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Louçano M, Oliveira J, Martins I, Vaz R, Tavares I. Pain Modulation from the Locus Coeruleus in a Model of Hydrocephalus: Searching for Oxidative Stress-Induced Noradrenergic Neuroprotection. Int J Mol Sci 2022; 23:ijms23073970. [PMID: 35409327 PMCID: PMC8999514 DOI: 10.3390/ijms23073970] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/12/2022] [Accepted: 03/31/2022] [Indexed: 01/27/2023] Open
Abstract
Pain transmission at the spinal cord is modulated by noradrenaline (NA)-mediated actions that arise from supraspinal areas. We studied the locus coeruleus (LC) to evaluate the expression of the cathecolamine-synthetizing enzyme tyrosine hydroxylase (TH) and search for local oxidative stress and possible consequences in descending pain modulation in a model of hydrocephalus, a disease characterized by enlargement of the cerebral ventricular system usually due to the obstruction of cerebrospinal fluid flow. Four weeks after kaolin injection into the cisterna magna, immunodetection of the catecholamine-synthetizing enzymes TH and dopamine-β-hydroxylase (DBH) was performed in the LC and spinal cord. Colocalization of the oxidative stress marker 8-OHdG (8-hydroxyguanosine; 8-OHdG), with TH in the LC was performed. Formalin was injected in the hindpaw both for behavioral nociceptive evaluation and the immunodetection of Fos expression in the spinal cord. Hydrocephalic rats presented with a higher expression of TH at the LC, of TH and DBH at the spinal dorsal horn along with decreased nociceptive behavioral responses in the second (inflammatory) phase of the formalin test, and formalin-evoked Fos expression at the spinal dorsal horn. The expression of 8-OHdG was increased in the LC neurons, with higher co-localization in TH-immunoreactive neurons. Collectively, the results indicate increased noradrenergic expression at the LC during hydrocephalus. The strong oxidative stress damage at the LC neurons may lead to local neuroprotective-mediated increases in NA levels. The increased expression of catecholamine-synthetizing enzymes along with the decreased nociception-induced neuronal activation of dorsal horn neurons and behavioral pain signs may indicate that hydrocephalus is associated with alterations in descending pain modulation.
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Affiliation(s)
- Marta Louçano
- Unit of Experimental Biology, Department of Biomedicine, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal; (M.L.); (I.M.)
- IBMC-Institute of Molecular and Cell Biology, University of Porto, 4200-135 Porto, Portugal
- I3S-Institute of Investigation and Innovation in Health, University of Porto, 4200-135 Porto, Portugal
- Chemical and Biomolecule Sciences, School of Health, Polytechnic of Porto, 4099-002 Porto, Portugal;
- International Doctoral School, University of Vigo, 36310 Vigo, Spain
| | - Joana Oliveira
- Neurosurgery Service of Centro Hospital São João, 4200-319 Porto, Portugal;
| | - Isabel Martins
- Unit of Experimental Biology, Department of Biomedicine, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal; (M.L.); (I.M.)
- IBMC-Institute of Molecular and Cell Biology, University of Porto, 4200-135 Porto, Portugal
- I3S-Institute of Investigation and Innovation in Health, University of Porto, 4200-135 Porto, Portugal
| | - Rui Vaz
- Chemical and Biomolecule Sciences, School of Health, Polytechnic of Porto, 4099-002 Porto, Portugal;
- Department of Clinical Neurosciences and Mental Health, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal
| | - Isaura Tavares
- Unit of Experimental Biology, Department of Biomedicine, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal; (M.L.); (I.M.)
- IBMC-Institute of Molecular and Cell Biology, University of Porto, 4200-135 Porto, Portugal
- I3S-Institute of Investigation and Innovation in Health, University of Porto, 4200-135 Porto, Portugal
- Correspondence: ; Tel.: +35-12-2551-3654
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Moriya S, Yamashita A, Masukawa D, Sakaguchi J, Ikoma Y, Sameshima Y, Kambe Y, Yamanaka A, Kuwaki T. Involvement of A5/A7 noradrenergic neurons and B2 serotonergic neurons in nociceptive processing: a fiber photometry study. Neural Regen Res 2021; 17:881-886. [PMID: 34472489 PMCID: PMC8530127 DOI: 10.4103/1673-5374.322465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
In the central nervous system, the A6 noradrenaline (NA) and the B3 serotonin (5-HT) cell groups are well-recognized players in the descending antinociceptive system, while other NA/5-HT cell groups are not well characterized. A5/A7 NA and B2 5-HT cells project to the spinal horn and form descending pathways. We recorded G-CaMP6 green fluorescence signal intensities in the A5/A7 NA and the B2 5-HT cell groups of awake mice in response to acute tail pinch stimuli, acute heat stimuli, and in the context of a non-noxious control test, using fiber photometry with a calcium imaging system. We first introduced G-CaMP6 in the A5/A7 NA or B2 5-HT neuronal soma, using transgenic mice carrying the tetracycline-controlled transactivator transgene under the control of either a dopamine β-hydroxylase or a tryptophan hydroxylase-2 promoters and by the site-specific injection of adeno-associated virus (AAV-TetO(3G)-G-CaMP6). After confirming the specific expression patterns of G-CaMP6, we recorded G-CaMP6 green fluorescence signals in these sites in awake mice in response to acute nociceptive stimuli. G-CaMP6 fluorescence intensity in the A5, A7, and B2 cell groups was rapidly increased in response to acute nociceptive stimuli and soon after, it returned to baseline fluorescence intensity. This was not observed in the non-noxious control test. The results indicate that acute nociceptive stimuli rapidly increase the activities of A5/A7 NA or B2 5-HT neurons but the non-noxious stimuli do not. The present study suggests that A5/A7 NA or B2 5-HT neurons play important roles in nociceptive processing in the central nervous system. We suggest that A5/A7/B2 neurons may be new therapeutic targets. All performed procedures were approved by the Institutional Animal Use Committee of Kagoshima University (MD17105) on February 22, 2018.
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Affiliation(s)
- Shunpei Moriya
- Department of Physiology, Kagoshima University Graduate School of Medical and Dental Science, Kagoshima, Japan
| | - Akira Yamashita
- Department of Physiology, Kagoshima University Graduate School of Medical and Dental Science, Kagoshima, Japan
| | - Daiki Masukawa
- Department of Molecular Pharmacology and Neurobiology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Junichi Sakaguchi
- Department of Physiology, Kagoshima University Graduate School of Medical and Dental Science, Kagoshima, Japan
| | - Yoko Ikoma
- Department of Physiology, Kagoshima University Graduate School of Medical and Dental Science, Kagoshima, Japan
| | - Yoshimune Sameshima
- Department of Pharmacology, Kagoshima University Graduate School of Medical and Dental Science, Kagoshima, Japan
| | - Yuki Kambe
- Department of Pharmacology, Kagoshima University Graduate School of Medical and Dental Science, Kagoshima, Japan
| | - Akihiro Yamanaka
- Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Tomoyuki Kuwaki
- Department of Physiology, Kagoshima University Graduate School of Medical and Dental Science, Kagoshima, Japan
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Costa-Pereira JT, Ribeiro J, Martins I, Tavares I. Role of Spinal Cord α 2-Adrenoreceptors in Noradrenergic Inhibition of Nociceptive Transmission During Chemotherapy-Induced Peripheral Neuropathy. Front Neurosci 2020; 13:1413. [PMID: 32009887 PMCID: PMC6974806 DOI: 10.3389/fnins.2019.01413] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 12/13/2019] [Indexed: 12/14/2022] Open
Abstract
Chemotherapy-induced peripheral neuropathy (CIPN) is a problem during cancer treatment and for cancer survivors but the central mechanisms underlying CIPN remain understudied. This study aims to determine if CIPN is associated with alterations of noradrenergic modulation of nociceptive transmission at the spinal cord. CIPN was induced in male Wistar rats by paclitaxel injections. One month after CIPN induction, the behavioral effects of the administration of reboxetine (noradrenaline reuptake inhibitor), clonidine (agonist of α2-adrenoreceptors; α2–AR) and atipamezole (antagonist of α2–AR) were evaluated using the von Frey and cold plate tests. Furthermore, we measured the expression of the noradrenaline biosynthetic enzyme dopamine-β-hydroxylase (DBH) and of α2–AR in the spinal dorsal horn. Reboxetine and clonidine reversed the behavioral signs of CIPN whereas the opposite occurred with atipamezole. In the 3 pharmacological approaches, a higher effect was detected in mechanical allodynia, the pain modality which is under descending noradrenergic control. DBH expression was increased at the spinal dorsal horn of paclitaxel-injected animals. The enhanced noradrenergic inhibition during CIPN may represent an adaptation of the descending noradrenergic pain control system to the increased arrival of peripheral nociceptive input. A potentiation of the α2–AR mediated antinociception at the spinal cord may represent a therapeutic opportunity to face CIPN.
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Affiliation(s)
- José Tiago Costa-Pereira
- Unit of Experimental Biology, Department of Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal.,Institute of Molecular and Cell Biology, University of Porto, Porto, Portugal.,I3S-Institute for Investigation and Innovation in Health, University of Porto, Porto, Portugal
| | - Joana Ribeiro
- Unit of Experimental Biology, Department of Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal.,Institute of Molecular and Cell Biology, University of Porto, Porto, Portugal.,I3S-Institute for Investigation and Innovation in Health, University of Porto, Porto, Portugal
| | - Isabel Martins
- Unit of Experimental Biology, Department of Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal.,Institute of Molecular and Cell Biology, University of Porto, Porto, Portugal.,I3S-Institute for Investigation and Innovation in Health, University of Porto, Porto, Portugal
| | - Isaura Tavares
- Unit of Experimental Biology, Department of Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal.,Institute of Molecular and Cell Biology, University of Porto, Porto, Portugal.,I3S-Institute for Investigation and Innovation in Health, University of Porto, Porto, Portugal
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Glutamate receptors of the A5 region modulate cardiovascular responses evoked from the dorsomedial hypothalamic nucleus and perifornical area. J Physiol Biochem 2018; 74:325-334. [PMID: 29577176 DOI: 10.1007/s13105-018-0623-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 03/15/2018] [Indexed: 01/16/2023]
Abstract
To assess the possible function of glutamate in the interaction between the dorsomedial hypothalamic nucleus-perifornical area (DMH-PeF) and the A5 pontine region (A5), cardiovascular and respiratory changes were studied in response to electrical stimulation of the DMH-PeF (1 ms pulses, 30-50 μA given at 100 Hz for 5 s) before and after the microinjection of kynurenic acid (non-specific glutamate receptor antagonist; 50 nl, 5 nmol), MK-801 (NMDA receptor antagonist; 50 nl, 50 nmol), CNQX (non-NMDA receptor antagonist; 50 nl, 50 nmol) or MCPG (metabotropic glutamate receptor antagonist; 50 nl, 5 nmol) within the A5 region. DMH-PeF electrical stimulation elicited a pressor (p < 0.001) and tachycardic response (p < 0.001) which was accompanied by an inspiratory facilitation characterised by an increase in respiratory rate (p < 0.001) due to a decrease in expiratory time (p < 0.01). Kynurenic acid within the A5 region decreased the tachycardia (p < 0.001) and the intensity of the blood pressure response (p < 0.001) to DMH-PeF stimulation. After the microinjection of MK-801 and CNQX into the A5 region, the magnitude of the tachycardia and the pressor response were decreased (p < 0.05 and p < 0.01; p < 0.001 and p < 0.05, respectively). After MCPG microinjection into the A5 region, a decrease in the tachycardia (p < 0.001) with no changes in the pressor response was observed during DMH-PeF stimulation. The respiratory response elicited by DMH-PeF stimulation was not changed after the microinjection of kynurenic acid, MK-801, CNQX or MCPG within the A5 region. These results suggest that A5 region glutamate receptors play a role in the cardiovascular response elicited from the DMH-PeF. The possible mechanisms involved in these interactions are discussed.
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Lyubashina O, Sivachenko I. The 5-HT 4 receptor-mediated inhibition of visceral nociceptive neurons in the rat caudal ventrolateral medulla. Neuroscience 2017; 359:277-288. [DOI: 10.1016/j.neuroscience.2017.07.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 03/26/2017] [Accepted: 07/17/2017] [Indexed: 12/23/2022]
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Martins I, Tavares I. Reticular Formation and Pain: The Past and the Future. Front Neuroanat 2017; 11:51. [PMID: 28725185 PMCID: PMC5497058 DOI: 10.3389/fnana.2017.00051] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 06/19/2017] [Indexed: 01/10/2023] Open
Abstract
The involvement of the reticular formation (RF) in the transmission and modulation of nociceptive information has been extensively studied. The brainstem RF contains several areas which are targeted by spinal cord afferents conveying nociceptive input. The arrival of nociceptive input to the RF may trigger alert reactions which generate a protective/defense reaction to pain. RF neurons located at the medulla oblongata and targeted by ascending nociceptive information are also involved in the control of vital functions that can be affected by pain, namely cardiovascular control. The RF contains centers that belong to the pain modulatory system, namely areas involved in bidirectional balance (decrease or enhancement) of pain responses. It is currently accepted that the imbalance of pain modulation towards pain facilitation accounts for chronic pain. The medullary RF has the peculiarity of harboring areas involved in bidirectional pain control namely by the existence of specific neuronal populations involved in antinociceptive or pronociceptive behavioral responses, namely at the rostroventromedial medulla (RVM) and the caudal ventrolateral medulla (VLM). Furthermore the dorsal reticular nucleus (also known as subnucleus reticularis dorsalis; DRt) may enhance nociceptive responses, through a reverberative circuit established with spinal lamina I neurons and inhibit wide-dynamic range (WDR) neurons of the deep dorsal horn. The components of the triad RVM-VLM-DRt are reciprocally connected and represent a key gateway for top-down pain modulation. The RVM-VLM-DRt triad also represents the neurobiological substrate for the emotional and cognitive modulation of pain, through pathways that involve the periaqueductal gray (PAG)-RVM connection. Collectively, we propose that the RVM-VLM-DRt triad represents a key component of the “dynamic pain connectome” with special features to provide integrated and rapid responses in situations which are life-threatening and involve pain. The new available techniques in neurobiological studies both in animal and human studies are producing new and fascinating data which allow to understand the complex role of the RF in pain modulation and its integration with several body functions and also how the RF accounts for chronic pain.
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Affiliation(s)
- Isabel Martins
- Departamento de Biomedicina, Faculdade de Medicina do PortoPorto, Portugal.,Unidade de Biologia Experimental, Faculdade de Medicina do Porto, Universidade do PortoPorto, Portugal.,Instituto de Biologia Celular e Molecular (IBMC), Universidade do PortoPorto, Portugal.,Instituto de Investigação e Inovação em Saúde, Universidade do Porto (I3S)Porto, Portugal
| | - Isaura Tavares
- Departamento de Biomedicina, Faculdade de Medicina do PortoPorto, Portugal.,Unidade de Biologia Experimental, Faculdade de Medicina do Porto, Universidade do PortoPorto, Portugal.,Instituto de Biologia Celular e Molecular (IBMC), Universidade do PortoPorto, Portugal.,Instituto de Investigação e Inovação em Saúde, Universidade do Porto (I3S)Porto, Portugal
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Pain modulation from the brain during diabetic neuropathy: Uncovering the role of the rostroventromedial medulla. Neurobiol Dis 2016; 96:346-356. [PMID: 27717882 DOI: 10.1016/j.nbd.2016.10.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 09/06/2016] [Accepted: 10/01/2016] [Indexed: 01/17/2023] Open
Abstract
Diabetic neuropathy has a profound impact in the quality of life of patients who frequently complain of pain. The mechanisms underlying diabetic neuropathic pain (DNP) are no longer ascribed only to damage of peripheral nerves. The effects of diabetes at the central nervous system are currently considered causes of DPN. Management of DNP may be achieved by antidepressants that act on serotonin (5-HT) uptake, namely specific serotonin reuptake inhibitors. The rostroventromedial medulla (RVM) is a key pain control center involved in descending pain modulation at the spinal cord through local release of 5-HT and plays a peculiar role in the balance of bidirectional control (i.e. inhibitory and facilitatory) from the brain to the spinal cord. This review discusses recently uncovered neurobiological mechanisms that mediate nociceptive modulation from the RVM during diabetes installation. In early phases of the disease, facilitation of pain modulation from the RVM prevails through a triplet of mechanisms which include increase in serotonin expression at the RVM and consequent rise of serotonin levels at the spinal cord and upregulation of local facilitatory 5HT3 receptors, enhancement of spontaneous activity of facilitatory RVM neurons and up-regulation of the expression of transient receptor potential vanilloid type 1 (TRPV1) receptor. With the progression of diabetes the alterations in the RVM increase dramatically, with oxidative stress and neuronal death associated to microglia-mediated inflammation. In a manner similar to other central areas, like the thalamus, the RVM is likely to be a "pain generator/amplifier" during diabetes, accounting to increase DNP. Early interventions in DNP prevention using strategies that simultaneously tackle the exacerbation of 5-HT3 spinal receptors and of microglial RVM activity, namely those that increase the levels of anti-inflammatory cytokines, should be considered in the future of DNP treatment.
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Noradrenergic Locus Coeruleus pathways in pain modulation. Neuroscience 2016; 338:93-113. [PMID: 27267247 DOI: 10.1016/j.neuroscience.2016.05.057] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 05/20/2016] [Accepted: 05/27/2016] [Indexed: 12/30/2022]
Abstract
The noradrenergic system is crucial for several activities in the body, including the modulation of pain. As the major producer of noradrenaline (NA) in the central nervous system (CNS), the Locus Coeruleus (LC) is a nucleus that has been studied in several pain conditions, mostly due to its strategic location. Indeed, apart from a well-known descending LC-spinal pathway that is important for pain control, an ascending pathway passing through this nucleus may be responsible for the noradrenergic inputs to higher centers of the pain processing, such as the limbic system and frontal cortices. Thus, the noradrenergic system appears to modulate different components of the pain experience and accordingly, its manipulation has distinct behavioral outcomes. The main goal of this review is to bring together the data available regarding the noradrenergic system in relation to pain, particularly focusing on the ascending and descending LC projections in different conditions. How such findings influence our understanding of these conditions is also discussed.
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NMDA Receptors of A5 Area in the Regulation of Blood Pressure and Respiratory Activity during Hypoxia in Rats. Bull Exp Biol Med 2015; 159:420-3. [PMID: 26388583 DOI: 10.1007/s10517-015-2980-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Indexed: 11/27/2022]
Abstract
In narcotized (40 mg/kg sodium ethaminal intraperitoneally) spontaneously breathing albino rats, experimental short-term hypoxia induced BP drop and increased phrenic nerve firing rate. Unilateral microinjection of a selective NMDA receptor blocker ketamine hydrochloride (50 nl; 4 mM) into A5 area did not affect BP and phrenic nerve fi ring rate. However, against the background of preliminary NMDA receptor blockage, hypoxia more markedly stimulated rhythmic activity of the respiratory center and hypotensive response. Unilateral microinjection of a selective blocker of non-NMDA receptors GAMS (50 nl; 4 mM) into A5 area did not change initial BP and phrenic nerve fi ring rate. The studied parameters in rats exposed to hypoxia after blockage of non-NMDA receptors in A5 area did not differ from the control levels. Thus, activity of the respiratory center and BP in rats during hypoxia is regulated by the structures in A5 area and NMDA glutamate receptors.
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López-González MV, Díaz-Casares A, Peinado-Aragonés CA, Lara JP, Barbancho MA, Dawid-Milner MS. Neurons of the A5 region are required for the tachycardia evoked by electrical stimulation of the hypothalamic defence area in anaesthetized rats. Exp Physiol 2013; 98:1279-94. [DOI: 10.1113/expphysiol.2013.072538] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Bär KJ, Berger S, Schwier C, Wutzler U, Beissner F. Insular dysfunction and descending pain inhibition in anorexia nervosa. Acta Psychiatr Scand 2013; 127:269-78. [PMID: 22747702 DOI: 10.1111/j.1600-0447.2012.01896.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Reduced perception of pain is a well-established phenomenon in patients with anorexia nervosa (AN). We tested the hypothesis that altered processing of pain within the insula might account for reduced perception of pain. METHOD Heat pain thresholds were obtained in nineteen patients with AN and matched controls. Thereafter, a thermode was used to deliver thermal painful stimuli to the right arm during functional magnetic resonance imaging (fMRI) measurements. Stimuli were initiated for 10 s from a baseline resting temperature (32°C) to three different levels (37, 42, 45°C). RESULTS Significantly increased heat pain thresholds were observed in patients. A stronger activation during heat pain perception was found in the left posterior insula in controls. In contrast, higher levels of activity were shown in the ipsilateral pons in patients when compared to controls. In patients, we found a significant interrelation between the depression score (Beck depression inventory) and heat pain activations. CONCLUSION We suggest that reduced activity in the left posterior insula might contribute to increased pain thresholds in patients, while increased activations in the right anterior insula and pons mirror augmented sympathetic modulation putatively related to amplification of adrenergic descending pain inhibition. In addition, pain thresholds and brain activations were influenced by disease-inherent depressed mood.
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Affiliation(s)
- K-J Bär
- Pain & Autonomics - Integrative Research (PAIR), Department of Psychiatry and Psychotherapy, University Hospital Jena, Jena, Germany.
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Martins I, Cabral L, Pinto A, Wilson S, Lima D, Tavares I. Reversal of inflammatory pain by HSV-1-mediated overexpression of enkephalin in the caudal ventrolateral medulla. Eur J Pain 2012; 15:1008-14. [DOI: 10.1016/j.ejpain.2011.04.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 03/11/2011] [Accepted: 04/05/2011] [Indexed: 01/28/2023]
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Pinto-Ribeiro F, Ansah OB, Almeida A, Pertovaara A. Response properties of nociceptive neurons in the caudal ventrolateral medulla (CVLM) in monoarthritic and healthy control rats: Modulation of responses by the paraventricular nucleus of the hypothalamus (PVN). Brain Res Bull 2011; 86:82-90. [DOI: 10.1016/j.brainresbull.2011.06.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 06/22/2011] [Accepted: 06/25/2011] [Indexed: 12/29/2022]
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Burke PGR, Neale J, Korim WS, McMullan S, Goodchild AK. Patterning of somatosympathetic reflexes reveals nonuniform organization of presympathetic drive from C1 and non-C1 RVLM neurons. Am J Physiol Regul Integr Comp Physiol 2011; 301:R1112-22. [PMID: 21795636 DOI: 10.1152/ajpregu.00131.2011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
To determine the organization of presympathetic vasomotor drive by phenotypic populations of rostral ventrolateral medulla (RVLM) neurons, we examined the somatosympathetic reflex (SSR) evoked in four sympathetic nerves together with selective lesions of RVLM presympathetic neurons. Urethane-anesthetized (1.3 g/kg ip), paralyzed, vagotomized and artificially ventilated Sprague-Dawley rats (n = 41) were used. First, we determined the afferent inputs activated by sciatic nerve (SN) stimulation at graded stimulus intensities (50 sweeps at 0.5-1 Hz, 1-80 V). Second, we recorded sympathetic nerve responses (cervical, renal, splanchnic, and lumbar) to intensities of SN stimulation that activated A-fiber afferents (low) or both A- and C-fiber afferents (high). Third, with low-intensity SN stimulation, we examined the cervical SSR following RVLM microinjection of somatostatin, and we determined the splanchnic SSR in rats in which presympathetic C1 neurons were lesioned following intraspinal injections of anti-dopamine-β-hydroxylase-saporin (anti-DβH-SAP). Low-intensity SN stimulation activated A-fiber afferents and evoked biphasic responses in the renal, splanchnic, and lumbar nerves and a single peak in the cervical nerve. Depletion of presympathetic C1 neurons (59 ± 4% tyrosine hydroxylase immunoreactivity profiles lesioned) eliminated peak 2 of the splanchnic SSR and attenuated peak 1, suggesting that only RVLM neurons with fast axonal conduction were spared. RVLM injections of somatostatin abolished the single early peak of cervical SSR confirming that RVLM neurons with fast axonal conduction were inhibited by somatostatin. It is concluded that unmyelinated RVLM presympathetic neurons, presumed to be all C1, innervate splanchnic, renal, and lumbar but not cervical sympathetic outflows, whereas myelinated C1 and non-C1 RVLM neurons innervate all sympathetic outflows examined. These findings suggest that multiple levels of neural control of vasomotor tone exist; myelinated populations may set baseline tone, while unmyelinated neurons may be recruited to provide actions at specific vascular beds in response to distinct stressors.
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Affiliation(s)
- Peter G R Burke
- Australian School of Advanced Medicine, Macquarie University, Sydney, Australia
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Morgado C, Silva L, Pereira-Terra P, Tavares I. Changes in serotoninergic and noradrenergic descending pain pathways during painful diabetic neuropathy: the preventive action of IGF1. Neurobiol Dis 2011; 43:275-84. [PMID: 21515376 DOI: 10.1016/j.nbd.2011.04.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 03/24/2011] [Accepted: 04/07/2011] [Indexed: 12/13/2022] Open
Abstract
Painful diabetic neuropathy (PDN) induces neuronal hyperactivity at the spinal cord and periaqueductal gray (PAG), a key area in descending nociceptive modulation. Since the PAG uses relay stations at serotoninergic and noradrenergic brainstem areas, we determined the serotonin and noradrenaline levels at the spinal cord of streptozotocin-diabetic rats and at those brainstem areas (serotoninergic rostroventromedial medulla and noradrenergic A(5) and A(7) cell groups). Since, during diabetes, the levels of insulin growth factor 1 (IGF1) decrease, reducing its neurotrophic effect in the brain, we also studied the effects of IGF1 treatment. One week after diabetes induction, subcutaneous injections of IGF1 (2.5mg/kg) were performed during 3 weeks. Body weights, glycemia, and mechanical nociception were weekly evaluated until the end of the study, the time when the animals were subjected to a modified formalin test to study chemical allodynia. Serotonin and noradrenaline levels were quantified by ELISA at the spinal cord, whereas at the brainstem, the quantification was performed by immunohistochemistry against, respectively, tryptophan hydroxylase (TpH) or tyrosine hydroxylase (TH). STZ-diabetic rats exhibited mechanical hyperalgesia and chemical allodynia, along with higher spinal levels of serotonin and noradrenaline and higher numbers of neurons expressing TpH at the RVM and TH at the A(5) noradrenergic cell group. Treatment with IGF1 prevented the behavioral signs of PDN and reversed the neuronal hyperactivity at the spinal cord and ventrolateral PAG and the neurochemical changes at the spinal cord and at the brainstem. Based on the facilitatory role of serotoninergic and noradrenergic descending modulation during chronic pain, the increased serotonin and noradrenaline innervation of the dorsal horn in STZ-diabetic rats may probably account for enhanced pain during PDN. The benefits of IGF1 in PDN are probably due to blockade of the increased peripheral input to the somatosensory system, but direct central actions cannot be discarded. The value of IGF1 in PDN treatment deserves further evaluation.
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Affiliation(s)
- Carla Morgado
- Institute of Histology and Embryology, Faculty of Medicine of Porto, IBMC, University of Porto, Alameda Professor Hernâni Monteiro, 4200–319 Porto, Portugal
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Marques-Lopes J, Pinho D, Albino-Teixeira A, Tavares I. The hyperalgesic effects induced by the injection of angiotensin II into the caudal ventrolateral medulla are mediated by the pontine A5 noradrenergic cell group. Brain Res 2010; 1325:41-52. [DOI: 10.1016/j.brainres.2010.02.043] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 02/10/2010] [Accepted: 02/11/2010] [Indexed: 11/15/2022]
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Heinricher MM, Tavares I, Leith JL, Lumb BM. Descending control of nociception: Specificity, recruitment and plasticity. BRAIN RESEARCH REVIEWS 2009; 60:214-25. [PMID: 19146877 PMCID: PMC2894733 DOI: 10.1016/j.brainresrev.2008.12.009] [Citation(s) in RCA: 636] [Impact Index Per Article: 42.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/29/2008] [Indexed: 12/23/2022]
Abstract
The dorsal horn of the spinal cord is the location of the first synapse in pain pathways, and as such, offers a very powerful target for regulation of nociceptive transmission by both local segmental and supraspinal mechanisms. Descending control of spinal nociception originates from many brain regions and plays a critical role in determining the experience of both acute and chronic pain. The earlier concept of descending control as an "analgesia system" is now being replaced with a more nuanced model in which pain input is prioritized relative to other competing behavioral needs and homeostatic demands. Descending control arises from a number of supraspinal sites, including the midline periaqueductal gray-rostral ventromedial medulla (PAG-RVM) system, and the more lateral and caudal dorsal reticular nucleus (DRt) and ventrolateral medulla (VLM). Inhibitory control from the PAG-RVM system preferentially suppresses nociceptive inputs mediated by C-fibers, preserving sensory-discriminative information conveyed by more rapidly conducting A-fibers. Analysis of the circuitry within the RVM reveals that the neural basis for bidirectional control from the midline system is two populations of neurons, ON-cells and OFF-cells, that are differentially recruited by higher structures important in fear, illness and psychological stress to enhance or inhibit pain. Dynamic shifts in the balance between pain inhibiting and facilitating outflows from the brainstem play a role in setting the gain of nociceptive processing as dictated by behavioral priorities, but are also likely to contribute to pathological pain states.
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Affiliation(s)
- M M Heinricher
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, USA.
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Role of NMDA- and non-NMDA Subtypes of Glutamate Receptors in A5 Neuronal Structures in the Regulation of Respiration and Circulation during Thermal Nociceptive Stimulation in Rats. Bull Exp Biol Med 2009; 146:551-4. [DOI: 10.1007/s10517-009-0341-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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19
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Microinjection of angiotensin II in the caudal ventrolateral medulla induces hyperalgesia. Neuroscience 2008; 158:1301-10. [PMID: 19116162 DOI: 10.1016/j.neuroscience.2008.11.044] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 11/20/2008] [Accepted: 11/24/2008] [Indexed: 02/07/2023]
Abstract
Nociceptive transmission from the spinal cord is controlled by supraspinal pain modulating systems that include the caudal ventrolateral medulla (CVLM). The neuropeptide angiotensin II (Ang II) has multiple effects in the CNS and at the medulla oblongata. Here we evaluated the expression of angiotensin type 1 (AT(1)) receptors in spinally-projecting CVLM neurons, and tested the effect of direct application of exogenous Ang II in the CVLM on nociceptive behaviors. Although AT(1)-immunoreactive neurons occurred in the CVLM, only 3% of AT(1)-positive neurons were found to project to the dorsal horn, using double-immunodetection of the retrograde tracer cholera toxin subunit B. In behavioral studies, administration of Ang II (100 pmol) in the CVLM gave rise to hyperalgesia in both the tail-flick and formalin tests. This hyperalgesia was significantly attenuated by local administration of the AT(1) antagonist losartan. The present study demonstrates that Ang II can act on AT(1) receptors in the CVLM to modulate nociception. The effect on spinal nociceptive processing is likely indirect, since few AT(1)-expressing CVLM neurons were found to project to the spinal cord. The renin-angiotensin system may also play a role in other supraspinal areas implicated in pain modulation.
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Pinto M, Sousa M, Lima D, Tavares I. Participation of mu-opioid, GABA(B), and NK1 receptors of major pain control medullary areas in pathways targeting the rat spinal cord: implications for descending modulation of nociceptive transmission. J Comp Neurol 2008; 510:175-87. [PMID: 18615498 DOI: 10.1002/cne.21793] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Several brain areas modulate pain transmission through direct projections to the spinal cord. The descending modulation is exerted by neurotransmitters acting both at spinally projecting neurons and at interneurons that target the projection neurons. We analyzed the expression of mu-opioid (MOR), gamma-aminobutyric acid GABA(B), and NK1 receptors in spinally projecting neurons of major medullary pain control areas of the rat: rostroventromedial medulla (RVM), dorsal reticular nucleus (DRt), nucleus of the solitary tract, ventral reticular nucleus, and lateralmost part of the caudal ventrolateral medulla. The retrograde tracer cholera toxin subunit B (CTb) was injected into the spinal dorsal horn, and medullary sections were processed by double immunocytochemistry for CTb and each receptor. The RVM contained the majority of double-labeled neurons followed by the DRt. In general, high percentages of MOR- and NK1-expressing neurons were retrogradely labeled, whereas GABA(B) receptors were mainly expressed in neurons that were not labeled from the cord. The results suggest that MOR and NK1 receptors play an important role in direct and indirect control of descending modulation. The co-localization of MOR and GABA(B) in DRt neurons also demonstrated by the present study suggests that the pronociceptive effects of this nucleus may be controlled by local opoidergic and GABAergic inhibition of the pronociception increased during chronic pain.
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Affiliation(s)
- Marta Pinto
- Institute of Histology and Embryology, Faculdade de Medicina, Universidade do Porto, 4200-319 Porto, Portugal
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Activity of neurons of the cerebral A5 zone of rat induced by adequate stimulation of muscle afferents: On the control of arterial pressure and respiration during muscle activity. NEUROPHYSIOLOGY+ 2008. [DOI: 10.1007/s11062-008-9009-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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22
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Pyatin VF, Tatarnikov VS, Glazkova EN. Control of respiratory and hypotensive response during hypoxic chemoreflex by A5 region neurons in rats. Bull Exp Biol Med 2007; 142:654-6. [PMID: 17603661 DOI: 10.1007/s10517-006-0442-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The responses of A5 region neurons, the phrenic nerve, and systemic blood pressure to short-term hypoxia were examined in rats under conditions of spontaneous respiration. Tonic and respiration-modulated neurons increasing their discharge activity during hypoxia were identified. This hypoxia-induced response was more pronounced in the neurons with baseline discharge rate of 0.1-4.5 Hz (electrical activity of neurons increased by 4-5 times) compared to neurons with the baseline activity of 5.4-49.6 Hz (discharge rate increased by 1.4-2.0 times). The latency and duration of activation of all types A5 neurons correlated with the parameters of activation of the phrenic nerve. During hypoxia, activation of A5 neurons corresponded to the period of blood pressure drop (one-third of the reaction time), but not to the period of plateau or recovery phase. Low-, middle, and high-frequency A5 neurons participated in the modulation of hypoxia-provoked respiratory and hypotensive responses. Modulation of the respiratory response by A5 neurons was observed during the entire period of phrenic nerve activation, while modulation of the hypotensive response occurred only during blood pressure decrease.
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Affiliation(s)
- V F Pyatin
- Department of Normal Physiology, Samara State Medical University, Ministry of Health of the Russian Federation, Samara, Russia.
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Tavares I, Lima D. From neuroanatomy to gene therapy: searching for new ways to manipulate the supraspinal endogenous pain modulatory system. J Anat 2007; 211:261-8. [PMID: 17593218 PMCID: PMC2375764 DOI: 10.1111/j.1469-7580.2007.00759.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/20/2007] [Indexed: 11/27/2022] Open
Abstract
The endogenous pain modulatory system is a complex network of brain areas that control nociceptive transmission at the spinal cord by inhibitory and facilitatory actions. The balance between these actions ensures effective modulation of acute pain, while during chronic pain the pronociceptive effects appear to prevail. The mechanisms underlying this imbalance were studied as to the role of two medullary components of the pain modulatory system: the dorsal reticular nucleus and the caudal ventrolateral medulla, which function primarily as pronociceptive and antinociceptive centres, respectively. Both areas are connected with the spinal dorsal horn by closed reciprocal loops. In the spino-dorsal reticular nucleus loop, the ascending branch is strongly inhibited by spinal GABAergic neurons, which may act as a buffering system of the dorsal reticular nucleus-centred amplifying effect. In the spino-caudal ventrolateral medulla loop, the ascending branch is under potent excitation of substance P (SP) released from primary afferents, which is likely to trigger the intense descending inhibition detected in acute pain. During chronic pain, the activity in the lateral reticular formation of the caudal ventrolateral medulla changes, so that the action of the caudal ventrolateral medulla upon SP-responsive spinal neurons shifts from inhibitory to excitatory. The mechanisms of this modulatory shift are unknown but probably relate to the decreased expression of micro-opioid, delta-opioid and GABAB receptors. Normalizing receptor expression in the caudal ventrolateral medulla or controlling noci-evoked activity at the dorsal reticular nucleus or caudal ventrolateral medulla by interfering with neurotransmitter release is now possible by the use of gene therapy, an approach that stands out as a unique tool to manipulate the supraspinal endogenous pain control system.
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Affiliation(s)
- I Tavares
- Institute of Histology and Embryology of the Faculty of Medicine of Oporto, Portugal.
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Pertovaara A. Noradrenergic pain modulation. Prog Neurobiol 2006; 80:53-83. [PMID: 17030082 DOI: 10.1016/j.pneurobio.2006.08.001] [Citation(s) in RCA: 395] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Revised: 08/25/2006] [Accepted: 08/30/2006] [Indexed: 11/18/2022]
Abstract
Norepinephrine is involved in intrinsic control of pain. Main sources of norepinephrine are sympathetic nerves peripherally and noradrenergic brainstem nuclei A1-A7 centrally. Peripheral norepinephrine has little influence on pain in healthy tissues, whereas in injured tissues it has variable effects, including aggravation of pain. Its peripheral pronociceptive effect has been associated with injury-induced expression of novel noradrenergic receptors, sprouting of sympathetic nerve fibers, and pronociceptive changes in the ionic channel properties of primary afferent nociceptors, while an interaction with the immune system may contribute in part to peripheral antinociception induced by norepinephrine. In the spinal cord, norepinephrine released from descending pathways suppresses pain by inhibitory action on alpha-2A-adrenoceptors on central terminals of primary afferent nociceptors (presynaptic inhibition), by direct alpha-2-adrenergic action on pain-relay neurons (postsynaptic inhibition), and by alpha-1-adrenoceptor-mediated activation of inhibitory interneurons. Additionally, alpha-2C-adrenoceptors on axon terminals of excitatory interneurons of the spinal dorsal horn possibly contribute to spinal control of pain. At supraspinal levels, the pain modulatory effect by norepinephrine and noradrenergic receptors has varied depending on many factors such as the supraspinal site, the type of the adrenoceptor, the duration of the pain and pathophysiological condition. While in baseline conditions the noradrenergic system may have little effect, sustained pain induces noradrenergic feedback inhibition of pain. Noradrenergic systems may also contribute to top-down control of pain, such as induced by a change in the behavioral state. Following injury or inflammation, the central as well as peripheral noradrenergic system is subject to various plastic changes that influence its antinociceptive efficacy.
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Affiliation(s)
- Antti Pertovaara
- Biomedicum Helsinki, Institute of Biomedicine/Physiology, PO Box 63, University of Helsinki, FIN-00014 Helsinki, Finland.
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Activation of neurons of zone A5 of the rat brain upon hypoxic and thermonociceptive stimulation and switching off of the central respiratory generator. NEUROPHYSIOLOGY+ 2006. [DOI: 10.1007/s11062-006-0054-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Koepp J, Lindsey CJ, Motta EM, Rae GA. Role of the paratrigeminal nucleus in nocifensive responses of rats to chemical, thermal and mechanical stimuli applied to the hind paw. Pain 2006; 122:235-244. [PMID: 16616416 DOI: 10.1016/j.pain.2006.01.038] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Revised: 12/16/2005] [Accepted: 01/25/2006] [Indexed: 11/29/2022]
Abstract
Anatomical and immunohystochemical data suggest the paratrigeminal nucleus (Pa5) may play a role in nociceptive processing. The current study examines the influence of unilateral Pa5 lesion on nocifensive responses of conscious rats to noxious thermal (Hargreaves test), mechanical (electronic von Frey and Randall-Selitto tests), and chemical (formalin 2.5%; 50 microl) stimuli applied to the hind paw. Lesion of the Pa5 induced by ibotenic acid did not affect the latency for radiant heat-induced withdrawal of either paw. In contrast, the mean mechanical threshold for withdrawal of the contralateral (but not ipsilateral) paw in Pa5-lesioned rats was reduced by approximately 45% and 20%, in electronic von Frey and Randall-Selitto tests, respectively, when compared to sham-operated animals. Conversely, animals with Pa5 lesions injected with formalin in the contralateral paw spent less time engaged in focused (licking, biting or scratching the injected paw) and total nocifensive behavior (i.e., focused nocifensive behavior plus protection of the injected paw during movements) in both the first and second phases of the test [ approximately 50% inhibition of each parameter during first phase (0-5 min) and at 20, 25, and 30 min of second phase, relative to the sham-operated group], but the number of paw-jerks was unaffected. Pa5 lesion also delayed the onset of second phase focused pain induced by formalin in the ipsilateral paw. The results suggest that the Pa5 integrates the supraspinal pain control system and plays a differential modulatory role in the central processing of mechanical and chemical nociceptive information.
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Affiliation(s)
- Janice Koepp
- Department of Pharmacology, Biological Sciences Center, Universidade Federal de Santa Catarina, Campus, Trindade, Florianópolis, SC 88010-970, Brazil Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo 04023-062, Brazil
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Sun W, Panneton WM. Defining projections from the caudal pressor area of the caudal ventrolateral medulla. J Comp Neurol 2004; 482:273-93. [PMID: 15690490 DOI: 10.1002/cne.20434] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We previously defined a functional area in the caudal medulla oblongata that elicits an increase in arterial pressure when stimulated (Sun and Panneton [2002] Am. J. Physiol. 283:R768-R778). In the present study, anterograde and retrograde tracing techniques were used to investigate the projections of this caudal pressor area (CPA) to the medulla and pons. Injections of biotinylated dextran amine into the CPA resulted in numerous labeled fibers with varicosities in the ipsilateral subnucleus reticularis dorsalis, commissural subnucleus of the nucleus tractus solitarii, lateral medulla, medial facial nucleus, A5 area, lateral vestibular nucleus, and internal lateral subnucleus of the parabrachial complex. Sparser projections were found ipsilaterally in the pressor and depressor areas of the medulla and the spinal trigeminal nucleus and contralaterally in the CPA. Injections of the retrograde tracer Fluoro-Gold into these areas labeled neurons in the CPA as well as the nearby medullary dorsal horn and reticular formation. However, we conclude that the CPA projects preferentially to the subnucleus reticularis dorsalis, commissural nucleus tractus solitarii, lateral medulla, A5 area, and internal lateral parabrachial nucleus. Weaker projections were seen to the CVLM and RVLM and to the contralateral CPA. The projection to the facial nucleus arises from nearby reticular neurons, whereas projections to the vestibular nucleus arise from the lateral reticular nucleus. Labeled neurons in the CPA consisted mostly of small bipolar and some triangular neurons. The projection to the CVLM, or to A5 area, may provide for the increase in arterial pressure with CPA stimulation. However, most of the projections described herein are to nuclei implicated in the processing of noxious information. This implies a unique role for the CPA in somatoautonomic regulation.
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Affiliation(s)
- Wei Sun
- Department of Anatomy and Neurobiology, St. Louis University School of Medicine, St. Louis, Missouri 63104-1004, USA
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Tavares I, Lima D. The caudal ventrolateral medulla as an important inhibitory modulator of pain transmission in the spinal cord. THE JOURNAL OF PAIN 2003; 3:337-46. [PMID: 14622734 DOI: 10.1054/jpai.2002.127775] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The caudal ventrolateral medulla (VLM) has emerged during the last decade as one of the main components of the endogenous pain control system. Profound and long-lasting analgesia is produced by mild stimulation of the VLM. The VLMlat, the reticular formation located between the spinal trigeminal nucleus and the lateral reticular nucleus (LRt), appears to play a major role in that antinociceptive action. The projections to spinal cord laminae involved in nociceptive transmission originate exclusively in the VLMlat. The VLMlat participates in a disynaptic pathway involving spinally projecting pontine A5 noradrenergic neurons, which appears to convey alpha(2)-adrenoreceptor-mediated analgesia produced from the VLM. Neurons in the VLMlat and in lamina I are reciprocally connected by a closed loop that is likely to mediate feedback control of supraspinal nociceptive transmission. On the other hand, the LRt, which is targeted by ventral (lamina VII) and deep dorsal (laminae IV to V) horn inputs, projects to the premotor lamina VII. Nociceptive input ascending from the cord and increases in blood pressure are discussed as possible physiologic triggers of the analgesia produced by the VLM. The overall role of the VLM as a center for integration of nociceptive, cardiovascular, and motor functions is discussed. The putative therapeutic benefits of manipulating the VLM for the control of chronic pain are envisaged.
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Affiliation(s)
- Isaura Tavares
- Institute of Histology and Embryology, Faculty of Medicine and IBMC, University of Porto, Portugal.
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Cobos A, Lima D, Almeida A, Tavares I. Brain afferents to the lateral caudal ventrolateral medulla: a retrograde and anterograde tracing study in the rat. Neuroscience 2003; 120:485-98. [PMID: 12890518 DOI: 10.1016/s0306-4522(03)00209-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The ventrolateral medulla (VLM) modulates autonomic functions, motor reactions and pain responses. The lateralmost part of the caudal VLM (VLMlat) was recently shown to be the VLM area responsible for pain modulation. In the present study, the brain sources of VLMlat afferent fibers were determined by tract-tracing techniques. Following injection of cholera toxin subunit B into the VLMlat, retrogradely labeled neurons in the forebrain occurred at the somatosensory, insular, motor, limbic and infralimbic cortices, and at the central amygdaloid nucleus. Retrogradely labeled neurons in diencephalic regions were observed in the lateral hypothalamus, posterior hypothalamus and paraventricular nucleus. In the brainstem, retrograde labeling occurred at the periaqueductal gray, red nucleus, parabrachial area, nucleus raphe magnus, nucleus tractus solitarii, lateral reticular nucleus and dorsal and ventral medullary reticular formation. In the cerebellum, retrogradely labeled neurons occurred at the lateral nucleus. Following injections of the anterograde tracer biotinylated dextran amine (BDA) into the lateral hypothalamus or paraventricular nucleus, anterogradely labeled fibers were mainly observed in the VLMlat. Injections of BDA into the periaqueductal gray, red nucleus or lateral nucleus of the cerebellum resulted in anterograde labeling in the VLMlat and lateral reticular nucleus. The present study gives an account of the brain regions putatively involved in triggering the modulatory actions elicited from the VLMlat. These include areas committed to somatosensory processing, autonomic control, somatic and visceral motor activity and affective reactions. The findings suggest that the VLMlat may play a major homeostatic role in the integration of nociception with other brain functions.
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Affiliation(s)
- A Cobos
- Institute of Histology and Embryology, Faculdade de Medicina and IBMC, University of Oporto, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal
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Proudfit HK. The challenge of defining brainstem pain modulation circuits. THE JOURNAL OF PAIN 2002; 3:350-4; discussion 358-9. [PMID: 14622736 DOI: 10.1054/jpai.2002.127777] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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31
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Fenik V, Marchenko V, Janssen P, Davies RO, Kubin L. A5 cells are silenced when REM sleep-like signs are elicited by pontine carbachol. J Appl Physiol (1985) 2002; 93:1448-56. [PMID: 12235046 DOI: 10.1152/japplphysiol.00225.2002] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The A5 noradrenergic neurons are considered important for cardiorespiratory regulation. We hypothesized that A5 cells are silenced during rapid eye movement (REM) sleep, thereby contributing to cardiorespiratory changes and suppression of hypoglossal (XII) motoneuronal activity. We used an anesthetized, paralyzed, and artificially ventilated rat in which pontine microinjections of carbachol trigger signs of REM sleep, including hippocampal theta rhythm, motor suppression, and silencing of locus coeruleus neurons. All 16 putative noradrenergic A5 cells recorded were strongly suppressed when the REM sleep-like episodes were elicited and also after intravenous clonidine. Antidromic mapping showed that none of six neurons tested projected to the XII nucleus, whereas three of five projected to the nucleus of the solitary tract and two of four to the rostral ventrolateral medulla. Bilateral microinjections of clonidine into the A5 regions did not alter XII nerve activity. These data suggest that A5 neurons are silenced during natural REM sleep. This will lead to decreased norepinephrine release and may alter synaptic transmission in the nucleus of the solitary tract and rostral ventrolateral medulla without, however, a detectable impact on XII motoneurons.
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Affiliation(s)
- Victor Fenik
- Department of Animal Biology, School of Veterinary Medicine, and Center for Sleep and Respiratory Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6046, USA.
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32
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Almeida A, Cobos A, Tavares I, Lima D. Brain afferents to the medullary dorsal reticular nucleus: a retrograde and anterograde tracing study in the rat. Eur J Neurosci 2002; 16:81-95. [PMID: 12153533 DOI: 10.1046/j.1460-9568.2002.02058.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The medullary dorsal reticular nucleus (DRt) was recently shown to belong to the supraspinal pain control system; neurons within this nucleus give origin to a descending projection that increases spinal nociceptive transmission and facilitates pain perception [Almeida et al. (1999), Eur. J. Neurosci., 11, 110-122]. In the present study, the areas of the brain that may modulate the activity of DRt neurons were investigated by using of tract-tracing techniques. Injection of a retrograde tracer into the DRt resulted in labelling in multiple areas of the brain. In the contralateral orbital, prelimbic, infralimbic, insular, motor and somatosensory cortices labelling was prominent, but a smaller ipsilateral projection from these same areas was also detected. Strong labelling was also noted in the central amygdaloid nucleus, bed nucleus of stria terminalis and substantia innominata. Labelled diencephalic areas were mainly confined to the hypothalamus, namely its lateral and posterior areas as well as the paraventricular nucleus. In the mesencephalon, the periaqueductal grey, red nucleus and deep mesencephalic nucleus were strongly labelled, whereas, in the brainstem, the parabrachial nuclei, rostroventromedial medulla, nucleus tractus solitarius, spinal trigeminal nucleus, and the parvocellular, dorsal, lateral and ventral reticular nuclei were the most densely labelled regions. All deep cerebellar nuclei were labelled bilaterally. These data suggest that the DRt integrates information from the somatosensory, antinociceptive, autonomic, limbic, pyramidal and extrapyramidal systems while triggering its descending facilitating action upon the spinal nociceptive transmission.
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Affiliation(s)
- Armando Almeida
- Institute of Histology and Embryology, Faculty of Medicine, Porto, Portugal.
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Goodchild AK, Phillips JK, Lipski J, Pilowsky PM. Differential expression of catecholamine synthetic enzymes in the caudal ventral pons. J Comp Neurol 2001; 438:457-67. [PMID: 11559901 DOI: 10.1002/cne.1328] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The analysis of colocalization of multiple catecholamine biosynthetic enzymes within the ventrolateral part of the medulla oblongata of the rat revealed distinct subpopulations of neurons within the C1 region (Phillips et al., J Comp Neurol 2001, 432:20-34). In extending this study to include the caudal pons, it was shown for the first time that the A5 cell group could be distinguished by the presence of immunoreactivity to tyrosine hydroxylase (TH), aromatic l-amino acid decarboxylase (AADC), and dopamine beta hydroxylase (DBH). A novel cell group was also identified. The cells within this new group were immunoreactive to DBH but not TH, AADC, or phenylethanolamine N-methyltransferase (PNMT) and will be referred to as the TH-, DBH+ cell group. The TH-, DBH+ neurons were not immunoreactive for either the dopamine or noradrenaline transporters, suggesting that these neurons do not take up these transmitters. A5 neurons were immunoreactive for the noradrenaline transporter but not the dopamine transporter (as previously shown). Retrograde tracing with cholera toxin B revealed that the TH-, DBH+ neurons do not project to the thoracic spinal cord or to the rostral ventrolateral medulla, but A5 neurons do. A calbindin immunoreactive cell group is located in a region overlapping TH-, DBH+ cell group. However, only a few neurons were immunoreactive for both markers. The physiological role of the TH-, DBH+ cell group remains to be determined.
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Affiliation(s)
- A K Goodchild
- Hypertension and Stroke Research Laboratories, Departments of Physiology and Neurosurgery, University of Sydney, Royal North Shore Hospital, Sydney, NSW, Australia
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Almeida A, Størkson R, Lima D, Hole K, Tjølsen A. The medullary dorsal reticular nucleus facilitates pain behaviour induced by formalin in the rat. Eur J Neurosci 1999; 11:110-22. [PMID: 9987016 DOI: 10.1046/j.1460-9568.1999.00411.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The influence of the dorsal reticular nucleus (DRt) on pain behaviour during the formalin test was studied in the rat by lesioning the nucleus through local application of electrical current or quinolinic acid. Animals in which the DRt was lesioned ipsilaterally to the paw injected with formalin spent less time in focused (licking, biting or scratching the injected paw) and total (focused pain behaviour plus protection of the injected paw during movements) pain behaviour, and showed paw-jerks less frequently than non-lesioned animals in both phases 1 and 2 of the test. Animals in which the DRt was lesioned contralaterally to the injected paw presented a decrease in total pain behaviour and number of paw-jerks only during phase 2. The number of superficial (laminae I-II) and deep (laminae III-VI) spinal dorsal horn cells expressing the c-fos proto-oncogene 2 h after subcutaneous injection of formalin was reduced by 34% and 50%, respectively, in animals with an ipsilateral DRt lesion as compared to non-lesioned rats. No differences in c-fos expression were observed after lesioning the DRt contralateral to the formalin injection. The results indicate that the DRt is involved in the facilitation of nociception during the formalin test by enhancing the response capacity of dorsal horn neurons to noxious stimulation. It is suggested that the pronociceptive action of the DRt is mediated by the reciprocal connections it establishes with the spinal dorsal horn.
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Affiliation(s)
- A Almeida
- Institute of Histology and Embryology of the Faculty of Medicine and IBMC, University of Oporto, Porto, Portugal.
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