bluuebunny/crossref_metadata_2025 huggingface dataset:
Development and organization of the ocular motor nuclei in the larval sea lamprey, Petromyzon marinus L.: An HRP study
Authors: Pombal Manuel A. , Rodicio M. Celina , Anadon Ramón
Published: January 2005

Retrograde transport of horseradish peroxidase (HRP) after its application into the orbit was used to investigate the development of the different ocular motor nuclei in larvae of the sea lamprey (Petromyzon marinus) and to identify their regions of origin. In the smallest larvae studied (10–19 mm in length), the oculomotor and abducens neurons were ipsilateral to the site of HRP application, whilst trochlear neurons were contralateral. These motoneurons did not have dendritic processes. In larvae more than 19 mm in length, both ipsilateral and contralateral components were found in the oculomotor and trochlear nuclei; dendrites were present, and their length and branching increased with larval age. An adult‐like pattern of topographic organization and dendritic arborization was reached in larvae of about 45–60 mm in length. In oculomotor neurons, medial dendrites appear first, then dorsolateral dendrites, and finally ventral dendries. Similarly, in trochlear neurons ventral and ventrolateral dendrites develop first, foll owed by dorsal dendrites that course either to the caudal optic tectum or to the terminal fields of the octaval and lateral line nerves in the cerebellar plate. Dorsal and ventral dendrites of the abducens neurons arise at the same time, but dorsal dendrites attain an adult‐like morphology earlier. A few motoneurons showed ventricular attachments in larvae longer than 40 mm. The significance of these processes and their possible usefulness as a marker for the regions of origin of the ocular motor nuclei are discussed. Finally, the results presented here indicate that differentiation of the ocular motor nuclei in larval lampreys precedes and is independent of the maturation of the eye at transformation.
A comparison of synapses onto the somata of intrinsically bursting and regular spiking neurons in layer V of rat SmI cortex
Authors: White Edward L. , Amitai Yael , Gutnick Michael J.
Published: January 2005

Regular spiking (RS) and intrinsically bursting (IB) neurons show distinct differences in their inhibitory responses. Under various conditions, the synaptic responses of RS cells display marked inhibitory postsynaptic potentials (IPSPs), whereas the responses of most IB cells do not (Silva et al: Soc Neurosci Abstr 14:883, 1988; Chagnac‐Amitai and Connors: J Neurophysiol 61:747, 62:1149, 1989; Connors and Gutnick: TINS 13:99, 1990). This investigation is designed to determine if differences in the inhibitory responses of RS versus IB cells are reflected in differences in the concentration of inhibitory synapses into their somata. RS and IB neurons in rat somatosensory cortex were identified by using intracellular recording and labeling, examined with the light microscope, and then serial thin‐sectioned prior to examination with the electron microscope. Axonal terminals presynaptic to their somata and proximal dendrites were identified and classified according to criteria described by Peters and coworkers (Peters et al: J Neurocytol 19:584, 1990; Peters and Harriman: J Neurocytol 19:154, 1990; 21:679, 1992). The locations of these boutons were displayed on the surfaces of 3‐D reconstructions of the somata and proximal dendrites. The reconstructions were produced directly from the serial thin sections by using a novel, electron microscopic, image‐processing computer resource. Our analysis showed no significant difference in the types and concentration of boutons presynaptic to the cell bodies and proximal dendrites of intrinsically bursting versus regular spiking neurons. We conclude that the differences observed in the inhibitory responses of intrinsically bursting versus regular spiking neurons cannot be explained by differences in the concentrations of synapses onto their somata. © 1994 Wiley‐Liss, Inc.
5‐HT innervation of reticulospinal neurons and other brainstem structures in lamprey
Authors: Di Prisco Gonzalo Viana , Dubuc Réjean , Grillner Sten
Published: January 2005

In order to determine if reticulospinal neurons involved in the control of locomotion and responsive to exogenously applied 5‐hydroxtryptamine (5‐HT) are innervated by fibers that contain serotonin, the serotoninergic innervation of reticulospinal neurons, identified by retrograde labeling with fluorescein‐conjugated dextran‐amine (FDA), was investigated by immunohistochemistry in the lamprey brainstem. A widespread distribution of 5‐HT immunoreactive (5‐HT‐ir) fibers was seen within the basal plate of the brainstem, an area containing reticulospinal somata and dendritic arborizations. Numerous 5‐HT varicose fibers were found in close relation to large reticulospinal cell bodies, particularly in the middle and anterior rhombencephalic reticular nuclei (MRRN and ARRN). Some of these reticulospinal somata were surrounded by a very dense pericellular 5‐HT innervation. 5‐HT‐ir fibers were also seen in other brain structures that are known to influence reticulospinal neurons such as the rhombencephalic alar plate containing sensory relay interneurons, cranial nerves (III–X), cerebellum, and tectum. These findings suggest that, as in the spinal cord, motor behavior controlled by reticulospinal neurons may be subject to a serotoninergic modulation. © 1994 Wiley‐Liss, Inc.
Neuropeptides myomodulin, small cardioactive peptide, and buccalin in the central nervous system of Lymnaea stagnalis: Purification, immunoreactivity, and artifacts
Authors: Santama Niovi , Wheeler Colin H. , Burke Julian F. , Benjamin Paul R.
Published: January 2005

The neuropeptides myomodulin, small cardioactive peptide (SCP), and buccalin are widely distributed in the phylum Mollusca and have important physiological functions. Here, we describe the detailed distribution of each class of peptide in the central nervous system (CNS) of the snail Lymnaea stagnalis by the use of immunocytochemical techniques combined with dye‐marking of electrophysiologically identified neurons. We report the isolation and structural characterization of a Lymnaea myomodulin, PMSMLRLamide, identical to myomodulin A of Aplysia californica. Myomodulin immunoreactivity was localized in all 11 ganglia, in their connectives, and in peripheral nerves. In many cases, myomodulin immunoreactivity appeared localized in neuronal clusters expressing FMRFamide‐like peptides, but also in a large number of additional neurons. Double‐labelling experiments demonstrated myomodulin immunoreactivity in the visceral white interneuron, involved in regulation of cardiorespiration. SCP‐like immunoreactivity also appeared in all ganglia, and double‐labelling experiments revealed that in many locations it was specifically associated with clusters expressing distinct exons of the FMRFamide gene that are differentially expressed in the CNS. Characterization of the two types of SCP‐antisera used in this study, however, suggested that they cross‐reacted with both FMRFamide and N‐terminally extended FMRFamide‐like peptides. Selective preadsorption with these cross‐reacting peptides resulted in elimination of the widespread staining and retention of bona fide SCP immunoreactivity in the buccal and pedal ganglia only. Buccalin immunoreactivity was limited to the buccal and pedal ganglia. It did not coincide with the distribution of either myomodulin or SCP. Most immunoreactive clusters were found in the pedal ganglia. © 1994 Wiley‐Liss, Inc.
Interaction between enkephalin and γ‐aminobutyric acid in the chicken retina: A double‐label immunoelectron microscopic analysis
Authors: Watt Carl B. , Glazebrook Patricia A.
Published: January 2005

In the present study, double‐label immunoelectron microscopy was used to examine the synaptic relationships between amacrine cell populations in the chicken retina that contain either enkephalin or γ‐aminobutyric acid (GABA) or both enkephalin and GABA. The objectives of the present study were twofold. First, the ultrastructural features and synaptic organization of enkephalin and enkephalin/GABA amacrine cells were compared. Second, the synaptic interactions between these populations and the population of GABA amacrine cells were examined.

A total of 475 synaptic arrangements were observed to involve enkephalin or enkephalin/GABA amacrine cell processes. The synaptic relationships of enkephalin and enkephalin/GABA amacrine cells were quite similar. Each population was pre‐ and postsynaptic to amacrine cells, postsynaptic to bipolar cells, and presynaptic to processes possibly originating from ganglion cells. A substantial percentage of each population's pre‐ and postsynaptic relationships were with the processes of GABAergic amacrine cells. Moreover, when enkephalin and enkephalin/ GABA amacrine cell processes were postsynaptic to bipolar cells, their dyadic partner was observed frequently to be a GABA amacrine cell process.

The present study suggests a diversity in the population of chicken enkephalin amacrine cells with respect to their expression of the classical inhibitory transmitter GABA. Moreover, a functional relationship between enkephalinergic and GABAergic pathways is indicated by studies showing that both enkephalin and enkephalin/GABA amacrine cells exhibit substantial synaptic interaction with GABA amacrine cells. © 1994 Wiley‐Liss, Inc.
Temporal onset of synapsin I gene expression coincides with neuronal differentiation during the development of the nervous system
Authors: Melloni Richard H. , Degennaro Louis J.
Published: January 2005

Synapsin I is the best characterized member of a family of nerve terminal‐specific phosphoproteins implicated in the regulation of neurotransmitter release. During development, the expression of synapsin I correlates temporally and topographically with synapse formation, and recent physiological studies (Lu et al. [1992] Neuron 8:521–529.) have suggested that synapsin I may participate in the functional maturation of synapses. To better understand the temporal relationship between synapsin I gene expression and particular cellular events during neuronal development, we have used in situ hybridization histochemistry to localize synapsin I mRNA throughout the rat central and peripheral nervous systems during embryonic and postnatal development. From the earliest embryonic time points assayed (E12), the expression of the synapsin I gene was detectable in both the central and peripheral nervous systems. While, in general, levels of synapsin I mRNAs were high in utero, synapsin I cDNA probes revealed specific patterns of hybridization in different regions of the embryonic nervous system. To determine precisely the temporal onset of expression of the synapsin I gene during neuronal development, we examined in detail the appearance of synapsin I mRNA during the well characterized postnatal development of granule cells of the rat cerebellum and hippocampus. In both regions, the onset of synapsin I gene expression correlated with the period of stem cell commitment to terminal differentiation. Finally, our data demonstrate that, in a second phase, synapsin I gene expression increases to a maximum for a given neuronal population during a particular phase of differentiation, i.e., synaptogenesis. © 1994 Wiley‐Liss, Inc.
Afferents to the nucleus reticularis parvicellularis of the cat medulla oblongata: A tract‐tracing study with cholera toxin B subunit
Authors: Fort Patrice , Luppi Pierre‐Hervé , Jouvet Michel
Published: January 2005

The aim of this study was to examine anatomical evidence in cats of whether the nucleus reticularis parvicellularis (Pc) is part of the circuit responsible for the inhibition of brainstem motoneurons during paradoxical sleep. For this purpose, we made iontophoretic injections of the retrograde and anterograde tracer cholera toxin B subunit (CTb) in the Pc.

After CTb injections in the Pc, a large number of retrogradely labeled neurons were seen in the central nucleus of the amygdala, the lateral part of the bed nucleus of the stria terminalis, the posterior hypothalamic areas, the mesencephalic reticular formation, the nucleus locus subcoeruleus, the nucleus pontis caudalis, other portions of the Pc, the nucleus reticularis dorsalis, the trigeminal sensory complex, and the nucleus of the solitary tract. We further found that the Pc receives (1) serotoninergic afferents from the raphe dorsalis, magnus, and obscurus nuclei; (2) noradrenergic inputs from the dorsolateral pontine tegmentum; (3) cholinergic afferents from the lateral medullary reticular formation; (4) substance P‐like afferents from the central nucleus of the amygdala, bed nucleus of the stria terminalis, periaqueductal gray, and nucleus of the solitary tract; and (5) methionine‐enkephalin‐like projections from the periaqueductal gray, the nucleus of the solitary tract, the lateral pontine and medullary reticular formation, and the spinal trigeminal nucleus. We further found that the Pc do not receive afferents from brainstem structures responsible for muscle atonia, such as the ventromedial medulla and the dorsomedial pontine tegmentum, and therefore may not be part of the circuit inhibiting the brainstem motoneurons during paradoxical sleep. © 1994 Wiley‐Liss, Inc.
Organization of N‐methyl‐D‐aspartate glutamate receptor gene expression in the basal ganglia of the rat
Authors: Standaert David G. , Testa Claudia M. , Young Anne B. , Penney John B.
Published: January 2005

Glutamate is an important neurotransmitter in the circuitry of the basal ganglia. Of the four pharmacological classes of receptors that many mediate the actions of glutamate, the N‐methyl‐D‐aspartate (NMDA) type is of particular interest insofar as it has been implicated in the neural processes underlying long‐term synaptic plasticity as well as excitotoxic injury. NMDA ligand binding sites are abundant in the structures of the basal ganglia, and NMDA receptors have been linked to neuronal excitability, neuropeptide gene expression, and regulation of dopamine release in these regions. NMDA receptors are believed to be heterooligomers of subunits from two families: NMDAR1, encoded by a single gene but alternatively spliced to produce eight distinct isoforms (NMDAR1A–H), and NMDAR2, encode by four separate genes (NMDAR2A–D).

We have used in situ hydridization with a total of 13 oligonucleotide probes to examine the expression of these genes in the rat basal ganglia. NMDAR1 subunits are expressed throughout the basal ganglia as well as in the rest of the brain; however, the alternatively spliced amino‐terminal region Insertion I is abundantly expressed only in the subthalamic nucleus and is not detectable in the neostriatum, globus pallidus, or substantia nigra pars compacta. In contrast, expression of the carboxy terminus segment Deletion I is prominent in the striatum but is not observed in other elements of the basal ganglia. NMDAR2 subunits also exhibit differential expression: NMDAR2B is abundant in the striatum, but NMDAR2A is present within the striatum only at low levels. NMDAR2C is present in the substantia nigra pars compacta only, while NMDAR2D exhibits an unusual distribution, with high levels of expression in the substantia nigra pars compacta, the subthalamic nucleus, the globus pallidus, and the ventral pallidum.

Since each isoform of the NMDAR1 and NMDAR2 subunits can confer distinct properties on the resultant NMDA receptor, these data imply that there is a high degree of regional specialization in the properties of NMDA receptors within the basal ganglia. © 1994 Wiley‐Liss, Inc.
Light and electron microscopic immunocytochemical analysis of the neurovascular relationships of choline acetyltransferase and vasoactive intestinal polypeptide nerve terminals in the rat cerebral cortex
Authors: Chédotal Alain , Umbriaco Denis , Descarries Laurent , Hartman Boyd K. , Hamel Edith
Published: January 2005

Acetylcholine or vasoactive intestinal peptide (VIP)nerve terminals closely related to intracortical blood vessels have previously been reported. Recent physiological evidence indicates that these central neuronal systems are involved in the fine control of local cerebral blood flow. In the present study, the intimate associations between choline acetyltransferase (ChAT) and VIP azon terminals and intracortical microvessels were characterized by light (LM) and electron microscopic (EM) immunocytochemistry. In semithin sections, LM analysis of the distribution of ChAT‐and VIP‐immunostained puncta juxtaposed to small intraparenchymal blood vessels demonstrated that neither type of terminal was enriched or improverished around microvessels within the cerebral cortex. At the EM level, most ChAT‐ or VIP ‐Immunolabelled elements located within a 3μm perimeter around vessel walls were axon terminals. These perivascular terminals were associated primarily with capillaries but also, to a lesser extent, with microarterioles. Even thought ChAT and VIP terminals were frequently found in the immediate vicinity (≤0.25 μm) of microvessels, they almost never contacted the outer basal lamina, usually abutting onto perivascular astroglial leaflets. There were no membrane specializations at the site of contact between ChAT or VIP terminals and perivascular astroglia. In all cortical areas examined, the average size of VIP‐Immunolabelled varicosities (0.56 ± 0.04 μm2) was significantly larger than that of their ChAT counterparts (0.32 ± 0.02 μm2; P< 0.001). Perivascular VIP terminals were more frequently engaged in synaptic contact than those immunostained for ChAT, which rarely exhibited a synaptic junction even in serial thin sections. Neither VIP nor ChAT immunostaining was ever observed in endothelial cells.

These results suggest that both acetylcholine and VIP exert their effects on intracortical microvessels through indirect, paracrine mechanisms. The marked difference in synaptic incidence and average size between both types of perivascular terminals indicates that these two vasoactive agents are primarily located in distinct neuronal populations. Further, our results show that the astrocytic glia is the major direct target for both ChAT and VIP perivascular terminals and suggest that neuronal/glial/vascular interactions are a key element in the neurogenic control of the intracortical microcirculation. © 1994 Wiley‐Liss, Inc.
Density of peptide histidine‐isoleucine‐ and vasoactive intestinal peptide‐immunoreactive nerve fibers in the sheep pineal gland is not affected by superior cervical ganglionectomy
Authors: Cozzi B. , Mikkelsen J. D. , Ravault J.‐P. , Locatelli A. , Fahrenkrug J. , Zhang E.‐T. , Møller M.
Published: January 2005

Peptide histidine‐isoleucine (PHI) is a regulatory peptide, synthesized as part of the same propeptide that includes also vasoactive intestinal peptide (VIP). The present study describes the distribution of PHI‐immunoreactive nerve fibers in the sheep pineal organ and compares their location with the distribution of VIP‐immunoreactive fibers in both normal and superior cervical ganglionectomized sheep in order to elucidate the origin of the PHI/VIP immunoreactive nerve fibers. Several PHI‐immunoreactive nerve fibers were present in the meninges and in the pineal capsule. Numerous positive nerve fibers entered the pineal gland and travelled within connective tissue spaces. Individual PHI‐positive nerve fibers were either smooth, without specialization, or varicose. Generally VIP‐ and PHI‐immunoreactive fibers were located close to connective septa and blood vessels. However, many PHIergic and VIPergic fibers possessing varicosities of variable sizes were also disperesed between pinealocytes. The distribution, density, and morphology of PHI‐ and VIP‐immunoreactive fibers in the sheep pineal gland were similar. In superior cervical ganglionectomized animals, intrapineal VIP‐ and PHI‐ immunoreactive nerve fibers were present with the same density as in control animals. In agreement, the concentration of immunoreactive VIP and PHI did not change after ganglionectomy. No VIP‐ and PHI‐immunoreactive cell bodies were observed in the superior cervical ganglia. Thus this study shows that the intrapineal VIP‐ and PHI‐immunoreactive nerve fibers do not originate from the sympathetic superior cervical ganglion. © 1994 Wiley‐Liss, Inc.
Distribution of substance P‐like immunoreactive neurons and terminals throughout the nucleus of the solitary tract in the human brainstem
Authors: McRitchie Deborah A. , Töurk Istvan
Published: January 2005

The anatomical distribution of substance P‐like immunoreactivity across the subnuclear divisions of the nucleus of the solitary tract has been examined in the human medulla oblongata. A differential distribution of neurons, fibers, and terminals was observed throughout the ten subnuclear divisions of this nucleus. Substance P‐like immunoreactive neurons were observed most frequently in the nucleus gelationsus, with moderate numbers in the medial, intermediate subnuclei and very few in the commissural, ventral, dorsal, and dorsolateral subnuclei. The paracommissural, ventrolateral, and interstitial subnuclei did not contain substance P‐like‐immunoreactive neurons. These neurons were typically bipolar and moderate‐sized to large, except for the neurons in the nucleus gelatinosus, which were substantially smaller. The highest densities of fibres and terminals were observed in the gelatinosus, medical, and intermediate nuclei, with moderate densities in the paracommissural and dorsal subnuclei. Sparse substance P‐like‐immunoreactive fibres and terminals were seen in the ventral and interstitial nuclei as well as within the solitary tract. The dorsolateral nucleus was characterized by a light distribution of fibres and terminals, except for a dense aggregation along its lateralmost border. A prominent innervation of pigmented neurons by substance P‐like‐immunoreactive terminals and fibres was also observed in the dorsolateral nucleus. The results reveal that the subnuclear complexity of the nucleus of the solitary tract is richly reflected by its differential pattern of substance P‐like‐immunoreactive structures. © 1994 Wiley‐Liss, Inc.
Horizontal cells and cone photoreceptors in primate retina: A Golgi‐light microscopic study of spectral connectivity
Authors: Ahnelt Peter , Kolb Helga
Published: January 2005

The relationship of primate horizontal cells (HC) to cone pedicles was assessed by superimposing the cone inner segment mosaic upon Golgi‐impregnated HC dendritic terminal clusters in a light microscope (LM) study. The HI, HII, and HIII types of HC were identified, hand‐drawn, photographed, and analyzed by computer graphics methods. Blue cone (B‐cones) inner segments and their projected pedicles were distinguished from red (R‐cones) and green (G‐cones) cones on morphological criteria. Thus the inclusion or avoidance of B‐cone pedicles by the various HC types dendritic terminal clusters establishes whether there is any color specificity to their connections. In addition, we made counts of the number of dendritic terminals in the clusters going to cone pedicles in the various HCs' dendritic fields and plotted these against distance the cone pedicles lay from the cell body. In this way we could evaluate the weighting of spectral type of cone input.

In general, the three HC types made the majority of their dendritic contacts with cones lying closest to their cell bodies at the center of their dendritic fields. However, HI and HIII cells, with their distinct terminal clusters, did not contact all the centrally located cones uniformly. They either avoided completely (HIII cells) or made only sparse dendritic connections (HI cells) with certain cones. The avoided or sparsely innervated cones were identified as B‐connes. HII cells, on the other hand, with their more profuse and diffusely branched dendrites, appeared to contact all overlying cone pedicles and, in contrast to HI and HIII cells, directed a relatively larger number of dendrites to B‐cone positions. Axon terminals of HIII cells appeared to contact B‐cones exclusively. © 1994 Wiley‐Liss, Inc.
Differential localization of two glutamic acid decarboxylases (GAD65 and GAD67) in adult monkey visual cortex
Authors: Hendrickson A. E. , Tillakaratne N. J. K. , Mehra R. D. , Esclapez M. , Erickson A. , Vician L. , Tobin A. J.
Published: January 2005

Adult monkey primary visual cortex contains a diverse population of stellate neurons that utilize the neurotransmitter γ aminobutyric acid (GABA). Two glutamic acid decarboxylase (GAD) enzymes that synthesize GABA, GAD65 and GAD67, were localized within these stellate neurons by in situ hybridization of 35S or digoxigenin (DIG) labeled riboprobes. Double labels were done by using 35S GAD67 riboprobe and GABA immunocytochemistry on the same section to verify that the neuronal population identified by immunocytochemistry was the same one studied in the in situ hybridization experiments.

We find that GAD65 mRNA and GAD67 mRNA are widely distributed in the cortex, with four bands of heavily labeled neurons in upper layer 2, lower 3, 4C, and 6. GAD67 labeled neurons were more obvious in layer 4Cβ, while GAD65 containing neurons were common in layer 1 and white matter. Northern blots and in situ hybridization on sections with both 35S and DIG riboprobes indicate that cortical neurons typically contain more GAD67 mRNA. Cell counts show that 18% of all cortical neurons contain GAD67 mRNA and 13% contain GAD65 mRNA, suggesting that a small population of GABA neurons might lack GAD65. Cell bodies that contain high amounts of GAD65 mRNA are prominent in layers deep 3, 4B, 4Cα, and 6 and often are the largest cells in their respective layers. Double labels demonstrate that 96% of all GABA+ neurons contain GAD67 mRNA. Neurons heavily labeled for GABA tend to have smaller cell bodies and contain less GAD67 mRNA, while lightly labeled GABA neurons are larger and contain more GAD67 mRNA.

These data indicate that most GABA neurons in monkey striate cortex contain both GAD enzymes. Although the differences in GABA content, cell size, laminar distribution, and GAD mRNA concentration suggest different requirements for GAD67 and GAD65 in cortical circuits, our experiments do not reveal what different roles these two enzymes subserve within GABAergic stellate neurons. © 1994 Wiley‐Liss, Inc.
Immunocytochemical characterization of the synaptic innervation of a single spinal neuron, the electric catfish electromotoneuron
Authors: Schikorski Thomas , Braun Norbert , Zimmermann Herbert
Published: January 2005

The electric catfish, Malapterurus electricus, possesses electric organs that are innervated by a pair of identifiable electromotoneurons located withi the cervical spinal cord. The pattern of synaptic innervation of the electromotoneurons can be revealed by an antibody against the synaptic vesicle protein SV2. Both somata and proximal dendrites are densely innervated. Several transmitters contribute to this punctuate immunoreactivity. The previously dorsal root sensory fibers, reveals a weak punctuate immunoreactivity. The previouslydescribed electrical synapses of the electromotoneurons wete visualized by an antibody against a gap‐ junctional protein. In contrast to the electromotoneurons of other electric fish, the electric catfish electromotoneurons possess many inhibitory synapses. With antibodies against glycine and against the glycinee receptor, a dense immunoreactivity of the surface of the somata and proximal dendrites can be revealed. The glycine receptor‐like immunoreactivity exhibits a patch‐like distribution similar to that revealed by the anti‐SV2 antibody. γ‐Aminobutyric acid (GABA)‐ immunopositive terminals contribute to the inhibitory electromotoneuron innervations to a lesser degree.

The chemical characteristics of the electromotoneuron innervations of Malapterurusresemble those of other spinal motoneurons rather than electromotoneurons of other electric fish. Thus our immunocytochemical study supports the view that the pattern of electromotoneuron innervations in Malapterurus reveals little specialization. The capacity for information processing required for the control of the electric organ discharge appears to be achieved by the increased integrational capacity of the newly evolved multiple dendrites and not by an additional parallel channel specific for the electromotor system. © 1994 Wiley‐Liss, Inc.
Projections to the cochlear nuclei from principal cells in the medial nucleus of the trapezoid body in guinea pigs
Authors: Schofield Brett R.
Published: January 2005

Spherical and globular cells in the cochlear nucleus provide input to the cell groups in the superior olivary complex devoted to the analysis of binaural cues. Desending projections from the superior olivary complex appear to inhibit the spherical and globular cells. It is not known which of the numerous cell types in the superior olive provide this descending input, but recent studies have shown that some of the cells are located in the medial nucleus of the trapezoid body (MTB). The present experiments were designed to determine whether the MTB projections arise from principal cells, which are known to play a role sound localization, and to determine whether their projections terminate on spherical or globular cells.

Principal cells in the MTB are characterized by their contacts with synaptic specializations called calyces, which arise from the axons of cells in the contralateral cochlear nucleus. In the first experiment, a fluorescent tracer was injected into one cochlear nucleus to label the calyces anterogradely. A dfferent tracer was injected into the opposite cochlear nucleus to label cells retogradely in the MTB. In every case, some of the labeled cells were enveloped by a labeled calyx, demonstrating that principal cells do project to the cochlear nucleus. In the second experiment, fluorescent tracers were injected into different parts of the cochlear nucleus. Anaysis of the distribution of labeled cells suggested that MTB projections selectively target the globular cell region of the cochlear nucleus. In a third experiment, the axonal arborizations arising from this projection were labeled with biocytin or wheat germ agglutinin conjugated to horseradish peroxidase. Labeled boutons appeared to contact globular cels but not spherical cells. Multipolar cells in the ventral cochlear nucleus and cells in the dorsal cochlear nucleus were also contacted.

The results suggest that MTB projections to the cochlear nucleus arise largely from principal cells and contact, at least in part, cells in the cochlear nucleus that give rise to ascending pathways involved in sound localization. © 1994 Wiley‐Liss, Inc.
Autoradiographic distribution of [3H]YM‐09151‐2, a high‐affinity and selective antagonist ligand for the dopamine D2 receptor group, in the rat brain and spinal cord
Authors: Yokoyama Chihiro , Okamura Hitoshi , Nakajima Teruo , Taguchi Jun‐Ichi , Ibata Yasuhiko
Published: January 2005

We determined the regional distribution of the dopamine D2 receptor group in the rat central nervous system by quantitative receptor autoradiography with a high‐affinity and selective antagonist, [3H]YM‐09151‐2. Saturation and competition experiments demonstrated that the binding of [3H]YM‐09151‐2 to striatal sections was saturable (Bmax=37.3 fmol/section), of high affinity (Kd=0.315 nM), and was inhibited selectively by prototypic D2 ligands.

The anatomical localization of binding sites was determined by comparison of autoradiograms and the original 3H‐ligand‐exposed sections stained with cresyl violet. Very high levels of [3H] YM‐09151‐2 binding were found in the caudate‐putamen, nucleus accumbens, tuberculum olfactorium and the insula of Calleja, to each of which midbrain dopaminergic neurons project densely. High levels of binding were also observed in other regiions rich in dopaminergic neurons and fibers including the glomerular layer of the olfactory bulb, the intermediate lobe of the pituitary, lateral septum, substantia nigra pars compacta, interfascicular nucleus, dorsal raphe nucleus, locus coeruleus, and nucleus of the solitary tract. Some regions poor in dopaminergi innervation, however, had high levels of [3H]YM‐09151‐2 binding including the molecular layer of gyrus dentatus, all layers of CA1 and the nonpyramidal layer of CA4 of hippocampus, and the deeper layer of medial entorhinal cortex. Motor neurons present in brainstem motor nuclei and spinal ventral horn were also strongly labeled. Neocortical, cerebellar, and thalamic regions had low levels of binding, except lobules 9–10 of the cerebellum, the olivary pretectal nucleus, zona incerta and lateral mammillary nucleus, in which moderate to high levels of binding were detected. Our findings concerning the widespread but region‐specific localization of [3]YM‐09151‐2 binding sites in the brain and spinal cord may prove useful for analyzing varoius dopaminergic functions in the central nervous system. © 1994 Wiley‐Liss, Inc.
Neuroendocrine control of egg‐laying behavior in the nudibranch, Archidoris montereyensis
Authors: Wiens Brenda L. , Brownell Philp H.
Published: January 2005

We describe a group of neurons with egg‐laying bioactivity in the cerebral ganglia of an opisthobranch mollusc, the nudibranch Archidoris montereyensis. These cells, the intercerebral white cells (IWCs), share morphological, biochemical, and electrophysiological characteristics with the egg‐laying neuroendocrine cells of two other molluscs, Aplysia californica (bag cells) and Lymnaea stagnalis(caudodorsal cells). The IWCs, comprising two superficial clusters of about 100 neurons each, were located immediately posterior to the intercerebral commissure in the cerebral ganglia. The somata of these cells were small ( < 20 μm) and possessed varicose, bifurcating unipolar processes that collectively formed a loop within the commissure and bilateral extensions into the cerebral ganglia. The IWC clusters and commissural processes were enveloped by a large ganglionic vascular sinus, forming a potential neurohemal release site. Homogenates of whole cerebral ganglia or isolated IWC clusters induced egg‐laying behavior within hours of injection into the hemocoel of quiescent animals. The IWCs were immunoreactive for alpha bag‐cell peptide, one of the neuropeptide transmitters encoded by the egg‐laying hormone gene of Aplysia. Electrophysiologically, the IWCs were silent neurons with large resting potentials and appeared to be highly refractory to electrical stimulation. The similarities of the IWCs to the egg‐laying neuroendocrine cells in Aplysiaand Lymnaeasuggest that they are members of a homologous group of neurons controlling egg‐laying behavior in gastropod molluscs. © 1994 Wiley‐Liss, Inc.
Light and electron microscopic characterization of cholinergic and dopaminergic structures in the striatal complex and the dorsal ventricular ridge of the lizard Gekko gecko
Authors: Henselmans J. M. L. , Wouterlood F. G.
Published: January 2005

The purpose of the present study was to visualize the morphological substrate underlying acetylcholine‐dopamine interactions in the striatal complex of the lizard Gekko gecko and to compare the results with data obtained by others in mammals. The results are also discussed in the light of data obtained previously by us on neurochemical aspects of acetylcholine‐dopamine interactions in Gekko and in rats. The study is part of a large research program in which the cholinergic and dopaminergic elements of the striatum of rats, and reptiles are studied at morphological and neurochemical levels. We employed light microscopic immunocytochemistry, using single‐label staining with antibodies against choline acetyltransferase (ChAT) and dopamine (DA) and double‐staining with antibodies against ChAT and tyrosine hydroxylase (TH). A detailed analysis of ultrastructural characteristics of ChAT‐ and DA‐immunolabeled striatal tissue was undertaken.

The morphology and synaptic relations of the ChAT‐immunopositive neurons in the basal forebrain of the lizard Gekko gecko are very similar to those of the cholinergic cells in the striatum of mammals. Probably, the cholinergic cells are in both mammals and reptiles interneurons that receive inputs of intrinsic or extrinsic origin and project upon output neurons. The location of ChAT‐immunopositive somata outside the patches of high TH‐ or DA‐immunoreactivity is at odds with the situation in the striatum of mammals and suggests the possibility of axoaxonal or axodendritic contacts at the level of these patches. We found no essential differences between the synaptic relations of the dopaminergic fibers in the striatal complex of Gekko and the conditions described for rats.

In conclusion, we found little evidence for the presence of synaptic interaction between the cholinergic and dopamindrgic systems in the striatum of this reptile. The possibility of nonsynaptic interaction, however, remains open. © 1994 Wiley‐Liss, Inc.
Immunohistochemical localization of thyrotropin‐releasing hormone in the brain of chinook salmon (oncorhynchus tshawytscha)
Authors: Matz Stuart P. , Takahashi Terry T.
Published: January 2005

This report describes the distribution of thyrotropin‐releasing hormone (TRH) immunoreactivity in the brain of juvenile chinook salmon. TRH‐positive cell bodies are observed in the preoptic region of the diencephalon, in the supracommissural nucleus of the ventral telencephalon, and in the internal cellular layer of the olfactory bulb. Immunoreactive fibers occur in the olfactory bulb, the dorsal and ventral telencephalon and were particularly extensive in hypothalamic regions. TRH‐positive fibers also are observed in the optic tectum, posterior pituitary and the brainstem.

The cell bodies in the preoptic area reside in the magnocellular preoptic nucleus. The position of these cell bodies along with the location of fibers in the hypothalamus and pituitary is consistent with the role of TRH as a hypothalamic releasing hormone. TRH‐positive cell bodies also occur in the supracommissural nucleus of the ventral telencephalon and in the internal cellular layer of the olfactory bulb. The cell bodies in the olfactory bulb may account for some of the fibers in the telencephalon, as there are TRH fibers in the olfactory tracts. The presence of TRH‐positive, fibers with bouton‐like swellings raise the possibility that the TRH peptide may act as a central neurotransmitter of neuromodulator. The results of this study suggest that TRH functions as a modulator of the pituitary activity in salmonids and that TRH is used as a transmitter or modulator in the olfactory system. The presence of TRH‐positive somata in the olfactory bulb and ventral telencephalon provides new insights into the comparative anatomy of the salmon telencephalon. © 1994 Wiley‐Liss, Inc.
Course of spinocerebellar axons in the ventral and lateral funiculi of the spinal cord with projections to the anterior lobe: An experimental anatomical study in the cat with retrograde tracing techniques
Authors: Xu Q. , Grant G.
Published: January 2005

The fiber course of the spinocerebellar tracts in the ventral and lateral funiculi of the cat spinal cord were studied by a new approach, making cordotomies at different spinal levels or lesions of the restiform body followed by injections of HRP or WGA‐HRP into the anterior cerebellar lobe. The retrogradely labeled axons showed characteristic distribution patterns related to the level and extent of the lesions. The results show the following. (1) The dorsal spinocerebellar tract (DSCT) originating ipsilaterally from the thoracic and upper lumbar segments, ascends in the dorsolateral fasciculus. It undergoes a dorsal shift during its rostral course. The tract is topically arranged and passes through the restiform body. (2) The ventral spinocerebellar tract (VSCT) arising contralaterally from lower thoracic, lumbar, and more caudal segments passes via the ventral funiculus and ascends in the ventrolateral fasciculus. This tract is also topically arranged. It makes a lateral and then a dorsal shift during its ascending course. The main portion of the VSCT enters the cerebellum via the superior cerebellar peduncle. A minor portion originating from the sacrococcygeal region enters via the restiform body. (3) The spinocerebellar fibers originating ipsilaterally from the cervical enlargement ascend in the lateralmost part of the lateral funiculus in the area between the dorsolateral and ventrolateral fasciculi. These fibers form two groups, one passing through the restiform body, the other through the superior cerebellar peduncle. (4) The spinocerebellar fibers originating contralaterally from the central cervical nucleus pass through the ventral funiculus and ascend in the lateralmost part of the lateral funiculus, mainly in the ventrolateral fasciculus. Most of the fibers seem to pass through the superior cerebellar peduncle. © 1994 Wiley‐Liss, Inc.
A physiological and structural study of neuron types in the cochlear nucleus. II. Neuron types and their structural correlation with response properties
Authors: Ostapoff E.‐Michael , Feng Jane J. , Morest D. Kent
Published: January 2005

The present study examined the morphological cell types of neurons labeled with intracellular horseradish peroxidase injections, many of them following electrophysiological recordings in the cochlear nucleus of gerbils and chinchillas. Most of the subdivisions and neuronal types previously described in the cat were identified in the present material, including spherical and globular bushy cells, stellate, bushy multipolar, elongate, octopus, and giant cells in the ventral cochlear nucleus, and a cartwheel cell in the dorsal cochlear nucleus. In many cases these structurally distinct neurons were correlated with their characteristic responses to stimulation by sound or intracellular injection of depolarizing current. The dendritic terminals of the elongate, antenniform, and clavate cells of the posteroventral cochlear nucleus link each of these cell types with neighboring structures in distinct patterns, which may provide a basis for differences in synaptic organization. These cell types differ from each other and from the stellate cells of the anteroventral cochlear nucleus. Despite their heterogeneous morphology, most of these neurons had a regular discharge in response to stimulation (choppers). Irregularly firing neurons (primary‐like) had very different structures, e. g., the spherical and globular bushy cells and the bushy multipolar neuron. They, too, represent a heterogeneous population. An onset neuron was identified as an octopus cell.

This paper compares the morphological observations with the electrophysiological properties of different cell types reported in a companion paper (Feng. et al. [1994] J. Comp. Neurol.). Together, these findings imply that response properties may be partially independent of neuronal structure. Morphologically distinct neurons can generate similar temporal patterns in response to simple acoustic stimuli. Nevertheless, the synaptic organization of these different neuron types, including their connections, would be expected to affect or alter the cells' responses to appropriate stimuli. The possibility is raised that membrane properties and synaptic organization complement and interact with each other. © 1994 Wiley‐Liss, Inc.
Fine structure of the supramammillary nucleus of the rat: Analysis of the ultrastructural character of dopaminergic neurons
Authors: Hayakawa Tetsu , Zyo Katuya
Published: January 2005

The supramammillary nucleus projecting to widespread regions contains dopaminergic and non‐dopaminergic neurons. The present study provided a comprehensive electron microscopic analysis of these dopaminergic and non‐dopaminergic neurons in the supramammillary nucleus of the rat. The normal supramammillary nucleus was composed of round spindle‐shaped, small and medium‐sized neurons (12.7 × 8.0 μm, 78.0 μm2) containing a light oval nucleus with invaginated envelop, mitochondria, Golgi apparatus, lysosomes, less‐developed rough endoplasmic reticulum, and no Nissl bodies, The majority of terminals (more than 70%) in the normal neuropil were small (diameter less than 1.0 μm) and contained round vesicles forming asymmetric synaptic contacts. The terminals often contained dense‐cored vesicles.

To determine the morphological features of dopaminergic neurons, we examined the ultrastructural localization of tyrosine hydroxylase (TH) immunoreactivity, which is the synthetic enzyme of dopamine, and compared TH‐immunoreactive neurons to non‐TH‐immunoreactive neurons. Their shape and size were similar. The average number of axosomatic terminals in a sectional plane was 5.0 in TH‐neurons and 2.4 in non‐TH‐neurons; the bouton covering ratio was 16.5% in the former and 8.6% in the latter. Both numbers were significantly larger in TH‐neurons than in non‐TH‐neurons. Serial ultrathin sections of these neurons revealed that the average total number of axosomatic terminals was 55.7 in the TH‐neuron and 28.4 in the non‐TH‐neuron. Characteristic lamellar bodies and subsurface cisternae were often present in TH neurons. There were no TH‐labeled terminals. These results indicate that dopaminergic neurons receive more inputs than neurons containing other neurotransmitters. © 1994 Wiley‐Liss, Inc.
Distribution of the α‐ketoglutarate dehydrogenase complex in rat brain
Authors: Calingasan Noel Y. , Baker Harriet , Sheu Kwan‐Fu Rex , Gibson Gary E.
Published: January 2005

The α‐ketoglutarate dehydrogenase complex (KGDHC) is a key enzyme in mitochondrial oxidation that appears critical to neurodegenerative diseases. Its activity in the brain declines in thiamine‐deficient animals, Alzheimer's disease, and Wernicke‐Korsakoff syndrome. Since selective cell populations are affected in these disorders, understanding the cellular distribution of KGDHC is important in order to define its role in the pathophysiology of these diseases. We used antisera against both bovine KGDHC and its Elk component to determine the immunocytochemical distribution of the enzyme and compare it with that of another mitochondrial enzyme, pyruvate dehydrogenase complex (PDHC) and a cholinergic neuronal marker, choline acetyltransferase (ChAT) in rat brain. Although low levels of immunoreactivity occurred in neurons, glia, and neuropil throughout the brain, some regions displayed relatively high perikaryal KGDHC enrichment. In the cerebral cortex, high immunoreactivity occurred mostly in layers III, V, and VI. The hippocampal pyramidal layer in CAl and CA2 exhibited more intense staining thah CA3. In the mammillary body, intensely labeled cells occurred in the supramammillary and lateral nuclei, while moderately stained cells predominated in the medial nucleus. The basal forebrain, basal ganglia, reticular and midline thalamic nuclei, red nucleus, pons, cranial nerve nuclei, inferior and superior colliculi, and cerebellar nuclei also contained highly immunoreactive neurons. The distribution of KGDHC overlapped with that of PDHC and colocalized to a limited extent with ChAT. These data are the first to demonstrate KGDHC immunoreactivity in discrete areas of rat brain and are vital to our understanding of selective vulnerability to metabolic insults and disease. © 1994 Wiley‐Liss, Inc.