摘要:

AbstractAcetylcholinesterase (AChE) activity was investigated in synaptic areas of the cat spinal trigeminal nucleus (pars interpolaris and pars caudalis) ipsilateral and contralateral to complete retrogasserian rhizotomy. Vibratome sections of tissue taken from animals of 1, 3, 6, 14, and 21 days survival were examined by electron microscopy following a histochemical reaction for AChE activity employing a method based on the Karnovsky‐Roots technique for demonstrating reaction product. As degeneration progressed with survival time, enzymatic activity was initially reduced in synaptic clefts of injured afferent terminals and subsequently was enhanced throughout the extracellular space, including within synaptic clefts of possibly reinnervated sites. These changes in enzymatic activity with primary deafferentation are discussed in relation to the process of reinnervation, the development of neuronal hyperactivity, and possible noncholinergic functions of ACh

ISSN:0887-4476    

DOI:10.1002/syn.890020402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe raphe nuclei also contained SP‐like immunoreactivity (up to 30%) while few monoamine‐synthesizing neurons in the lateral and dorsomedial medulla contained SP‐like immunoreactivity approximately 5% of presumed serotonin‐, noradrenaline‐, and adrenthe adult human. The majority of SP‐like immunoreactive neurons were found in four main regions: the lateral medulla, the dorsomedial medulla, the spinal trigeminal nucleus, and the raphe nuclei. The morphology of immunoreactive cells varied according to the region in which they were found. In contrast to previous studies, we found large numbers (90,000) of SP‐like immunoreactive neurons throughout the adult human medulla oblongata. The distribution of these SP‐like immunoreactive neurons appears to be significantly different from those described in the rat and cat.These results were compared to the distributions of monoamine‐synthesizing and neuropeptide Y (NPY)‐like immunoreactive neurons in the human medulla previously reported (Halliday et al.:Neuroscience, in press, 1988a;J. Comp. Neurol., in press, 1988b). Colocalization studies revealed that many presumed serotonin‐synthesizing neurons in the raphe nuclei also contained SP‐like immunoreactivity (up to 30%) while few monoamine‐synthesizing neurons in the lateral and dorsomedial medulla contained SP‐like immunoreactivity (approximately 5% of presumed serotonin‐, noradrenaline‐, and adrenaline‐synthesizing neurons). The distributions of SP‐ and NPY‐like immunoreactive neurons were similar, although SP‐like immunoreactive neurons were concentrated in the lateral regions of the same structures. We have found that the distributions of monoaminesynthesizing, NPY‐, and SP‐like immunoreactive neurons significantly overlap, particularly in the lateral medulla of the adult human. There is a large increase in the number of these cells in this region compared to other species, emphasizing the neuroanatomical d

ISSN:0887-4476    

DOI:10.1002/syn.890020403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractImmunocytochemical techniques have been used to identify a striking interneuronal population which is immunoreactive for the peptide, somatostatin. The cell population, which is seen most densely in stratum oriens and at the oriens/alveus border of the CA1 region of rabbit hippocampus, was characterized in light and electron microscopic observations. The cells have dendrites which extend parallel to and into the alveus, with occasional processes ascending through stratum pyramidale toward the hippocampal fissure. The dendrites receive numerous synaptic contacts directly onto aspinous dendritic shafts. Axon collaterals ramify profusely within the pyramidale region, and among the proximal apical and basal pyramidal cell dendrites in areas of stratum radiatum and stratum oriens. Somatostatin‐like immunoreactive terminals make synaptic contact, primarily of the symmetric type, with the somata and proximal dendrites of pyramidal neurons. Somatostatin‐like neurons are found at approximately equal density in the hippocampus of immature (8 days postnatal) and mature (30 days postnatal) rabbit. Double‐labelling techniques, to identify both somatostatin‐like and glutamic acid decarboxylase (GAD) immunoreactive neurons, demonstrated that a large proportion of the somatostatin neurons were also GA

ISSN:0887-4476    

DOI:10.1002/syn.890020404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractIntracellular recordings were obtained from nonpyramidal neurons (interneurons) in stratum lacunosum‐moleculare (L‐M) of the CA1 region of guinea pig hippocampal slices. These interneurons had response characteristics that distinguish them from pyramidal cells and other interneuron types: the L‐M neurons had relatively broad action potentials with large spike afterhyperpolarizations, high input resistance and little spike‐firing adaptation, and low spontaneous activity. Lucifer Yellow (LY) and horseradish peroxidase (HRP) were injected intracellularly into physiologically identified L‐M interneurons, and the cells were characterized morphologically using light and electron microscopy.L‐M somata were fusiform‐shaped (15 × 25 μm), had multiple processes, and were located at the border between stratum (str.) lacunosum‐moleculare and str. radiatum. L‐M dendrites coursed through str. lacunosum‐moleculare and projected into str. radiatum. L‐M axons made axodendritic synaptic contacts primarily in str. lacunosum‐moleculare and str. radiatum, but also in str. moleculare of the dentate gyrus. These axodendritic synaptic contacts were made onto spiny dendritic processes (presumably pyramidal cell and granule cell dendrites) and onto aspinous dendrites (presumably interneuron dendrites), and appeared to be of the symmetric type (type 2), characteristic of inhibitory synapses.In separate groups of animals, selective lesions were made of afferents to the CA1 and dentate regions of hippocampus, and subsequent degeneration of contacts onto L‐M interneuron somata and dendrites was examined at the ultrastructural level. Fibers originating from contralateral and ipsilateral CA3 region, and from ipsilateral entorhinal cortex, were found to make synaptic contact onto presumed L‐M interneurons. Degenerating terminals appeared to be of the asymmetric type (type 1), characteristic of excitatory synapses. These morphological data are consistent with electrophysiological results showing that L‐M interneurons can mediate feedforward in

ISSN:0887-4476    

DOI:10.1002/syn.890020405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe tritiated dopamine D1antagonist SCH23390 was employed to determine the densities of D1receptors in seven discrete and functionally identified cortical areas (cingulate, frontal, parietal, primary somatosensory, primary visual, retrosplenial and entorhinal‐piriform) as well as in the neostriatum, hippocampus and olfactory bulbs. In addition, the tissue levels of the catecholamines NA, AD, DA, the indoleamine 5‐HT and their main metabolites (MHPG, DOPAC, HVA, 3‐MT, 5‐HTP and 5‐HIAA) were measured in the different regions by HPLC with electrochemical detection. The Scatchard analysis of saturation curves revealed the highest density of [3H]SCH23390 binding sites for the neostriatum, while the densities were 10×20 times lower for total cerebral cortex and hippocampus respectively. For the olfactory bulb and other cortical areas, D1receptor densities were determined by equilibrium binding at a fixed radioligand concentration approaching saturation. The distribution of D1receptors was heterogeneous with the greatest densities in entorhinal‐piriform and cingulate cortices. The endogenous DA levels measured for all regions correlated with their metabolite (DOPAC, HVA and 3‐MT) contents (r = 0.999; P<0.001). There was also a very good correlation (r = 0.981; P<0.001) between tissue DA and D1receptor densities. This quantitative information reflects particular features of the organization of the DA systems and is discussed in relation to turnover and recently established aspects of the

ISSN:0887-4476    

DOI:10.1002/syn.890020406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe influx of the11C‐labeled choline analog pyrrolidinocholine into tissue was measured in the brain of three dogs by positron emission tomography (PET). During the first 90 s after the intravenous bolus injection of the tracer, transfer of tracer from plasma to tissue was unidirectional. The influx constant for pyrrolidinocholine into intracranial tissue, Kin, was 0.017 ml/g/min (0.008 SD), and the initial volume of distribution, V0, was 0.08 ml/g (0.03 SD). The influx constant was at least five times larger than the value expected if simple diffusion were to account for tissue uptake. The method presented in this paper can be used to investigate the availability of plasma choline and its analogs to the living human brain and other tissue in degenerative diseases affecting the cholinergic system, and to provide in vivo information on a choline transport syste

ISSN:0887-4476    

DOI:10.1002/syn.890020407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe potential importance of copper (Cu) in neurosecretion can be inferred from the demonstration that extracellular Cu modulates the secretory function of peptidergic neurons (in vitro studies) and from the presence of high Cu concentrations in nerve terminals and secretory vesicles, primarily within the soluble matrix of the latter. We have previously hypothesized that vesicular Cu is released from neurons undergoing exocytosis and that such extracellular Cu plays an important modulatory role in the central nervous system. To test this Cu release hypothesis, rat hypothalami were incubated under in vitro conditions for 1 or 2 hr with 20 nM radiolabeled Cu (67Cu), and then67Cu release was stimulated by a depolarizing concentration (60 mM) of K+. K+markedly (P<0.001) stimulated67Cu release in a Ca2+‐dependent manner (stimulated release was 95 fmol/10 min/mg protein after 1 hr67Cu loading and 160 after 2 hr). These amounts of released67Cu account for about 10% of the total67Cu taken up by the tissue. These results indicate that part of the67Cu taken up by hypothalamic explants is directed into an intracellular compartment from where it can be released by a Ca2+‐dependent mechanism, thus providing strong support to our hypothesis that release of copper is operative in situ in the br

ISSN:0887-4476    

DOI:10.1002/syn.890020408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractPrevious electrophysiological studies have failed to identify significant effects of the D1 dopamine (DA) agonist SKF 38393, either alone or in combination with the D2 agonist quinpirole (LY 171555), on the spontaneous firing rate of midbrain DA neurons. We have utilized extracellular single‐unit recording techniques to examine whether SKF 38393 can alter D2‐mediated inhibition of DA cell activity. Quinpirole induced inhibition of the spontaneous activity of midbrain DA neurons was observed to be positively correlated with the basal firing rate of the neuron being examined (i.e., faster cells required higher doses to achieve 50% and maximal inhibition). Pretreatment with SKF 38393 (1.0 mg/kg, i.v.; 4 minutes) eliminated the rate dependency of quinpirole induced inhibition of nigrostriatal but not mesoaccumbens DA neurons. This effect of SKF 38393 was blocked both by the D1 antagonist SCH 23390 and by hemitransections of the forebrain. In summary, SKF 38393 appears to exert Dl‐specific, feedback pathway‐dependent effects on the profile of responsiveness of nigrostriatal DA neurons to D2‐mediated inhibition of cell fi

ISSN:0887-4476    

DOI:10.1002/syn.890020409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractA Ca++‐dependent secretion of norepinephrine ([3H]NE) was evoked in adrenergic nerve endings in rat heart ventricle slices incubated in a modified KrebsHCO3medium containing choline C1 as the replacement for NaC1 (Ch+‐Ca++). Exogenous ATP inhibited secretion and lithium ion, a known inhibitor of NE uptake dependent upon Mg++‐ATPase activity in vesicles (but not ouabain) prevented the response to ATP (Bogdanski, 1983, 1986). It was suggested that vesicles attached to the axolemma recaptured[3H]NE from the extracellular fluid. This report indicates that other known inhibitors of uptake in isolated vesicles also inhibited the response to ATP in the attached vesicles. Included were two inhibitors of Mg++‐ATPase activity, N‐ethylmaleimide (NEM) and dicyclohexylcarbodiimide (DCCD), and the proton transporters 2,4‐dinitrophenol (2,4‐ DNP 1.0 mM) and chlorpromazine (CPZ). Potassium ionophores (valinomycin with 2,4‐DNP 0.1 mM and, nigericin) and a pH neutralizing reagent for vesicles (NH3from ammonium sulfate in solution) were also effective. The uptake inhibitors, except 2,4‐DNP, could also increase the rate of depletion of stored NE and its deamination in nonsecreting nerve endings incubated in Krebs‐HCO3(KRB) medium. Valinomycin by itself stimulated uptake in the presence of ATP. It is sugested that mechanisms of uptake and retention of NE in isolated vesicles (symposium (1982) Fed. Proc. 41:2742–2780) apply to the axoplasmic vesicles as well. Thus, the activity of Mg++‐ATPase drives proton transport to establish the electrochemical gradients of H+, which drive the transport of NE. A lowering of the gradients can mobilize amines and evoke secretion. However, isolated vesicles in the presence of ATP and C1−eventually take up a sufficient number of ions to cause osmotic lysis. By contrast, exocytosis was not biochemically apparent in the model vesicular‐axolemmal secretory an

ISSN:0887-4476    

DOI:10.1002/syn.890020410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractResponses to substance P (SP) and to hypogastric nerve stimulation were recorded from voltage‐clamped guinea pig inferior mesenteric ganglion (IMG) neurons, and compared with those to muscarine. Muscarine produced a voltage‐dependent inward current accompanied by a reduced input conductance and inhibition of IMa time‐ and voltage‐dependent K+‐current (Brown and Adams:Nature283:673–676, 1980). SP also produced an inward current, accompanied by a fall in input conductance (20 out of 31 cells) or a rise in input conductance (7 out of 31 cells). The fall in input conductance was not accompanied by an inhibition of M‐current (unlike frog ganglia: Adams et al.:British Journal of Pharmacology79:330–333, 1983) or an inhibition of the inward rectifier current (unlike globus pallidus neurons: Stanfield et al.:Nature315:498–501, 1985). Repetitive hypogastric nerve stimulation (10–20 Hz, 2–10 s) produced a slow inward postsynaptic current lasting 1–3 min, with decreases or increases of input conductance matching those produced by SP. The postsynaptic current did not show a consistent or reproducible change in amplitude on varying the holding potential between ‐90 and ‐25 mV. It is concluded that SP and hypogastric stimulation produce complex and variable changes in ionic

ISSN:0887-4476    

DOI:10.1002/syn.890020411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY