bluuebunny/crossref_metadata_2025 huggingface dataset:
Spindle neurons of the human anterior cingul. Ate cortex
Authors: Nimchinsky Esther A. , Vogt Brent A. , Morrison John H. , Hof Patrick R.
Published: January 2005

The human anterior cingulate cortex is distinguished by the presence of an unusual cell type, a large spindle neuron in layer Vb. This cell has been noted numerous times in the historical literature but has not been studied with modern neuroanatomic techniques. For instance, details regarding the neuronal class to which these cells belong and regarding their precise distribution along both ventrodorsal and anteroposterior axes of the cingulate gyrus are still lacking. In the present study, morphological features and the anatomic distribution of this cell type were studied using computer‐assisted mapping and immunocytochemical techniques. Spindle neurons are restricted to the subfields; of the anterior cingulate cortex (Brodmann's area 24), exhibiting a greater density in anterior portions of this area than in posterior portions, and tapering off in the transition zone between anterior and posterior cingulate cortex. Furthermore, a majority of the spindle cells at any level is located in subarea 24b on the gyral surface. Immunocytochemical analysis revealed that the neurofilament protein triplet was present in a large percentage of these neurons and that they did not contain calcium‐binding proteins. Injections of the carbocyanine dye DiI into the cingulum bundle revealed that these cells are projection neurons. Finally, spindle cells were consistently affected in Alzheimer's disease cases, with an overall loss of about 60%. Taken together, these observations indicate that the spindle cells of the human cingulate cortex represent a morphological subpopulation of pyramidal neurons whose restricted distribution may be associated with functionally distinct areas.
Postnatal maturation of GABA‐immunoreactive neurons of rat medial prefron tal cortex
Authors: Vincent Stephen L. , Pabreza Laurie , Benes Francine M.
Published: January 2005

A light microscopic immunocytochemical approach has been used to examine the distribution and maturation of γ‐aminobutyric acid‐ (GABA) containing cells in rat medial prefrontal cortex (mPFC) at progressive postnatal stages. Between P1 and P5, labeled cells in the cortical plate show less differentiated morphological characteristics when compared to cells in the deeper laminae. By P10, however, most labeled cells in superficial laminae show more differentiated characteristics with some having a distinctive multipolar appearance. Between P1 and P5, there is a significant increase (50%) in the density of GABA‐containing cells in the superficial laminae, while concurrently there is an overall decrease in the subjacent deeper laminae. As the cortex continues to expand, there is a corresponding decrease in the density of GABA‐immunoreactive cells in the outer two‐thirds of the cortical mantle until approximately P15, stabilizing at 20–25 cells/100,000 μm2 for all laminae. Between P1 and P15, there is also a significant increase (133%) in the average size of labeled cells, followed by a gradual decrease of 30% between P15 and P41. During P1–7, there is a marked increase in the density of labeled axosomatic terminals in both the superficial (200%) and deep laminae (116%). In the superficial layers, however, the density of labeled terminals again increases by 86% between P12 and P18. In general, the present findings are consistent with the idea that there is a progressive maturation of the intrinsic GABAergic system in rat mPFC in a classic “inside‐out” pattern, and this involves extensive postnatal changes occurring during the first 3 postnatal weeks.
Glial cells of the lamprey nervous system contain keratin‐like proteins
Authors: Merrick Sandra E. , Pleasure Samuel J. , Lurie Diana I. , Pijak Donald S. , Selzer Michael E. , Lee Virginia M. ‐Y.
Published: January 2005

Lamprey axons regenerate following spinal cord transection despite the formation of a glial scar. As we were unable to derect a lamprey homologue of glial tibrillary acidic protien (GFAP), a major constituent of astrocytes, we studied the composition of intermediate filament(IF) proteins of lamprey glia. Monoclonal antibodies (mAbs) were raised to lamprey spinal cord cytoskeletal extracts and these mAbs were characterized by using Western blotting and immunocytochemistry. On two‐dimensional (2‐D) Western blots, five of the mAbs detected three major IF polypeptides in the molecular weight (MW) range of 45–56 kD. Further studies were conducted to determine the relationship between the lamprey glial‐specific antigen and other mammalian IF proteins. Antikeratin 8 antibody recognized two of the three polypeptides. Several of the glial‐specific mAbs reacted with human keratins 8 and 18 on Western blots. Keratin‐like immunoreactivity was found in all parts of the central and peripheral nervous systems in both larval and adult lampreys. The immunocytochemical staining patterns of glial‐specific mAbs were indistinguishable on lamprey spinal cord sections. However, on brain sections, two distinct patterns were observed. A subset of mAbs stained only a few glial fibers in the brain, whereas others stained many more brain glia, particularly the ependymal cells. The former group of mAbs recognized only the two lower MW polypeptides on 2‐D Western blots, but the latter group of mAbs recognized all three mejor IF polypeptides. This correlation is supported by the observation that the highest MW IF polypeptide has an increased level of expression in the brain relative to the spinal cord. Thus, in the lamprey, the glial cells of both spinal cord and brain express molecules similar to simple epithelial cytokeratins, but their IFs may contain these keratins in different stoichiometric proportions. The widespread presence in the lamprey of primitive glial cells containing keratin‐like intermediate filaments may have significance for the extraordinary ability of lamprey spinal axons to regenerate.
5‐HT1A receptor localization on the axon hillock of cervical spinal motoneurons in primates
Authors: Kheck N. M. , Gannon P. J. , Azmitia E. C.
Published: January 2005

Serotonin (5‐HT) has direct and specific effects on the activity of spinal cord motoneurons. The 5‐HT1A receptor has been shown to mediate motoneuron responses in spinal reflex pathways using the highly selective 5‐HT1A receptor agonist 8‐OH‐DPAT. We have developed an antipeptide antibody that recognizes a specific region (the second external loop) of the 5‐HT1A receptor. This 5‐HT1A receptor antibody labels populations of neurons and glia in the primate cervical spinal cord. The highest receptor density is present in the superficial lamina of the dorsal horn, around the central canal, and on the axon hillock of large ventral horn motoneurons. The cellular labeling pattern on motoneurons shows a single, densely stained, tapering process emanating from the perikaryon. A more diffuse label is also present throughout the soma. Dendritic labeling was not apparent. These results suggest that post‐synaptic 5‐HT1A receptors may be involved in modulating spinal motoneuron activity at the key site of action potential initiation, the axon hillock.
Characterization of inducible cyclooxygenase in rat brain
Authors: Breder Christopher D. , Dewitt David , Kraig Richard P.
Published: January 2005

Considerable debate exists regarding the cellular source of prostaglandins in the mammalian central nervous system (CNS). At least two forms of prostaglandin endoperoxide synthase, or cyclooxygenase (COX), the principal enzyme in the biosynthesis of these mediators, are known to exist. Both forms have been identified in the CNS, but only the distribution of COX 1 has been mapped in detail. In this study, we used Western blot analysis and immunohistochemistry to describe the biochemical characterization and anatomical distribution of the second, mitogen‐inducible form of this enzyme, COX 2 in the rat brain.

COX 2‐like immunoreactive (COX 2‐ir) staining occurred in dendrites and cell bodies of neurons, structures that are typically postsynaptic. It was noted in distinct portions of specific cortical laminae and subcortical nuclei. The distribution in the CNS was quite different from COX 1. COX 2‐ir neurons were primarily observed in the cortex and allocortical structures, such as the hippocampal formation and amygdala. Within the amygdala, neurons were primarily observed in the caudal and posterior part of the deep and cortical nuclei. In the diencephalon, COX 2–ir cells were also observed in the paraventricular nucleus of the hypothalamus and in the nuclei of the anteroventral region surrounding the third ventricle, including the vascular organ of the lamina terminalis. COX 2–ir neurons were also observed in the subparafascicular nucleus, the medial zona incerta, and pretectal area. In the brainstem, COX 2‐ir neurons were observed in the dorsal raphe nucleus, the nucleus of the brachium, of the inferior colliculus, and in the region of the subcoeruleus. The distribution of COX 2‐ir neurons in the CNS suggests that COX 2 may be involved in processing and integration of visceral and special sensory input and in elaboration of the autonomic, endocrine, and behavioral responses.
Early postmitotic neurons transiently express TOAD‐64, a neural specific protein
Authors: Minturn Jane E. , Geschwind Daniel H. , Fryer Hugh J. L. , Hockfield Susan
Published: January 2005

To identify proteins involved in the early development of the mammalian cerebral cortex, we previously used two‐dimensional gels to compare proteins synthesized at different stages in corticogenesis in the embryonic rat at embryonic day 14 (E14), E17, and E21. During this period, the cortex develops from a morphologically homogeneous population of proliferative precursor cells into a complex structure containing a diverse array of terminally differentiated neurons. Several proteins are up‐regulated coincident with the generation of postmitotic neurons. Here we describe the purification, partial amino acid sequencing, and characterization of one of these proteins, TOAD‐64 (Turned On After Division; 64 kDa), using polyclonal antisera to two synthetic peptides from the protein. This analysis reveals that TOAD‐64 is a 64,000 Da protein that increases in abundance over the period of corticogenesis and then subsequently decreases to very low levels in the adult. The protein is neural specific and is expressed by postmitotic neurons as they begin their migration out of the ventricular zone into the developing cortical plate. It is expressed in advance of most other neuronal proteins. Progenitor cells do not express TOAD‐64. Therefore, this protein is a marker for postmitotic cells that have made a commitment to a neuronal phenotype. The extremely early expression, the relative abundance in newly born neurons, as well as the restriction in expression to the period of initial neuronal differentiation suggest that TOAD‐64 may be a key structural protein for early neuronal function.
Distribution and spatial geometry of dopamine interplexiform cells in the retina. II. External arborizations in the adult rat and monkey
Authors: Savy Claudine , Moussafi Fatima , Durand Jacques , Yelnik Jérôme , Simon Axelle , Nguyen‐Legros Jeanine
Published: January 2005

The morphology and distribution of dopaminergic interplexiform cells in adult rat and monkey retinas were analyzed to determine any correlation with the function of dopamine in the outer retinal layers. The retinas were processed as whole mounts for tyrosine hydroxylase immunohistochemistry. There was a network formed by the sclerally directed processes of interplexiform cells in the inner nuclear, outer plexiform, and outer nuclear layers running throughout the retina. Their density was higher in the superior retina than in the inferior retina of the rat and was especially high in the superior temporal quadrant. The external network in this quadrant was significantly less dense in the monkey than in the rat, as are the interplexiform cells. The somata of interplexiform and other dopaminergic cells were about the same size in both rats and monkeys. Computer‐assisted reconstruction of external arborizations of individual cells showed that external processes lay very close to horizontal and photoreceptor cells and also to blood capillaries. Because they were long, thin, and highly varicose; branched at right angles; and often arose from an axon hillock, the external processes were identified as axons. Therefore, we define the dopaminergic interplexiform cells as multiaxonal neurons, with at least one outwardly directed axon that reaches the outer plexiform layer. The function of the network of external processes from the interplexiform dopaminergic cells is discussed in terms of modulating the release of dopamine to external layers.
Immunohistochemical study of two phosphoinositide‐linked metabotropic glutamate receptors (mGluR1α and mGluR5) in the cat visual cortex before, during, and after the peak of the critical period for eye‐specific connections
Authors: Reid S. N. M. , Romano C. , Hughes T. , Daw N. W.
Published: January 2005

The distribution of two phosphoinositide‐linked metabotropic glutamate receptors (mGluR1α and mGluR5) was studied immunohistochemically in area 17 before, during and after the peak of use‐dependent modification of eye‐specific connections. In the adult, mGluR1α immunoreactivity is high in all layers except layer IV, where mGluR5 immunoreactivity is concentrated. This difference in distribution indicates different functions for these two receptor subtypes. The laminar pattern of mGluR1α immunoreactivity is similar in all three ages, but the overall labeling intensity decreases after the peak (6 weeks of age) of the critical period. The laminar pattern of mGluR5 immunoreactivity changes with age, It is expressed in most layers at 2 days of age and is found mainly in layer IV in the adult. This laminar distribution and developmental pattern match the distribution and the development of the geniculocortical terminals. The change in mGluR1α labeling intensity and mGluR5 laminar distribution over time is consistent with both of these mGluRs being involved in sensory‐dependent plasticity for eye‐specific connections in the visual cortex.
Cortical areas within the lateral sulcus connected to cutaneous representations in areas 3b and 1: A revised interpretation of the second somatosensory area in macaque monkeys
Authors: Burton Harold , Fabri Mara , Alloway Kevin
Published: January 2005

Cortical connections between various body representations in areas 3b and 1 and lateral parietal cortex were examined in 18 macaque monkeys. We injected tracers (Fast Blue, Diamidino Yellow, Horseradish Peroxidase, and Rhodamine Dextran), alone or in combination, into closely related cutaneous responsive sites, e. g., adjacent digits. Separated patches of labeling were found across the parietal operculum and insula for all injected locations. On the basis of cytoarchitectural criteria, the labeled regions include the second somatosensory area (SH), retroinsular area (Ri) and granular insula (Ig). Assuming the connections are homotopical from physiologically identified body representations in primary somatosensory cortex, the labeling patterns in SII include complete anterior and posterior body maps. The orientation of the body is erect in the posterior and supine in the anterior SII region. Area 3b has greater density of connections with anterior SIL The maps are mirror images aligned along the distal extremities. The anterior‐posterior (A‐P) length of the “SII region” exceeds 7 mm; it extends in the coronal plane from the fundus of the lateral sulcus to surface cortex near the anterior tip of the intraparietal sulcus. Two additional topographically organized maps are likely in Ri. These are “worm‐like” body maps oriented along the A‐P axis and joined at the head representation. Connections with the center of Ig are not somatotopically organized.

The diversity of somatosensory areas in lateral parietal cortex revealed by the labeled connections was discussed in reference to prior mapping of SII in monkeys and was compared to reports of multiple areas in this region of cortex in other species.
Transneuronal labeling of neurons in the adult rat brainstem and spinal cord after injection of pseudorabies virus into the urethra
Authors: Vizzard Margaret A. , Erickson Vickie L. , Card J. Patrick , Roppolo James R. , de Groat William C.
Published: January 2005

Transneuronal tracing techniques were used to identify sites in the central nervous system involved in the neural control of urethral function. The distribution of virus‐infected neurons was examined in the spinal cord and brainstem at various intervals (56‐96 hours) following pseudorabies virus (PRV) injection into the urethra. In the lumbosacral (L6‐Sl) spinal cord at 56 hours, neurons containing PRV immunoreactivity (PRV‐IR) were located in the region of the sacral parasympathetic nucleus (SPN), around the central canal, and in the dorsal commissure. Some animals also exhibited PRV‐IR in cells in the L6 dorsolateral motor nucleus. At longer survival times (72‐96 hours), PRV‐IR cells were observed in the superficial and deeper laminae of the dorsal horn, and increased numbers of PRV‐IR cells were consistently detected in the region of the SPN, around the central canal, and in the dorsal commissure. PRV‐IR fiber‐like staining also occurred along the lateral edge of the dorsal horn extending from Lissauer's tract to the region of the SPN. In rostral lumbar segments (Ll‐L2), PRV‐IR cells were located in the region of the dorsal commissure and the intermediolateral cell nucleus (IML), around the central canal, and in the dorsal horn. After 72‐84 hours, PRV‐IR cells were also noted at more rostral levels of the neuraxis including the medulla, pons, midbrain, and diencephalon. At 72 hours, PRV‐IR cells were consistently observed in Barrington's nucleus (pontine micturition center), nucleus raphe magnus (RMg), parapyramidal reticular formation, and the A5 and A7 regions. At 78–84 hours, additional regions exhibited PRV‐IR cells, including the periaqueductal gray, locus coeruleus, the dorsal and ventral subcoeruleus alpha, and the red nucleus. A few cells were also located in the lateral hypothalamic area. This distribution of PRV‐labeled cells in the spinal cord and brainstem is similar in many respects to the distribution of cells labeled in previous studies by PRV injection into the urinary bladder. This overlap of urethra and bladder neurons is consistent with the results of physiological experiments indicating a close coordination between the central nervous control of bladder and urethral activity.
Anatomical compartments in the white matter of the rabbit flocculus
Authors: Tan J. , Simpson J. I. , Voogd J.
Published: January 2005

The white matter of the rabbit flocculus is subdivided into five compartments by narrow sheets of densely staining acetylcholinesterase‐positive fibers. The most lateral compartment is continuous with the C2 compartment of the paraflocculus and contains the posterior interposed nucleus. The other four compartments are numbered from lateral to medial as floccular compartments 1, 2, 3, and 4 (FC1 −4). FC1 −3 continue across the posterolateral fissure into the adjacent folium (folium p) of the ventral paraflocculus. FC4 is present only in the rostral flocculus. In the caudal flocculus FC1 and FC3 about dorsal to FC2. Fibers of FC1 −4 can be traced into the lateral cerebellar nucleus and the floccular peduncle. The presence of acetylcholinesterase in the deep stratum of the molecular layer of the flocculus and ventral paraflocculus distinguishes them from the dorsal paraflocculus. The topographical relations to the flocculus and the floccular peduncle with group y and the cerebellar nuclei are discussed. © 1995 Wiley‐Liss, Inc.
Zonal organization of the climbing fiber projection to the flocculus and nodulus of the rabbit: A combined axonal tracing and acetylcholinesterase histochemical study
Authors: Tan J. , Gerrits N. M. , Nanhoe R. , Simpson J. I. , Voogd J.
Published: January 2005

The localization and termination of olivocerebellar fibers in the flocculus and nodulus of the rabbit were studied with anterograde axonal transport methods [wheatgerm agglutinin‐horseradish peroxidase (WGA‐HRP) and tritiated leucine] and correlated with the compartments in the white matter of these lobules delineated with acetylcholinesterase histochemistry (Tan et al. J. Comp. Neurol., 1995, this issue). Olivocerebellar fibers originating from the caudal dorsal cap travel through floccular compartments FC2 and FC4 to terminate as climbing fibers in floccular zones FZII and FZIV. Fibers from the rostral dorsal cap and the ventrolateral outgrowth traverse compartments FC1 and FC3, which are interleaved with compartments FC2 and FC4, and terminate in zones FZI and FZIII. Fibers from the rostral pole of the medial accessory olive traverse the C2 compartment and terminate in the C2 zone. FZI ‐III extend into the adjoining folium (folium p) of the ventral paraflocculus. The C2 zone continues across folium p into other folia of the ventral paraflocculus and into the dorsal paraflocculus. Four compartments and five zones were distinguished in the nodulus. Medial compartment XC1 contains olivocerebellar fibers from the caudal dorsal cap and subnucleus β that terminate in the XZI zone. Olivocerebellar fibers from the rostral dorsal cap and the ventrolateral outgrowth occupy XC2 and terminate in XZII. The XC4 compartment contains fibers from both the caudal dorsal cap and from the rostral dorsal cap and the ventrolateral outgrowth. The latter terminate in a central portion of the XZIV zone. The dorsomedial cell column projects to the XZIII zone, which is present only in the dorsal part of the nodulus, The rostral, medial accessory olive projects to the XZV zone, which occupies the lateral border of the nodulus. These results confirm and extend the conclusions of Katayama and Nisimaru ([1988] Neurosci. Res. 5:424–438) on the zonal pattern in the olivo‐nodular projection in the rabbit. Additional observations were made on the presence of a lateral A zone (Buisseret‐Delmas [1988] Neurosci. Res. 5:475–493) in the hemisphere of lobules VI and VII. Retrograde labeling of the nucleo‐olivary tract of Legendre and Courville ([1987] Neuroscience 21:877–891) was observed after WGA‐HRP injections into the inferior olive including the rostral dorsal cap and the ventrolateral outgrowth. The anatomical and functional implications of these observations are discussed. © 1995 Wiley‐Liss, Inc.
Immunocytochemical localization of sGnRH and cGnRH‐II in the brain of goldfish, Carassius auratus
Authors: Kim Myung‐Hee , Oka Yoshitaka , Amano Masafumi , Kobayashi Makito , Okuzawa Koichi , Hasegawa Yoshihisa , Kawashima Seiichiro , Suzuki Yuzuru , Aida Katsumi
Published: January 2005

The immunocytochemical distribution of salmon gonadotropin‐releasing hormone (sGnRH) and chicken GnRH‐II (cGnRH‐II) neurons in the brain of goldfish was examined using respective antisera. Salmon GnRH‐immunoreactive (ir) cell bodies were localized in the area between the olfactory nerve and the olfactory bulb (the terminal nerve ganglion), the ventral telencephalon, the preoptic area, and the hypothalamus. Chicken GnRH‐II‐ir cell bodies were observed in the same areas as were those of sGnRH, although the number of cell bodies were fewer than those of sGnRH. In addition, chicken GnRH‐II‐ir cell bodies were also observed in the midbrain tegmentum where no sGnRH‐ir cell bodies were found. Both sGnRH‐ir and cGnRH‐II‐ir fibers were distributed not only in the hypothalamus and the pituitary gland but also in various brain areas from the olfactory bulb to the spinal cord.

The wide distribution of GnRH‐ir fibers suggests that in the goldfish, sGnRH and cGnRH‐II not only regulate gonadotropin release from the pituitary gland but also function as neuromodulators in various brain regions. © 1995 Wiley‐Liss, Inc.
Structure–function relationships in rat brainstem subnucleus interpolaris. XI. Effects of chronic whisker trimming from birth
Authors: Jacquin Mark F. , Rhoades Robert W. , Klein Bradley G.
Published: January 2005

Whisker trimming from birth reduces activity and alters receptive fields (RFs) in the barrel cortex and thalamus. To assess whether or not this reflects deprivation effects on trigeminal (V) first‐ and second‐order neurons, 59 primary afferents and 343 cells in V brainstem subnucleus interpolaris (SpVi) were studied in rats whose whiskers were trimmed daily for 6–9 weeks from birth. Deprivation did not effect brainstem somatotopy or primary afferent RFs. However, many SpVi cells had abnormal RFs and higher‐order inputs, resembling the changes caused by infraorbital nerve injury. For example, in controls, only 3% of whisker‐sensitive local circuit neurons responded to more than one whisker, whereas 35% of the deprived and 41% of the infraorbital nerve cut samples had multiwhisker RFs. Deprived rats also had higher than normal incidences of cells with split or absent RFs, RFs spanning more than one V division, intermodality convergence, and directional or high‐velocity sensitivity. Because these changes mimic those caused by nerve section, deprivation may underlie some nerve injury effects on V brainstem RF size and character.

Insofar as cytochrome oxidase, anterograde labeling, and unit recordings revealed normal topography in deprived primary afferents and SpVi cells, RF changes in SpVi cells may reflect altered SpVi circuitry. To test this hypothesis, we assessed the morphology of 32 similarly deprived V primary afferents. In SpVi, deprived fibers had normal numbers of collaterals with normal shapes, transverse arbor areas, and topography. However, the total number of boutons per collateral was significantly reduced. Thus, deprivation effects on V higher‐order RFs reflect quantitative changes in V afferent terminals. © 1995 Wiley‐Liss, Inc.
Motoneurons dorsolateral to the central canal innervate perineal muscles in the mongolian gerbil
Authors: Ulibarri Catherine , Popper Paul , Micevych Paul E.
Published: January 2005

The Mongolian gerbil provides a model in which sexually dimorphic areas in the hypothalamus are correlated with sociosexual behaviors such as scent marking and male copulatory behavior. To extend this model, investigations were conducted to determine whether sexually dimorphic areas existed in the spinal cord that could be relevant to male sexual behavior. The focus of these investigations was the perineal muscles associated with the penis. Therefore, this research identified the spinal motoneurons that innervate the bulbocavernosus, levator ani, anal sphincter, and ischiocavernosus muscles of Mongolian gerbils. The motoneuron pool that innervates the bulbocavernosus, levator ani, and anal sphincter was designated the spinal nucleus of the bulbocavernosus (SNB), as for other species of rodents. The motoneuron pool innervating the ischiocavernosus was identified as the dorsolateral nucleus, again, to be consistent with the designation for other rodents. The motoneurons of the gerbil SNB were distributed dorsolateral to the central canal in the lumbosacral transition zone of the spinal column. These motoneurons are located in the region classically defined as area X of the spinal cord. The number of SNB motoneurons was sexually dimorphic, with male gerbils having about five times as many SNB motoneurons as do female gerbils. The size of SNB motoneurons was also sexually dimorphic. The SNB motoneurons of males were 1. 5 times larger than the SNB motoneurons of females. The effects of adult castration on the male SNB were also studied. After castration, the size, but not the number, of SNB motoneurons in males was significantly decreased. This decrease was prevented by testosterone treatment. The percentage of calcitonin gene‐related peptide (CGRP)‐immunoreactive SNB motoneurons was also affected by adult castration. The percentage of CGRP‐immunoreactive motoneurons was significantly decreased after adult castration. Again, this decrease was reversed by testosterone treatment. These findings suggest that the SNB of gerbils is sexually dimorphic and is sensitive to circulating levels of gonadal steroids. The unique placement of the SNB motoneurons suggests that an alternative laminar organizational scheme may be necessary for Mongolian gerbil. © 1995 Wiley‐Liss, Inc.
Distribution of calcium‐binding proteins within the parallel visual pathways of a primate (Galago crassicaudatus)
Authors: Johnson J. K. , Casagrande V. A.
Published: January 2005

Bush babies possess three distinct parallel pathways to striate cortex (V1 or area 17). The calcium‐binding proteins parvalbumin (PV) and calbindin (CB) typically show complementary regional distributions in the brain, often associated with specific aspects of functionally related groups of cells. We asked whether PV+ and CB+ immunoreactivity differentiate central visual parallel pathways in this species.

Results show that PV and CB cell and neuropil staining is strongly complementary in the lateral geniculate nucleus (LGN) and is associated with separate parallel pathways. CB+ immunoreactivity is dense, but cytochrome oxidase (CO) staining is light in the paired koniocellular layers. PV+ and CO+ immunoreactivity is most dense in the parvocellular and magnocellular layers. Combined analyses of cell size, retrograde labeling, and double labeling have confirmed that all PV+ and CB+ LGN cells are geniculocortical relay cells; none was found to be σ‐aminobutyric acid (GABA)ergic. In V1, dense PV+ neuropil closely matches the expression of CO in layer 4 and in the blobs of layer 3. CB+ staining is most dense in layers 2 and 3A and is not strongly expressed within the CO interblobs. Finally, PV and CB are not found in related parallel pathway components in the LGN and V1 (e. g., in V1, CO blobs exhibit dense PV+ neuropil, yet they are targets of the small K geniculocortical relay cells that are CB+ in the LGN). Our findings support the view that three functionally distinct visual pathways project to V1 from the LGN. However, the differences in the patterns of localization of PV and CB in the LGN and in V1 suggest that these proteins may be utilized in different ways in these two visual areas. © 1995 Wiley‐Liss, Inc.
The increase in B‐50/GAP‐43 in regenerating rat sciatic nerve occurs predominantly in unmyelinated axon shafts: A quantitative ultrastructural study
Authors: Verkade P. , Oestreicher A. B. , Verkleij A. J. , Gispen W. H.
Published: January 2005

The growth‐associated protein B‐50/GAP‐43 is thought to play a crucial role in axonal growth. We investigated, by quantitative immunoelectron microscopy, whether there are differences in the subcellular distribution of B‐50 in unmyelinated and myelinated axons of intact and regenerating sciatic nerves. Adult rats received an unilateral sciatic nerve crush and were euthanized 8 days later. Nerve pieces proximal from the crush site were embedded, and B‐50 was visualized by specific B‐50 antibodies and immunogold detection in ultrathin sections.

The density of B‐50 at the plasma membrane of unmyelinated axon shafts was significantly increased in the ipsilateral regenerating nerve in comparison to that of the contralateral intact nerve. In contrast, there was no significant difference in the B‐50 density at the axolemma of myelinated regenerating and intact axon shafts.

In the contralateral intact nerve, more B‐50 was associated with the axolemma of unmyelinated axons than with the plasma membrane of myelinated axons. The density of axoplasmic B‐50 was similar in intact unmyelinated and myelinated axon shafts, but was higher in regenerating nerve than in intact nerve. This suggests that enhanced axonal transport of B‐50 occurs during axon outgrowth.

Our study demonstrates a differential subcellular distribution of B‐50 in unmyelinated and myelinated axon shafts in both the intact and regenerating sciatic nerve, indicating a differential inducible capacity for remodeling of the axon shafts. © 1995 Wiley‐Liss, Inc.
Characterization of crustacean cardioactive peptide‐like immunoreactivity in the horseshoe crab, Limulus polyphemus
Authors: Groome James R. , Lehman Herman K.
Published: January 2005

The localization of crustacean cardioactive peptide‐like immunoreactivity in the horseshoe crab Limulus polyphemus was investigated with enzyme‐linked immunosorbent assay and fluorescence microscopy. Immunoreactivity was quantified in the opisthosomal nervous system (67.7 ± 11.4 ng/g), cardiac ganglion (45.0 ± 10.3 ng/g), prosomal nervous system (28. 5 ± 6. 6 ng/g), and midgut (24.6 ± 6.7 ng/g). In the brain, immunoreactive somata were observed in ganglion cells of the central body, in the medullary group and within the ventral medial group. Clusters of immunoreactive cells were found in each of the circumesophageal, pedal ganglia, and in the opisthosomal, abdominal ganglia. In the periphery, immunoreactive varicose fibers were observed in branches of the intestinal nerves, and near longitudinal and circular muscle fibers of the midgut. Immunoreactivity was observed in the cardiac ganglion and myocardium of the neurogenic heart. Synthetic crustacean cardioactive peptide had slight excitatory effects on the cardiac rhythm at doses up to 10−6 M. This peptide had excitatory effects on the midgut at nanomolar doses. Ventral nerve cord extracts were partially purified with reverse phase high performance liquid chromatography. Two regions of immunoreactivity were detected, one of which coeluted with the authentic peptide. The distribution of crustacean cardioactive peptide immunoreactivity is compared with other transmitter systems in the Limulus nervous system, and myotropic actions of this peptide are discussed with respect to peptidergic modulation of intestinal motility. © 1995 Wiley‐Liss, Inc.
Neuronal organization of the cochlear nuclei in alligator lizards: A light and electron microscopic investigation
Authors: Szpir Michael R. , Wright Debora D. , Ryugo David K.
Published: January 2005

The organization of neurons and fibers in the cochlear nuclei of the alligator lizard (Gerrhonotus multicarinatus) was examined with light and electron microscopy. In this species, much is known about the anatomy and physiology of the inner ear including the cochlear nerve, but little is known about the synaptic connections of cochlear fibers on second‐order neurons. These data will help to develop general principles addressing the cellular organization of the vertebrate auditory system.

Subdivisions of the cochlear nuclei were defined on the basis of their histologic appearance and neuronal composition. Neuron classes were proposed from their light microscopic and ultrastructural features. Nucleus magnocellularis medialis consists of a homogeneous population of neurons called “lesser ovoid” cells. Nucleus magnocellularis lateralis consists of “greater ovoid” and “small” cells. Nucleus angularis lateralis consists of “spindle” cells. Lastly, nucleus angularis medialis contains a population of large neurons called “duckhead” and “multipolar” cells, and a population of smaller neurons called “bulb” and “agranular” cells.

These neuron populations are differentially innervated by tectorial and free‐standing cochlear fibers that are associated with separate frequency ranges. All neuronal populations except agranular cells were observed to receive synaptic input from cochlear nerve fibers. In nucleus magnocellularis medialis and nucleus angularis medialis, primary afferents form both chemical and electrical synapses with resident neurons. These observations imply that acoustic information is synaptically processed in fundamentally distinct ways in the cochlear nuclei of alligator lizards and distributed along separate neural circuits. Thus, the characteristic structural and functional dichotomy of the alligator lizard inner ear is extended to central auditory pathways by way of cochlear nerve projections. © 1995 Wiley‐Liss, Inc.
Identification of cells expressing galectin‐1, a galactose‐binding receptor, in the rat olfactory system
Authors: Puche A. C. , Key B.
Published: January 2005

Interactions between carbohydrate ligands and their receptors play an important role in cell adhesion and migration in many tissues. Cell‐surface carbohydrates that contain terminal galactose have previously been implicated in primary sensory axon growth in the rodent olfactory system. The aim of the present study was to determine whether galectin‐1, a galactose‐binding receptor, was expressed within the rat primary olfactory pathway. Immunohistochemical and in situ hybridisation analyses revealed expression of galectin‐1 by primary sensory olfactory neurons during the major embryonic period of axonogenesis as well as in maturity. In the adult olfactory bulb, galectin‐1 was expressed by both second‐order projection neurons and interneurons and was selectively localised to the synaptic neuropil layers. Mitral cells, the principal postsynaptic target of primary olfactory axons, began expressing this lectin soon after genesis and maintained high levels into adulthood. The expression of galectin‐1 in the primary olfactory pathway and olfactory bulb neuropil suggests a role for this lectin both in the initial formation and in the subsequent maintenance of neuronal connections between the peripheral and the central olfactory neurons as well as between neurons within the bulb. © 1995 Wiley‐Liss, Inc.
Origin of ascending projections to the nuclei of the lateral lemniscus in the big brown bat, Eptesicus fuscus
Authors: Huffman Russell F. , Covey Ellen
Published: January 2005

The nuclei of the lateral lemniscus in the echolocating bat, Eptesicus fuscus, are large and highly differentiated. In each nucleus, different characteristic response properties predominate. To determine whether the dissimilar response properties are due in part to dfferential ascending input, we examined the retrograde transport from small deposits of horseradish peroxidase (HRP) or HRP conjugated with wheat germ agglutinin (WGA‐HRP) in the nuclei of the lateral lemniscus.

The intermediate nucleus (INLL) and the two divisions of the ventral nucleus (VNLL) receive almost exclusively monaural input from the anteroventral and posteroventral cochlear nuclei and from the medial nucleus of the trapezoid body. Lesser inputs originate in the lateral nucleus of the trapezoid body and the ventral periolivary area. Although the three monaural nuclei of the lateral lemniscus all receive input from the same set of nuclei, and from the same identified cell types in the cochlear nucleus, there is a difference in the relative proportions of input from these sources. The dorsal nucleus (DNLL) receives input mostly from binaural structures, the lateral and medial superior olives and the contralateral DNLL, with only a minor projection from the coc hlear nucleus. The lateral and medial superior olives project bilaterally; the bilateral projection from the medial superior olive is unusual in that it is found in only a few mammalian species.

The results show a segregated pattern of binaural projections to DNLL and monaural projections to INLL and VNLL that is consistent with the binaural response properties found in DNLL and the exclusively monaural response properties found in INLL and VNLL. The differences in response properties between monaural nuclei, however, are not due to input from different nuclei or cell types but may be influenced by differing magnitudes of the constituent ascending projections. © 1995 Wiley‐Liss, Inc.
Development of muscarinic receptor subtypes in the forebrain of the mouse
Authors: Hohmann Christine F. , Potter Elizabeth D. , Levey Allan I.
Published: January 2005

Cholinergic mechanisms are involved in the regulation of developmental events in the nervous system. Muscarinic cholinergic receptors are thought to be the predominant mediator of cholinergic neurotransmission in the forebrain; however, their developmental role is less well understood. The present study takes advantage of subtype‐specific antibodies to muscarinic receptor proteins to investigate the cellular localization of the subtypes in developing mouse forebrain. Receptor protein expression wag assessed between postnatal day (PND) 5 and adulthood by immunocytochemical methods with antibodies to ml, m2, and m4 receptors, the most abundant subtypes in rodent brain. We have found dramatic developmental changes in the distribution of all three receptors. In the adult mouse, ml and m2 receptor immunoreactivity displayed complementary staining patterns in most forebrain areas with m4 sharing simiarities in pattern with both ml and m2. Furthermore, each receptor was expressed transiently in gray matter areas or fiber bundles at various developmental stages. The m4 receptor was also expressed in developing blood vessels. Such transient immunoreactivity was usually associated with times and areas of dynamic morphogenesis, thus suggesting distinct roles for the receptor subtypes in ontogenetic events. © 1995 Wiley‐Liss, Inc.
Organization of connections between the thalamic reticular and the anterior thalamic nuclei in the rat
Authors: Lozsádi D. A.
Published: January 2005

The thalamic reticular nucleus (TRN) receives topographically organized input from specific sensory nuclei such as the lateral geniculate nucleus. The present study shows this in the rat. However, the pattern of thalamic connections to the limbic reticular sector is unknown.

Injecting biocytin into the ventral parts of anteroventral and anteromedial nuclei labeled neurons and axons in the rostral TRN. Filled axon collaterals and their terminals occupied a rectangular sheet in a plane close to the horizontal, and were confined to the inner zone (the medial portion) of the limbic TRN. Retrogradely filled cells were in the middle of the rostral pole in the same horizontal plane, receiving synapses from surrounding labeled boutons. In electron micrographs, thalamic terminals were found to contain round, densely packed synaptic vesicles and formed asymmetrical synapses onto reticular somata and dendritic profiles. Displacing the injection site along the dorso‐ventral and rostro‐caudal axs in the anterior nuclei produced corresponding shifts of antero‐ and retrograde labeling within the inner reticular zone. Projections from the dorsal portions of the anterior nuclei did not follow this pattern. Axons from the anterodorsal nucleus occupied the rostralmost tip of both inner and outer zones of the dorsal limbic sector. In accordance with earlier reports, the limbie sector was found to represent several dorsal thalamic nuclei parallel to each other medio‐laterally. A topography is described for the limbic reticulo‐thalamic connections, suggesting that the rostral TRN is able to influence circumscribed areas of the limbic thalamus. © 1995 Wiley‐Liss, Inc.
Distribution of big tau in the central nervous system of the adult and developing rat
Authors: Boyne L. J. , Tessler A. , Murray M. , Fischer I.
Published: January 2005

The diversity of neuronal morphology and function is correlated with specific expression of various microtubule associated proteins (MAPs). One of the major neuronal MAPs, tau, has multiple isoforms formed as a result of alternative splicing and phosphorylation that are differentially expressed during development. Big tau is a high molecular weight isoform that contains an additional large exon (4a) and is expressed primarily by neurons in the peripheral nervous system (PNS). We cloned the complete 4a exon in an expression vector, isolated the recombinant protein and produced antibodies specific to Big tau that were used to localize Big tau in the developing spinal cord and in the adult central nervous system (CNS). In developing spinal cord, Big tau is first expressed in the central projections of the dorsal root ganglia neurons and in motor neurons at embryonic day 18 and postnatal day 2, respectively. In the adult rat CNS, almost all neurons that extend processes into the PNS express Big tau, including all cranial nerve motor nuclei and central processes of most sensory ganglia; of these ganglia, only the bipolar neurons of the olfactory, Vestibular and spiral ganglia did not express Big tau. Retinal ganglion cells are the only CNS neurons, whose processes remain entirely within the CNS, that express high levels of Big tau. The limited and specific distribution of Big tau is consistent with a role in stabilizing microtubules in axons that are subjected to great shear forces. © 1995 Wiley‐Liss, Inc.
Ultrastructural heterogeneity of enkephalin‐containing terminals in the rat hippocampal formation
Authors: Commons Kathryn G. , Milner Teresa A.
Published: January 2005

Opioid peptides, including leu‐enkephalin (LE), are important neuromodulators in the hippocampal formation where they may play a role in learning and memory as well as epileptogenesis. We examined the cellular substrates that underlie the function of LE in each lamina of the rat hippocampal formation by immunocytochemistry at the electron microscopic level in single section analysis. LE‐like immunoreactivity (LE‐LI) was primarily associated with large dense‐core vesicles (80–100 nm), usually found in axons and axon terminals, but was also observed in perikarya and occasionally in dendrites. The morphology and synaptic associations of LE‐LI‐containing terminals were strikingly distinct in each region of the hippocampal formation. In the molecular layer of the dentate gyrus, terminals with LE‐LI were typically small (0.6 μm) and formed primarily asymmetric (excitatory type) synapses on single dendritic spines, which is consistent with the presence of LE in the lateral perforant path. In the hilus of the dentate gyrus, twd types of LE‐containing terminals were present: (1) small round terminals that were heterogeneous in size (0.4–1 μm) and in type of contact formed and (2) larger (3–5 μm) terminals exhibiting the characteristic morphology of mossy fiber boutons that formed asymmetric synapses on spines. This variation in morphology and the type of contact suggests LE may have a heterogeneous influence on diverse hilar interneurons. In the CA3 region of the hippocampus, LE‐LI was localized to large mossy fiber boutons (3–7 μm) that formed multiple asymmetric synapses on complex spiny dendritic processes and often formed puncta adherentia with the shafts of large CA3 pyramidal cell dendrites, indicating that this peptide may be directly released onto pyramidal cells. At the border of stratum radiatum and lacunosum moleculare in the CA1 region of the hippocampus, LE‐labeled terminals averaged 0.8 μm in diameter and often formed symmetric (inhibitory type) synapses on dendritic shafts, which is consistent with a role in disinhibition. In conclusion, these heterogeneous cellular interactions indicate that LE has diverse functional roles and mechanisms of action within each lamina of the hippocampal formation and may directly and indirectly modulate hippocampal cell activity. © 1995 Wiley‐Liss, Inc.