bluuebunny/crossref_metadata_2025 huggingface dataset:
Spinal projection neurons to the laterodorsal pontine tegmental nucleus: Relationship to preganglionic neurons and nitric oxide synthase
Authors: Hamilton Murray O. , Papka Raymond E. , O'donoghue Daniel L. , Vaidya Atul M. , Williams Sonya J. , Poff Clifton R. D. , McNeill Daniel L.
Published: January 2005

The region of the rat sacral parasympathetic nucleus (SPN) contains distinct subpopulations of neurons that project supraspinally or are preganglionic neurons. Some preganglionic neurons in the SPN serve as the motor outflow for urinary bladder contraction; other neurons in the SPN project to regions of the rostral pons that subserve micturition reflexes. Previous studies utilizing immunohistochemistry or staining for nicotinamide adenine dinucleotide phosphate‐diaphorase (NADPH‐d) have demonstrated that numerous neurons in the SPN contain nitric oxide synthase (NOS), the enzyme for nitric oxide synthesis. Thus, the objectives of this study were to determine (1) the distribution of neurons in the region of the SPN that project to the laterodorsal tegmenturn (LDT) of the pons, (2) whether spinal neurons projecting to a peripheral autonomic ganglion also project to the LDT, and (3) whether NOS or NADPH‐d is present in LDT projection neurons. Preganglionic neurons were identified by injecting the retrograde tracer fluorogold (FG) into the major pelvic ganglion (MPG). Supraspinally projecting neurons were identified by injecting the retrograde tracer fast blue (FB) into the LDT. Numerous FB‐labeled neurons were present in the ipsi‐ and contralateral SPN and were immediately dorsal to FG‐labeled preganglionic neurons. Neurons containing both tracers were not observed. Approximately 20% of preganglionic neurons, but no LDT projection neurons, were reactive for NOS and NADPH‐D. These data suggest that the region of the SPN is a site for distinct subpopulations of neurons that project to the LDT and to the MPG and that NOS is contained in some preganglionic neurons, but is not a marker for LDT projection neurons. © 1995 Wiley‐Liss, Inc.
Development of the longitudinal projection patterns of lumbar primary sensory afferents in the chicken embryo
Authors: Eide Anne Lill , Glover Joel C.
Published: January 2005

The literature on the anatomical organization of primary sensory afferents, though extensive, contains relatively little information about the longitudinal extent of the central collateral projections. Our understanding of intersegmental sensorimotor integration in the spinal cord and of the developmental mechanisms that establish its underlying circuitry could be significantly enhanced by a more complete description of these projections. To address this issue from a developmental perspective, we labeled the central projections of lumbar primary afferents in fixed preparations of the chicken embryo with the lipophilic tracer DiI. At late embryonic stages, the afferent projections had the following characteristics: Primary afferents originating from a single lumbar dorsal root ganglion bifurcated to project longitudinally in the dorsal funiculus or Lissauer's tract. Dorsal funiculus axons extended up to seven segments caudally and to at least ten segments rostrally, whereas axons in Lissauer's tract extended up to seven segments in each direction. Collaterals branched off the longitudinal axons over a range of about seven segments in each direction. Within this range, collaterals to specific terminal fields exhibited more restricted ranges.

The development of these longitudinal patterns during earlier embryonic stages was followed from the time the afferents first reached the neural tube on day 4 of embryogenesis. The longitudinal axons lengthened as a single bundle up to day 10, with medial axons consistently longer than lateral axons. After day 10, the longitudinal axons were segregated into the dorsal funiculus and Lissauer's tract. Collaterals sprouted after about 2 days of longitudinal axon growth, by which time the axons had extended several segments in each direction. The segmental range over which collaterals were present reached a maximum of 20 segments at day 10. Collaterals to the different terminal areas differed in their segmental ranges already by this time. After day 10, the total segmental range of collaterals decreased to the stable level of about seven segments in each direction, which is characteristic of late‐stage embryos. © 1995 Wiley‐Liss, Inc.
Monosynaptic input from Leu5‐enkephalin‐immunoreactive terminals to vagal motor neurons in the nucleus ambiguus: Comparison with the dorsal motor nucleus of the vagus
Authors: Milner T. A. , Okada J. , Pickel V. M.
Published: January 2005

Vagal motor neurons in the rat dorsal motor nucleus of the vagus (DMN) are known to receive direct synaptic input from enkephalin‐containing terminals. We examined (1) whether the vagal motor neurons within the nucleus ambiguus (NA) also received monosynaptic input from enkephalin‐immunoreactive terminals and (2), if so, whether their ultrastructural relations differed from those in the DMN. In both regions, terminals containing Leu5‐enkephalinlike immunoreactivity (LE‐LI) were examined in relation to motor neurons identified by retrograde transport of wheat germ‐agglutinated horseradish peroxidase (WGA‐HRP) applied to the cut end of the cervical vagus nerve in single sections of the medulla oblongata of adult rats. By light microscopy, the most significant overlap between varicose processes with LE‐LI and WGA‐HRP‐containing neurons was seen in the rostral compact portion of the NA and the DMN at the level of the obex. Thus, only these regions were examined by electron microscopy. The most distinguishing ultrastructural feature of WGA‐HRP‐labeled neurons in the NA compared to the DMN was their higher incidence of nonsynaptic appositions with other neurons. In both the NA and the DMN, terminals with LE‐LI formed primarily symmetric synapses on smaller (presumably distal) dendrites; many of these dendrites, as well as most target perikarya, contained WGA‐HRP. Additionally, in the compact portion of the NA compared to the DMN (1) multiple LE‐labeled terminals more frequently contacted single perikarya or dendrites and (2) single terminals with LE‐LI more commonly showed two contacts or active zones and contained more abundant LE‐immunoreactive large (80–100 nm) densecore vesicles (dcvs). In contrast to small (40–50 nm), clear vesicles, which were usually aggregated near active zones, the immunoreactive dcvs were usually located near glial processes distal to these zones. These results indicate that enkephalin immunoreactivity is intensely localized to dcvs within terminals that may have direct inhibitory (symmetric synapses) actions on vagal motor neurons in both the compact portion of the NA and the DMN. Moreover, because numbers of dcvs and active zones have been equated with synaptic strength, our findings suggest enhanced potencies of enkephalin‐immunoreactive terminals in the compact portion of the NA. Our findings support a prominent role for enkephalin in the coordinated activity of esophageal motor neurons located in the compact portion of the NA. © 1995 Wiley‐Liss, Inc.
Postnatal development and synaptic connections of hilar mossy cells in the hippocampal dentate gyrus of rhesus monkeys
Authors: Seress László , Ribak Charles E.
Published: January 2005

Mossy cells of the hippocampal dentate gyrus were analyzed through postnatal development. At birth, a few thorny excrescences were found on the proximal dendrites of mossy cells, whereas distal dendrites displayed pedunculate spines. Thorny excrescences increased in number and complexity until the third month. After that age, the complexity of thorny excrescences is so great that an increase in spine density can be seen only in electron microscopic preparations. An increase in the number of pedunculate spines per unit length of distal dendrite was detected via light microscopy during the first 9 postnatal months. The somata and dendrites of mossy cells displayed adult‐like characteristics after the ninth postnatal month.

Mossy fiber terminals at birth frequently displayed immature ultrastructural characteristies and formed synapses with dendritic shafts and spines. At later postnatal ages and in adults, axospinous synapses were found almost exclusively. This is consistent with the postnatal development of the complex spines of the mossy cells.

Axons of mossy cells were generally confined to the hilus in our 150 ‐μm‐thick sections, where they gave rise to several collaterals. The axon terminals from these collaterals formed asymmetric synapses with dendrites and dendritic spines in the hilar region of the dentate gyrus. These data provide the first anatomical evidence that hilar mossy cells of the primate dentate gyrus have excitatory projections similar to their equivalent cell type in subprimates.

The present study indicates that mossy cells of the dentate gyrus are in a more advanced stage of development at birth and mature faster than similar neurons of the human hippocampus. This may represent a faster maturation of hippocampal circuitry in nonhuman primates compared to that in the human.
GABA and glycine in the central auditory system of the mustache bat: Structural substrates for inhibitory neuronal organization
Authors: Winer Jeffery A. , Larue David T. , Pollak George D.
Published: January 2005

The distribution and morphology of neurons and axonal endings (puncta) were analyzed in auditory brainstem, thalamic, and cortical centers in the mustache bat. The goals of the study were (1) to compare and contrast the location of GABAergic and glycinergic neurons and puncta, (2) to determine whether nuclei containing immunoreactive neurons likewise have a similar concentration of puncta, (3) to assess the uniformity of immunostaining within a nucleus and to consider regional differences that were related to or independent of cytoarchitecture, and (4) to compare the patterns recognized in this bat with those in other mammals.

There are nine major conclusions. (1) Glycinergic immunostaining is most pronounced in the hindbrain. (2) In the forebrain, GABA alone is present. (3) Some nuclei have GABAergic or glycinergic neurons exclusively; a few have neither. (4) Although there is sometimes a close relationship between the relative number of immunopositive neurons and the density of the puncta, just as often there is no particular correlation between them; this reflects the fact that many GABAergic and glycinergic neurons project beyond their nucleus of origin. (5) Even nuclei devoid of or with few GABAergic or glycinergic neurons contain relatively abundant numbers of puncta; some neurons receive axosomatic terminals of each type. (6) In a few nuclei there are physiological subregions with specific local patterns of immunostaining. (7) The patterns of immunostaining resemble those in other mammals; the principal exceptions are in nuclei that, in the bat, are hypertrophied (such as those of the lateral lemniscus) amd in the medial geniculate body. (8) Cellular colocalization of GABA and Gly is specific to only a few nuclei. (9) GABA and glutamic acid decarboxylase (GAD) immunostaining have virtually identical distributions in each nucleus.

Several implications follow. First, the arrangements of GABA and Gly in the central auditory system represent all possible patterns, ranging from mutually exclusive to overlapping within a nucleus to convergence of both types of synaptic endings on single neurons. Second, although both transmitters are present in the hindbrain, glycine appears to be dominant, and it is often associated with circuitry in which precise temporal control of aspects of neuronal discharge is critical. Third, the auditory system, especially at or below the level of the midbrain, contains significant numbers of GABAergic or glycinergic projection neurons. The latter feature distinguishes it from the central visual and somatic sensory pathways.
Distribution of metabotropic glutamate receptor mGluR5 immunoreactivity in rat brain
Authors: Romano Carmelo , Sesma Michael A. , McDonald Colin T. , O'malley Karen , van den Pol Anthony N. , Olney John W.
Published: January 2005

The receptor mGluR5 is a metabotropic glutamate receptor with messenger RNA abundantly present throughout cortex, hippocampus, and caudate/putamen that is also coupled to phosphatidyl inositide hydrolysis and calcium mobilization. In this study, the distribution of mGluR5 was examined in rat brain by immunocytochemistry. The antibody utilized is highly specific and does not cross react with the most closely related other metabotropic glutamate receptor, as determined by Western blot analysis of nonneuronal cells transfected with metabotropic receptor coding sequences. The receptor mGluR5 is widely expressed with the highest density in olfactory bulb, caudate/putamen, lateral septum, cortex, and hippocampus, as confirmed with both immunocytochemistry and Western blot analysis. Electron microscopic studies in hippocampus and cortex indicate that the labeling is mostly on membranes of dendritic spines and shafts. Light and electron microscopic evidence indicates that some mGluR5 immunoreactivity is located in presynaptic axon terminals, suggesting that mGluR5 may function as a presynaptic receptor.
Prenatal development of rat primary afferent fibers: II. Central projections
Authors: Mirnics Károly , Koerher H. Richard
Published: January 2005

These studies were designed to determine the pattern of initial afferent fiber ingrowth into the prenatal spinal gray matter and the establishment of the topographic organization of the presynaptic neuropil in the dorsal horn. A total of 113 lumbar dorsal root ganglia were labeled with carbocyanine fluorescent dye DiI or DiA in 67 rat embryos and neonatal pups aged embryonic day 13 to postnatal day O (E13–PO).

The initial fiber penetration of the lumbar spinal gray began at E15 and was restricted to the segments of entry. Subsequent growth of fibers into gray matter of adjacent segments began approximately one day later, and this delay was continued, about one day for each successive segment. A second wave of ingrowth of putative small‐diameter afferents into the substantia gelatinosa began at E19 and also displayed the same rostrocaudal delay. Fiber ingrowth was specific and occupied the somatotopic area appropriate for the adult, from the earliest stages (E 18) in which dorsal horn laminae could be adequately defined. The somatotopic organization of the presynaptic neuropil in laminae III and IV did not change significantly throughout embryonic development as the amount of overlap between adjacent and non‐adjacent ganglion projections remained constant throughout embryonic development. In addition, it was found that fibers innervating the proximal and distal hindlimb entered the spinal gray simultaneously at E 15 before the innervation of the distal toes was established.

The results of these studies indicate that the somatotopic organization of the presynaptic neuropil is established very early in development and requires little refinement to match that seen in the adult. The simultaneous penetration of the fibers originating from the proximal and distal areas of the limb before innervation is complete suggests that this ingrowth may be independent of the establishment of specific peripheral connections.
Accumulation of neuropeptides in the cerebral neurosecretory system of Manduca sexta Larvae Parasitized by the Braconid Wasp Cotesia congregata
Authors: Žitňan Dušan , Kingan Timothy G. , Kramer Steven J. , Beckage Nancy E.
Published: January 2005

Fifth in star larvae of Manduca sexta that were parasitized by the braconid wasp Cotesia congregata failed to develop after the parasitoid larvae emerged, and these host larvae lingered for 2–3 weeks in a quiescent, nonfeeding state without initiating a larval molt or metamorphosis. This study was focused on the neuroendocrine changes associated with the host's developmental arrest. Immunohistochemical studies suggested that the host brain neurosecretory cells as well as their axon terminals in the corpora cardiaca‐corpora allata complex accumulated multiple neuropeptides. The extent of accumulation in cells and axons increased with time, so that hosts examined 7–14 days after the wasps emerged showed the most intense staining with antibodies against prothoracicotropic hormone, bombyxin, allatotropin, allatostatin, diuretic hormone, eclosion hormone, proctolin, and FMRFamide. Increased levels of prothoracicotropic hormone and FMRFamide‐like peptides in the brains of parasitized larvae were confirmed using Western blots and enzyme‐linked immunosorbent assay (ELISA), respectively. Starvation of the unparasitized larvae induced some accumulation of the neuropeptides; however, the intensity of staining and number of immunopositive cells and axons were in most cases clearly higher in the parasitized larvae. Our results suggest that accumulation of the neuropeptides is associated with developmental arrest of parasitized larvae. Because a similar developmental arrest occurs in a wide range of parasitized insects, our findings may have relevance for many other species. Moreover, these data illustrate the potential value of using parasitized M. sexta larvae as a model for studying the mechanisms governing the rates of neuropeptide expression, processing, packaging, and release, as well as providing a rich source of neuropeptides, thus facilitating their isolation and characterization. © 1995 Wiley‐Liss, Inc.
Octopamine immunoreactivity in the fruit fly Drosophila melanogaster
Authors: Monastirioti Maria , Gorczyca Michael , Rapus Jürgen , Eckert Manfred , White Kalpana , Budnik Vivian
Published: January 2005

Octopamine has been proposed as a neurotransmitter/ modulator/ hormone serving a variety of physiological functions in invertebrates. We have initiated a study of octopamine in the fruit fly Drosophila melanogaster, which provides an excellent system for genetic and molecular analysis of neuroactive molecules. As a first step, the distribution of octopamine immunoreactivity was studied by means of an octopamine‐specific antiserum. We focused on the central nervous system (CNS) and on the innervation of the larval body wall muscles. The larval octopamine neuronal pattern was composed of prominent neurons along the midline of the ventral ganglion, whereas brain lobes were devoid of immunoreactive somata. However, intense immunoreactive neuropil was observed both in the ventral ganglion and in the brain lobes. Some of the immunoreactive neurons sent peripheral fibers that innervated most of the muscles of the larval body wall. Octopamine immunoreactivity was observed at neuromuscular junctions in all larval stages, being present in a well‐defined subset of synaptic boutons, type II. Octopamine immunoreactivity in the adult CNS revealed many additional neurons compared to the larval CNS, indicating that at least a subset of adult octopamine neurons may differentiate during metamorphosis. Major octopamine‐immunoreactive neuronal clusters and neuronal processes were observed in the subesophageal ganglion, deutocerebrum, and dorsal protocerebrum, and intense neuropil staining was detected primarily in the optic lobes and in the central complex. © 1995 Wiley‐Liss, Inc.
Intrinsic connections of the rat amygdaloid complex: Projections originating in the lateral nucleus
Authors: Pitkänen Asla , Stefanacci Lisa , Farb Claudia R. , Go G.‐Genevieve , Ledoux Joseph E. , Amaral David G.
Published: January 2005

The amygdaloid complex receives sensory information from a variety of sources. A widely held view is that the amygdaloid complex utilizes this information to orchestrate appropriate species‐specific behaviors to ongoing experiences. Relatively little is known, however, about the circuitry through which information is processed within the amygdaloid complex. The lateral nucleus is the major recipient of extrinsic sensory information and is the origin of many intra‐amygdaloid projections. In this study, we reinvestigated the organization of intraamygdaloid projections originating from the lateral nucleus using the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA‐L). The lateral nucleus has highly organized intranuclear connections. Dense projections interconnect rostral and caudal levels of the lateral and the medial divisions of the nucleus, and the lateral and medial divisions of the lateral nucleus are also interconnected. The major extranuclear projections of the lateral nucleus are (in descending order of magnitude) to the accessory basal nucleus, the basal nucleus, the periamygdaloid cortex, the dorsal portion of the central division of the medial nucleus, the posterior cortical nucleus, the capsular division of the central nucleus, and the lateral division of the amygdalohippocampal area. The pattern of extranuclear projections varied depending on the rostrocaudal or mediolateral location of the injection site within the lateral nucleus. These findings indicate that intra‐amygdaloid projections originating in the lateral nucleus are both more widespread and more topographically organized than was previously appreciated. © 1995 Wiley‐Liss, Inc.
Morphological characterization of substance P receptor‐immunoreactive neurons in the rat spinal cord and trigeminal nucleus caudalis
Authors: Brown Jessica L. , Liu Hantao , Maggio John E. , Vigna Steven R. , Mantyh Patrick W. , Basbaum Allan I.
Published: January 2005

Although there is considerable evidence that primary afferent‐derived substance P contributes to the transmission of nociceptive messages at the spinal cord level, the population of neurons that expresses the substance P receptor, and thus are likely to respond to substance P, has not been completely characterized. To address this question, we used an antibody directed against the C‐terminal portion of the rat substance P receptor to examine the cellular distribution of the receptor in spinal cord neurons. In a previous study, we reported that the substance P receptor decorates almost the entire dendritic and somatic surface of a subpopulation of spinal cord neurons. In the present study we have taken advantage of this labeling pattern to identify morphologically distinct subpopulations of substance P receptorimmunoreactive neurons throughout the rostral‐caudal extent of the spinal cord. We observed a dense population of fusiform substance P receptor‐immunoreactive neurons in lamina I at all segmental levels. Despite having the highest concentration of substance P terminals, the substantia gelatinosa (lamina II) contained almost no substance P receptor‐immunoreactive neurons. Several distinct populations of substance P receptor‐immunoreactive neurons were located in laminae III‐V; many of these had a large, dorsally directed dendritic arbor that traversed the substantia gelatinosa to reach the marginal layer. Extensive labeling was also found in neurons of the intermediolateral cell column. In the ventral horn, we found that labeling was associated with clusters of motoneurons, notably those in Onuf's nucleus in the sacral spinal cord. Finally, we found no evidence that primary afferent fibers express the substance P receptor. These results indicate that relatively few, but morphologically distinct, subclasses of spinal cord neurons express the substance P receptor. The majority, but not all, of these neurons are located in regions that contain neurons that respond to noxious stimulation. © 1995 Wiley‐Liss, Inc.
Immunocytochemical localization of the renal neutral and basic amino acid transporter in rat adrenal gland, brainstem, and spinal cord
Authors: Nirenberg Melissa J. , Tate Suresh S. , Mosckovitz Rachel , Udenfriend Sidney , Pickel Virginia M.
Published: January 2005

A neutral and basic amino acid transporter (NBAT) cloned from rat kidney was recently localized to enteroendocrine cells and enteric neurons. We used an antibody directed against a synthetic peptide representing a putative extracellular domain of NBAT to determine whether this transporter was also present in other endocrine and neural tissues, including rat adrenal gland, brainstem, and spinal cord. Abundant, highly granular labeling for NBAT was observed in the cytoplasm of chromaffin and ganglion cells in the adrenal medulla. A small population of intensely labeled varicose processes was also seen in both the cortex and the medulla of the adrenal gland. More numerous, intensely labeled varicose processes were detected in brainstem and spinal cord nuclei, including the locus coeruleus, rostral ventrolateral medulla, nuclei of the solitary tract, dorsal motor nucleus of the vagus, and intermediolateral cell column of the thoracic spinal cord. Significant perikaryal labeling for NBAT was only detected in brainstem and spinal cord following intraventricular colchicine treatment, which increased the number, distribution, and intensity of NBAT‐immunolabeled cells. These NBAT‐immunoreactive perikarya were most numerous in the locus coeruleus, rostral ventrolateral medulla, nuclei of the solitary tract, and raphe nuclei. Ultrastructural examination of the nuclei of the solitary tract of normal rats showed that NBAT was localized predominantly to axon terminals. Within these labeled terminals, NBAT was associated with large dense core vesicles and discrete segments of plasma membrane. The observed localization of NBAT suggests that this renal specific amino acid transporter subserves a role as a vesicular or plasmalemmal transporter in monoamine‐containing cells, including chromaffin cells and autonomic neurons. © 1995 Wiley‐Liss, Inc.
Effects of target deprivation on the morphology and survival of adult dorsal column nuclei neurons
Authors: Marty Serge , Peschanski Marc
Published: January 2005

During development, interaction with target cells plays a critical role in the regulation of survival of afferent neurons. In an attempt to define the role of target cells in the adult central nervous system, the somatodendritic morphology and survival of adult cuneate neurons deprived of their targets by in situ injection of kainic acid in the rat thalamus were studied.

In neuron‐specific, enolase‐immunostained sections, a 20% decrease in the mean longest diameter of the labeled cells was detected at 4 months postlesion. This somatic atrophy was accompanied by a loss of distal dendritic arborizations as observed after labeling by intracellular diffusion of horseradish peroxidase. Cytochrome oxidase staining did not reveal detectable alterations of the metabolic activity of these neurons, and an ultrastructural study also failed to demonstrate major changes in the neuronal somata. Cell counts indicated a much delayed death of 25% of the neurons at 10 months postlesion, whereas no neuronal death was detected at 7 months. The glial cells appeared unaltered both in number and in immunolabeling when using OX‐42 antibodies or antiglial fibrillary acidic protein (anti‐GFAP) antibodies.

Results obtained in this time‐course study indicate that neuronal death and alteration of the somatodendritic morphology are much delayed events after excitotoxic loss of targets. Somatodendritic atrophy occurs several months postlesion, and neuronal death occurs close to 1 year after lesion. These results suggest that the hypothesis of a necessary continuous trophic support by target cells does not hold as firmly for the adult central nervous system as during development. © 1995 Wiley‐Liss, Inc.
Organization of permanent and transient neuropeptide Y‐immunoreactive neuron groups and fiber systems in the developing hamster diencephalon
Authors: Botchkinal G. I. , Morin L. P.
Published: January 2005

The development of neuropeptide Y‐immunoreactive (NPY‐IR) cell and fiber systems in the hamster diencephalon was studied. Eight perinatal groups of NPY‐IR neurons develop into 12 distinct sets in nuclei of the adult diencephalon and mesencephalon. NPY‐IR neurons of the thalamic precommissural nucleus, nucleus of the optic tract, and olivary pretectal nucleus are derived from the superior group. Those in the adult magnocellular nucleus of the posterior commissure and deep mesencephalic nucleus are from the dorsal group. An arcuate group contributes neurons to the arcuate nucleus and median eminence and a mammillary group transiently exists in the mammillary, region. A medial group gives rise to two sets of neurons, one that migrates to the intergeniculate leaflet and another that develops in the medial nucleus reuniens. A very large ventral group provides NPY‐IR neurons to the adult medial zona incerta and caudal reticular thalamus. Groups of NPY‐IR neurons also appear in the bed nucleus of the stria terminalis and centromedian thalamic nucleus.

Superior group neurons may undergo apoptosis. In several groups, neurons become fewer during development, and NPY‐IR may disappear. NPY‐IR neurons of several groups initially migrate away from the neuroepithelial zone with later emergence of a distinct, persistent set of NPY‐IR neurons in the same neuroepithelial region. The data show that neuropeptide content can be used to identify particular sets of neurons early in development, thereby allowing migration patterns to be followed and principles of brain development to be elucidated. © 1995 Wiley‐Liss, Inc.
Cholinergic synaptic circuitry in the macaque prefrontal cortex
Authors: Mrzijak Ladislav , Pappy Miriamma , Leranth Csaba , Goldman‐Rakic Patricia S.
Published: January 2005

Surprisingly little is known about the synaptic architecture of the cholinergic innervation in the primate cerebral cortex in spite of its acknowledged relevance to cognitive processing and Alzheimer's disease. To address this knowledge gap, we examined serially sectioned cholinergic axons in supra‐ and infragranular layers of the macaque prefrontal cortex by using an antibody against the acetylcholine synthesizing enzyme, choline acetyltransferase (ChAT). The tissue bound antibody was visualized with both immunoperoxidase and silver‐enhanced diaminobenzidine sulfide (SEDS) techniques. Both methods revealed that cholinergic axons make synapses in all cortical layers and that these synapses are exclusively symmetric. Cholinergic axons formed synapses primarily on dendritic shafts (70.5%), dendritic spines (25%), and, to a lesser extent, cell bodies (4.5%). Both pyramidal neurons and cells exhibiting the morphological features of GABAergic cells were targets of the cholinergic innervation. Some spiny dendritic shafts received multiple, closely spaced synapses, suggesting that a subset of pyramidal neurons may be subject to a particularly strong cholinergic influence. Analysis of synaptic incidence of cholinergic profiles in the supragranular layers of the prefrontal cortex by the SEDS technique revealed that definitive synaptic junctions were formed by 44% of the cholinergic boutons. An unexpected finding was that chohnergic boutons were frequently apposed to spines and small dendrites without making any visible synaptic specializations. These same spines and dendrites often received asymmetric synapses, presumably of thalamocortical or corticocortical origin. Present ultrastructural findings suggest that acetylcholine may have a dual modulatory effect in the neocortex: one through classical synaptic junctions on dendritic shafts and spines, and the other through nonsynaptic appositions in close vicinity to asymmetric synapses. Further physiological studies are necessary to test the hypothesis of the nonsynaptic release of acetylcholine in the Cortex. © 1995 Wiley‐Liss, Inc.
Locus coeruleus cell loss in the aging human brain: A non‐random process
Authors: Manaye Kebreten F. , McIntire Donald D. , Mann David M. A. , German Dwight C.
Published: January 2005

Quantitative neuroanatomical techniques were used to determine whether with aging there is random or systematic loss of locus coeruleus (LC) neurons in the human brain. The cells were identified by immunohistochemical staining for the catecholaminergic enzyme tyrosine hydroxylase and/or by neuromelanin pigment content. Cell locations were mapped, using computer imaging procedures, in horizontal sections spaced 0.5 to 0.8 mm throughout the rostrocaudal extent of the nucleus in 17 cases, from 1 to 104 years of age. Neuromelanin pigment accumulated within the neurons with aging. In brains less than 25 years of age there were many fewer pigment‐containing neurons than tyrosine hydroxylase‐containing neurons; however, by the fifth decade the number of cells identified by the two markers was comparable. From the first to the tenth decade of life there is over a 50% loss of LC neurons: in four cases from “Young” individuals (1–28 years of age) there were 21,084 ± 653 tyrosine hydroxylase immunostained cells (mean ± standard error of the mean) on one side of the brain; in seven cases from “old” individuals (60–82 years of age) there were 16,502 ± 921 pigment‐containing cells; and in the three cases frpm the “oldest” individuals (103–104 years of age) there were 9,493 ± 1,236 pigment‐containing neurons. In both the “old” and “oldest” groups, compared to the “young,” there was significantly greater loss of rostral cells than caudal cells. These data indicate a systematic loss of cells such that the rostral, forebrain‐projecting neurons decrease in number with aging to a greater extent than do the caudal, spinal cord‐projecting neurons. The pattern of cell loss that occurs with normal aging is similar to that found in Alzheimer's disease and in Down's syndrome. © 1995 Wiley‐Liss, Inc.
Glial environment in the developing superior colliculus of hamsters in relation to the timing of retinal axon ingrowth
Authors: Wu Da‐Yu , Jhaveri Sonal , Schneider Gerald E.
Published: January 2005

We have examined the developmental changes of glial cell organization in the superior colliculus of embryonic and neonatal hamsters in reference to the known sequence of retinal axon ingrowth and arborization in the midbrain. Immunolocalization of vimentin, a marker for neuronal and glial cell precursors, reveals a uniform distribution of radially oriented cells, with perikarya located at the ventricular surface and thin, elongated processes fanning out toward the pia. These vimentin‐positive cells, referred to as the lateral radial cells, are present in the tectum from embryonic day (E) 10 (earliest day examined) until approximately postnatal day (P) 5. Vimentin expression in the lateral radial cells decreases markedly during the second week of postnatal life: application of DiI to the ventricular surface reveals that the pial attachment of the lateral radial cells is withdrawn and that the radial processes are gradually pulled back toward the ventricular zone. By P14, virtually no vimentin‐positive radial cells are detectable in the superior colliculus. At no time during development are the lateral radial cells immunopositive for the glial fibrillary acidic protein (GFAP); however, shorter, vimentin‐positive astrocytic profiles can be seen in the tectum, around the time the radial fibers have been withdrawn, suggesting that at least some radial cells are transformed into astrocytes that will colonize the mature colliculus.

At approximately E12, a second group of cells, referred to as the midline radial glia, is detected at the tectal midline. These cells are tightly bundled, forming a raphe in the tectum. They are intensely vimentin positive from E13 until at least P14. From the time of birth, the midline radial cells also exhibit intense immunoreactivity for GFAP.

The lateral radial cells are present in the superior colliculus prior to and during the period of neurogenesis but remain well past the time when collicular neuronal migration is completed. Pial processes of the lateral radial cells are present within the superficial tectal layers during the time retinal axons are entering this target; they may be involved in directing the growth and initial collateralization of retinotectal axons. Their withdrawal from retinorecipient collicular zones begins at about the time arbors are being elaborated on retinal axons. In constrast, the midline glia become distinct just prior to the time retinal axons enter the superior colliculus and persist during the time retinotectal projections are being fully established. These raphe glia may be involved in maintaining the laterality of the retinotectal projection. © 1995 Wiley‐Liss, Inc.
Histochemical and immunocytochemical localization of nitric oxide synthase in the central nervous system of the goldfish, Carassius auratus
Authors: Brüning Gerold , Katzbach Ralf , Mayer Bernd
Published: January 2005

The distribution of the neuronal type of nitric oxide synthase in the goldfish brain and spinal cord was investigated via NADPH‐diaphorase histochemistry and immunocytochemistry using an antiserum raised against the purified mammalian enzyme. Many structures, including magnocellular neurosecretory cells, motoneurons, mesencephalic trigeminal neurons, and radial glial fibers, were stained by the NADPH‐diaphorase reaction but were not immunoreactive. This nonspecific NADPH‐diaphorase activity was strongly reduced after preincubation of the sections. Therefore, when sections were first reacted for immunofluorescence and, thereafter, stained for NADPH‐diaphorase, a corresponding staining pattern was obtained that allowed the reliable localization of neuronal nitric oxide synthase based on both complementary staining methods.

In the telencephalon, positive neurons were concentrated in the ventral and posterior parts of the area ventralis. Many intensely stained neurons were present in various diencephalie nuclei, including the nucleus centralis posterior and the ventromedial nucleus of the thalamus, the nucleus tori lateralis, the nucleus recessus lateralis, the nucleus tuberis posterior, and the central nucleus of the inferior lobe. In the midbrain, neurons containing nitric oxide synthase were located in the periventricular zone of the optic tectum, the nucleus vermiformis, and the nucleus reticularis mesencephali. Specific staining in the cerebellum was concentrated in Golgi cells. In the hindbrain, nitroxergic neurons were numerous in all four sensory nuclei of the trigeminus, in the facial lobe, the superior olive, the inferior reticular formation, and the medial general visceral nucleus of the vagus. The dorsal horn of the spinal cord was enriched with positive neurons. A few strongly stained cells were also present in the ventral horn.

In conclusion, neurons capable of synthesizing nitric oxide occur throughout the teleost central nervous system. The presence of nitric oxide synthase in projection areas of most afferent nerves suggests a widespread involvement of nitric oxide in sensory information processing. The distribution of nitric oxide synthase‐containing neurons in certain areas, e. g., the tectum opticum and the spinal cord, indicates an evolutionarily conserved pattern. Similar to the case in other vertebrates, there appears to be no comprehensive overlap between the distribution of nitric oxide synthase and that of any other chemically characterized neuronal population described thus far. However, strongly positive cell groups in the mesencephalic reticular formation suggest the idea of an evolutionarily conserved mesopontine cholinergic system coexpressing nitric oxide synthase. © 1995 Wiley‐Liss, Inc.
Convergence of somatosensory and auditory projections in the avian torus semicircularis, including the central auditory nucleus
Authors: Wild J. Martin
Published: January 2005

Projections of dorsal column, spinal, and cochlear nuclei upon the central nucleus of the torus semicircularis (otherwise known as nucleus mesencephalicus lateralis, pars dorsalis, or MLd) and upon other toral nuclei were investigated in pigeon by anterograde and retrograde tracing and electrophysiological methods. The anatomical results showed that caudal regions of the dorsal column nuclei and medial lamina V of the upper four cervical spinal segments have extensive projections upon the contralateral central auditory nucleus and upon other nuclei of the torus, in particular the core portion of the preisthmic superficial area of Puelles et al. (L. Puelles, C. Rrobles, M. Martiez‐de‐la‐Torre, and S. Martinez, 1994, J. Comp. Neurol. 340:98–125). The projections of nucleus angularis were found to terminate throughout most of the contralateral central nucleus except the dorsomedial portion at rostral levels, where the majority of the projections of nucleus laminaris were concentrated. Nucleus angularis (and to a lesser extent nucleus laminaris) was also found to have substantial projections to certain noncentral toral nuclei, in particular to the caudomedial shell nucleus of Puelles et al. (1994). As shown positively with both Nissl and cytochrome oxidase staining and negatively with substance P labeling, this nucleus is a medial extension of more caudal regions of the central nucleus, and it is suggested that it should be included as part of the auditory midbrain.

The electrophysiological results confirmed the anatomical findings by showing that evoked potentials and multiunit activity can be recorded throughout the central and noncentral toral nuclei by using electrical stimulation of the radial nerve and auditory click stimuli. The core portion of the preisthmic superficial area, however, can be regarded as a distinct somatosensory nucleus of the midbrain.

It is concluded that there is substantial convergence of somatosensory and auditory inputs within both central auditory and noncentral nuclei of the torus semicircularis in pigeon. © 1995 Wiley‐Liss, Inc.
Cellular sites of expression of the neurokinin‐1 receptor in the rat gastrointestinal tract
Authors: Sternini Catia , Su Dennis , Gamp Patrick D. , Bunnett Nigel W.
Published: January 2005

In the digestive system, substance P is an excitatory transmitter to muscle, a putative excitatory neuro‐neuronal transmitter, a vasodilator, and a mediator in inflammatory processes. Many of the biological effects of substance P are mediated by a high‐affinity interaction with the tachykinin receptor neurokinin‐1. The aim of the present study was to identify the sites of expression of this receptor in the rat stomach and intestine by immunchistochernistry with a polyclonal antiserum raised to the intracellular C‐terminal portion of the rat neurokinin‐1 receptor. Neurokinin‐1‐ receptor immunoreactivity is present in a large population of enteric neurons. The relative density of these neurons along the gut is colon > ileum ≫ stomach. In the intestine, stained neurons have a smooth cell body with processes that can be followed within and between plexuses, and make close approaches to other neuronal cells, but do not appear to project outside the plexuses, suggesting that they are interneurons. In the stomach, neurokinin‐1 receptor‐immunoreactive neurons are infrequent and have a poorly defined and irregular shapet Neurokinin‐1 receptor immunoreactivity is also localized to numerous non‐neuronal cells in the inner portion of the circular muscle layer of the small intestine, which have the appearance of small dark smooth muscle cells or interstitial cells of Cajal. These cells are postulated to form a “stretch‐sensitive” system with the deep muscular plexus and thus constitute an important site of regulation of muscle activity. Double labeling immunofluorescence was used to simultaneously localize neurokinin‐1 receptor and substance P/tachykinin immunoreactivities. These experiments demonstrate that in the enteric plexuses, substance P/tachykinin‐immunoreactive varicose fibers encircle the cell bodies of most neurokinin‐1 receptor‐containing neurons, and in the inner portion of the circular muscle layer of the small intestine they lie close to neurokinin‐1 receptor‐immunoreactive non‐neuronal cells. In addition, some enteric‐neurons express both neurokinin‐1 receptor and substance P/tachykinin immunoreactivities. The present study provides strong evidence that the neurokinin‐1 receptor is the tachykinin receptor mediating the actions of substance P on enteric neurons and smooth muscle. © 1995 Wiley‐Liss, Inc.
Retinoid cycling proteins redistribute in light‐/dark‐adapted octopus retinas
Authors: Robles Laura J. , Camacho Jose L. , Torres Steven C. , Flores Anthony , Fariss Robert N. , Matsumoto Brian
Published: January 2005

In cephalopods, the comblex rhodopsin‐retinochrome system serves to regenerate metarhodopsin and metaretinochrome after illumination. In the dark, a solubleprotein, retinal‐binding protein (RALBP), shuttles 11‐cis retinal released from metaretinochrome located in the photoreceptor inner segments to metarhodopsin present in the rhabdoms. While in the rhabdoms, RALBP delivers 11‐cis retinal to regenerate rhodopsin and in turn binds the all‐trans isomer released by metarhodopsin. RALBP then returns all‐trans retinal to the inner segments to restore retinochrome. The conventional interpretation of retinoid cycling is contradicted by immunocytochemical studies showing that, in addition to rhodopsin, retinochrome is present in the rhabdomal compartment, making possible the direct exchange of chromophores between the metapigments with the potential exclusion of RALBP. By using immunofluorescence and laser scanning confocal microscopy, we have precisely located opsin, aporetinochrome, and RALBP in light‐/dark‐adpated octopus retinas. We found differences in the distribution of all three proteins throughout the retina. Most significantly, comparison of cross sections though light‐ and dark‐adpated rhabdoms showed a dramatic shift in position of the proteins. In the dark, opsin and retinochrome colocalized at the base of the rhabdomal microvilli. In the light, opsin redistributed along the length of the microvillar membranes, and retinochrome retreated to a location that is perhaps extracellular. RALBP was present in the core cytoplasm of the photoreceptor outer segments in the dark, and RALBP moved to the periphery in the light. Because of the colocalization of opsin and retinochrome in the dark, we believe that the two metapigments participate directly in chromophore exchange. RALBP may serve to transport additional chromophore from the inner segments to the rhabdoms and may not be immediately involved in the exchange process. © 1995 Wiley‐Liss, Inc.