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Karthik S, Huang D, Delgado Y, Laing JJ, Peltekian L, Iverson GN, Grady F, Miller RL, McCann CM, Fritzsch B, Iskusnykh IY, Chizhikov VV, Geerling JC. Molecular ontology of the parabrachial nucleus. J Comp Neurol 2022; 530:1658-1699. [PMID: 35134251 PMCID: PMC9119955 DOI: 10.1002/cne.25307] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 01/22/2022] [Accepted: 01/25/2022] [Indexed: 11/07/2022]
Abstract
This article has been removed because of a technical problem in the rendering of the PDF. 11 February 2022.
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Affiliation(s)
| | - Dake Huang
- Department of NeurologyUniversity of IowaIowa CityIowaUSA
| | | | | | - Lila Peltekian
- Department of NeurologyUniversity of IowaIowa CityIowaUSA
| | | | - Fillan Grady
- Department of NeurologyUniversity of IowaIowa CityIowaUSA
| | - Rebecca L. Miller
- Department of Anatomy and NeurobiologyWashington University School of MedicineSaint LouisMissouriUSA
| | - Corey M. McCann
- Department of Anatomy and NeurobiologyWashington University School of MedicineSaint LouisMissouriUSA
| | - Bernd Fritzsch
- Iowa Neuroscience InstituteIowa CityIowaUSA
- Department of BiologyUniversity of IowaIowa CityIowaUSA
| | - Igor Y. Iskusnykh
- Department of Anatomy and NeurobiologyUniversity of Tennessee Health Science CenterMemphisTennesseeUSA
| | - Victor V. Chizhikov
- Department of Anatomy and NeurobiologyUniversity of Tennessee Health Science CenterMemphisTennesseeUSA
| | - Joel C. Geerling
- Department of NeurologyUniversity of IowaIowa CityIowaUSA
- Iowa Neuroscience InstituteIowa CityIowaUSA
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Chiang MC, Bowen A, Schier LA, Tupone D, Uddin O, Heinricher MM. Parabrachial Complex: A Hub for Pain and Aversion. J Neurosci 2019; 39:8225-8230. [PMID: 31619491 PMCID: PMC6794922 DOI: 10.1523/jneurosci.1162-19.2019] [Citation(s) in RCA: 143] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 07/29/2019] [Accepted: 08/03/2019] [Indexed: 02/06/2023] Open
Abstract
The parabrachial nucleus (PBN) has long been recognized as a sensory relay receiving an array of interoceptive and exteroceptive inputs relevant to taste and ingestive behavior, pain, and multiple aspects of autonomic control, including respiration, blood pressure, water balance, and thermoregulation. Outputs are known to be similarly widespread and complex. How sensory information is handled in PBN and used to inform different outputs to maintain homeostasis and promote survival is only now being elucidated. With a focus on taste and ingestive behaviors, pain, and thermoregulation, this review is intended to provide a context for analysis of PBN circuits involved in aversion and avoidance, and consider how information of various modalities, interoceptive and exteroceptive, is processed within PBN and transmitted to distinct targets to signal challenge, and to engage appropriate behavioral and physiological responses to maintain homeostasis.
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Affiliation(s)
- Michael C Chiang
- Department Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania, 15213
| | - Anna Bowen
- Graduate Program in Neuroscience, University of Washington, Seattle, Washington, 98195
| | - Lindsey A Schier
- Department Biological Sciences, University of Southern California, Los Angeles, California, 90089
| | - Domenico Tupone
- Biomedical and Neuromotor Sciences, University of Bologna, 40126 Bologna, Italy
- Department Neurological Surgery, Oregon Health and Science University, Portland, Oregon, 97239, and
| | - Olivia Uddin
- Department of Anatomy and Neurobiology, University of Maryland, Baltimore, Maryland, 21201
| | - Mary M Heinricher
- Department Neurological Surgery, Oregon Health and Science University, Portland, Oregon, 97239, and
- Department Behavioral Neuroscience, Oregon Health and Science University, Portland, Oregon, 97239
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Abstract
Wind-up is a frequency-dependent increase in the response of spinal cord neurons, which is believed to underlie temporal summation of nociceptive input. However, whether spinoparabrachial neurons, which likely contribute to the affective component of pain, undergo wind-up was unknown. Here, we addressed this question and investigated the underlying neural circuit. We show that one-fifth of lamina I spinoparabrachial neurons undergo wind-up, and provide evidence that wind-up in these cells is mediated in part by a network of spinal excitatory interneurons that show reverberating activity. These findings provide insight into a polysynaptic circuit of sensory augmentation that may contribute to the wind-up of pain's unpleasantness.
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Jansen NA, Giesler GJ. Response characteristics of pruriceptive and nociceptive trigeminoparabrachial tract neurons in the rat. J Neurophysiol 2015; 113:58-70. [PMID: 25298386 PMCID: PMC4294571 DOI: 10.1152/jn.00596.2014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 10/06/2014] [Indexed: 12/11/2022] Open
Abstract
We tested the possibility that the trigeminoparabrachial tract (VcPbT), a projection thought to be importantly involved in nociception, might also contribute to sensation of itch. In anesthetized rats, 47 antidromically identified VcPbT neurons with receptive fields involving the cheek were characterized for their responses to graded mechanical and thermal stimuli and intradermal injections of pruritogens (serotonin, chloroquine, and β-alanine), partial pruritogens (histamine and capsaicin), and an algogen (mustard oil). All pruriceptive VcPbT neurons were responsive to mechanical stimuli, and more than half were additionally responsive to thermal stimuli. The majority of VcPbT neurons were activated by injections of serotonin, histamine, capsaicin, and/or mustard oil. A subset of neurons were inhibited by injection of chloroquine. The large majority of VcPbT neurons projected to the ipsilateral and/or contralateral external lateral parabrachial and Kölliker-Fuse nuclei, as evidenced by antidromic mapping techniques. Analyses of mean responses and spike-timing dynamics of VcPbT neurons suggested clear differences in firing rates between responses to noxious and pruritic stimuli. Comparisons between the present data and those previously obtained from trigeminothalamic tract (VcTT) neurons demonstrated several differences in responses to some pruritogens. For example, responses of VcPbT neurons to injection of serotonin often endured for nearly an hour and showed a delayed peak in discharge rate. In contrast, responses of VcTT neurons endured for roughly 20 min and no delayed peak of firing was noted. Thus the longer duration responses to 5-HT and the delay in peak firing of VcPbT neurons better matched behavioral responses to stimulation in awake rats than did those of VcTT neurons. The results indicate that VcPbT neurons may have important roles in the signaling of itch as well as pain.
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Affiliation(s)
- Nico A Jansen
- Department of Neuroscience, Erasmus University Medical Center, Rotterdam, The Netherlands; and
| | - Glenn J Giesler
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota
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Xie Q, Li X, Xu X. The difficult relationship between occlusal interferences and temporomandibular disorder - insights from animal and human experimental studies. J Oral Rehabil 2013; 40:279-95. [PMID: 23356664 DOI: 10.1111/joor.12034] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2013] [Indexed: 11/30/2022]
Affiliation(s)
- Q. Xie
- Department of Prosthodontics; Peking University School and Hospital of Stomatology; Beijing China
| | - X. Li
- Department of Prosthodontics; Peking University School and Hospital of Stomatology; Beijing China
| | - X. Xu
- Department of Prosthodontics; Peking University School and Hospital of Stomatology; Beijing China
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Dong YL, Fukazawa Y, Wang W, Kamasawa N, Shigemoto R. Differential postsynaptic compartments in the laterocapsular division of the central nucleus of amygdala for afferents from the parabrachial nucleus and the basolateral nucleus in the rat. J Comp Neurol 2011; 518:4771-91. [PMID: 20963828 DOI: 10.1002/cne.22487] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Neurons in the laterocapsular division of the central nucleus of the amygdala (CeC), which is known as the "nociceptive amygdala," receive glutamatergic inputs from the parabrachial nucleus (PB) and the basolateral nucleus of amygdala (BLA), which convey nociceptive information from the dorsal horn of the spinal cord and polymodal information from the thalamus and cortex, respectively. Here, we examined the ultrastructural properties of PB- and BLA-CeC synapses identified with EGFP-expressing lentivirus in rats. In addition, the density of synaptic AMPA receptors (AMPARs) on CeC neurons was studied by using highly sensitive SDS-digested freeze-fracture replica labeling (SDS-FRL). Afferents from the PB made asymmetrical synapses mainly on dendritic shafts (88%), whereas those from the BLA were on dendritic spines (81%). PB-CeC synapses in dendritic shafts were significantly larger (median 0.072 μm(2)) than BLA-CeC synapses in spines (median 0.058 μm(2); P = 0.02). The dendritic shafts that made synapses with PB fibers were also significantly larger than those that made synapses with BLA fibers, indicating that the PB fibers make synapses on more proximal parts of dendrites than the BLA fibers. SDS-FRL revealed that almost all excitatory postsynaptic sites have AMPARs in the CeC. The density of AMPAR-specific gold particles in individual synapses was significantly higher in spine synapses (median 510 particles/μm(2)) than in shaft synapses (median 427 particles/μm(2); P = 0.01). These results suggest that distinct synaptic impacts from PB- and BLA-CeC pathways contribute to the integration of nociceptive and polymodal information in the CeC.
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Affiliation(s)
- Yu-Lin Dong
- Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki, Japan.
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Niu JG, Yokota S, Tsumori T, Qin Y, Yasui Y. Glutamatergic lateral parabrachial neurons innervate orexin-containing hypothalamic neurons in the rat. Brain Res 2010; 1358:110-22. [DOI: 10.1016/j.brainres.2010.08.056] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 07/26/2010] [Accepted: 08/17/2010] [Indexed: 12/12/2022]
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Díaz-Casares A, López-González MV, Peinado-Aragonés CA, Lara JP, González-Barón S, Dawid-Milner MS. Role of the parabrachial complex in the cardiorespiratory response evoked from hypothalamic defense area stimulation in the anesthetized rat. Brain Res 2009; 1279:58-70. [DOI: 10.1016/j.brainres.2009.02.085] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Revised: 02/27/2009] [Accepted: 02/27/2009] [Indexed: 11/25/2022]
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Chen J, Zhang J, Zhao Y, Yuan L, Nie X, Li J, Ma Z, Zhang Y, Wang Q, Chen Y, Jin Y, Rao Z. Hyperalgesia in response to traumatic occlusion and GFAP expression in rat parabranchial nucleus: modulation with fluorocitrate. Cell Tissue Res 2007; 329:231-7. [PMID: 17443351 DOI: 10.1007/s00441-007-0409-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2006] [Accepted: 02/28/2007] [Indexed: 11/24/2022]
Abstract
We have examined, by immunocytochemical methods and nociceptive behavior assessment in rats, whether astrocytes in the parabrachial nucleus (PBN) are involved in the regulation of traumatic occlusion. The expression of glial fibrillary acidic protein (GFAP) in PBN of ipsilateral and contralateral sides was up-regulated 4 h after occlusal changes in molars, reached peak levels at 24 h, and was then gradually down-regulated. PBN astrocytes activated by traumatic occlusion were found to have enlarged cell bodies and thickened processes within 8 h. An inhibitor of glia metabolism (FCA, fluorocitrate) reduced astrocyte activation and significantly attenuated the development of pain hypersensitivity in this model. The results suggested that the GFAP-immunoreactive astrocytes in PBN within the bridge of Varolius were activated by traumatic occlusion, and that they were involved in the transmission and modulation of nociceptive information in the central nervous system. However, although astrocytes in PBN are thus probably involved in causing post-occlusal hyperalgesia, we have not been able to exclude that astrocytes at other locations also contribute to this effect.
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Affiliation(s)
- Jinwu Chen
- Department of Oral Radiology and General Dentistry, School of Stomatology, Fourth Military Medical University, Xi'an, 710032, People's Republic of China.
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Saxon DW, Hopkins DA. Ultrastructure and synaptology of the paratrigeminal nucleus in the rat: primary pharyngeal and laryngeal afferent projections. Synapse 2006; 59:220-34. [PMID: 16385507 DOI: 10.1002/syn.20233] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The paratrigeminal nucleus (PTN) receives primary afferent projections from the aerodigestive tract and orofacial regions and plays a role in the integration of visceral and somatic information. This study describes the fine structure of the rat PTN and the synaptology of primary afferent projections from the pharynx and larynx. Injections of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) or cholera toxin-HRP (CT-HRP) were made into the wall of the pharynx or larynx to label primary afferent axon terminals. Light microscopic observations demonstrated that afferent axons terminated bilaterally in overlapping fields in the PTN. Electron microscopic observations of the PTN revealed that there were three distinct classes of neurons, based on morphology and axosomatic contacts. The most abundant neurons, Type 1, were fusiform in shape and received very few or no axosomatic contacts. Type 2 neurons contained prominent Nissl substance (rough endoplasmic reticulum) and few axosomatic contacts, while Type 3 neurons had many axosomatic synapses. Terminals containing round, clear vesicles and forming asymmetric contacts (round asymmetric, RA) with dendrites were the predominant synaptic type in the PTN. Primary afferent terminals from the pharynx and larynx were of the RA type and formed synaptic contacts with small-diameter (<1 microm) dendrites. Visceral primary afferent inputs from the pharynx and larynx overlap with trigeminal somatic afferents in the PTN and have similar synaptic morphology. The results support the concept that the PTN provides an anatomical substrate for mediating viscerovisceral and somatovisceral reflexes via efferent connections with autonomic centers in the brainstem.
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Affiliation(s)
- Dale W Saxon
- Department of Anatomy, Faculty of Medicine, Indiana University, Evansville Center for Medical Education, Evansville, Indiana 47712, USA
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Song G, Yu Y, Poon CS. Cytoarchitecture of pneumotaxic integration of respiratory and nonrespiratory information in the rat. J Neurosci 2006; 26:300-10. [PMID: 16399700 PMCID: PMC6674322 DOI: 10.1523/jneurosci.3029-05.2006] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The "pneumotaxic center" in the Kölliker-Fuse and medial parabrachial nuclei of dorsolateral pons (dl-pons) plays an important role in respiratory phase switching, modulation of respiratory reflex, and rhythmogenesis. Recent electrophysiological and neural tracing data implicate additional pneumotaxic nuclei in (and a broader role for) the dl-pons in integrating respiratory and nonrespiratory information. Here, we examined the cytoarchitecture of the greater pneumotaxic center and its integrating function by using combined extracellular recording and juxtacellular labeling of unit respiratory rhythmic neurons in dl-pons in urethane-anesthetized, vagotomized, paralyzed, and servo-ventilated adult Sprague Dawley rats. Perievent histogram analysis identified four major types of neuronal discharge patterns: inspiratory, expiratory (with three subdivisions), inspiratory-expiratory, and expiratory-inspiratory phase spanning, sometimes with mild tonic background activity. Most recorded neurons were localized in the Kölliker-Fuse and medial parabrachial nuclei, but some were also found in lateral parabrachial nucleus, intertrigeminal nucleus, principal trigeminal sensory nucleus, and supratrigeminal nucleus. The majority of labeled neurons had large and spatially extended dendritic trees that spanned several of these dl-pons subnuclei, often with terminal dendrites ending in the ventral spinocerebellar tract. The distal sections of the primary and higher-order dendrites exhibited rich varicosities, sometimes with dendritic spines. Axons of some labeled neurons were traced all the way to the ventrolateral pons (vl-pons). These findings extend and generalize the classical definition of the pneumotaxic center to include extensive somatic-axonal-dendritic integration of complex descending and ascending respiratory information as well as nociceptive and possibly musculoskeletal and trigeminal information in multiple dl-pons and vl-pons structures in the rat.
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Affiliation(s)
- Gang Song
- Harvard University-Massachusetts Institute of Technology Division of Health Sciences and Technology, Cambridge, Massachusetts 02139, USA
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Sarhan M, Freund-Mercier MJ, Veinante P. Branching patterns of parabrachial neurons projecting to the central extended amgydala: single axonal reconstructions. J Comp Neurol 2006; 491:418-42. [PMID: 16175547 DOI: 10.1002/cne.20697] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Electrophysiological evidence suggests that the spinoparabrachioamygdaloid pathway carries nociceptive information that may be important for the elaboration of physiological and emotional responses to noxious events. The pontine parabrachial nucleus (pPB) sends a massive projection to the central nucleus of the amygdala (CeA) and lateral bed nucleus of the stria terminalis (BSTL), both regions belonging to a broader macrostructure, the central extended amygdala (EAc). The aim of this study was to examine whether different EAc components are targeted by a same pPB neuron, by reconstructing single axonal branching patterns after anterograde labelling. Small deposits of biotinylated dextran amine in the region of the external lateral pPB result in dense and specific labelling in the whole EAc. Reconstructed axons innervate either the lateral or the capsular part of the CeA with perisomatic or bushy terminals, respectively. A subset of axons enters the stria terminalis rostrally to follow its trajectory caudally toward the CeA. Individual axons targeting the CeA usually send collaterals to other EAc components, especially those projecting to the lateral CeA, which often coinnervate the BSTL. By contrast, only few branches were found outside the EAc. These results suggest that the noxious information travelling from the pPB to the CeA may also be transmitted to other EAc components. This pPB-EAc pathway, which appears distinct from the parabrachiohypothalamic and parabrachiothalamic projections, would be the anatomical basis through which the EAc elaborates the autonomic, endocrine, and emotional components of pain.
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Affiliation(s)
- Maysa Sarhan
- Unité Mixte de Recherche 7519, Centre National de la Recherche Scientifique/Université Louis Pasteur, 67084 Strasbourg, France
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Richard S, Engblom D, Paues J, Mackerlova L, Blomqvist A. Activation of the parabrachio-amygdaloid pathway by immune challenge or spinal nociceptive input: a quantitative study in the rat using Fos immunohistochemistry and retrograde tract tracing. J Comp Neurol 2005; 481:210-9. [PMID: 15562506 DOI: 10.1002/cne.20384] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Peripheral nociceptive stimulation results in activation of neurons in the pontine parabrachial nucleus (PB) of rats. Electrophysiological studies have suggested that noxiously activated PB neurons project to the amygdala, constituting a potential pathway for emotional aspects of pain. In the present study we examined this hypothesis by combining retrograde tract tracing with Fos immunohistochemistry. Cholera toxin subunit B was injected into the amygdala of rats. After a minimum of 48 hours the rats were given a subcutaneous injection of 100 microl of 5% formalin into one hindpaw and killed 60-90 minutes later. A dense aggregation of retrogradely labeled neurons was seen in the external lateral PB. Fos-expressing neurons were present preferentially in the central, dorsal, and superior lateral subnuclei as well as in the lateral crescent area, as described previously. There was little overlap between the retrogradely labeled and Fos-expressing populations and double-labeled neurons were rare. In contrast, systemic immune challenge by intravenous injection of bacterial wall lipopolysaccharide resulted in a Fos expression that overlapped the retrograde labeling in the external lateral PB, and many double-labeled neurons were seen. While these data provide direct functional anatomical evidence that nociceptive information from the hindlimb is relayed to the amygdala via the parabrachial nucleus, the number of parabrachio-amygdaloid neurons involved is small. Considering the widespread activation of parabrachio-amygdaloid neurons by a variety of visceral and humoral stimuli, the parabrachio-amygdaloid pathway thus appears to be more involved in the mediation of information related to viscerally and humorally elicited activity than in transmission of spinal nociceptive inputs.
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Affiliation(s)
- Sabine Richard
- Station de Recherches Avicoles, Institut National de la Recherche Agronomique, 37 380 Nouzilly, France
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Jiang M, Alheid GF, Calandriello T, McCrimmon DR. Parabrachial-lateral pontine neurons link nociception and breathing. Respir Physiol Neurobiol 2005; 143:215-33. [PMID: 15519557 DOI: 10.1016/j.resp.2004.07.019] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/20/2004] [Indexed: 11/17/2022]
Abstract
We investigated the role of the parabrachial complex in cutaneous nociceptor-induced respiratory stimulation in chloralose-urethane anesthetized, vagotomized rats. Noxious stimulation (mustard oil, MO) applied topically to a forelimb or hindlimb enhanced the peak amplitude of the integrated phrenic nerve discharge and, with forelimb application, increased phrenic nerve burst frequency. Bilateral inactivation of neural activity in the parabrachial complex with injection of the GABA agonist muscimol (3nl) markedly attenuated the response to MO application. Injection of the retrograde tracer FluoroGold within the medullary ventral respiratory column labeled neurons in dorsolateral pontine regions known to receive nociceptive inputs (i.e., Kolliker-Fuse, lateral crescent, and superior lateral subnuclei of the parabrachial complex). Extracellular recordings of 65 dorsolateral parabrachial neurons revealed about 15% responded to a noxious cutaneous pinch with either an increase or a decrease in discharge and approximately 40% of these exhibited a phasic respiratory-related component to their discharge. In conclusion, parabrachial pontine neurons contribute to cutaneous nociceptor-induced increases in breathing.
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Affiliation(s)
- Mingchen Jiang
- Department of Physiology and Institute for Neuroscience, Feinberg School of Medicine, Northwestern University, M211, 303 E. Chicago Ave., Chicago, IL 60611-3008, USA
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Chen T, Hui R, Dong YX, Li YQ, Mizuno N. Endomorphin 1- and endomorphin 2-like immunoreactive neurons in the hypothalamus send axons to the parabrachial nucleus in the rat. Neurosci Lett 2004; 357:139-42. [PMID: 15036594 DOI: 10.1016/j.neulet.2003.12.079] [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: 11/27/2003] [Accepted: 12/04/2003] [Indexed: 12/01/2022]
Abstract
Endomorphin 1 (EM1) and endomorphin 2 (EM2) are the endogenous peptides with high affinity and selectivity for the mu-opioid receptor (MOR). We examined whether or not EM1- and EM2-expressing hypothalamic neurons might send their axons to the parabrachial nucleus (PBN), where many MOR-expressing neurons have been observed. Immunofluorescence histochemistry was combined with fluorescent retrograde tract-tracing method. In the rats injected with Fluoro-Gold (FG) into the PBN, some of EM1- and EM2-immunoreactive hypothalamic neurons were labeled retrogradely with FG. The majority of the EM1/FG and EM2/FG double-labeled neurons were distributed in the dorsomedial hypothalamus nucleus, centromedial hypothalamic region, and arcuate nucleus; a few of them were also seen in the periventricular hypothalamic nucleus and posterior hypothalamic nucleus. Endomorphins released from PBN-projecting hypothalamic neurons may modulate the gustatory, autonomic and nociceptive functions through MOR-expressing PBN neurons.
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Affiliation(s)
- Tao Chen
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an 710032, China
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