摘要:

AbstractThis study deals with the three‐dimensional arrangement of populations of pontocerebellar cell bodies projecting to the parafloccular complex. The fluorescent tracers rhodamine B isothiocyanate, fluoro‐gold and fast blue were injected in either adjacent or separated cerebellar folia. A set of coordinates (x, y, z) was assigned to each retrogradely labelled cell and the total distribution reconstructed and displayed on a graphics workstation. At a large scale, we found that the majority of the cells of each labelled population (all projecting to the same folium) were confined to a lamella‐shaped tissue volume. Each lamella extended from medial to lateral, and accordingly followed the curving of the pontine grey around the corticospinal and corticobulbar fibre tracts. At a smaller scale, i.e. within each lamellar subspace, the neurons belonging to one labelled population were distributed in aggregates of various shapes. To enable further analysis of the shapes of the intralaminar aggregates, we developed a computer program for unfolding of the lamellae, based on cubic B‐spline approximation. The flattened reconstructions were three‐dimensional polygonal windows, circumscribing the large majority of the labelled cell swarm (usually 70–80% of the total number of labelled cells in one population). The present findings, taken together with previous data on a gradual, rather than disjunctive, shift of pontocerebellar neuronal position in relation to a gradual shift of target region (Bjaalieet al., Anat Rec,231, 510–523, 1991), suggest that the cerebropontocerebellar system may be organized according to a set of fairly simple topo

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1994.tb00259.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractAn attempt was made to study the release of acetylcholine (ACh) and noradrenaline and their presynaptic modulation in isolated slice preparations dissected from different subfields of the hippocampus: CA1, CA3 and the dentate gyrus. The slices were perfused and loaded with [3H]choline or with [3H]noradrenaline. The release in response to field stimulation was determined radiochemically and the content of transmitters was assayed by a chemiluminescent method or by HPLC combined with electrochemical detection. After 30 min of loading with [3H]choline there were marked subregional differences in the specific activity of [3H]ACh content. The highest concentration was measured in the dentate gyrus and the lowest in CA3. Evidence was obtained that in all three subfields the cholinergic axon terminals are equipped with inhibitory muscarinic autoreceptors and the noradrenergic terminals with α2‐autoreceptors, as indicated by an increase in transmitter release when the tissue was exposed to selective muscarinic or α2‐adrenoceptor antagonists. In contrast, the cholinergic boutons are not equipped with α2‐adrenoceptors, and noradrenergic terminals do not possess inhibitory muscarinic receptors. It is therefore concluded that while the release of both ACh and noradrenaline is controlled by negative feedback modulation, there is no possibility of establishing a presynaptic inhibitory interaction between

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1994.tb00260.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe aim of this study was to investigate the development of visual callosal transfer in the normally reared cat. Two‐ to nine‐week‐old kittens and adults (used as controls) underwent section of the optic chiasm. Three days later, the animals were placed under anaesthesia and paralysed; unit activities were recorded from visual cortical areas 17 and 18 and from the white matter in one hemisphere. The units were tested for their responses to visual stimulation of each eye successively. Out of 1036 recorded neurons, 185 could be activated through the eye contralateral to the explored cortex via callosal transfer. Most of them could also be driven through the ipsilateral eye via the ‘direct’ geniculo‐cortical pathway. For animals aged ≤2 weeks, virtually all of these units were located at the 17/18 border zone, with a majority in the supragranular layers. When activated through the corpus callosum, they displayed receptive fields located either on the central vertical meridian of the visual field or in the hemifield ipsilateral to the explored cortex. Such extension into the ipsilateral hemifield as well as receptive field disparities of binocular units decreased with age, while spontaneous activity, strength of response, orientation selectivity and ability to respond to slits moving at middle‐range velocity increased. The main conclusion is that the transient callosal projections described by anatomists, which are present until 3 months of age, do not achieve supraliminar synaptic contacts with parts of areas 17 and 18 other than the 17/18 border zone, at least from 12 days after birth. However the visual callosal transfer in young animals displays some characteristics which dis

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1994.tb00261.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe aim of the present investigation was to assess a bimanual goal‐oriented movement sequence with particular emphasis on its temporal structure. The three monkeys (Macaca fascicularis) used in this study chose the left arm as the leading and more postural arm to reach out and pull back a spring‐loaded drawer containing a food morsel. The right arm followed the left and picked up the food with a precision grip. Video recordings, trajectory recordings of the two index fingers, drawer displacement and the measurements of discrete events of the left and right hand revealed a considerable trial‐by‐trial variability in the temporal and spatial domain. The variability of latencies progressively increased from the initiation of the bimanual sequence to the left‐hand and right‐hand events defining goal achievement. The main result was that, in spite of this variability in each of the two limbs, there was an invariant left‐right goal‐related synchronization. The timing of the goal‐related event pairs covaried and showed high correlation coefficients. Covariation of the two hands resulting in an invariant synchronization was particularly striking when monkeys performed the task without vision, and timing of right and left movement components was delayed with further increase in variability. The results indicate that, in the present bimanual skill, kinaesthetic signals may be sufficient to coordinate the two limbs in a goal‐oriented unitary action in accord wi

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1994.tb00262.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe synthesis of the intracellular messenger, cyclic GMP, is catalysed by particulate or soluble guanylyl cyclase (sGCY). sGCY is activated by nitric oxide, a compound with putative neurotransmitter functions, especially in long‐term potentiation. Hybridization histochemistry with a probe complementary to the rat lung large (α1) subunit was used to assess the exact localization of sGCY mRNA in the rat brain. Many cells in the olfactory bulb contained sGCY mRNA. In the whole cerebral cortex, sGCY mRNA was found in all layers, with a predominance in layers II ‐ III. A similar pattern was found in the olfactory tuberculum, in continuation with the piriform cortex and the cortical amygdaloid nucleus. All parts of the striatum expressed sGCY mRNA. sGCY mRNA was also found in the habenula medialis, in the pinealis in some diencephalic nuclei, and in the granule cell layers of the cerebellum. This study provides a description of the normal anatomy of sGCY gene expression in the rat forebrain as a basis for the study of the modulation of expression after physiological and pharmacological manipulat

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1994.tb00263.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractCiliary neurotrophic factor (CNTF) is a pleiotrophic cytokine which is detectable only at very low levels in the intact adult rat CNS, but following an aspirative lesion to the dorsal hippocampus and overlying cortex, CNTF mRNA levels are dramatically up‐regulated in reactive astrocytes. In cultured rat hippocampal astrocytes, CNTF mRNA levels are high, similar to the levels in reactive astrocytesin vivo, but are strongly suppressed after administration of isoproterenol and forskolin, which stimulate the production of intracellular cyclic AMP, induce marked morphological change in the astrocytes and up‐regulate glial fibrillary acidic protein mRNA and nerve growth factor mRNA in these cells. Following a single administration of forskolin to cultured astrocytes, suppression of CNTF mRNA was sustained for up to 7 days. A similar down‐regulation was observed with the endogenous adrenergic agonists noradrenaline and adrenaline as well as, to a lesser extent, dopamine and adenosine. Down‐regulation of CNTF mRNA resulted in a gradual reduction in the level of CNTF protein within the astrocytes. A single addition of forskolin or isoproterenol resulted in a drop in CNTF protein levels to 29 and 52% of control levels respectively after 9 daysin vitro, although the rate of turnover of CNTF remained the same. Down‐regulation of CNTF mRNA in cultured hippocampal astrocytes by adenylyl cyclase activation was quite specific, as a wide range of growth factors, cytokines and neurotransmitters had little or no effect upon CNTF mR

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1994.tb00264.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn the search for substances with a potential role in plastic responses of spinal motoneurons we have studied the distribution of trkC‐like immunoreactivity in the spinal cord of adult monkeys(Macaca fascicularis).The presence of trkC, which is a signal‐transducing receptor for neurotrophin‐3, was detected by the use of indirect immunofluorescence with a rabbit polyclonal antibody raised against a synthetic peptide corresponding to the carboxy‐terminal domain of the mouse trkC‐encoded protein, thus detecting only full‐length signal‐transducing receptors.trkC‐immunoreactive fibres/varicosities could be found at all spinal cord levels and the densest innervation was found in the autonomic intermediolateral and Onuf's nuclei, but somatic motoneuron pools also received a significant contribution of trkC‐immunoreactive fibres. Terminals immunoreactive for trkC were also seen in the dorsal horn. Double‐labelling experiments revealed a high degree of coexistence between trkC‐ and 5‐hydroxytryptamine (serotonin)‐like immunoreactivity in all areas except in the dorsal horn. The results of the present study suggest that neurotrophic signalling with an influence on serotoninergic as well as non‐serotoninergic inputs to the adult mo

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1994.tb00265.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe effects of postnatal development, aging and the oestrous cycle on muscarinic acetylcholine receptor (mAChR) properties were examined inin vitroliving slices of rat neocortex. Using the hydrophilic antagonist ([3H]NMS) to label cell surface mAChRs, an increase in bothBmaxandKdwas found during the first postnatal weeks. These values peaked at between 20–40 days postnatally and then declined to adult levels. After 3 months of age, a steady decline in receptor number started: it was 10.1% lower at 10 months and 38.7% lower at 17 months of age. In contrast,Kdvalues increased, being 31.7 and 20% higher respectively at these ages. Carbachol‐induced (4 h at 37°C) down‐regulation of receptor number was ‐22.2% in newborn and 26.1% in adult (3‐month‐old) rats, but only 16.3% at 20–40 days of age. The degree of carbachol‐induced down‐regulation of mAChR was not affected in the older animals. Veratridine, which increases neural activity, also induced a significant reduction in [3H]NMS binding sites of 11.4% in rats aged 0–20 days and 22.4% in 3‐month‐old rats, but at 20–40 and 40–60 days of age no significant down‐regulation of receptor number was observed. Furthermore, down‐regulation was absent in the 10‐month‐old rats as well. Since a great variation in SmaxandKdvalues was seen in 3‐month‐old females but not in male rats, we investigated mAChR characteristics during the oestrous cycle of female rats. In pro‐oestrus, mACh receptor number was increased and affinity decreased in comparison with di‐oestrus. The transition from pro‐oestrus into oestrus was accompanied by a significant decrease in receptor number and an increase in receptor affinity. Injection of ovariectomized females with oestradiol and progesterone induced an increase in the number of binding sites and a decrease in affinity. These values are comparable to those seen in pro‐oestrous rats. These results demonstrate (i) that both carbachol‐ and veratridine‐induced down‐regulation of the mACh receptor is limited during the critical period of cortical plasticity, (ii) that after 3 months of age mACh receptor number is gradually declining, and (iii) that the steroid hormones oestrogen and progesterone are capable of modifying the characteristics of muscarinic anta

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1994.tb00266.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractFibroblast growth factor‐5 (FGF‐5) is a member of the fibroblast growth factor gene family, which has a signal sequence characteristic of secretory proteins. FGF‐5 mRNA has previously been shown to be present in the adult mouse brain. Here we demonstrate that recombinant FGF‐5 has neurotrophic activity on cultured rat septal cholinergic and raphe serotonergic neurons. The effect of FGF‐5 on serotonin uptake was stronger than that evoked with either brain‐derived neurotrophic factor or neurotrophin‐3. FGF‐5 also increased the choline acetyltransferase activity of cultured rat septal cholinergic neurons, the effect being additive to that of nerve growth factor.In situhybridization experiments and immunohistochemistry using a specific anti‐FGF‐5 antibody demonstrated that FGF‐5 is expressed in rat hippocampal neurons. Like nerve growth factor mRNA, the levels of FGF‐5 mRNA in the rat hippocampus increased substantially during early postnatal development. In addition, injection of the muscarinic receptor agonist pilocarpine elevated FGF‐5 mRNA. The presence of the secretory FGF‐5 in the rat hippocampus, a target field of septal cholinergic and raphe serotonergic neurons, suggests that FGF‐5 acts as a trophic factor

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1994.tb00267.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThis study describes the development of the ferret thalamic reticular nucleus from Nissl‐stained and from parvalbumin‐immunostained sections. From early stages [embryonic day (E) 23‐E25], there is a large group of ventral thalamic cells which lies between the dorsal thalamus and the primordial internal capsule. This group of cells, the primordial reticular nucleus, gives rise to the main body of the reticular nucleus, the perigeniculate nucleus and the perireticular nucleus. In the reticular nucleus, there are two waves of parvalbumin expression during development. The first wave begins prenatally in small cells which are seen rarely after birth. Their fate is not clear: they may have lost immunoreactivity, migrated elsewhere, or died. At the end of the first wave, a second wave begins in a distinct group of larger ovoid reticular cells, which appear to remain into adulthood. At about birth, the dorsocaudal pole of the reticular nucleus first forms the perigeniculate nucleus. During this developmental stage, cells which make up the reticular and perigeniculate nuclei are the only parvalbumin‐immunostained structures in the thalamus. Thus, rather than develop from the dorsal thalamus, the perigeniculate nucleus seems to have its origins in the ventral thalamus together with the reticular nucleus. During development, the reticular nucleus is associated closely with a large mass of cells located in the internal capsule, called the perireticular nucleus. Later, the perireticular nucleus is dramatically reduced in size: that is, there is a large reduction in the number of perireticular cells seen per section and in the extent of the nucleus across the internal capsule. There are two cytoarchitectonically distinct groups of perireticular cells. One group of cells, called the large‐celled perireticular zone (LPR), enters the internal capsule from early prenatal development (E25). Many of these cells reach the globus pallidus and extend as far as the cortical subplate zone. The LPR together with the subplate form an extensive neuronal network in the white matter during early development, which disappears later in development (about postnatal day 20). The second group of perireticular cells is made up of smaller cells and is called the small‐celled perireticular zone (SPR). These small cells enter the internal capsule from the reticular nucleus just prior to birth. Many of the cells in the SPR remain i

ISSN:0953-816X    

DOI:10.1111/j.1460-9568.1994.tb00268.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY