bluuebunny/crossref_metadata_2025 huggingface dataset:
Prefrontal connections of medial motor areas in the rhesus monkey
Authors: Bates Julianna F. , Goldman‐Rakic Patricia S.
Published: January 2005

Several areas on the medial surface of the frontal lobe in both monkeys and humans, including the supplementary motor area and specific areas within the ventral bank of the cingulate sulcus called the cingulate motor areas, have been implicated in the initiation and execution of skiled movements. These areas project directly to the motor cortex and spinal cord, and, on this basis alone, can be considered premotor areas. The present study investigated whether these premotor areas are specific targets of prefrontal cortical projections in the rhesus monkey and thereby provide links between this association cortex and motor effector pathways. Circumscribed injections of wheat germ agglutinin‐conjugated horseradish peroxidase were placed into different cytoarchitectonic subdivisions of prefrontal cortex, and resultant retrograde and anterograde labeling examined with respect to designated premotor targets. Conversely, injections were also made in the supplementary and cingulate motor areas and labeled cells and terminals charted in the prefrontal cortex.

A principal finding in this study is the identification of multiple prefrontal regions that project to the supplementary motor area, the cingulate motor areas, or both. Areas 46, 8a, 9, 11, and 12 are reciprocally connected with an area of the superior frontal gyrus in or near the supplementary motor area at its rostral margin. A smaller constellation of prefrontal areas, areas 46, 8a, and 11, is reciprocally connected with portions of cingulate cortex that have been classified as premotor arm and/or leg representations (Hutchins et al., Exp Brain Res 71:667–672, 1988). In accordance with numerous previous reports, prefrontal areas 46, 8a, 9, 10, 11, and 12 are reciprocally connected with “nonmotor” subdivisions of cingulate cortex.

The results presented here specify the corticocortical connections by which prefrontal cortex may influence motor output. © 1993 Wiley‐Liss, Inc.
Roles of estradiol and progesterone in regulation of hippocampal dendritic spine density during the estrous cycle in the rat
Authors: Woolley Catherine S. , McEwen Bruce S.
Published: January 2005

We have previously shown that the density of dendritic spines on hippocampal CA1 pyramidal cells is dependent on circulating estradiol and progesterone and fluctuates naturally during the 5 day estrous cycle in the adult rat. To date, however, no detailed characterization of the roles that these hormones play in regulation of spine density has been made. In order to determine the time courses and extent of the effects of estradiol and progesterone on dendritic spine density, we have analyzed the density of dendritic spines on the lateral branches of the apical dendritic tree of Golgi‐impregnated CA1 hippocampal pyramidal cells in several experiments. In summary, our findings included the following: (1) Following ovariectomy, circulating estradiol is undetectable within 24 hours; however, spine density decreases gradually over a 6 day period. (2) Spine density does not decrease any further up to 40 days following ovariectomy. (3) Treatment with estradiol alone can reverse the ovariectomy‐induced decrease in spine density. (4) Spine density begins to increase within 24 hours following estradiol benzoate injection in an ovariectomized animal, peaks at 2 and 3 days, then gradually decreases over the next 7 day period. (5) Although free estradiol is metabolized more rapidly than estradiol benzoate, there is no difference in the rate of decrease in spine density following injection of either form. (6) Progesterone has a biphasic effect on spine density in that progesterone treatment following estradiol initially increases spine density for a period of 2 to 6 hours but then results in a much sharper decrease than is observed following estradiol alone. By 18 hours following progesterone treatment, spine density is decreased nearly to 6 day ovariectomy values. (7) Treatment of intact rats with the progesterone receptor antagonist, RU 486, during the proestrus phase of the estrous cycle inhibits the proestrus to estrus drop in spine density. These findings account for both the gradual increase and rapid decrease in spine density which we have previously observed during the estrous cycle and indicate that progesterone in particular may be an important factor in the regulation of rapid morphologic changes which occur naturally in the adult brain. © 1993 Wiley‐Liss, Inc.
Postnatal development of the cholecystokinin innervation of monkey prefrontal cortex
Authors: Oeth Kristen M. , Lewis David A.
Published: January 2005

Although the structure and function of primate prefrontal cortex undergo substantial modifications during postnatal development, relatively little is known about the maturation of neurotransmitter systems in these cortical regions. In the primate brain, cholecystokinin is present in the greatest concentrations in prefrontal regions. Thus, in this study, we used immunohistochemical techniques to investigate the postnatal development of the cholecystokinin innervation of monkey prefrontal cortex.

In animals aged 4 days through adult, cholecystokinin immunoreactivity was present in nonpyramidal neurons that appeared to represent at least two distinct cell types. The most common type was a vertically oval bitufted neuron, located in layers II‐superficial III, which typically had a radially descending axon that gave rise to short collaterals in layer IV. Another frequently observed cell type was a larger multipolar neuron located in the superficial half of layer III. The axon of these neurons branched locally in the vicinity of the cell body.

The greatest density of cholecystokinin‐containing neurons and processes was present in monkeys less than 1 month of age. The density of immunoreactive structures in every prefrontal region then progressively declined with increasing age, with the most marked changes occurring during the first postnatal year. As a result, the density of labeled neurons in adult monkeys was less than one‐third of that in neonatal monkeys. However, labeled structures were significantly more dense in some ventromedial and orbital regions than in dorsal regions of the prefrontal cortex in neonatal, but not in older animals.

In all animals, cholecystokinin‐containing neurons were present in highest density in layers II‐superficial III, and labeled terminal fields were observed in layers II, IV, and VI. In animals less than 1 month of age, fascicles of radial fibers traversed through layers III and V, whereas in animals 1 to 3 months of age, individual radial fibers rather than fiber bundles were present in layers III and V. In addition, immunoreactive pericellular arrays, which appeared to surround unlabeled nonpyramidal cells, were present in layers V and VI and the subcortical white matter in the youngest monkeys.

Although many aspects of the cholecystokinin innervation of monkey prefrontal cortex remain constant during postnatal life, the distinct developmental changes in the cholecystokinin innervation of these regions suggest that it may play an important role in the maturation of the cortical circuitry that mediates the acquisition of certain cognitive abilities. © 1993 Wiley‐Liss, Inc.
Neurons synthesizing nitric oxide innervate the mammalian carotid body
Authors: Wang Z.‐Z. , Bredt D. S. , Fidone S. J. , Stensaas L. J.
Published: January 2005

The carotid body is an arterial chemoreceptor organ sensitive to blood levels of O2, CO2 and pH. The present immunocytochemical and neurochemical study has demonstrated the presence of an extensive plexus of nitric oxide (NO)‐synthesizing nerve fibers in this organ. These nitric oxide synthase (NOS)‐containing axons are closely associated with parenchymal type I cells and with blood vessels in the carotid body. Denervation and retrograde tracing experiments have revealed that these fibers arise from NOS‐immunoreactive and nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase‐positive neuronal cell bodies located in the petrosal ganglion and the carotid body, and dispersed along the glossopharyngeal and carotid sinus nerves (CSN). Within the petrosal ganglion, these neurons are topographically segregated from the catecholaminergic cells, and they contain the neuropeptide, substance P. NOS‐positive autonomic microganglial cells in the carotid body and CSN also exhibit choline acetyltransferse (ChAT) immunoreactivity. Our results suggest that nitric oxide may be a novel neuronal messenger in the mammalian carotid body involved in the modulation of chemosensory transduction and transmission in this organ. © 1993 Wiley‐Liss, Inc.
NCAM expression by subsets of taste cells is dependent upon innervation
Authors: Smith David V. , Akeson Richard A. , Shipley Michael T.
Published: January 2005

The expression of the neural cell adhesion molecule (NCAM) and distinct carbohydrate groups by cells of the taste buds of the rat vallate papilla was investigated by immunohistochemical and biochemical techniques. We employed antibodies against (1) the extracellular (mAb 3F4) and cytoplasmic (mAb 5B8) portions of the NCAM polypeptide, (2) the highly sialylated form of NCAM (mAb 5A5), (3) carbohydrate epitopes associated with glycosylated NCAM forms in the rat (mAb 2B8) or frog (mAb 9‐OE) olfactory system, and also (4) the Lewisb blood group carbohydrate epitope (mAb CO431). NCAM mRNA was demonstrated by polymerase chain reaction (PCR) in samples of the vallate papilla, suggesting the presence of NCAM in cells of the taste buds. Antibodies against NCAM (mAbs 3F4 and 5B8) recognized a subset (about 20%) of cells within the vallate taste buds; fibers of the glossopharyngeal nerve, including those innervating the gustatory epithelium, were NCAM immunoreactive. Taste bud cells did not express polysialic acid (mAb 5A5), but mAb 5A5 immunoreactivity was observed on fibers of the IXth nerve, including a few that entered the taste buds. All or nearly all of the cells within the vallate taste buds were immunoreactive to mAb 2B8, whereas mAbs 9‐OE and CO431 reacted with subsets of cells. The carbohydrates recognized by mAbs 2B8 and 9‐OE were also abundantly expressed in the ducts and acini of the lingual salivary glands. Bilateral crush of the IXth nerve resulted in the loss of expression of all of these molecules from the gustatory epithelium. If cells of the taste bud express NCAM during their final stage(s) of differentiation, then NCAM could play a role(s) in the growth of gustatory axons toward their target epithelial cells and in the recognition between the nerve fibers and mature taste receptor cells, or among the taste bud cells themselves. © 1993 Wiley‐Liss, Inc.
Immunohistochemical localization of tyrosine hydroxylase in corneal nerves
Authors: Marfurt Carl F. , Ellis Lawrence C.
Published: January 2005

The sympathetic innervation of the mammalian cornea is thought to play an important role in the regulation of epithelial ion transport, mitogenesis, and wound healing following corneal injuries. Anatomically, the three‐dimensional organization and relative density of corneal sympathetic innervation in many species remains inadequately described. In the present study, the sympathetic innervation of five different mammals (guinea pig, rat, mouse, hamster, and human) was studied in corneas sectioned parallel to the main axis of fiber orientation by labeling the fibers immunohistochemically with antiserum against tyrosine hydroxylase and an avidin‐biotin‐diaminobenzidine technique. The results showed that each species displayed a distinctive pattern and density of tyrosine hydroxylase immunoreactive (TH‐IR) corneal innervation that was unique to that species. The overall level of TH‐IR innervation was highest in the guinea pig, moderate in the human, hamster, and rat, and lowest in the mouse. In all species examined, TH‐IR nerves were most numerous in the corneoscleral limbus where they either formed intimate associations with blood vessels or coursed through the connective tissue matrix apparently unrelated to vascular elements. Other TH‐IR nerves entered the cornea proper in radially directed stromal nerve bundles to give rise to subepithelial plexuses of varying complexity. Occasional intraepithelial penetrations were observed in the guinea pig, human, and rat. Removal of the superior cervical ganglion resulted in the total loss of TH‐IR staining from guinea pig and hamster corneas and in the substantial but incomplete loss of TH‐IR staining from rat and mouse corneas, thus demonstrating their predominantly sympathetic origin. Combined sympathetic and sensory ocular denervation in the rat eliminated almost all corneal and limbal TH‐IR immunostaining, thus suggesting a minor TH‐IR sensory component in this species. In agreement with this conclusion, small numbers of TH‐IR sensory neurons and an abundance of TH‐IR fibers were observed in the trigeminal ganglia of the rat and guinea pig. Removal of the rat main ciliary ganglion resulted in the loss of additional TH‐IR fibers from the chamber angle and iris, thereby confirming a partial parasympathetic contribution to the rat iridial TH‐IR innervation. Following unilateral removal of the superior cervical ganglion in rats and guinea pigs, the contralateral cornea contained increased numbers of TH‐IR nerves, suggesting an upregulation of tyrosine hydroxylase (TH) expression in some contralateral axons. In summary, these data have shown pronounced interspecies differences in the organization and density of the mammalian corneal TH‐IR innervation that may reflect species‐specific variation in the level of sympathetic control over select aspects of corneal physiology. © 1993 Wiley‐Liss, Inc.
Deafferentation‐induced changes in neuropeptides of the adult rat dorsal horn following pronase injection of the sciatic nerve
Authors: El‐Bohy Ashraf , Lamotte Carole C.
Published: January 2005

The effect of deafferentation on the neuropeptides substance P (SP), calcitonin generelated peptide (CGRP), somatostatin (SS), and cholecystokinin (CCK) in the lumbar dorsal horn of the adult rat was examined by the indirect immunohistochemical method. Deafferentation was induced by injecting the sciatic nerve of anesthetized rats with proteolytic enzymes (20 mg pronase), which cause selective death of the nerve's ganglion cells and degeneration of their terminal arborization in the spinal cord. The density of immunolabel of each peptide was determined by using a computerized densitometry analysis system in two animal groups, i.e., short‐term (10–13 days after injection) and long‐term (4–9 months). In both groups, the deafferentation produced a significant ipsilateral depletion of CGRP, SP, CCK, and SS immunoreactivity. This depletion was limited to the area occupied by the sciatic terminals in the dorsal horn. In the long‐term group, the loss of CGRP and SP staining was significantly less than that in the short‐term animals, thus indicating partial recovery. A similar, but not statistically significant, trend was observed for CCK and SS. The large decrease in CGRP and SP seen in short‐term animals reflects the large contribution of the sciatic nerve to the lumbar dorsal horn. The partial recovery of peptides demonstrates the plasticity of the nervous system and may parallel sprouting of primary afferents from other nerves, such as the saphenous nerve, as we have demonstrated in previous studies. © 1993 Wiley‐Liss, Inc.
Reorganization of mossy fiber synapses in male and female hypothyroid rats: A stereological study
Authors: Madeira M. Dulce , Paula‐Barbosa Manuel M.
Published: January 2005

Thyroid hormone deficiency has been reported to interfere with synaptogenesis, particularly in those regions of the brain where the neurons display a late and protracted histogenesis, although the extent of the synaptic alterations remains unknown. To provide detailed quantitative data on the effects of hypothyroidism upon synapses, a link of the hippocampal circuitry was selected: the contact between mossy fibers and dendritic excrescences of CA3 pyramidal cells (MF‐CA3 synapses). Groups of six male and six female rats aged 30 and 180 days were analyzed separately after being treated as follows: (1) hypothyroid from day 0 until day 30 (30 day old hypothyroid group); (2) hypothyroid from day 0 until day 180 (180 day old hypothyroid group); (3) hypothyroid until day 30 and thenceforth maintained euthyroid (recovery group); and (4) and (5) 30 and 180 day old control groups, respectively. Timm staining, Golgi impregnation, and electron microscopy were employed to estimate the volume of the mossy fiber system, the number and size of mossy fiber boutons, and the number and related features of MF‐CA3 synapses.

The volume of the mossy fiber system and the number of synaptic boutons were reduced in all experimental groups. The total number of synapses was decreased in 30 day old hypothyroid rats, but did not differ among 180 day old animals. Postsynaptic densities were shorter in hypothyroid and recovery groups than in controls, although the reduction was not as marked in recovery rats as it was in hypothyroid animals. Structural alterations were noted in the pre‐ and postsynaptic compartments of MF‐CA3 synapses of both 180 day old hypothyroid and recovery rats. These changes can be regarded as mechanisms of reorganization as they underlie the compensation for the hypothyroid‐induced numerical reduction of synapses observed in 30 day old animals and enable a complete catch‐up of their total number. However, synaptic reorganization was not fully achieved, as revealed by the reduction in the size of the synaptic sites in hypothyroid and recovery animals. Finally, we demonstrate that hypothyroidism did not interfere with the sex‐related differences of MF‐‐CA3 synapses described in normal rats. © 1993 Wiley‐Liss, Inc.
Structure, vascularization, and innervation of the mystacial pad of the rat as revealed by the lectin griffonia simplicifolia
Authors: Rice Frank L.
Published: January 2005

The mystacial pad of the rat is endowed with rows of vibrissal follicle‐sinus complexes (F‐SCs) that receive a dense and rich variety of innervation, much of which is C fibers. Each F‐SC consists of a follicle at the core of a spindle‐shaped, encapsulated vascular sinus. Previous studies have shown that the B subunit of the lectin Griffonia simplicifolia (GSA I‐B4) binds selectively to a subset of small neurons in the trigeminal ganglion and to a subset of C fibers preferentially distributed to inner lamina II and outer lamina III of nucleus caudalis in the brainstem trigeminal complex in the rat. These laminae are also a major site of termination for afferents in superficial vibrissal nerves (SVNs) that innervate the upper portion of F‐SCs. To determine the peripheral distribution of the afferents that bind GSA I‐B4 mystacial pads from rats were prepared for fluorescence microscopy with GSA I‐B4 conjugated to rhodamine. At the neck of each F‐SC, nemerous circumferentially oriented bundles of fine‐caliber axonal profiles were labeled in the inner conical body, which receives nearly all of its innervation from the SVNs. A sparse, random distribution of fine‐caliber profiles from deep vibrissal nerves was labeled at the level of the cavernous sinus in the deep half of the F‐SCs.

GSA I‐B4 also labeled a variety of nonneural structures. By binding to vascular linings, GSA I‐B4 revealed a dense, highly organized capillary system within the mesenchymal sheath that forms the inner lining of the vascular sinuses. Thus each F‐SC appears to have a closed capillary system within the open vascular sinus. Trabeculae within the lumen of the cavernous sinus were also revealed to span between the sinus capsule and the mesenchymal sheath only about midway along the length of the follicle instead of the entire deeper half, as was previously believed. In addition, GSA I‐B4 bound to the surface of follicular cells preferentially in the superficial half of the F‐SCs. Sweat glands within the intervibrissal fur and some cells within sebaceous glands in F‐SCs were also labeled as well as their ducts. The potential functional implications of these various features are discussed. © 1993 Wiley‐Liss, Inc.
Morphology of interneurones in pathways from group II muscle afferents in sacral segments of the cat spinal cord
Authors: Jankowska E. , Riddell J. S. , Szabo‐Läckberg Z. , Hammar I.
Published: January 2005

The morphology of 12 sacral interneurones with peripheral input from group II muscle afferents was analyzed after intracellular injection of horseradish peroxidase (HRP). The neurones were located in Rexed's laminae III–V overlying the pudendal (Onuf's) motor nucleus. The interneurones had medium sized elongated somata and dendrites projecting radially. All of the interneurones were funicular neurones and fell into two categories depending on whether their axons ran within the dorsal part of the lateral funiculus (DLF; n = 7) or within the ventral funiculus, or the ventral part of the lateral funiculus (VF or VLF; n = 4). The latter were located more rostrally. Within the DLF similar proportions of stem axons and secondary axonal branches descended and ascended. Within the VF and VLF all of the axons ascended. Collaterals of axons running in the DLF arborized primarily within the dorsal horn and the intermediate zone; none were found to approach the motor nuclei. In contrast, collaterals of axons running in the VF/VLF arborized in both the intermediate zone and the ventral horn and passed close to the motor nuclei. We conclude that sacral interneurones with group II input are morphologically nonhomogenous and that only those located most rostrally might have direct actions upon motoneurones. Both the axonal projections and the input (from group II but not from group I muscle afferents and from skin afferents) of sacral interneurones indicate that they are homologous to dorsal horn group II interneurones in the midlumbar segments. They appear, however, to form part of more local neuronal networks than their midlumbar counterparts. © 1993 Wiley‐Liss, Inc.
Cerebellar influences on accessory oculomotor nuclei of the rat: A neuroanatomical, immunohistochemical, and electrophysiological study
Authors: Berretta Sabina , Bosco Gianfranco , Giaquinta Genoveffa , Smecca Giuseppe , Perciavalle Vincenzo
Published: January 2005

With the aim to evaluate a possible neocerebellar control on eye movements, the projections from the cerebellar lateral nucleus (LN) to the accessory oculomotor nuclei (i.e., the nucleus of posterior commissure, the nucleus of Darkschewitsch, and the interstitial nucleus of Cajal), the putative neurotransmitters subserving this pathway, and the nature of the synaptic influences exerted by these projections were studied in adult rats.

We used the orthograde transport of horseradish peroxidase conjugated with wheat germ agglutinin (WGA‐HRP) to identify the mesencephalic areas where cerebellofugal fibers terminate, and retrograde labeling with the fluorescent dye fluoro‐gold to estimate the incidence of cerebellar neurons projecting to the accessory oculomotor nuclei. Orthograde labeling showed that only a small contingent of cerebellofugal fibers reaches the contralateral accessory oculomotor nuclei. The retrogradely labeled cells were located primarily in the small‐celled part of LN.

By immunohistochemistry, we observed that all the cells retrogradely labeled from the accessory oculomotor area were also stained by using glutamate or aspartate antisera, but none of them were double‐stained with a GABA antiserum.

Electrical stimulation of the contralateral LN elicited changes in firing rate of a significant fraction of cells belonging to the accessory oculomotor nuclei (36.4% in the nucleus of posterior commissure, 47.1% in the nucleus of Darkschewitsch, and 44.6% in the interstitial nucleus of Cajal). In 57.8% of the cases, the responses were excitations, most of which had latencies and response characteristics compatible with a monosynaptic linkage. The remaining 42.2% of the cases were inhibitions with latencies ranging between 5 and 22 ms. Extracellular field potential recordings within the contralateral accessory oculomotor nuclei were interpreted as arising from impulses propagating along excitatory axons projecting in a bundle from the cerebellum. Stimulation of LN area in rats following intranuclear injection of kainic acid was not capable of evoking short latency excitations, so these responses can be considered to depend on the activation of LN efferents. The LN projection on accessory oculomotor nuclei could be part of the final precise control exerted by the neocerebellum on those brain structures concerned with movements of the eyes. © 1993 Wiley‐Liss, Inc.
Descending projections of the songbird nucleus robustus archistriatalis
Authors: Wild J. Martin
Published: January 2005

The descending, efferent projections of nucleus robustus archistriatalis were investigated in male zebra finches and greenfinches with injections of either biotinylated dextran amine or cholera toxin B‐chain conjugated to horseradish peroxidase. The results show that in addition to the well‐known projections to the tracheosyringeal motor nucleus and the dorsomedial nucleus of the intercollicular complex, there are other projections of comparable density to the ipsilateral nucleus ambiguus and nucleus retroambigualis. Within nucleus ambiguus, robustus axons terminate in close proximity to laryngeal motoneurons which were retrogradely labelled in the same bird by injections of cholera B‐chain into the laryngeal muscles; and within nucleus retroambigualis robustus axons terminate in relation to bulbospinal neurons previously shown to project to regions of spinal cord containing motoneurons innervating abdominal expiratory muscles (J.M. Wild, Brain Res. 606:119–124, 1993). These projections of nucleus robustus thus seem well placed to coordinate syringeal, laryngeal, and expiratory muscle activity during vocalization. Other relatively sparse, but distinct, projections of nucleus robustus were found to nucleus dorsolateralis anterior thalami, pars medialis, to a narrow region between the superior olivary nucleus and the spinal lemniscus, and to the rostral ventrolateral medulla. Neurons in these last two locations were retrogradely labelled bilaterally following injections of cholera B‐chain into nucleus retroambigualis of one side. Together with sparse contralateral projections of nucleus robustus to all brainstem targets receiving ipsilateral projections, potential pathways are thus identified by which the respiratory‐vocal activity controlled by one side of the lower medulla can be influenced by the nucleus robustus of either side, thereby possibly bringing about bilateral coordination of respiratory‐vocal output. © 1993 Wiley‐Liss, Inc.
Topography of pyramidal neuron intrinsic connections in macaque monkey prefrontal cortex (areas 9 and 46)
Authors: Levitt Jonathan B. , Lewis David A. , Yoshioka Takashi , Lund Jennifer S.
Published: January 2005

An understanding of the normal organization of prefrontal cortex is essential to the recognition of pathology underlying human behavioral disorders believed to depend on this region. We have therefore studied the pattern of intrinsic intra‐ and interlaminar pyramidal neuron connectivity in prefrontal areas 9 and 46 (of Walker) in macaque monkey cerebral cortex (anterior to the arcuate sulcus between the principal sulcus and midline). We made focal (200–400 μm) injections of biocytin and mapped the pattern of orthogradely transported label. Injections made into the superficial layers label wide‐ranging lateral projections within the same areas of prefrontal cortex. Projections local to such small injections form a narrow band of terminals in layers 1–3 (200–400 μm wide, 2–4 mm long) centered on the injection site. Collateral fibers spread orthogonal to this terminal band, making frequent bifurcations, to establish a series of parallel bands of terminals with uninnervated bands between, spaced regularly across the cortex (center to center 500–600 μm). The entire pattern of terminal label is stripelike, with occasional narrower interbands and crosslinks between the bands, and can extend over 7–8 mm across the cortex. These projections arise from pyramidal neurons in layers 2, 3, and 5 and terminate in layers 1–3. The stripelike pattern contrasts with patchlike patterns in other cortical regions (V1, V2, V4, motor, somatosensory) and is smaller in scale than stripelike zones of corticocortical afferent terminals to this region, reported to be 300–750 μm wide and spaced 1.0–1.5 mm center to center. © 1993 Wiley‐Liss, Inc.
Modulation of low‐affinity nerve growth factor receptor in injured adult rat spinal cord motoneurons
Authors: Rende Mario , Provenzano Carlo , Tonali Pietro
Published: January 2005

Spinal and brainstem motoneurons of the adult rat reexpress low‐affinity nerve growth factor receptor (LNGFR) and its mRNA after axotomy. We have previously reported the time courses of this reexpression after cut (no regeneration) or crush (followed by regeneration) of the sciatic nerve. We have shown that the length of the different phases of this reexpression (appearance, maintenance and disappearance) can vary according to the type of axotomy. With the present study we expand our previous data and describe and analyze the modulation the LNGFR expression in adult spinal cord motoneurons following different lesion paradigms. In one approach we have imposed three traumatic injuries that still allow regeneration of the sciatic nerve but with a different time course with respect to the crush injury (application of a silicone regeneration chamber, multiple crushes and delayed repair of ligated nerves). In a second approach, we have determined the capability of three toxic or metabolic injuries to induce LNGFR expression without any direct trauma of the nerve (experimental diabetogenesis, botulinum and alpha‐bungarotoxin intoxication and 2,5‐hexanedione intoxication). In a third approach, we have investigated the effect of the block of the axoplasmic transport on the LNGFR expression following different topical applications of vincristine combined with a nerve crush. The results we present are consistent with the idea that: (1) LNGFR immunoreactivity in adult motoneurons is expressed by motoneurons that are attending to an axonal outgrowth and not a generic signal of cellular damage or impairment of the motor function; (2) LNGFR expression in these motoneurons is related to and parallels the outgrowth process time frame, and (3) the signal/s that trigger and sustain this reexpression may be retrogradely transported from the periphery. © 1993 Wiley‐Liss, Inc.
Crustacean cardioactive peptide‐immunoreactive neurons in the hawkmoth Manduca sexta and changes in their immunoreactivity during postembryonic development
Authors: Davis Norman T. , Homberg U. , Dircksen H. , Levine R. B. , Hildebrand J. G.
Published: January 2005

An antiserum against crustacean cardioactive peptide was used, in indirect immunocytochemistry on whole‐mounts and Vibratome sections, to map immunoreactive neurons at various stages of postembryonic development of the hawkmoth Manduca sexta. About 90 immunoreactive neurons were identified. Many of these cells are immunoreactive at hatching and persist into the adult stage; others become immunoreactive late in postembryonic development. During adult development, transient immunoreactivity is expressed in several cells in the subesophageal and thoracic ganglia. Two sets of immunoreactive neurons are found in the protocerebrum of larvae, but only one of these sets persists into the adult stage. Paired lateral interneurons and neurosecretory neurons are segmentally repeated in the abdominal ganglia and are present from the first larval stage to the adult; the abdominal interneurons project contralaterally to arborizations in adjacent ganglia, and some ascend to tritocerebral arborizations. The abdominal neurosecretory cells, which correspond to a pair of cells reported to contain bursicon, project posteriorly to neurohemal release organs. Motor neurons of dorsal external oblique abdominal muscles become immunoreactive in the fourth larval stage. Paired median neurosecretory cells of abdominal ganglia become immunoreactive during the fifth larval stage. The immunoreactive median and lateral abdominal neurosecretory cells are a subset of a group of cells known to contain cardioactive peptides. Paired lateral neurosecretory cells of the subesophageal ganglion become immunoreactive during pupation and project to the corpor cardiaca and aorta of the adult. Many of the neurons identified here are comparable to crustacean cardioactive peptide‐immunoreactive cells described previously in locusts and the mealworm beetle. © 1993 Wiley‐Liss, Inc.
GABAA/benzodiazepine receptor α6 subunit mRNA in granule cells of the cerebellar cortex and cochlear nuclei: Expression in developing and mutant mice
Authors: Varecka Ludovit , Wu Chieh‐Hsi , Rotter Andrej , Frostholm Adrienne
Published: January 2005

The gamma aminobutyric acidA/benzodiazepine (GABAA/BZ) receptor is a multisubunit (α, β, γ, δ, and ρ) ligand‐gated chloride channel; there are several variants of the α, β, and γ subunits, each of which has been localized throughout the central nervous system. A large number of GABAA/BZ subunit variants are expressed within the cerebellar cortex. In previous studies from other laboratories, α6 subunit mRNA has been reported to be present exclusively in cerebellar granule cells. The developmental expression of α6 mRNA in cerebellar and cochlear granule cells is of interest because it has been suggested that each of these cell types is derived from a common precursor pool. The polymerase chain reaction was used to generate a cDNA fragment encoding a portion of the M3–M4 intracellular loop of the α6 subunit of the GABAA/BZ receptor. A [35S] riboprobe, transcribed from this cDNA fragment, was used to examine the expression of the α6 subunit mRNA by in situ hybridization in developing normal mice and in adult mutant mice with known deficits in synaptic circuitry. A strong hybridization signal was observed over the granule cell layers of both the cerebellum and cochlear nuclei in adult mice. The signal over the cochlear nuclei appeared after birth toward the end of postnatal week 1, coinciding with the appearance of labeling in the cerebellar cortex. The intensity of the hybridization signal in both regions increased rapidly until postnatal day 14, after which it increased more gradually, reaching adult levels during postnatal week 3. In the weaver mutant, α6 labeling was detected in surviving granule cells, but not in cerebellar regions devoid of granule cells. Significant levels of the α6 hybridization signal were also present in cerebellar granule cells of Purkinje cell degeneration, lurcher, and staggerer mutants, suggesting that aberrations in synaptic circuitry do not prevent α6 subunit gene expression.

Our results demonstrate that α6 subunit mRNA is not limited to the cerebellum, but is expressed in other neurons which share a common cellular precursor pool. These data also suggest that these granule cell precursors may be intrinsically programmed to acquire a specific form of the GABAA/BZ receptor, irrespective of their final location and lack of connections with target neurons. © 1994 Wiley‐Liss, Inc.
Clusterin (SGP‐2): A multifunctional glycoprotein with regional expression in astrocytes and neurons of the adult rat brain
Authors: Pasinetti Giulio M. , Johnson Steven A. , Oda Tomiichiro , Rozovsky Irina , Finch Caleb E.
Published: January 2005

Clusterin (SGP‐2) is a newly described glycoprotein associated with several putative functions including responses to brain injury. This study reports the regional and cell type expression of clusterin mRNA and its encoded glycoprotein in the rat brain; a limited comparison was also done with the human brain. Using in situ hybridization combined with immunocytochemistry, we found that astrocytes and neurons may express clusterin mRNA in the normal adult brain. While astrocytes throughout the brain contained clusterin mRNA, there was regional selectivity for neuronal clusterin expression. In the striatum, clusterin mRNA was not detected in neurons. Only a subset of substantia nigra dopaminergic neurons or locus ceruleus noradrenergic neurons (tyrosine hydroxylase immunopositive) contained clusterin mRNA. However, neuronal clusterin mRNA was prevaìent in pontine nuclei and in the red nucleus of the midbrain tegmentum. Similarly, clusterin mRNA was prevalent in both rat and human hippocampal neuron‐specific enolase immunopositive pyramidal neurons, although rat CA1 neurons had less mRNA than CA2–CA3 neurons. Monotypic primary cell cultures from the neonatal rat showed clusterin mRNA in both neurons and astrocytes, but not in microglia.

By immunocytochemistry, no clusterin immunopositive glia were observed in any region of the rat brain, confirming previous studies. However, clusterin immunopositive cells (putative neurons) were observed in the Purkinje cell layer of the cerebellum, medial and interposed cerebellar nuclei, trigeminal motor nucleus, and red nucleus. Finally, in vitro studies suggest that astrocytes, but not neurons, secrete clusterin, which is pertinent to clusterin immunodeposits found after experimental lesioning. © 1994 Wiley‐Liss, Inc.
Vestibulo‐oculomotor connections in an elasmobranch fish, the atlantic stingray, Dasyatis sabina
Authors: Puzdrowski R. L. , Leonard R. B.
Published: January 2005

In elasmobranch fishes, including the Atlantic stingray, the medial rectus muscle is innervated by the contralateral oculomotor nucleus. This is different from most vertebrates, in which the medial rectus is innervated by the ipsilateral oculomotor nucleus. This observation led to the prediction that the excitatory vestibulo‐extraocular motoneuron projections connecting each semicircular canal to the appropriate muscle should use a contralateral projection from the vestibular nuclei to the motoneurons. This hypothesis was examined in the Atlantic stingray by injecting horseradish peroxidase unilaterally into the oculomotor nucleus. It was found that vestibulo‐oculomotor projections arise from the ipsilateral anterior octaval nucleus and the contralateral descending octaval nucleus. The same pattern was observed when the trochlear nucleus was involved in the injection. There were no cells labeled in the region of the abducens nucleus, and no candidate for a nucleus prepositus hypoglossus was identified. The presence of compensatory eye movements, the directional sensitivity of the semicircular canals, the location of the motoneurons innervating each eye muscle, and our results indicate that the excitatory input to the extraocular motoneurons is derived from the contralateral descending octaval nucleus, and the inhibitory input is derived from the ipsilateral anterior octaval nucleus. The absence of both abducens internuclear interneurons and a nucleus prepositus hypoglossus suggests that eye movements, particularly those in the horizontal plane, are controlled differently in elasmobranchs than in other vertebrates examined to date. © 1994 Wiley‐Liss, Inc.
Compartmentation of glutamate and glutamine in the lateral cervical nucleus: Further evidence for glutamate as a spinocervical tract neurotransmitter
Authors: Kechagias Stergios , Broman Jonas
Published: January 2005

Previous observations indicate that spinocervical tract terminals contain relatively high levels of glutamate. To examine whether these high glutamate levels are likely to represent a neurotransmitter pool or an elevated metabolic pool, the distributions of glutamate‐ and glutamine‐like immunoreactivities were examined in adjacent immunogold‐labeled sections of the lateral cervical nucleus. Spinocervical tract terminals were identified by anterograde transport of horseradish peroxidase and wheat germ agglutinin‐horseradish peroxidase conjugate from the spinal cord.

Spinocervical tract terminals were found to contain significantly higher levels of glutamate‐like immunoreactivity than other examined tissue compartments (large neuronal cell bodies, terminals with pleomorphic vesicles, astrocytes, and average tissue level). In contrast, the highest levels of glutamine‐like immunoreactivity were detected in astrocytes. The different analyzed tissue elements formed three groups with respect to glutamate: glutamine ratios: one high ratio group including spinocervical tract terminals, a second group with intermediate ratios consisting of neuronal cell bodies and terminals containing pleomorphic synaptic vesicles, and a third low ratio group including astrocytes.

Our findings indicate the presence of a compartmentation of glutamate and glutamine in the lateral cervical nucleus, similar to that postulated in biochemical studies of the central nervous system. The results also show that spinocervical tract terminals have high glutamate: glutamine ratios, similar to those previously observed in putative glutamatergic terminals in the cerebellar cortex. Thus, spinocervical tract terminals display biochemical characteristics that would be expected of glutamatergic terminals and the present findings therefore provide further evidence for glutamate as a spinocervical tract neurotransmitter. © Wiley‐Liss, Inc.
Three‐dimensional organization of endoplasmic reticulum in the ventral photoreceptors of Limulus
Authors: Feng Jane J. , Carson John H. , Morgan Frank , Walz Bernd , Fein Alan
Published: January 2005

Living Limulus ventral photoreceptor cells were injected with long chain lipophilic carbocyanine fluorescent dyes to label the endoplasmic reticulum (ER). The purpose of this study was to examine the continuity, dynamic changes, and structure of the ER in the living cell, using laser scanning confocal microscopy and three‐dimensional image reconstruction.

In this highly polarized neuron, three lines of evidence indicate that the ER is a continuous network extending throughout both lobes of the cell. First, injection of DiO or DiI results in the labeling of ER throughout both lobes of the cell. Second, three‐dimensional image reconstruction of the optical sections reveals a dispersed membrane meshwork which may be the structure that serves to interconnet the ER in the two lobes. Third, in cells fixed before dye injection, the pattern of labelling was similar to that in living cells, indicating that vesicle transport was not responsible for the spread of dye throughout the cell.

The overall organization of the ER in the photoreceptor cell is relatively stable; however, the fine structure changes over time. This dynamic process appears to represent continual reorganization of the intracellular membranes in the cell.

Three morphological types of ER were observed. The ER of the light‐sensitive lobe, identified by coinjection of rhodamine‐phalloidin to label the microvillar actin, is characterized by a concentration of stratiform membranes interconnected by thin tubular cross‐bridges. The perinuclear ER is characterized by a tangle of convoluted tubules sometimes terminating in bulbous structures. Finally, there is a fine tubular reticulum dispersed throughout the cell.
Embryonic sensory development: Local expression of neurotrophin‐3 and target expression of nerve growth factor
Authors: Elkabes Stella , Dreyfus Cheryl F. , Schaar Dale G. , Black Ira B.
Published: January 2005

Development and maintenance of peripheral sensory and sympathetic neurons are regulated by target‐derived neurotrophins, including nerve growth factor (NGF). To determine whether trophins are potentially critical prior to and during target innervation, for neuronal survival or axon guidance, in situ hybridization was performed in the rat embryo. We examined the expression of genes encoding NGF, neurotrophin‐3 (NT‐3), and their putative high‐affinity receptors, trk A and trk C, respectively. Trks A and C were detected in dorsal root sensory ganglia (DRG) on embryonic day 12.5 (E12.5), implying early responsiveness to NGF and NT‐3. NGF mRNA was expressed in the central spinal cord target and by the peripheral somite, at this early time, which thereby may function as a transient “guidepost” target for sensory fibers. Somitic expression was transient and was undetectable by E17.5. NT‐3 was expressed in the DRG itself from E13.5 to 17.5, suggesting local transient actions on sensory neurons. NT‐3 was also expressed in the ventral spinal cord at low levels on E13.5. We examined the trigeminal ganglion to determine whether cranial sensory neurons are similarly regulated. Trk A was detected in the trigeminal ganglion, while NGF was expressed in the central myelencephalon target, paralleling observations in the DRG and spinal cord. However, NT‐3 and trk C were undetectable, in contrast to DRG, suggesting that the environment or different neural crest lineages govern expression of different trophins and trks. Apparently, multiple trophins regulate sensory neuron development through local as well as transient target mechanisms prior to innervation of definitive targets.
Excitatory amino acid antagonists protect cochlear auditory neurons from excitotoxicity
Authors: Puel J.‐L. , Pujol R. , Tribillac F. , Ladrech S. , Eybalin M.
Published: January 2005

Since ischemic damage in the brain is linked to glutamate excitotoxicity, the effects of an acute exposure to glutamate, α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazole proprionic acid (AMPA) or N‐‐methyl‐D aspartate (NMDA) on the radial dendrites were compared with these occurring after a severe cochlear ischemia. Glutamate and AMPA, but not NMDA, produced a drastic swelling restricted to the radial dendrites below the inner hair cells (IHCs). At a concentration of 20 μM AMPA, a full electrophysiological recovery could be observed in some cochleas after washing the drug out. A prior perfusion of 6‐7‐dinitroquinoxaline‐2,3‐dione (DNQX, 50 μM) prevented the 25 μM AMPA‐induced dendritic swelling. No protective effect of D‐2‐amino‐5‐phosphonopentanoate (D‐AP5) could be observed. In the same way, ischemia (5‐40 minutes) resulted in a clear swelling of the radial dendrites. While D‐AP5 had no protective effects, 50 μM DNQX protected most of the radial dendrites from the ischemia‐induced swelling, excepting those contacting the modiolar side of the IHCs. Finally, 50 μM DNQX + 50 μM D‐AP5 resulted in a nearly complete protection of all the radial dendrites. Altogether, these results suggest that the acute swelling of radial dendrites primarily occurs via AMPA/kainate receptors. However, in radial dendrites contacting the inner hair cells on their modiolar side, NMDA receptors may be also involved.