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Aicher SA, Hermes SM, Whittier KL, Hegarty DM. Descending projections from the rostral ventromedial medulla (RVM) to trigeminal and spinal dorsal horns are morphologically and neurochemically distinct. J Chem Neuroanat 2012; 43:103-11. [PMID: 22119519 PMCID: PMC3319838 DOI: 10.1016/j.jchemneu.2011.11.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 11/08/2011] [Accepted: 11/09/2011] [Indexed: 01/16/2023]
Abstract
Neurons in the rostral ventromedial medulla (RVM) are thought to modulate nociceptive transmission via projections to spinal and trigeminal dorsal horns. The cellular substrate for this descending modulation has been studied with regard to projections to spinal dorsal horn, but studies of the projections to trigeminal dorsal horn have been less complete. In this study, we combined anterograde tracing from RVM with immunocytochemical detection of the GABAergic synthetic enzyme, GAD67, to determine if the RVM sends inhibitory projections to trigeminal dorsal horn. We also examined the neuronal targets of this projection using immunocytochemical detection of NeuN. Finally, we used electron microscopy to verify cellular targets. We compared projections to both trigeminal and spinal dorsal horns. We found that RVM projections to both trigeminal and spinal dorsal horn were directed to postsynaptic profiles in the dorsal horn, including somata and dendrites, and not to primary afferent terminals. We found that RVM projections to spinal dorsal horn were more likely to contact neuronal somata and were more likely to contain GAD67 than projections from RVM to trigeminal dorsal horn. These findings suggest that RVM neurons send predominantly GABAergic projections to spinal dorsal horn and provide direct input to postsynaptic neurons such as interneurons or ascending projection neurons. The RVM projection to trigeminal dorsal horn is more heavily targeted to dendrites and is only modestly GABAergic in nature. These anatomical features may underlie differences between trigeminal and spinal dorsal horns with regard to the degree of inhibition or facilitation evoked by RVM stimulation.
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Viana F. Chemosensory properties of the trigeminal system. ACS Chem Neurosci 2011; 2:38-50. [PMID: 22778855 PMCID: PMC3369707 DOI: 10.1021/cn100102c] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Accepted: 12/14/2010] [Indexed: 11/28/2022] Open
Abstract
The capacity of cutaneous, including trigeminal endings, to detect chemicals is known as chemesthesis or cutaneous chemosensation. This sensory function involves the activation of nociceptor and thermoreceptor endings and has a protective or defensive function, as many of these substances are irritants or poisonous. However, humans have also developed a liking for the distinct sharpness or pungency of many foods, beverages, and spices following activation of the same sensory afferents. Our understanding of the cellular and molecular mechanisms of chemosensation in the trigeminal system has experienced enormous progress in the past decade, following the cloning and functional characterization of several ion channels activated by physical and chemical stimuli. This brief review attempts to summarize our current knowledge in this field, including a functional description of various sensory channels, especially TRP channels, involved in trigeminal chemosensitivy. Finally, some of these new findings are discussed in the context of the pathophysiology of trigeminal chemosensation, including pain, pruritus, migraine, cough, airway inflammation, and ophthalmic diseases.
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Ishihama K, Kogo M, Wakisaka S, Turman JE. Prenatal development of NMDA receptor composition and function in trigeminal neurons. ACTA ACUST UNITED AC 2009; 68:321-35. [PMID: 16477151 DOI: 10.1679/aohc.68.321] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The prenatal development of neural circuits for rhythmical oral-motor behaviors used for feeding is essential for the survival of the newborn mammal. The N-methyl-D-aspartate (NMDA) receptor plays a critical role in brainstem circuits underlying postnatal oral-motor behaviors. To understand a role for the NMDA receptor in the emergence of sucking behavior we conducted physiological and immunohistochemical experiments using fetal rats. Physiology experiments examined the development of the NMDA dose response of the brainstem circuit responsible for generating rhythmical trigeminal activity by recording trigeminal motor outputs using an in vitro preparation. The high dose of NMDA agonist bath application affected the mean cycle duration of rhythmical trigeminal activity (RTA) at both embryonic day (E) 18-19 and E20-21 in comparison with standard concentration of NMDA agonist. NMDA receptor immunohistochemistry studies, using antibodies directed against subunits NR1, NR2A, NR2B, NR3A and NR3B were performed to determine the prenatal regulation of NMDA subunits in trigeminal motoneurons (Mo5), and mesencephalic trigeminal neurons (Me5) between E17 to E20. In Mo5, NR1, NR2A, NR2B and NR3A immunoreactivity was observed throughout the time frame sampled. NR3B immunoreactivity was not observed in Mo5 or Me5. In Mo5, there was a significant decrease in the percentage of NR2B immunoreactive neurons between E17 and E20, and a concurrent increase in the NR2A/NR2B ratio between E17 and E20. In Me5, NR1, NR2A and NR3A immunoreactivity was observed throughout the time frame sampled; a significant decrease in the percentage of NR2A immunoreactive neurons between E17 and E20, and NR3A immunoreactive neurons between E17 and E18 occurred. The timing of subunit changes between E17 and E18 is coincident with the prenatal emergence of rhythmical jaw movements, and in vitro rhythmical trigeminal activity, shown in earlier studies. Our data suggest that NMDA receptor plays an important role in the development and function of prenatal oral-motor circuits.
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Auvenshine RC. Menstrual migraine. TEXAS DENTAL JOURNAL 2006; 123:182-7. [PMID: 16579505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
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Fristad I, Berggreen E, Haug SR. Delta (delta) opioid receptors in small and medium-sized trigeminal neurons supporting the dental pulp of rats. Arch Oral Biol 2005; 51:273-81. [PMID: 16266688 DOI: 10.1016/j.archoralbio.2005.08.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Revised: 08/18/2005] [Accepted: 08/30/2005] [Indexed: 01/17/2023]
Abstract
The control of pain perception is a challenge in clinical dentistry, most prominent during tooth pulp inflammation. The tooth pulp is a well-defined target, and is densely supplied by a sensory trigeminal innervation. Opioids are signaling molecules that are suggested to participate in pain perception. Here we analysed the presence of delta opioid receptor (DOR) in trigeminal neurons innervating the tooth pulp of rat molars. Immunohistochemical and ultrastructural analysis revealed that DOR was identified in peripheral nerves in the molar dental pulp, both in the root and the coronal pulpal parts, with branching in the highly innervated subodontoblast layer. DOR was localised in about one third of all the trigeminal dental neurons, identified by means of retrograde neuronal transport of fluorogold (FG) from the dental pulp. Of the DOR-labeled neurons, nearly all were small and medium-sized (147.5-1,810.2 microm(2), mean 749.1 +/- 327.3 microm(2)). Confocal microscopy confirmed that DOR-immunoreactivity was distributed as granules in the neuronal cytoplasm. Approximately 70% of the DOR-immunoreactive neurons were also immunopositive for vanilloid receptor 1 (TRPV1). Ultrastructural analysis demonstrated DOR-immunoreactivity in the unmyelinated and in some of the myelinated nerve fibers in the dental pulp. These results indicate that DOR may influence the function in a subset of small and medium-sized trigeminal sensory neurons supporting the tooth, which are mainly known for their ability to mediate nociceptive stimuli. Agonists, acting on DOR, may thus have an influence on a subpopulation of nociceptive neurons supporting the rat tooth.
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Cometto-Muñiz JE, Cain WS, Abraham MH. Determinants for nasal trigeminal detection of volatile organic compounds. Chem Senses 2005; 30:627-42. [PMID: 16141291 DOI: 10.1093/chemse/bji056] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We explored the influence of methodological and chemical parameters on the detection of nasal chemesthesis (i.e., trigeminal stimulation) evoked by volatile organic compounds (VOCs). To avoid odor biases, chemesthesis was probed via nasal pungency detection in anosmics and via nasal localization (i.e., lateralization) in normosmics, in both cases using forced-choice procedures. In the experiments with anosmics, 12 neat VOCs were selected based on previous reports of lack of chemesthetic response. Although none of the VOCs reached 100% detection, detectability and confidence of detection were higher when using a glass vessel system adapted with nosepieces to fit the nostrils tightly than when using wide-mouth glass jars. Half the stimuli were detected well above chance and half were not. When the latter were tested again after being heated to 37 degrees C, that is, body temperature (from room temperature, 23 degrees C), to increase their vapor concentration, only one, octane, significantly increased its detectability. Chemesthesis gauged with normosmics mirrored that with anosmics. Gas chromatography measurements showed that, even at 23 degrees C, the saturated vapor concentrations of the undetected stimuli, except vanillin, were well above the respective calculated nasal pungency threshold (NPT) from an equation that, in the past, had accurately described and predicted NPTs. We conclude that, except for octane and perhaps vanillin, the failure of the other four VOCs to precipitate nasal chemesthesis rests on a chemical-structural limitation, for example, the molecules lack a key property to fit a receptor pocket, rather than on a concentration limitation, for example, the vapor concentration is too low to reach a threshold value.
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Multon S, Pardutz A, Mosen J, Hua MT, Defays C, Honda SI, Harada N, Bohotin C, Franzen R, Schoenen J. Lack of estrogen increases pain in the trigeminal formalin model: a behavioural and immunocytochemical study of transgenic ArKO mice. Pain 2005; 114:257-65. [PMID: 15733652 DOI: 10.1016/j.pain.2004.12.030] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2004] [Revised: 10/25/2004] [Accepted: 12/20/2004] [Indexed: 11/27/2022]
Abstract
In order to examine the effect of estrogen on facial pain, we first compared the face-rubbing evoked by a formalin injection in the lip of aromatase-knockout (ArKO) mice, lacking endogenous estrogen production, 17 beta-estradiol-treated ArKO mice (ArKO-E2) and wild-type (WT) littermates. During the 'acute' phase of pain the time spent rubbing was similar in the three groups, whereas during the following 'interphase' and the second phase of pain, grooming was increased in ArKO mice. Estradiol-treatment restored a behaviour similar to WT group. To better understand estrogens modulation on pain processes, we examined changes in 5-HT and CGRP innervations of trigeminal nucleus caudalis (TNC) in ArKO, ArKO-E2 and WT groups sacrificed during the interphase. Whereas serotonin and CGRP immunoreactivities were comparable in WT and ArKO non-injected control groups, our data showed that 9 min after formalin injection, the density of serotoninergic terminals increased significantly in WT, but not in ArKO mice, while that of CGRP-immunoreactive fibers was lower in WT than in ArKO mice on the injected side. Estradiol-treatment only partially reversed these changes in ArKO-E2 mice. We conclude that estrogen deprivation in ArKO mice can be responsible for increased nociceptive response and that it is accompanied by transmitter changes favouring pro- over anti-nociceptive mechanisms in TNC during interphase of the formalin model. That estradiol-treatment completely reverses the behavioural abnormality suggests that estrogens absence produces chiefly functional activation-dependent changes. However, the fact that the immunohistochemical abnormalities were not totally normalized by estradiol-treatment suggested that some permanent developmental alterations may occur in ArKO mice.
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Zhu D, Keifer J. Pathways controlling trigeminal and auditory nerve-evoked abducens eyeblink reflexes in pond turtles. BRAIN, BEHAVIOR AND EVOLUTION 2004; 64:207-22. [PMID: 15319552 DOI: 10.1159/000080242] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2003] [Accepted: 03/06/2004] [Indexed: 11/19/2022]
Abstract
An in vitro brain stem preparation from turtles exhibits a neural correlate of eyeblink classical conditioning during pairing of auditory (CS) and trigeminal (US) nerve stimulation while recording from the abducens nerve. The premotor neuronal circuits controlling abducens nerve-mediated eyeblinks in turtles have not been previously described, which is a necessary step for understanding cellular mechanisms of conditioning in this preparation. The purpose of the present study was to neuroanatomically define the premotor pathways that underlie the trigeminal and auditory nerve-evoked abducens eyeblink responses. The results show that the principal sensory trigeminal nucleus forms a disynaptic pathway from both the trigeminal and auditory nerves to the principal and accessory abducens motor nuclei. Additionally, the principal abducens nucleus receives vestibular inputs, whereas the accessory nucleus receives input from the cochlear nucleus. The late R2-like component of abducens nerve responses is mediated by the spinal trigeminal nucleus in the medulla. Both the principal sensory trigeminal nucleus and the abducens motor nuclei receive CS-US convergence and therefore both, or either, might be considered potential sites of synapse modification during in vitro abducens conditioning. Further data are required to determine the role of the principal sensory trigeminal nucleus in in vitro conditioning.
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Kvinnsland IH, Luukko K, Fristad I, Kettunen P, Jackson DL, Fjeld K, von Bartheld CS, Byers MR. Glial cell line-derived neurotrophic factor (GDNF) from adult rat tooth serves a distinct population of large-sized trigeminal neurons. Eur J Neurosci 2004; 19:2089-98. [PMID: 15090036 DOI: 10.1111/j.0953-816x.2004.03291.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Glial cell line-derived neurotrophic factor (GDNF) mediates trophic effects for specific classes of sensory neurons. The adult tooth pulp is a well-defined target of sensory trigeminal innervation. Here we investigated potential roles of GDNF in the regulation of adult trigeminal neurons and the dental pulp nerve supply of the rat maxillary first molar. Western blot analysis and radioactive 35S-UTP in situ hybridization revealed that GDNF in the dental pulp and its mRNAs were localized with Ngf in the coronal pulp periphery, in particular in the highly innervated subodontoblast layer. Retrograde neuronal transport of iodinated GDNF and Fluorogold (FG) from the dental pulp indicated that GDNF was transported in about one third of all the trigeminal dental neurons. Of the GDNF-labelled neurons, nearly all (97%) were large-sized (> or =35 microm in diameter). Analysis of FG-labelled neurons revealed that, of the trigeminal neurons supporting the adult dental pulp, approximately 20% were small-sized, lacked isolectin B4 binding and did not transport GDNF. Of the large-sized dental trigeminal neurons approximately 40% transported GDNF. About 90% of the GDNF-accumulating neurons were negative for the high-temperature nociceptive marker VRL-1. Our results show that a subclass of large adult trigeminal neurons are potentially dependent on dental pulp-derived GDNF while small dental trigeminal neurons seems not to require GDNF. This suggests that GDNF may function as a neurotrophic factor for subsets of nerves in the tooth, which apparently mediate mechanosensitive stimuli. As in dorsal root ganglia both small- and large-sized neurons are known to be GDNF-dependent; these data provide molecular evidence that the sensory supply in the adult tooth differs, in some aspects, from the cutaneous sensory system.
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Keifer J, Mokin M. Distribution of anterogradely labeled trigeminal and auditory nerve boutons on abducens motor neurons in turtles: Implications for in vitro classical conditioning. J Comp Neurol 2004; 471:144-52. [PMID: 14986308 DOI: 10.1002/cne.20032] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A conditioned abducens nerve response is generated in in vitro brainstem preparations from turtles by pairing a weak conditioned stimulus (CS) applied to the auditory nerve that immediately precedes an unconditioned stimulus (US) applied to the trigeminal nerve. Tract-tracing studies showed direct projections from auditory and trigeminal nerves to abducens motor neurons. In light of these findings for convergent CS-US inputs, it is hypothesized that auditory and trigeminal nerve synaptic inputs onto abducens motor neurons are in spatial proximity because the CS is a weak input that may be required to be near the US inputs to have an associative effect, and conditioning occurs only when the CS and US are temporally separated by less than 100 ms. This study examined the spatial relationship of 133 anterogradely labeled synaptic boutons conveying CS or US information on retrogradely labeled abducens motor neurons. The results show that trigeminal and auditory nerve terminal fields occupy primarily the soma and proximal dendrites of abducens motor neurons. Quantitative analysis shows that the majority of labeled boutons (76% and 85% from injections of the trigeminal and auditory nerves, respectively) were apposed to somata or were localized to dendritic segments no more than about 30 microm from the nucleus. There were no quantitative differences between trigeminal and auditory nerve boutons in terms of their localization on dendrites or bouton diameter. Finally, triple labeling experiments demonstrated that individual abducens motor neurons receive inputs from both nerves and that these inputs may be in close spatial proximity to one another. This synaptic arrangement allows for the possibility that in vitro abducens conditioning is generated by coincident CS-US detection mediated by NMDA receptors and may utilize a Hebbian-like plasticity mechanism.
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Hassel B, Boldingh KA, Narvesen C, Iversen EG, Skrede KK. Glutamate transport, glutamine synthetase and phosphate-activated glutaminase in rat CNS white matter. A quantitative study. J Neurochem 2003; 87:230-7. [PMID: 12969269 DOI: 10.1046/j.1471-4159.2003.01984.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Glutamatergic signal transduction occurs in CNS white matter, but quantitative data on glutamate uptake and metabolism are lacking. We report that the level of the astrocytic glutamate transporter GLT in rat fimbria and corpus callosum was approximately 35% of that in parietal cortex; uptake of [3H]glutamate was 24 and 43%, respectively, of the cortical value. In fimbria and corpus callosum levels of synaptic proteins, synapsin I and synaptophysin were 15-20% of those in cortex; the activities of glutamine synthetase and phosphate-activated glutaminase, enzymes involved in metabolism of transmitter glutamate, were 11-25% of cortical values, and activities of aspartate and alanine aminotransferases were 50-70% of cortical values. The glutamate level in fimbria and corpus callosum was 5-6 nmol/mg tissue, half the cortical value. These data suggest a certain capacity for glutamatergic neurotransmission. In optic and trigeminal nerves, [3H]glutamate uptake was < 10% of the cortical uptake. Formation of [14C]glutamate from [U-14C]glucose in fimbria and corpus callosum of awake rats was 30% of cortical values, in optic nerve it was 13%, illustrating extensive glutamate metabolism in white matter in vivo. Glutamate transporters in brain white matter may be important both physiologically and during energy failure when reversal of glutamate uptake may contribute to excitotoxicity.
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Marfurt CF, Murphy CJ, Florczak JL. Morphology and neurochemistry of canine corneal innervation. Invest Ophthalmol Vis Sci 2001; 42:2242-51. [PMID: 11527937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
PURPOSE To determine the architectural pattern and neuropeptide content of canine corneal innervation. METHODS Corneal nerve fibers in normal dog eyes were labeled immunohistochemically with antibodies against protein gene product (PGP)-9.5, calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal polypeptide (VIP), and tyrosine hydroxylase (TH). Relative innervation densities and distribution patterns for each fiber population were assessed qualitatively by serial line-drawing reconstructions and quantitatively by computer-assisted analyses. RESULTS More than 99% of all corneal PGP-9.5-immunoreactive (IR) nerves contained both CGRP and SP, approximately 30% contained TH, and none contained VIP. Distribution patterns of corneal PGP-9.5-, CGRP-, SP-, and TH-IR nerves were indistinguishable, except that TH-IR fibers were absent from the corneal epithelium. Morphologically, canine corneal innervation consisted of a rich anterior stromal plexus, divided on the basis of morphologic criteria into anterior and posterior levels, and a rich epithelial innervation, characterized by large numbers of horizontally oriented, basal epithelial "leash" formations. Leash axons in all quadrants of the corneal epithelium oriented preferentially toward a common locus in the perilimbal cornea. CONCLUSIONS The results of this study demonstrate for the first time the detailed architectural features, distinctive basal epithelial leash orientations, and peptidergic content of canine corneal innervation. The normal innervation pattern described in this study will provide other investigators with essential baseline data for assessing corneal nerve alterations in canine patients with spontaneous chronic corneal epithelial defects (SCCED) and other ocular diseases or injuries.
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Abstract
The neuropeptide galanin (Gal) is found throughout the central nervous system. Of particular interest is the fact that Gal is present within the majority of noradrenergic locus coeruleus (LC) neurons. However, very few, if any, Gal-immunoreactive fibers have been identified in many of the major efferent targets of LC, including sensory neocortex and dorsal thalamus. The goal of the present study was to examine the Gal fiber innervation of the rodent trigeminal somatosensory system and its connection to the LC. Our results show that at least two different morphological profiles of Gal-immunoreactive fibers are present within relay nuclei along the ascending trigeminal pathway. Numerous small caliber Gal-immunoreactive fibers with bouton-like swellings were noted within the barrel cortex, the ventroposterior medial (VPM) nucleus, the posterior medial (POm) nucleus, the zona incerta (ZI), the reticular nucleus (nRT) of the thalamus, and the principal (PrV) and spinal (SpV) nuclei of the trigeminal complex. Immunoreactive fibers were prevalent in, but not restricted to, layer I of the barrel cortex. Within the somatosensory thalamus, the density of Gal-immunoreactive fibers was higher in POm than in VPM. Laminae I and II of SpV and the nRT and ZI also contained dense, large-diameter Gal-immunoreactive fibers. These large-diameter Gal-immunoreactive fibers did not co-contain dopamine beta-hydroxylase (DBH). In contrast, virtually every small-caliber Gal-immunoreactive fiber colocalized with DBH. To determine whether Gal-immunoreactive fibers originated from LC, we combined immunohistochemical procedures with fluorescent tracing techniques. After retrograde tracer injections into several trigeminal relay nuclei, we observed that approximately 50% of the labeled LC neuronal population was immunoreactive for Gal. Our results suggest an extensive Gal-immunoreactive fiber innervation of the rodent trigeminal system, much of which may originate from LC neurons in the brainstem.
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Verzé L, Paraninfo A, Ramieri G, Viglietti-Panzica C, Panzica GC. Immunocytochemical evidence of plasticity in the nervous structures of the rat lower lip. Cell Tissue Res 1999; 297:203-11. [PMID: 10470490 DOI: 10.1007/s004410051348] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this immunocytochemical study we investigated the distribution of nervous structures in the lower lip of adult rats. The region is characterized by a rich cutaneous and mucosal sensory innervation originating from terminal branches of the trigeminal system. Lower lip innervation was investigated by detection of the general neuronal marker protein gene product 9.5 (PGP 9.5) and the growth-associated protein 43 (GAP-43), a neurochemical marker of neuronal plasticity. The entire neural network of both cutaneous and mucosal aspects was stained by the antibody to PGP 9.5. In particular, nerve fibers were observed in the submucosal and the subepithelial plexuses. Thin immunoreactive fibers were observed within the epithelial layers ending as free fibers or as fibers associated with immunopositive Merkel cells. Well-identified anatomical structures receiving sensory or autonomic innervation were also surrounded by PGP 9.5-ir nerve fibers, in particular, hair follicles, vibrissae, glands, and blood vessels. GAP-43-immunostained nerve fibers were observed in all these structures; however, they were generally less numerous than the PGP 9.5-immunoreactive elements. An equal amount of PGP 9.5 and GAP-43 immunoreactivity occurred, in contrast, in the subepidermal and the submucosal plexuses, or in the epidermis and the mucosal epithelium. The present results show that GAP-43 is normally expressed in the mature trigeminal sensory system of the rat. Skin and oral mucosa are characterized by continuous remodeling that may also involve the sensory nervous apparatus. Continuous neural remodeling, regeneration and sprouting may be the reason for the observed expression of GAP-43.
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Hansson SR, Cabrera-Vera TM, Hoffman BJ. Infraorbital nerve transection alters serotonin transporter expression in sensory pathways in early postnatal rat development. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1998; 111:305-14. [PMID: 9838174 DOI: 10.1016/s0165-3806(98)00148-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The serotonin transporter MRNA has been found throughout the trigeminal sensory system late in gestation and during early postnatal development, a period known to be critical for maturation of the sensory circuitry. The purpose of the present study was to determine whether sensory denervation in newborn rat pups would alter either the density or pattern of expression of the 5-HT transporter (5-HTT) within the trigeminal system. We combined autoradiographic localization of 5-HT transporters and in situ hybridization techniques to visualize both the transporter protein and mRNA in thalamic sensory neurons and in the somatosensory cortex following unilateral infraorbital nerve transection at postnatal day 1. For comparative purposes, similar measurements were conducted in thalamic visual neurons as well as in the visual cortex. Lesion of the infraorbital nerve decreased the [3H]citalopram labelling of 5-HT transporters in the ventral basal and ventral medial areas of the thalamus contralateral to the lesion, while labelling of 5-HT transporters was decreased in both contralateral and ipsilateral sides of the lateral genicuate (visual thalamus). Citalopram labelling of 5-HT transporters was not significantly altered in somatosensory or in cingulate cortex, however a significant decrease was observed in the visual cortex. In contrast, there were no obvious changes in the intensity of the 5-HT mRNA hybridization signal in sensory or visual thalamic areas. Given that the serotonin transporter regulates extracellular concentrations of 5-HT, the present data suggest that altered peripheral innervation and thereby altered sensory inputs to the thalamus during fetal development can potentially influence 5-HT transporter densities and thus, may influence extracellular levels of 5-HT in thalamus and cortex during a critical period of synapse formation. In turn, modulation of 5-HT transporter levels may influence extracellular concentrations of 5-HT in thalamus and cortex during a critical period of synapse formation.
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Cairns BE, Sessle BJ, Hu JW. Evidence that excitatory amino acid receptors within the temporomandibular joint region are involved in the reflex activation of the jaw muscles. J Neurosci 1998; 18:8056-64. [PMID: 9742172 PMCID: PMC6792993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
We have previously shown that injection of the inflammatory irritant and small-fiber excitant mustard oil (MO) into the temporomandibular joint (TMJ) region can reflexively induce a prolonged increase in the activity of both digastric and masseter muscles in rats. It is possible that peripheral excitatory amino acid (EAA) receptors play a role in this effect, because MO-evoked increases in jaw muscle activity are attenuated by preapplication of the noncompetitive NMDA receptor antagonist MK-801 into the TMJ region. In the present study the EAA receptor agonists glutamate, NMDA, kainate, and AMPA were applied locally to the TMJ region. Jaw muscle responses similar to those evoked by MO application to the TMJ region were achieved with glutamate, NMDA, AMPA, and kainate. Repeated application of glutamate, NMDA, or AMPA at intervals of 30 min evoked responses in the ipsilateral jaw muscles that were of comparable magnitude. Co-application of the NMDA receptor antagonist DL-2-amino-5-phosphonovalerate (0.5 micromol) significantly reduced the magnitude of the glutamate- and NMDA-evoked ipsilateral jaw muscle responses without affecting responses evoked by AMPA. In contrast, co-application of the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (1 nmol) significantly reduced the magnitude of the glutamate- and AMPA-evoked ipsilateral jaw muscle responses without affecting responses evoked by NMDA. This evidence suggests that both NMDA and non-NMDA EAA receptor types are located within the TMJ region and may contribute to jaw muscle activity that can be reflexively evoked from the TMJ region.
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Hamano K, Takeya T, Iwasaki N, Nakayama J, Ohto T, Okada Y. A quantitative study of the progress of myelination in the rat central nervous system, using the immunohistochemical method for proteolipid protein. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1998; 108:287-93. [PMID: 9693804 DOI: 10.1016/s0165-3806(98)00063-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The temporal changes in intensity of myelination of the nervous pathways in 0 to 42-day-old Wistar rats were quantitatively analyzed by immunohistochemistry with anti-proteolipid protein and compared with that obtained by immunohistochemistry with anti-myelin basic protein. Immunohistochemistry was performed on paraffin-embedded tissue according to the standard ABC technique. Intensity of myelination was examined by an image analyzing system. We analyzed nine nervous pathways: corpus callosum, optic tract, internal capsule, spinal tract of the trigeminal nerve, inferior cerebellar peduncle, cerebellar white matter, pyramidal tract, medial longitudinal fasciculus, and cuneate fasciculus. The presence of immunoreactive fibers for proteolipid protein (PLP) in the spinal tract of the trigeminal nerve, medial longitudinal fasciculus and cuneate fasciculus was noted on postnatal day 0. Those of the corpus callosum, inferior cerebellar peduncle, cerebellar white matter, pyramidal tract and internal capsule were noted on day 7, and that of optic tract on day 14. The time required to reach the intensity of myelination of day 42 was day 14 for the cuneate fasciculus, day 21 for the spinal tract of the trigeminal nerve, inferior cerebellar peduncle and medial longitudinal fasciculus, day 28 for the optic and pyramidal tracts, day 35 for the corpus callosum and day 42 for the internal capsule and cerebellar white matter. The appearance of immunoreactive fibers for PLP was usually earlier than that for myelin basic protein (MBP) and the pattern of difference between PLP and MBP can be classified into three groups: (1) their time of appearance and progress are almost the same, as in the optic tract; (2) the appearance and progress of PLP occurs earlier than those of MBP, as in the pyramidal tract; (3) the appearance of PLP occurs earlier than that of MBP, but their progress is the same. Our findings revealed that the time of appearance and progress of myelination as measured by PLP are different among the nervous pathways, and that there is also a difference between PLP and MBP. This difference between PLP and MBP may indicate a functional difference between them.
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Hsiao CF, Del Negro CA, Trueblood PR, Chandler SH. Ionic basis for serotonin-induced bistable membrane properties in guinea pig trigeminal motoneurons. J Neurophysiol 1998; 79:2847-56. [PMID: 9636091 DOI: 10.1152/jn.1998.79.6.2847] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Intracellular recordings and pharmacological manipulations were employed to investigate the ionic basis for serotonin-induced bistable membrane behaviors in guinea pig trigeminal motoneurons (TMNs). In voltage clamp, 10 microM serotonin (5-HT) induced a region of negative slope resistance (NSR) in the steady-state current-voltage (I-V) relationship at potentials less negative than -58 mV, creating the necessary conditions for membrane bistability. The contributions of sustained Na+ and Ca2+ currents to the generation of the NSR were investigated using specific ion channel antagonists and agonists. The NSR was eliminated by the L-type Ca2+ channel antagonist nifedipine (5-10 microM), indicating the contribution of L channels. In nifedipine, inward rectification was present in the I-V relationship in a similar voltage range (greater than -58 mV). This region was subsequently linearized by tetrodotoxin (TTX), indicating the presence of a persistent Na+ current. When the 5-HT-induced NSR was eliminated by perfusion in low Ca2+ solution (0.4 mM), it was restored by the Na+ channel agonist veratridine (10 microM). Commensurate with bistability, in current clamp during bath application of 5-HT, plateau potentials were elicited by transient depolarizing or hyperpolarizing stimuli. Plateau potentials evoked by depolarization were observed under control and TTX conditions, but were blocked by nifedipine, suggesting the participation of an L-type Ca2+ current. Plateau potentials initiated after release from hyperpolarization (anode break) were blocked by 300 microM Ni2+, suggesting the responses relied on deinactivation of a T-type Ca2+ current. Conditional bursting was also observed in 5-HT. Nifedipine or low Ca2+ solutions blocked bursting, and the L-channel agonist Bay K 8644 (10 microM) extended the duration of individual bursts, demonstrating the role of L-type Ca2+ currents. Interestingly, when bursting was blocked by nifedipine or low Ca2+, it could be restored by veratridine application via enhancement of the persistent Na+ current. We conclude that bistable membrane behaviors in TMNs are mediated by L-type Ca2+ and persistent Na+ currents. 5-HT is associated with enhancement of TMN activity during oral-motor activity; the induction of bistable membrane properties by 5-HT represents a cellular mechanism for this enhancement.
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Alia S, Azérad J, Pollin B. Effects of RPR 100893, a potent NK1 antagonist, on the jaw-opening reflex in the guinea pig. Brain Res 1998; 787:99-106. [PMID: 9518568 DOI: 10.1016/s0006-8993(97)01545-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
RPR 100893 appears as a new potent NK1 selective non-peptide antagonist both in vitro and in vivo, and exhibits high affinity for guinea pig and human NK1 receptor [M. Tabart, J.-F. Peyronel, Synthesis of RPR 100893, prototype of a new series of potent and selective non-peptide NK1 antagonists: the triarylperhydroisoindolols, Bioorg. Med. Chem. Lett., 4 (1994) 673-676.]. Intra-oral administration of RPR 100893 (3, 15, 10, 30 mg/kg) was performed in freely moving guinea pigs during recording of the short- (6-10 ms) and long-latency (18-26 ms) jaw-opening reflex (JOR) elicited by electrical stimulation (0.5 Hz) of the lower incisor tooth pulp. RPR 100893 induced a noticeable and dose-dependent increase of the long-latency reflex thresholds (P<0. 001) but was ineffective on the short-latency responses (P=0.14). The results suggest that, in guinea pigs, the long-latency JOR requires activation of NK1 receptors, while the earlier reflex component, elicited by activation of periodontal afferents, does not. These NK1 receptors could be located either on JOR interneurons activated by tooth pulp afferents or on digastric motoneurons, receiving the tooth pulp input through a polysynaptic pathway.
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Longmore J, Shaw D, Smith D, Hopkins R, McAllister G, Pickard JD, Sirinathsinghji DJ, Butler AJ, Hill RG. Differential distribution of 5HT1D- and 5HT1B-immunoreactivity within the human trigemino-cerebrovascular system: implications for the discovery of new antimigraine drugs. Cephalalgia 1997; 17:833-42. [PMID: 9453271 DOI: 10.1046/j.1468-2982.1997.1708833.x] [Citation(s) in RCA: 191] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Sumatriptan, a 5HT1B/1D-receptor agonist, is clinically effective as an antimigraine agent. Its therapeutic action may result partly from vasoconstriction of excessively dilated cranial blood vessels (a 5HT1B-receptor mediated response). The antimigraine activity of sumatriptan may also result from inhibition of the release of vasoactive neuropeptides from trigeminal sensory fibres within the meninges. The identity of the 5HT1B/1D-receptor subtype mediating this effect is unknown. Using 5HT1D- and 5HT1B-receptor-specific antibodies we have demonstrated a differential distribution of these receptor subtypes within the human trigemino-cerebrovascular system. Only 5HT1B-receptor protein was detected on dural arteries. In contrast, only 5HT1D-receptor protein was detected on trigeminal sensory neurones including peripheral and central projections to dural blood vessels and to the medulla. Within the medulla 5HT1D-receptor protein was confined to discrete areas associated with the trigeminal sensory system. These findings have important implications for the design of new antimigraine drugs.
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Okabe H, Okubo T, Adachi H, Ishikawa T, Ochi Y. Immunohistochemical demonstration of cytokeratin in human embryonic neurons arising from placodes. Brain Dev 1997; 19:347-52. [PMID: 9253488 DOI: 10.1016/s0387-7604(97)00034-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Sensory neurons of the olfactory, trigeminal, facial, vestibulo-cochlear, glossopharyngeal and vagal nerves, and neurons migrating along the olfactory nerve to the brain have special anlagen, made up of placodes located in the epithelial layer. To investigate the characteristic phenotype of placode-derived neurons, immunohistochemical analysis of intermediate filaments was conducted on formalin-fixed human embryonic tissues. Neurons arising from placodes including luteinizing-hormone releasing hormone (LHRH) neurons migrating from the olfactory placode to the brain had immunoreactivity to antibodies specific to cytokeratin, AE1 and CAM5.2 during the embryonic stage. However, this immunoreactivity disappeared during the late embryonic to the post-embryonic stage and was not observed in the roots of these nerves in the post-natal stage. Immunoreactivity was detected in both the somata and processes, and the distribution differed from that described in rodent brain neurons. With this exception, no other human peripheral neurons, including spinal dorsal root ganglia, had immunoreactivity with anti-cytokeratin antibodies throughout the entire developmental stage. Although the cephalic neural crest also directly generates neurons to most of the cranial sensory ganglia, we could not find any evidence that it contributed to the genesis of cytokeratin-positive embryonic neurons. We concluded that cytokeratin is an intermediate filament common to human embryonic neurons of cephalic placodal origin and that this immunohistochemical marker may be useful in analyzing the developmental sequence of several congenital diseases involving the cranial nerves, such as Moebius syndrome and Goldenhar syndrome.
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Holz A, Schwab ME. Developmental expression of the myelin gene MOBP in the rat nervous system. JOURNAL OF NEUROCYTOLOGY 1997; 26:467-77. [PMID: 9306245 DOI: 10.1023/a:1018529323734] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The myelin-associated/oligodendrocyte basic proteins (MOBPs) are recently discovered constituents of myelin and are small, cytoplasmic, and highly basic proteins exclusively expressed postnatally by oligodendrocytes. Due to a clustering of positively charged amino acids observed in the most abundant MOBP isoform similar to myelin basic protein (MBP) and P0, it was speculated that MOBP could function in myelin sheath compaction. The present report strongly supports this view. A direct comparison of MBP and proteolipid protein (PLP) gene expression with that of MOBP by in situ hybridization revealed a very similar regional distribution. It was found that MOBP expression was abundant in the rat CNS at postnatal day 15 (P 15) but is restricted to densely myelinated regions. In contrast to MBP and PLP, expression of MOBP was undetectable in the peripheral nervous system during the entire development. Interestingly, MOBP mRNA was localized in oligodendrocyte processes even at early postnatal stages and throughout development. MOBP showed a very specific timing of expression: in spinal cord and brain, MOBP gene expression occurred significantly later (2-3 days) than that of MBP and PLP, but slightly earlier than myelin oligodendrocyte glycoprotein gene expression. MOBP proteins appeared in spinal cord and brain stem also after MBP protein, suggesting that the MOBPs functionally act after the structural myelin proteins MBP and PLP. Our findings imply a function of MOBP during the late steps of myelin formation, presumably at the initiation of sheath compaction.
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Goadsby PJ, Hoskin KL. The distribution of trigeminovascular afferents in the nonhuman primate brain Macaca nemestrina: a c-fos immunocytochemical study. J Anat 1997; 190 ( Pt 3):367-75. [PMID: 9147223 PMCID: PMC1467617 DOI: 10.1046/j.1469-7580.1997.19030367.x] [Citation(s) in RCA: 171] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
An understanding of migraine must be based on data concerning the anatomy and physiology of the painsensitive intracranial structures. Stimulation of the superior sagittal sinus produces changes in brain blood flow and changes in neuropeptide levels similar to those seen in humans during migraine. To better understand the anatomy of the central ramifications of pain-sensitive intracranial structures we have examined the distribution of c-fos immunoreactivity in the monkey when the sinus is stimulated. Six adult Macaca nemestrina monkeys were anaesthetised. The superior sagittal sinus was isolated after a midline craniotomy and a paraffin well created. At 24 h after completion of the surgery the sinus was stimulated electrically for 1 h and the brain subsequently removed and processed for c-fos. In control animals in which the sinus was isolated but not stimulated there was a small amount of c-fos expression in the caudal brainstem and upper cervical spinal cord. Stimulation of the superior sagittal sinus evoked expression of c-fos in the caudal superfical laminae of the trigeminal nucleus and in superficial laminae of the dorsal horn of the C1 level of the upper cervical spinal cord. A lesser amount of c-fos was seen at C2 while no significant labelling above control was observed at C3. These data, while largely confirming the results from the cat concerning the central distribution trigeminovascular afferents, underscore a possibly unique specialisation of trigeminovascular afferents at the C1 level. Given the close evolutionary relationship of the monkey to man it is likely that the cells described in this study represent for primates the nucleus that mediates the pain of migraine.
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Hamano K, Iwasaki N, Takeya T, Takita H. A quantitative analysis of rat central nervous system myelination using the immunohistochemical method for MBP. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1996; 93:18-22. [PMID: 8804688 DOI: 10.1016/0165-3806(96)00025-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The temporal order of the myelination of the nervous pathways in 0-42-day-old Wistar rats was quantitatively analyzed using immunohistochemistry with anti-myelin basic protein (MBP) antibody. Immunohistochemistry was performed on paraffin-embedded tissue according to the standard ABC technique. For the objective evaluation of myelination, we converted the level stained with the immunohistochemical method into continuous numbers of 0-256 giving the intensity of myelination, using an image analyzing system. We analyzed nine nervous pathways: corpus callosum, optic tract, internal capsule, spinal tract of trigeminal nerve, inferior cerebellar peduncle, cerebellar white matter, pyramidal tract, medial longitudinal fasciculus, and cuneate fasciculus. The onset of the myelination of the spinal tract of the trigeminal nerve, inferior cerebellar peduncle, medial longitudinal fasciculus and cuneate fasciculus was day 7 (postnatal). That of the corpus callosum, optic tract, internal capsule and cerebellar white matter was day 14, and that of the pyramidal tract was day 21. The time required to reach the level of myelination of day 42 was day 21 for the spinal tract of the trigeminal nerve and the inferior cerebellar peduncle, day 28 for the internal capsule, day 35 for the corpus callosum, optic tract, cerebellar white matter and pyramidal tract, and day 42 for the medial longitudinal fasciculus. Our method using immunohistochemistry with anti-MBP antibody provided a highly sensitive and objective criterion for judging precisely the time and the progress of myelination in each nervous pathway and compare one nervous pathway with another.
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Ericson AC, Blomqvist A, Craig AD, Ottersen OP, Broman J. Evidence for glutamate as neurotransmitter in trigemino-and spinothalamic tract terminals in the nucleus submedius of cats. Eur J Neurosci 1995; 7:305-17. [PMID: 7757265 DOI: 10.1111/j.1460-9568.1995.tb01066.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The nucleus submedius in the medial thalamus of cats is an important termination site for lamina I trigemino-and spinothalamic tract (TSTT) neurons, many of which are nociceptive-specific, and the nucleus submedius has been proposed to be a dedicated nociceptive substrate involved in the affective aspect of pain. In the present study, the distribution of glutamate was examined by immunocytochemical methods in order to evaluate the possible role of this amino acid as a neurotransmitter in TSTT terminals in the nucleus submedius. TSTT terminals were identified by anterograde transport of horseradish peroxidase and wheatgerm agglutinin-horseradish peroxidase conjugate from the spinal cord or the medullary dorsal horn. Quantitative analysis of immunogold labelling revealed that TSTT terminals contain about twice the tissue average of glutamate-like immunoreactivity. A strong positive correlation was found between the density of synaptic vesicles and the density of gold particles in these terminals, whereas no relationship was seen between these variables in GABAergic presynaptic dendrites. Enrichment of glutamate-like immunoreactivity (approximately 250% of the tissue average) was also observed in terminals of presumed cortical origin. Presynaptic dendrites and neuron cell bodies in the nucleus submedius were found to contain relatively low levels of glutamate-like immunoreactivity, at or below the tissue average. These observations provide evidence that glutamate is a neurotransmitter in lamina I TSTT terminals in the nucleus submedius. The findings also suggest glutamatergic neurotransmission between cortical afferents and nucleus submedius neurons. Glutamate is therefore likely to be an important mediator of nociceptive processing in the medial thalamus.
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