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Biomedical subjects

U Arvidsson

Publications and source records attributed to U Arvidsson.

At least 37 records · Page 2Linked to original sources
PubMed1994

trkC-like immunoreactivity in the primate descending serotoninergic system.

In the search for substances with a potential role in plastic responses of spinal motoneurons we have studied the distribution of trkC-like immunoreactivity in the spinal cord of adult monkeys (Macaca fascicularis). The presence of trkC, which is a signal-transducing receptor for neurotrophin-3, was detected by the use of indirect immunofluorescence with a rabbit polyclonal antibody raised against a synthetic peptide corresponding to the carboxy-terminal domain of the mouse trkC-encoded protein, thus detecting only full-length signal-transducing receptors. trkC-immunoreactive fibres/varicosities could be found at all spinal cord levels and the densest innervation was found in the autonomic intermediolateral and Onuf's nuclei, but somatic motoneuron pools also received a significant contribution of trkC-immunoreactive fibres. Terminals immunoreactive for trkC were also seen in the dorsal horn. Double-labelling experiments revealed a high degree of coexistence between trkC- and 5-hydroxytryptamine (serotonin)-like immunoreactivity in all areas except in the dorsal horn. The results of the present study suggest that neurotrophic signalling with an influence on serotoninergic as well as non-serotoninergic inputs to the adult monkey spinal cord is at hand.

Animals↗
PubMed1994

Quantitative and qualitative aspects on the distribution of 5-HT and its coexistence with substance P and TRH in cat ventral medullary neurons.

By use of the indirect immunofluorescence technique the distributions of 5-hydroxytryptamine (5-HT)-, substance P- and thyrotropin-releasing hormone (TRH)-immunoreactive (IR) neurons have been studied in the midline raphe nuclei and nucleus reticularis lateralis of the caudal brainstem (levels P18.3-P8.5; according to Berman (1968), in the cat, after treatment with colchicine. In addition, by use of the double-labelling technique, the coexistence between 5-HT-, substance P- and TRH-like immunoreactivity (LI) in these neurons was analysed. The results show that cell bodies in the midline raphe nuclei and nucleus reticularis lateralis contain 5-HT-, substance P- and TRH-LI. 5-HT-IR cells were more abundant than peptidergic neurons in all areas analysed. Quantitative estimations indicated that the total number of 5-HT-IR cells in the regions studied was about 17 x 10(3), while the corresponding numbers for substance P- and TRH-IR cells were 11 x 10(3) and 12 x 10(3), respectively. From double-labelled sections it was concluded that the vast majority of peptidergic cells also contained 5-HT-LI (87-100%). However, a subpopulation of 5-HT-IR neurons lacked peptide-LI (10-55%). The degree of coexistence varied with the brainstem level, in that neurons at more rostral locations showed a lower incidence of coexistence between 5-HT and peptide(s). The presence of all three compounds in one and the same cell body could also be demonstrated. In summary, 5-HT-, substance P- and TRH-IR cell bodies were encountered in medullary nuclei known to contain neurons with projection to the spinal cord. A high degree of coexistence between the compounds was demonstrated in these nuclei. The obtained results fit well with earlier studies on the patterns of distribution and peptide colocalization of 5-HT fibres in the spinal cord. The existence of biochemically distinct neuronal subpopulations within the 5-HT bulbospinal pathway is discussed.

Animals↗
PubMed1994

Serotoninergic, peptidergic and GABAergic innervation of the ventrolateral and dorsolateral motor nuclei in the cat S1/S2 segments: an immunofluorescence study.

Indirect single- and double-staining immunofluorescence techniques were used to study the serotoninergic, peptidergic and GABAergic innervation of the ventrolateral (Onuf's nucleus) and dorsolateral (innervating intrinsic foot sole muscles) nuclei, located in the S1/S2 segments of the cat spinal cord. The relative density of 5-hydroxytryptamine-, thyrotropin-releasing hormone-, substance P- and gamma-aminobutyric acid-immunoreactive axonal varicosities was similar in both nuclei. The highest relative density was recorded for varicosities immunoreactive to gamma-aminobutyric acid, while those immunoreactive to 5-hydroxytryptamine or thyrotropin-releasing hormone yielded the lowest values. The density of enkephalin-immunoreactive varicosities was higher in the ventrolateral than in the dorsolateral nucleus. Calcitonin gene-related peptide-like immunoreactivity could be seen in neurons of the ventrolateral and dorsolateral nuclei. Occasionally, calcitonin gene-related peptide-immunoreactive axonal fibers were also encountered in these nuclei. Virtually all thyrotropin-releasing hormone-immunoreactive varicosities in the ventrolateral and dorsolateral nuclei also contained 5-hydroxytryptamine-like immunoreactivity, while a somewhat smaller number of them were co-localized with substance P. About 5-10% of the 5-hydroxytryptamine-immunoreactive varicosities were devoid of peptide-like immunoreactivity, and the number of 5-hydroxytryptamine-immunoreactive varicosities lacking thyrotropin-releasing hormone-like immunoreactivity was higher in the dorsolateral than in the ventrolateral nucleus. Finally, the free fraction of substance P-immunoreactive varicosities, i.e., those lacking both 5-hydroxytryptamine and thyrotropin-releasing hormone, was about 39% in the ventrolateral and 26% in the dorsolateral nucleus. Spinal cord transection at the lower thoracic level induced a depletion of 5-hydroxytryptamine and thyrotropin-releasing hormone-immunoreactive fibers from the ventrolateral and dorsolateral nuclei, indicating an exclusive supraspinal origin for these fibers. A reduction in substance P-like immunoreactivity following spinal cord transection alone or spinal cord transection combined with unilateral dorsal rhizotomy was also detected in both nuclei, suggesting a dual origin for substance P-immunoreactive fibers, i.e., both supra- and intraspinal. The decrease in number of substance P-immunoreactive fibers was however smaller than expected from the analysis of the fraction of substance P-immunoreactive fibers co-localized with 5-hydroxytryptamine, indicating thus that the experimental lesions may have triggered a sprouting of substance P-immunoreactive axons originating from spinal cord sources. The distribution of gamma-aminobutyric acid in the ventrolateral and dorsolateral nuclei was not affected by the different lesion paradigms. It is therefore assumed that these inputs are intrinsic to the spinal cord.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Glutamate transporter mRNA and glutamate-like immunoreactivity in spinal motoneurones.

Glutamate is the major excitatory neurotransmitter in the central nervous system. The release of glutamate is terminated by rapid uptake of glutamate into the presynaptic nerve terminals and into surrounding glial cells. Recently, a neuronal glutamate transporter was cloned from rabbit small intestine, thereby providing the possibility to study the distribution of cells that express glutamate transporter mRNA. Using oligonucleotide probes and in situ hybridization, glutamate transporter mRNA was demonstrated in large cell bodies, presumably motoneurones, in the thoracic spinal cord of the rabbit. Immunohistochemical analysis with rabbit polyclonal antibodies to glutamate showed immunoreactivity in the cytoplasm of large cell bodies in the ventral horn, presumably motoneurones, of the rat spinal cord. Glutamate-LI was in addition demonstrated in the motor end plate in hindlimb muscle of the rat, as visualized by double-labelling with mouse monoclonal antibodies to synaptophysin. Taken together, these data raise the possibility that glutamate has a function at the vertebrate neuromuscular junction.

Amino Acid Transport System X-AG↗
PubMed1993

trkC expression in the injured rat spinal cord.

Reactive non-neuronal cells express high levels of low-affinity neurotrophin receptor and truncated trkB receptors after spinal cord injury. Here we report that descending nerve fibres in the rat lateral spinal cord column show strong trkC-like immunoreactivity after traumatic spinal cord lesions in the adult rat. No change in trkC expression by glial cells could be detected by immunohistochemistry or in situ hybridization at the lesion site. The data suggest that regeneration of descending spinal cord axons could be encouraged by the trkC ligand, neurotrophin 3.

Animals↗
PubMed1993

GAP-43, aFGF, CCK and alpha- and beta-CGRP in rat spinal motoneurons subjected to axotomy and/or dorsal root severance.

The mRNA levels for growth-associated protein 43 (GAP-43), acidic fibroblast growth factor (aFGF), alpha- and beta-calcitonin gene-related peptide (CGRP), cholecystokinin (CCK) and choline acetyltransferase (ChAT) in rat lumbar spinal motoneurons were studied by in situ hybridization 1, 5 and 21 days and 20 weeks following unilateral peripheral nerve sectioning, ventral rhizotomy or dorsal rhizotomy. Furthermore, CGRP- and aFGF-like immunoreactivities in the ventral horn were studied using immunohistochemistry. One to 21 days after axotomy, GAP-43 and alpha-CGRP mRNAs increased in lesioned motoneurons, while the aFGF mRNA levels were marginally higher in motoneurons on the lesion side as compared to the control side. beta-CGRP, CCK and ChAT mRNA levels, on the other hand, decreased during the short-term response (1-21 days) to axotomy. After ventral rhizotomy, but not peripheral axotomy, there was complete disappearance of aFGF-like immunoreactivity in the ventral root proximal to the lesion. In animals subjected to long-term survival (20 weeks) after peripheral axotomy, the expression of all studied substances had returned to normal levels. Unilateral dorsal rhizotomy did not induce any substantial short- or long-term shifts in the cellular expression of the GAP-43, aFGF, CGRP and CCK peptides or their mRNAs in motoneurons of lesioned segments. These results indicate that peptides/proteins in motoneurons are expressed differentially after axotomy. Whereas alpha-CGRP and GAP-43 are up-regulated, CCK and beta-CGRP become down-regulated and aFGF is largely unaffected.

Animals↗
PubMed1993

Calcitonin gene-related peptide-like immunoreactivity in motoneuron pools innervating different hind limb muscles in the rat.

The content of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) in motoneurons was studied in four motor pools supplying muscles in the rat hind limb subserving different types of motor activity. The motor pools were identified by retrograde labeling with horseradish peroxidase or fluorophore-conjugated dextran amines, which were injected into the soleus, tibialis anterior, lateral gastrocnemius, or abductor digiti minimi muscles. After processing for immunohistochemistry, a semiquantitative evaluation was carried out to estimate the proportion of strongly, intermediately, and weakly labeled motoneurons, as well as motoneurons totally lacking CGRP staining. This revealed a considerable diversity in the intensity of CGRP labeling even for motoneurons in the same motoneuron pool. Thus, strongly labeled cells, as well as cells devoid of CGRP label, were found in all four motoneuron pools. However, a difference was found in the distribution of motoneurons innervating muscles with a dominant composition of fast and slow motor units, respectively, in that a larger fraction of the latter type lacked CGRP-LI. Moreover, generally motoneurons in the small motor units of the abductor digiti minimi muscle displayed weaker staining, and a larger proportion of cells was totally devoid of CGRP-LI (16%) compared with larger motor units of the other three muscles (1-10%). Small-sized cells within the gamma-motoneuron size range were weakly stained or, more frequently, totally devoid of CGRP label (50%) as compared to larger cells, presumably representing alpha-motoneurons (1-16%). Five days after axotomy all four studied motoneuron pools displayed stronger CGRP labeling than corresponding unlesioned pools. However, a considerable variation in CGRP labeling persisted also among axotomized motoneurons. These results indicate that motoneurons normally display a great variation in CGRP-LI levels, but that motoneurons of small and slow-twitch motor units in general have lower levels than motoneurons of large and fast-twitch motor units, respectively. After axotomy, CGRP-LI increases in lesioned motoneuron pools compared with normal, but in a fraction of the axotomized motoneurons the increase seems to be discrete or even absent. The possible physiological implications of these findings are discussed.

Animals↗
PubMed1993

The peptidergic motoneurone.

Acetylcholine is the classic transmitter in the spinal cord motoneurone. Recent studies have shown that motoneurones also contain calcitonin-gene related peptide (CGRP) and other peptides. In addition to transmitter-like effects, CGRP may also exert trophic actions, as suggested by changes in CGRP expression in motoneurones during development and following experimental perturbations.

Amino Acid Sequence↗
PubMed1992

Galanin message-associated peptide (GMAP)- and galanin-like immunoreactivities: overlapping and differential distributions in the rat.

Using the indirect immunofluorescence method the distribution of galanin message associated peptide (GMAP)- and galanin-like immunoreactivities (LI) was compared in brain, intestine and some endocrine tissues of rat. In general, neurons in the peripheral and central nervous system contained both immunoreactivities. However, in retina the cones were GMAP-positive but galanin-negative. A strong GMAP-LI was observed in the prolactin cells in the anterior lobe of the pituitary and in the insulin cells in the islets of Langerhans in the pancreas, whereas incubation with galanin antiserum resulted in staining of fewer cells (anterior pituitary) or a very weak fluorescence (pancreas). The results show that most neurons express both GMAP- and galanin-LI, but raise the possibility that in some systems there is a tissue specific, posttranslational differential processing of preprogalanin.

Amino Acid Sequence↗
PubMed1992

Thyrotropin-releasing hormone (TRH)-like immunoreactivity in the grey monkey (Macaca fascicularis) spinal cord and medulla oblongata with special emphasis on the bulbospinal tract.

The distribution of thyrotropin-releasing hormone (TRH)-like immunoreactivity (LI) has been studied in the grey monkey (Macaca fascicularis) spinal cord and medulla oblongata by the use of indirect immunofluorescence and the peroxidase-antiperoxidase (PAP) technique. Furthermore, double-labeling experiments were performed in order to study colocalization of 5-hydroxytryptamine (5-HT)- and substance P-LI. A dense innervation of TRH-immunoreactive (IR) varicose fibers was found in the ventral horn motor nuclei, in the region surrounding the central canal, in the intermediolateral cell column, and in the dorsal horn laminae II and III. In addition, cell bodies harboring TRH-LI were found in the dorsal horn laminae II-IV. In the ventral horn, many of the large cell bodies and their proximal dendrites were totally encapsulated by TRH-IR fibers. From double-labeled sections a high degree of coexistence could be established between TRH-/5-HT-LI, TRH-/substance P-LI, and 5-HT-/substance P-LI in fibers in the motor nuclei; as a consequence, a large proportion of these fibers should harbor TRH-/5-HT-/substance P-LI. A coexistence between TRH-/5-HT-LI could also be demonstrated in the intermediolateral cell column. However, no unequivocal coexistence could be found between TRH-/substance P-LI and 5-HT-/substance P-LI in this region. In the dorsal horn, no clear coexistence could be encountered for any of the above indicated combinations. Electron microscopic analysis of material from the lumbar lateral motor nucleus demonstrated TRH-IR terminals making synapses with large cell bodies and dendrites. In addition, contacts lacking synaptic specializations could also be verified. In the medulla oblongata, with the use of the PAP technique, a large number of cell bodies containing TRH-LI were encountered in the midline raphe nuclei and in nucleus reticularis lateralis. A similar distribution pattern could be found for 5-HT-LI, but no cell bodies containing substance P-LI could be seen in these regions. Chemical analysis of specimens from cervical, thoracic, and lumbar spinal cord revealed higher concentrations of TRH- and 5-HT-LI in the ventral quadrants, whereas substance P-LI dominated in the dorsal quadrants. Thus, the concentrations of TRH-, 5-HT-, and substance P-LI was in accordance with the observed regional variation in density of IR-fibers and varicosities found in the spinal cord. We have shown that TRH-LI has a distribution in the monkey spinal cord and medulla oblongata similar to that previously demonstrated in other species.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Reappearance of calcitonin gene-related peptide-like immunoreactivity in the dorsal horn in the long-term dorsal root transected rat.

Calcitonin gene-related peptide (CGRP)-immunoreactive (IR) fibers in the rat dorsal horn superficial laminae vanish almost completely 3 weeks following unilateral dorsal rhizotomy. After a prolonged survival (20 weeks) of dorsal rhizotomy there is, however, a reappearance of CGRP-IR fibers in the corresponding laminae of the dorsal horn. The density of such IR fibres showed a clear gradient with the lowest number found in the midlesion region and an increase in density towards the neighboring, intact segments. In normal as well as lesioned rats, no neurons intrinsic to the dorsal horn contained detectable levels of CGRP-like immunoreactivity (LI). Furthermore, no cells could, by use of in situ hybridization, be demonstrated to contain detectable levels of mRNA encoding for CGRP in the dorsal horn. Based on these findings, we suggest that the CGRP-IR fibers observed following long-term survival of dorsal rhizotomy derive from proliferating collateral branches of primary afferents of neighboring intact segments.

Animals↗
PubMed1992

Distribution of enkephalin and its relation to serotonin in cat and monkey spinal cord and brain stem.

The distribution of enkephalin (ENK)-like immunoreactivity (LI) in spinal cord and medulla oblongata of cat and gray monkey (Macaca fascicularis) was studied by use of immunofluorescence and peroxidase antiperoxidase (PAP) techniques. Possible coexistence between ENK- and 5-hydroxytryptamine (5-HT)-LI was also analyzed with double labeling immunofluorescence. Furthermore, in situ hybridization was used to demonstrate cell bodies in the brain stem expressing mRNA encoding for ENK. ENK-immunoreactive (IR) axonal varicosities and fibers were demonstrated throughout the spinal cord gray matter, with the highest density in the superficial dorsal horn, the area around the central canal, the intermediolateral cell column, the sacral parasympathetic nucleus, and in Onuf's nucleus. In the monkey ventral horn, ENK-IR varicose fibers could in some cases be demonstrated in very close apposition to cell bodies. A low degree of co-localization between ENK- and 5-HT-LI was seen in the spinal cord of both species. Still, fibers containing both compounds could as a rule be demonstrated in every section studied. The highest degree of coexistence was encountered in the motor nucleus of the ventral horn. Six weeks after a low thoracic spinal cord transection a decreased staining for ENK-LI was demonstrated in the ventral horn motor nucleus, whereas other parts of the spinal cord appeared unaffected. In the brain stem of cats after colchicine treatment, ENK-LI was found in a majority of the 5-HT-IR cell bodies in the raphe nuclei (nucleus raphe magnus, pallidus and obscurus) and in the lateral reticular nucleus (rostroventrolateral reticular nucleus). In cat not pretreated with colchicine, a few weakly stained ENK-IR cell bodies could be found in the midline raphe nuclei and in the lateral reticular nucleus with the PAP technique. In the monkey brain stem without colchicine treatment, using the PAP technique, heavily stained ENK-IR cell bodies could be seen in the lateral reticular nucleus whereas, as in the cat, only a few, weakly stained ENK-IR cell bodies could be seen in the midline raphe nuclei. Using in situ hybridization technique, ENK mRNA expressing cells were demonstrated in the lateral reticular nucleus while no convincing mRNA signal could be found over cell bodies in the raphe nuclei. It is concluded that part of the ENKergic innervation of the cord in both species derives from supraspinal or suprasegmental levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Expression of GAP-43 mRNA in the adult mammalian spinal cord under normal conditions and after different types of lesions, with special reference to motoneurons.

In situ hybridization histochemistry was used to detect cell bodies expressing mRNA encoding for the phosphoprotein GAP-43 in the lumbosacral spinal cord of the adult rat, cat and monkey under normal conditions and, in the cat and rat, also after different types of lesions. In the normal spinal cord, a large number of neurons throughout the spinal cord gray matter were found to express GAP-43 mRNA. All neurons, both large and small, in the motor nucleus (Rexed's lamina IX) appeared labeled, indicating that both alpha and gamma motoneurons express GAP-43 mRNA under normal conditions. After axotomy by an incision in the ventral funiculus or a transection of ventral roots or peripheral nerves, GAP-43 mRNA was clearly upregulated in axotomized motoneurons, including both alpha and gamma motoneurons. An increase in GAP-43 mRNA expression was already detectable 24 h postoperatively in lumbar motoneurons both after a transection of the sciatic nerve at knee level and after a transection of ventral roots. At this time, a stronger response was seen in the motoneurons which had been subjected to the distal sciatic nerve transection than was apparent for the more proximal ventral root lesion. An upregulation of GAP-43 mRNA could also be found in intact motoneurons located on the side contralateral to the lesion, but only after a peripheral nerve transection, indicating that the concomitant influence of dorsal root afferents may play a role in GAP-43 mRNA regulation. However, a dorsal root transection alone did not seem to have any detectable influence on the expression of GAP-43 mRNA in spinal motoneurons, while the neurons located in the superficial laminae of the dorsal horn responded with an upregulation of GAP-43 mRNA. The presence of high levels of GAP-43 in neurons has been correlated with periods of axonal growth during both development and regeneration. The role for GAP-43 in neurons under normal conditions is not clear, but it may be linked with events underlying remodelling of synaptic relationships or transmitter release. Our findings provide an anatomical substrate to support such a hypothesis in the normal spinal cord, and indicate a potential role for GAP-43 in axon regeneration of the motoneurons, since GAP-43 mRNA levels was strongly upregulated following both peripheral axotomy and axotomy within the spinal cord.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1992

Serotonin-, substance P- and glutamate/aspartate-like immunoreactivities in medullo-spinal pathways of rat and primate.

Serotonergic neurons of the medulla oblongata have been proposed to play a role in the control of sensory, motor and autonomic cells in the spinal cord. Many of these raphe neurons have been shown to contain the undecapeptide substance P as well as the tripeptide thyrotropin-releasing hormone, but evidence for the presence of an excitatory amino acid in these pathways has not yet been documented. In colchicine-treated rats, we have used a combination of retrograde tracing and tri-color immunohistofluorescence techniques to study co-localization of serotonin- and substance P- with glutamate- or aspartate-like immunoreactivities in medullary neurons and the possible spinal projections of these cells. In addition, the distributions of serotonin-, substance P- and glutamate-immunoreactive terminal fields in the dorsal, ventral and lateral horns of the spinal cord were examined with tri-color immunofluorescence in the rat and the primate Macaca fasciculata. In colchicine-treated rats, glutamate- and aspartate-like immunoreactivity was found in practically all serotonin- and substance P-immunoreactive neurons of the B1, B2 and B3 cell groups. Some of these neurons also contained wheat-germ agglutinin conjugated to inactivated horseradish peroxidase and colloidal gold particles retrogradely transported from the spinal cord. In the spinal cords of non-colchicine-treated monkeys and rats, striking co-localization of serotonin, substance P- and glutamate-like immunoreactivities was seen in large boutons, surrounding the dendrites and cell bodies of large alpha motor neurons in the ventral horn. These observations suggest the existence of spinally projecting serotonin/substance P neurons containing excitatory amino acids such as glutamate or aspartate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

The relationship between the transfer factor obtained at rest, and arterial oxygen tension during exercise, in patients with miscellaneous pulmonary diseases.

Forty-one consecutive patients with the symptom 'exertional dyspnoea' were referred to the Department of Clinical Physiology for evaluation. Pulmonary fibrosis and chronic obstructive pulmonary disease were the most common diagnoses but other diagnoses were also represented. Some patients had no clinical diagnosis or radiological signs. All patients underwent exercise testing with sampling of arterial blood for blood gas analysis and pulmonary function testing including measurement of the transfer factor (carbon monoxide diffusing capacity) at rest. Independent of spirometric findings and diagnosis a significant correlation (r = 0.80, P < 0.001) was shown to exist between the transfer factor measured at rest and the arterial oxygen tension at maximal exercise level. We recommend measurement of the transfer factor as a screening test for exertional hypoxaemia and suggest that exercise blood gas analysis only seems necessary in patients with a transfer factor between 55% and 80% of the predicted value.

Adult↗
PubMed1992

Distribution of calbindin D28k-like immunoreactivity (LI) in the monkey ventral horn: do Renshaw cells contain calbindin D28k-LI?

By use of indirect immunofluorescence and peroxidase-antiperoxidase immunohistochemistry, we show that the monkey (Macaca fascicularis) ventral horn harbors small- to medium-sized neurons in lamina VII as well as a dense network of fibers in laminae IX and VII that contain calbindin D28k (calbindin)-like immunoreactivity. The highest frequency of immunoreactive (IR) cell bodies was found at the levels of the cervical and lumbar intumescences. Furthermore, rostrocaudally oriented calbindin-IR fibers were encountered in the ventral and ventrolateral funiculi throughout the whole length of the cord, with the highest density at cervical and lumbar intumescences. Analysis at the EM level revealed calbindin-IR terminals in contact preferentially with dendrites of variable size and occasionally also large cell bodies, presumably belonging to motoneurons, in the lateral motor nucleus. The location of calbindin-IR neurons, as well as the distribution and ultrastructural characteristics of the calbindin-IR axonal system, makes it highly likely that these neurons are Renshaw cells that mediate recurrent inhibition to motoneurons.

Animals↗