bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synapses on axons of sympathetic preganglionic neurons in rat and rabbit thoracic spinal cord
Authors: Llewellyn‐Smith Ida J. , Pilowsky Paul , Minson Jane B. , Chalmers John 
Published: January 2005

AbstractAxosomatic and axodendritic synapses occur on sympathetic preganglionic neurons, but it is not yet known whether their axons receive synaptic input, which could be particularly effective at regulating sympathetic outflow. Here, we examined retrogradely labelled sympathetic preganglionic axons to see if they received synapses. Cholera toxin B subunit (CTB) or CTB conjugated to horseradish peroxidase (CTB‐HRP) was used to label neurons projecting to the rat or rabbit superior cervical ganglion, the rat adrenal medulla, or the rabbit stellate ganglion. At the light microscopic level, small groups of CTB‐immunoreactive axons travelled through the ventral horn near its lateral boundary, with occasional axons taking a more medial course. The axons passed through the ventrolateral funiculus to exit at the ventral roots. In parasagittal section, a few axons branched within the ventral horn, sending processes rostrally and caudally for short distances before they turned ventrally to exit the spinal cord. At the ultrastructural level, CTB‐immunoreactive rat and rabbit sympathetic preganglionic axons were almost exclusively unmyelinated. In contrast, labelling with CTB‐HRP revealed both myelinated and unmyelinated axons in the ventral horn, the ventrolateral white matter, and the ventral roots. CTB‐HRP also allowed the detection of the initial segment of a sympathetic preganglionic axon. Synapses, with vesicles clustered presynaptically and membrane specializations postsynaptically, were found on some unmyelinated CTB‐immunoreactive axons. Occasional axons received several synapses. Synapses were most common on CTB‐containing axons just ventral to the intermediolateral cell column. One synapse was found on an axon within 2 μm of its origin from a proximal dendrite. Rare synapses were found several hundred micrometers ventral to the intermediolateral cell column. One branching axon had synapses just below the branch point on both the main axon and the axonal branch. These findings indicate an extensive synaptic input to the axons of at least some sympathetic preganglionic neurons. These axoaxonic synapses could have a profound effect on sympathetic activity. © 1995 Wiley‐Liss, Inc.
Regenerative axonal sprouting in the cat trochlear nerve
Authors: Iannuzzelli Pasquale G. , Murray Marion , Murphy E. Hazel 
Published: January 2005

AbstractFollowing peripheral trochlear nerve axotomy in the cat, the normal number of myelinated axons is restored despite significant motor neuron death, suggesting regulation of the number of myelinated axons in the regenerated nerve. In this study we used light and electron microscopy to examine the production and maintenance of axonal sprouts at different locations in the nerve and at different postoperative intervals. Despite proliferative sprouting and an overproduction of nonmyelinated axons in the regenerating trochlear nerve, the number of myelinated axons was strictly regulated. Only ∼1,000 regenerated axons were eventually remyelinated, but many nonmyelinated axons were still present 6–8 months postaxotomy. Regenerated axons were remyelinated in a proximal‐to‐distal direction between 3 and 4 weeks postaxotomy.We also examined the maturation of regenerated myelinated axons by measuring axon diameter and myelin index (an expression of myelin thickness). Mean myelinated axon diameter remained significantly below normal in long‐term regenerated nerves. Mean myelin index was not different from normal at 4 weeks postaxotomy but was significantly decreased at long postoperative intervals, reflecting a slightly thicker myelin sheath relative to the axon diameter. This relative increase in mean myehn thickness could serve to restore normal conduction velocity despite the decrease in mean axon diameter.We suggest that the regulation of the number of myelinated axons at the normal number despite cell death and the increase in mean myelin thickness may both be compensatory mechanisms that function to restore preoperative conditions and maximize functional recovery. © 1995 Wiley‐Liss, Inc.
Somatostatin‐like immunoreactivity in primary afferents of the medial articular nerve and colocalization with substance P in the cat
Authors: Hanesch U. , Heppelmann B. , Schmidt R. F. 
Published: January 2005

AbstractThe proportion of somatostatin‐containing dorsal root ganglion cells innervating the knee joint of the cat via the medial articular nerve was determined by using retrograde labeling with fast blue and immunohistochemistry. Immunoreactivity was found in 8.6% of labeled cell bodies. In colchicine‐treated ganglia, the proportion increased to 16.8%.Only small and intermediate‐sized perikarya showed somatostatin‐like immunoreactivity, indicating that this neuropeptide is synthesized predominantly in primary afferent units with unmyelinated sensory axons but may also be present in primary afferents with thinly myelinated sensory fibers. Colchicine treatment had no influence on the cell size distribution.Colocalization of somatostatin with substance P was determined by comparing the proportions of immunopositive dorsal root ganglion cells after incubation with antibodies against substance P or somatostatin or with a mixture of both. Substance P‐like immunoreactivity was found in 18.1% (untreated ganglia) and 19.6% (colchicine treated ganglia) of the labeled neurons. After incubation with a mixed antibody solution, 18.2% of joint afferents in untreated and 19.9% of the cells in colchicine‐treated ganglia were immunopositive. Comparing this result with the results obtained using somatostatin and substance P antibodies alone, one can calculate that both neuropeptides are colocalized in about 17% of the cat's knee joint afferents. About 3% of the neurons contain only substance P, whereas almost none of the neurons contain only somatostatin. Based on this fact, one can assume that both neuropeptides are coreleased in peripheral tissue as well as in the central nervous system. © 1995 Wiley‐Liss, Inc.
Noxious heat‐evoked Fos–like immunoreactivity in the rat medulla, with emphasis on the catecholamine cell groups
Authors: Jones S. L. , Blair R. W. 
Published: January 2005

AbstractThe objectives of the present study were 1) to utilize Fos immunohistochemistry as a marker for neuronal activity in order to examine the population of neurons in the medulla that is engaged by activation of nociceptive peripheral afferents and 2) to determine whether catecholamine‐containing neurons in the medulla also express noxious heat‐evoked Fos‐like immunoreactivity. Noxious heating of the hindpaw evoked specific patterns of Fos‐like immunoreactivity in the medulla in regions known to be involved in both nociceptive processing and cardiovascular regulation. Noxious heating of the hindpaw significantly increased the mean number of neurons expressing Fos‐like immunoreactivity in the contralateral ventrolateral medulla. Increased numbers of Fos‐positive neurons also were observed in both the ipsilateral and the contralateral A1 catecholamine cell groups. Similarly, in the contralateral medullary dorsal reticular fields, noxious heating of the hindpaw significantly increased the mean number of neurons expressing Fos‐like immunoreactivity. In contrast, in the paramedian reticular nucleus, noxious heating of the hindpaw resulted in a significant decrease in the mean number of neurons expressing Fos‐like immunoreactivity. No significant differences in the mean numbers of neurons expressing Fos‐like immunoreactivity were noted in the A2, C1, or C2/C3 medullary catecholamine cell groups. These results suggest that noxious stimuli affect pools of neurons in the medulla with multiple physiological functions. © 1995 Wiley‐Liss, Inc.
Relationship of the time of origin and death of neurons in rat somatosensory cortex: Barrel versus septal cortex and projection versus local circuit neurons
Authors: Miller Michael W. 
Published: January 2005

AbstractThe birth of a neuron initiates a series of ontogenetic events, e. g., neuronal migration and differentiation. The outcomes of these events are neurons that successfully integrate into the cortical circuitry and neurons that are unsuccessful and ultimately die. The present study determined whether there is a relationship between the generation and death of cortical neurons.The decrease in the density of postmigratory neurons (heavily labeled by a single injection of [3H]thymidine) during normal development was used as an index of neuronal death. The survival indices of neurons varied with their times of origin. Neurons born from gestational day (G) 15 to G18 had the highest rates of survival. In contrast, the earliest and latest generated neurons (i. e., those born on G12‐G13 and those born on G19‐G21, respectively) had the lowest survival rates.The role of neuronal death in the formation of cortical patterns was determined by assessing the survival of neurons in the barrels and septa of somatosensory cortex. No differences in the survival index were determined for neurons in the C‐row barrels and adjacent septa with a particular time of origin.The survival rate of projection and local circuit neurons was determined with a doublelabeling technique. One label, [3H]thymidine, was used to determine the time of origin of the neurons. The second label was used to identify the chemical or hodological characteristics of a neuron; projection neurons were labeled either by retrograde transport of horseradish peroxidase or by glutamate immunohistochemistry, and local circuit neurons were immunohistochemically identified with an antibody directed against gamma‐aminobutyric acid (GABA) antibody. The survival rate for projection neurons (labeled by either technique) was as much as twice that for GABA‐immunoreactive local circuit neurons.Thus, the death of cortical neurons is related to their time of origin. Although neuronal death is not important for sculpting cortical patterns, death does selectively affect neurons with a specific hodological phenotype.
Cholinergin innervation of the primate hippocampal formation. I. Distribution of choline acetyltransferasse immunoreactivity in the Macaca fascicularis and Macaca mulatta monkeys
Authors: Alonso José R. , Amaral David G. 
Published: January 2005

AbstractThe cholinergic innervation of the hippocampal formation of Macaca fascicularis (cynomolgus) and Macaca mulatta(rhesus) monkeys was investigated by immunohistochemical procedures using a monoclonal antibody directed agaist choline acetyltransferase. The distribution of choline acetyltransferase in the monkey demonstrated both similarities and differences with the staining patterns observed in the rat or with acetylcholinesterase in the monkey. While both of these latter preparations demonstrated labeled cells, for example, no choline acetyltransferase labeled neurons were observed in the monkey observed in the monkey hippocampal formation. Choline acetyltransferase activity was restricted to fibers which varied in thickness and number of varicosities and in their regional and laminar distribution. The highest densities of labeled fibers were observed in the unacal protion of the hippocampus, in the parasubiculum, and in the entorhinal cortex; the lowest densities of labeled fibers were observed in CA1 and in midrostrocaudal levels of the dentate gyrus. In the dentate gyrus, immunoreactive fibers were densely distributed in the molecular layer and in an infragranular plexus. One of the few striking noticeable interspecies differences was observed in the dentate gyrus. In the rhesus monkey, labeled fibers in the molecular layer were divided into a superficial denser and an inner lighter lamina, whereas in M. fascicularis, the cholinergic fibers were distributed more homogeneously throughout the molecular layer. In the hippocampus proper, there was a progressive decrease in the density of ChAT‐immunoreactive fibers from CA3/CA2 into CA1. The subiculum also demonstrated modest labeling which was nonetheless higher than in CA1; the border of these fields demonstrated increased fiber labeling. The density of choline acetyltransferase staining was high in the presubiculum and parasubiculum. In the entorhinal cortex, a relatively clear boundary was observed between the more heavily stained superficial layers (I, II, and III) and the more weakly labeled deep layers (V and VI), especially in the intermediate and caudal fields. A transverse decreasing gradient was observed with the densest plexus of cholinergic fibers found in the medially situated olfactory field of the entorhinal cortex and the lowest density in the laterally located caudal and lateral fields.
The human entorhinal cortex: A cytoarchitectonic analysis
Authors: Insausti R. , Tuñón T. , Sobreviela T. , Insausti A. M. , Gonzalo L. M. 
Published: January 2005

AbstractThe entorhinal cortex of man is in the medial aspect of the temporal lobe. As in other mammalian species, it constitutes an essential component of the hippocampal formation and the route through which the neocortex interacts with the hippocampus. The importance of knowing its architecture in detail arises from the possibility of extrapolating it to experimental findings, notably in the nonhuman primate. We have investigated the cytoarchitectonic features of the human entorhinal cortex by using as a base our previous study (D. G. Amaral, R. Insausti, and W. M. Cowan [1987] J. Comp. Neurol. 264:326–355) of the nonhuman primate entorhinal cortex. We prepared serial sections of the temporal lobe from 35 normal brains. Thionin‐ and myelin‐stained series were made of all cases. Sections spaced 500 μm apart through the full rostrocaudal extent of the entorhinal cortex were analyzed. The human entorhinal cortex is made up of six layers, of which layer IV does not appear throughout all subfields of the entorhinal cortex. The overall appearance resembles that of the adjacent neocortex in lateral and caudal portions. In harmony with general structural principles in the nonhuman primate entorhinal cortex, our analysis supports the partitioning of the human entorhinal cortex into eight different subfields. (1) The olfactory subfield (EO), the rostralmost field, is little laminated. (2) The lateral rostral subfield (ELr), laterally located, merges with the laterally adjacent perirhinal cortex. (3) The rostral subfield (ER) is between EO and ELr, with better differentiation of layers II and III than EO. (4) The medial intermediate subfield (EMI) is located at the medial border. (5) The intermediate field (EI) is a lateral continuation of EMI; lamina dissecans (layer IV) can be best appreciated in this field. (6) The lateral caudal subfield (ELc) laterally borders on EI as a continuation of ELr. (7) The caudal subfield (EC) lies caudal to the beginning of the hippocampal fissure, with a distinctive, clear space (Vc) between layers V and VI. (8) The caudal limiting field (ECL) forms the caudal termination of the entorhinal cortex. Thus our parcellation of the entorhinal cortex in man is largely parallel to that arrived at in the monkey. This close homology provides a rational basis for the application to clinical problems of anatomical and functional information obtained in experimental work in nonhuman primates.
Synaptic connectivity of local circuit neurons in laminae III and IV of hamster spinal cord
Authors: Schneider S. P. , Sandiford D. R. , Kavookjian A. M. , Johnson B. D. 
Published: January 2005

AbstractThe present study was undertaken to examine the morphological bases of local synaptic interactions between dorsal horn interneurons. Seven interneurons responding to innocuous mechanical stimuli were intracellularly recorded in lamina III/IV of an isolated preparation of hamster spinal cord with partially intact innervation from an excised patch of hairy skin. Axonal arborizations were stained with horseradish peroxidase (HRP) and examined with an electron microscope. Five cells had extensive synaptic terminations (375‐1, 785 boutons/axon) with localized distributions (rostrocaudal distance, 425‐1,251 μm) overlapping the dendritic trees. Two cells gave rise to deep stem axons that bifurcated into rostrocaudal daughter branches with collaterals ventral to the parent cell bodies (79‐661 boutons/axon). Axons of local interneurons were thinly myelinated and formed terminal and en passant enlargements (mean [±S. D.] diameter = 0.88 ± 0.24 μm, n = 157) containing clear, round vesicles 20‐60 nm in diameter. Collateral branches of deep axon cells produced round, vesicle‐containing boutons comparable in diameter (0.93 ± 0.22 μm, n = 31) to local axon cells. Both types of interneurons formed asymmetric synaptic contacts with dendritic profiles, but not with cell bodies or axon terminals. Postsynaptic profiles contained sparse ribosomes and had a mean diameter of 1.0 ± 0.5 μm (n = 49), significantly smaller than a population of identified proximal dendrites (2.3 ± 0.9 μm, n = 47). HRP‐labeled boutons were rarely (5/45 or 11%) in synaptic contact with more than one profile. We conclude that lamina III/IV interneurons make axodendritic synapses predominantly with distal dendrites. Thus, terminations of deep dorsal horn interneurons appear to have a postsynaptic distribution overlapping with axodendritic contacts formed by several functional classes of cutaneous sensory fibers signaling innocuous mechanical stimuli. Such overlap suggests that local spinal networks selectively and strongly influence afferent signals at initial stages of somatosensory integration.
Anatomical localisation of preproatrial natriuretic peptide mRNA in the rat brain by in situ hybridisation histochemistry: Novel identification in olfactory regions
Authors: Ryan Mary C. , Gundlach Andrew L. 
Published: January 2005

AbstractAtrial natriuretic peptide (ANP) is one of three structurally homologous natriuretic peptides present in heart and brain, which is thought to be involved in the regulation of water and salt intake, blood pressure, and hormone secretion. In the present study, the distribution of preproatrial natriuretic peptide (ppANP) mRNA in the central nervous system of the rat was examined by in situ hybridisation histochemistry by using [35S]‐labelled oligonucleotides. Cells expressing ppANP mRNA were apparent in several major neuronal systems, being present in hypothalamic, limbic, pontine and forebrain olfactory regions. Relatively high densities of ppANP mRNA‐positive neurones were found in the anterior medial preoptic hypothalamic nucleus, medial habenular nucleus, and in Barrington's nucleus in the pons. Moderate numbers of ppANP mRNA‐positive cells were present in a number of amygdaloid nuclei, including the posterolateral and anterior cortical nuclei, in the zona incerta, and the pedunculopontine tegmental nucleus. Other areas, including the ventromedial hypothalamic nucleus and the laterodorsal tegmental nucleus, displayed only low densities of ppANP mRNA‐positive neurones. A number of structures in which ppANP mRNA (or ANP‐like immunoreactivity) has not previously been reported were found to contain moderate to high numbers of ppANP mRNA‐positive neurones including several nuclei associated with the olfactory system, such as the anterior olfactory nucleus and neurones of the tenia tecta and ventrolateral orbital cortex. Although ppANP mRNA in CA1 pyramidal cells of the hippocampus has been described, we also detected labelling in CA2 and ventral CA3 regions of the hippocampus. Conversely, nuclei such as the bed nucleus of the stria terminalis and the nucleus of the solitary tract, which are reported to possess ANP‐like immunoreactivity, were found not to contain ppANP mRNA. Overall, these results demonstrate the presence of ANP gene expression in discrete neuronal populations of the rat central nervous system and provide additional evidence to support a putative role for this peptide in regulating and integrating hypothalamic, olfactory, limbic, and neuroendocrine systems. © 1995 Wiley‐Liss, Inc.
Localization of nicotinamide adenine dinucleotide phosphate‐diaphorase activity in electrosensory and electromotor systems of a gymnotiform teleost, Apteronotus leptorhynchus
Authors: Turner Ray W. , Moroz Leonid L. 
Published: January 2005

AbstractThe distribution of nicotinamide adenine dinucleotide phosphate‐diaphorase (NADPH‐d) activity was determined in electrosensory and electromotor systems of the weakly electric gymnotiform teleost Apteronotus leptorhynchus as an indicator of putative nitric oxide synthase‐containing cells. NADPH‐d activity was detected in electroreceptors and in afferent nerves of both ampullary and type I and type II tuberous organs. All cell bodies within the anterior lateral line nerve ganglion were positive for NADPH‐d activity, as were the primary afferent axons and termination fields in the medullary electrosensory lateral line lobe. In the corpus cerebelli and valvula cerebelli, NADPH‐d label was present in Purkinje cell somata, mossy fiber synaptic glomeruli, granule cells, and parallel fibers. In the midbrain, NADPH‐d activity was apparent in layer VIIIB of the torus semicircularis dorsalis and in electrosensory laminae of the optic tectum. NADPH‐d was particularly associated with diencephalic electrosensory and electromotor nuclei, including the prepacemaker nucleus, the nucleus subelectrosensorius, and the central posterior nucleus of the thalamus. Intense NADPH‐d activity was present in pacemaker and relay cells of the medullary pacemaker nucleus but was absent from a novel class of smaller cells in this structure. Relay cell axons and spinal electromotor neurons and their axons within the electric organ were positive for NADPH‐d activity. These results indicate that putative nitric oxide synthase‐containing neurons in Apteronotus are localized preferentially to electrosensory and electromotor structures, suggesting a role for nitric oxide in determining the activity of cells involved in detecting or generating weakly electric fields. © 1995 Wiley‐Liss, Inc.
Developmental changes in the distribution of NADPH‐diaphorase‐containing neurons in telencephalic nuclei of the zebra finch song system
Authors: Wallhäusser‐Franke E. , Collins C. E. , Devoogd T. J. 
Published: January 2005

AbstractExtensive recent research has focused on the potential role of nitric oxide (NO) in synaptic plasticity. Could the capacity to synthesize NO be associated with neural and behavioral plasticity in the song system? The timing of song learning and of major developmental changes in song system anatomy are known. We searched for an association between NO and these developmental events by observing the distribution of neurons staining for NADPH‐diaphorase, an enzyme used in the synthesis of NO, in the brains of zebra finches. Both male and female brains were taken at different developmental ages from day 21 to adulthood. We found that the incidence of stained neurons in the song system nuclei is lower than in surrounding areas. The incidence of staining decreases with development, with most of the decrease occurring prior to the auditory learning phase of song learning. The developmental changes were quantified for area X and found to be highly significant, with a 56% decrease in staining frequency from day 21 to adulthood in males and a 23% decrease in females for the equivalent region. We also found a sexual dimorphism in the song system of adult birds, consisting of a reduced incidence of stained neurons in song system nuclei area X, high vocal center (HVC), and nucleus robustus (RA) archistrialis in males compared with females. These findings suggest that NO is less involved in the plasticity underlying song acquisition than in the earlier formation of the song system. © 1995 Wiley‐Liss, Inc.