secretoneurin‐ and substance P‐like immunoreactivity in all examined areas of the basal ganglia. In the bed nucleus of the stria terminalis and medial amygdala secretoneurin‐like immunoreactivity was distributed very similarly to enkephalin‐like immunoreactivity. These data provide evidence that in different subsets of neurons and neuronal pathways secretoneurin‐like immunoreactivity coexists with substance P‐ and enkephalin‐like imm

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1993.tb00227.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractIn order to further understand the role(s) of fibroblast growth factors (FGFs) in the development, differentiation and function of the central nervous system, we analysed the expression of the mRNA, and the presence and tissue distribution of the translated product, of one member of the FGF family, acidic FGF (aFGF), within the mammalian retina. Firstly, the relative abundance of aFGF mRNA was assayed in embryonic (between 14 and 17 days of gestation), postnatal (between 1 and 17 days after birth) and adult rat retina by quantitative reverse transcription‐coupled polymerase chain reaction amplification using specific aFGF oligonucleotides. The level of expression remained uniformly low throughout the embryonic period and until postnatal day 7. Therefore the quantity of aFGF mRNA increased rapidly, reaching 80% of adult levels by eye opening (postnatal day 13). Adult levels were three‐fold higher than at early developmental times.In situhybridization of adult rat retina using specific antisense aFGF riboprobes revealed labelling in all cellular layers. Antisera raised against recombinant human aFGF revealed very little labelling of 4‐day postnatal retina, but by postnatal days 8 and 17 immunoreactive aFGF was localized mainly within the photoreceptor cell bodies. Western blots of retinal extracts derived from 17‐day embryonic, 4‐day postnatal and adult retina probed with the same antibody revealed a single immunoreactive band of the expected molecular weight (18 kDa) in all extracts. Thus aFGF is mostly transcribed and translated within the retina subsequent to the major steps of cell birth, migration and differentiation, and seems to be abundantly expressed by maturing photorecep

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1993.tb00228.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractWe have used the species‐specific monoclonal antibodies OM1 and OM4 to identify the histiotypic pattern of projection from late embryonic rat entorhinal explants to the outer molecular layer of the dentate gyrus in organotypic cultures of 6‐day postnatal mouse hippocampal slices. The presence of this entorhinal projection was detectable with the rat‐specific OM1 and OM4 markers after 3–7 days in co‐culture, and confirmed by use of the later‐forming rat neuron‐specific marker Thy‐1.1, which appeared during the second week. Hippocampal slices confronted with control explants of superior colliculus for 4 weeks in culture showed only sparse, non‐specific growth of axons with no histiotypic pattern in the dentate gyrus. In order to assess whether the formation of specific entorhino‐dentate projectionsin vitrois age‐dependent, embryonic rat entorhinal cortical explants were cultured alone for periods of 1 ‐ 5 weeks before cutting across the halo of axons radiating into the collagen matrix and presenting each with 6‐day‐old mouse hippocampal slices as targets to innervate. After allowing a 2 week period for fibre growth to take place, the density of immunostained axonal outgrowth was scored on a five‐point scale for each weekly interval. The amount of new axon growth when the cuts were made after 1 week was slightly reduced compared to undamaged control cultures. However, outgrowth was greatly diminished when the cuts were made after 2 or 3 weeks, and essentially abolished if the interval was extended to ≥4 weeks. Thus we demonstrate that, although hippocampal slices can survive in organotypic co‐culture with entorhinal explants and maintain previously formed connections, the explants show an age‐related failure in the ability to form new connections. Such a system provides a possiblein vitromodel for study of the factors influencing the failure of regeneration

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1993.tb00229.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractRecent evidence suggests that protein kinase C (PKC) is involved in the pathophysiology of neurodegenerative diseases. We examined the effect of basic fibroblast growth factor (bFGF) on the survival of cultured rat hippocampal neurons exposed to conditions in which PKC is likely to play a role. bFGF reduced neuron damage caused by the PKC‐activating phorbol ester 12‐O‐tetradecanoylphorbol 13‐acetate (TPA), glutamate and ischaemia‐like culture conditions. bFGF was able to counteract the excessive activation of PKC caused by these treatments. Moreover, bFGF prevented the loss of PKC occurring after prolonged exposure to TPA or ischaemia‐like conditions. These results indicate that both the overactivation and the abnormal degradation of PKC can lead to neuron degeneration, and that the neurotrophic competence of bFGF may reside in its ability to regulate and normalize the PKC phosphoryla

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1993.tb00230.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractUsing monoiodinated radioligands of peptide YY (PYY), and the recently introduced neuropeptide Y (NPY) analogue [Leu31,Pro34]NPY, receptor binding sites of the Y1and Y2type were localized in the rat brain by quantitativein vitroautoradiography. The binding specificity and affinity of both radiolabeled ligands were analysed by ligand binding studies employing rat brain membrane homogenates from cerebral cortex and hippocampus. Usingin situhybridization histochemistry, the regional distribution and cellular localization of mRNA encoding the Y1receptor were investigated in rat brain sections and compared to the distribution of Y1‐specific binding sites. PYY binds to both Y1and Y2receptors, while long C‐terminal fragments such as NPY13–36and NPY16–36bind preferentially to Y2receptors. [Leu31, Pro34]NPY is a specific agonist for Y1receptors. Highest densities of [125I]PYY binding sites were found in the cerebral cortex, the thalamus, the lateral septum, the hippocampus and the mesencephalic dopaminergic areas. In order to block putative Y2receptors, a series of [125I]PYY binding experiments was performed in the presence of NPY13–36(1 μM), a Y2preferring C‐terminal fragment. High densities of binding sites remained present in the cerebral cortex, the thalamus and the medial mammillary nucleus when NPY13–36was present in the incubation medium. Furthermore, these areas were highly enriched with [125l][Leu31, Pro34]NPY binding sites. In contrast, the hippocampal complex had its binding capacity reduced by ‐50%, while the lateral septum and mesencephalic dopaminergic areas had their binding capacities reduced even further. Linear regression analysis showed a high degree of correspondence between [125l][Leu31, Pro34]NPY binding and that obtained with [125I]PYY in the presence of 1 μM NPY13–36, suggesting that the two independent approaches to visualizing Y1binding sites are comparable.In situhybridization histochemistry revealed high levels of Y1mRNA in the granular cell layer of the hippocampal dentate gyrus, several thalamic nuclei and the hypothalamic arcuate nucleus. Moderate levels of Y1mRNA were seen in the frontoparietal cortex, several thalamic nuclei, the hippocampal pyramidal layers, the subiculum, the olfactory tubercle, the claustrum and a number of hypothalamic nuclei. The mesencephalon, the amygdala and most basal ganglia showed very low levels of hybridization. The present study further clarifies the anatomical distribution of multiple NPY binding sites within the central nervous system of the rat, and extends earlier suggestions that Y1and Y2receptor types are present within the cen

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1993.tb00231.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractIn the murine somatosensory pathway, the metabolic whisker map in barrel cortex derived with the autoradiographic deoxyglucose method is spatially in register with the morphological whisker map represented by the barrels. The barrel cortex of adult mice, in which we had removed three whisker follicles from the middle row of whiskers shortly after birth, contained a disorganized zone surrounded by enlarged barrels with partially disrupted borders. With the fully quantitative autoradiographic deoxyglucose method, we investigated in barrel cortex of such mice the magnitude and the pattern of metabolic responses evoked by the deflection of whiskers. Most remarkably, the simultaneous deflection of six whiskers neighbouring the lesion activated not only the territory of the corresponding barrels, but also the unspecifiable area intercalated between the clearly identified barrels. This metabolic whisker map, unpredictable from the morphological ‘barrel’ map, may reflect a functional compensation for the deficit in in

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1993.tb00232.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractExpression in the rat forebrain of immediate early genes belonging to the fos andjunfamilies was investigated at various time points following an intrastriatal infusion of quinolinic acid. Fos immunoreactivity was rapidly and transiently induced, exhibiting maximal intensity 2 h post‐lesion, and was principally located in neuronal nuclei situated around the periphery of the lesioned striatum, in regions that subsequently show little, if any, neurodegeneration. Fos immunoreactivity was additionally expressed throughout the ipsilateral cortex. In contrast, Jun immunoreactivity, which remained undetectable for 12 h after the lesion, reached its maximal intensity 24 h post‐lesion, at which time it was most densely distributed in neuronal nuclei found within the central lesioned areas of the striatum.In situhybridization analysis using radiolabeled oligonucleotide probes confirmed this spatial and temporal separation betweenc‐fosandc‐junexpression within the striatum and extended it further, showing that, whilstjunmRNA displayed very similar expression characteristics to those of c‐fos mRNA, both fosBmRNA andjun DmRNA exhibited induction patterns closely resembling those ofc‐junmRNA. These results clearly suggest that two distinct programmes of immediate early gene expression can be inducedin vivo.The rapid (2 h) and transient induction ofc‐fos/jun Bmay well be a response to NMDA receptor activation, whereas the molecular signal for the late (24 h) and sustained induction ofc‐jun/ fos B/jun Dis currently a focus for our

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1993.tb00233.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractTwo new oligonucleotide anti‐sense probes and their corresponding sense probes specific for mouse GAP‐43 mRNA were synthesized and end‐labelled with digoxygenin. They were used to localize GAP‐43 mRNA in the spinal cords of normal mice and in mice 3 and 7 days following unilateral sciatic nerve cut. GAP‐43 mRNA was found to be expressed at low levels in motor and other neurons of the normal spinal cords. As expected from other studies, up‐regulation occurred in the cell bodies of axotomized motor neurons but, in addition, up‐regulation was also observed in the cell bodies of intact motor neurons contralateral to the lesion. Densitometer measurements showed that the up‐regulation of GAP‐43 mRNA was less in the intact, contralateral motor neuron cell bodies than in the axotomized motor neuron cell bodies and furthermore was transient, being higher at 3 days than at 7 days following axotomy. Both anti‐sense probes gave the same result, although differences in cellular localization were observed, and the two sense probes were negative. Probe binding was abolished by pretreatment of the sections with ribonuclease and hybridization was carried out under different conditions of stringency in order to ascertain whether the contralateral expression of GAP‐43 mRNA was a true reflection of its distributionin vivo.There is conflicting evidence on the presence or absence of contralateral effects following unilateral peripheral nerve injury in the literature, and it is suggested that these differences can be accounted for by the methodology a

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1993.tb00234.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY