1
|
Osuna-Carrasco LP, Dueñas-Jiménez SH, Toro-Castillo C, De la Torre B, Aguilar-García I, Alpirez J, Castillo L, Dueñas-Jiménez JM. Neonatal Mice Spinal Cord Interneurons Send Axons through the Dorsal Roots. Exp Neurobiol 2022; 31:89-96. [PMID: 35673998 PMCID: PMC9194636 DOI: 10.5607/en21019] [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] [Received: 06/18/2021] [Revised: 03/02/2022] [Accepted: 03/19/2022] [Indexed: 11/24/2022] Open
Abstract
Spontaneous interneuron activity plays a critical role in developing neuronal networks. Discharges conducted antidromically along the dorsal root (DR) precede those from the ventral root’s (VR) motoneurons. This work studied whether spinal interneurons project axons into the neonate’s dorsal roots. Experiments were carried out in postnatal Swiss-Webster mice. We utilized a staining technique and found that interneurons in the spinal cord’s dorsal horn send axons through the dorsal roots. In vitro electrophysiological recordings showed antidromic action potentials (dorsal root reflex; DRR) produced by depolarizing the primary afferent terminals. These reflexes appeared by stimulating the adjacent dorsal roots. We found that bicuculline reduced the DRR evoked by L5 dorsal root stimulation when recording from the L4 dorsal root. Simultaneously, the monosynaptic reflex (MR) in the L5 ventral root was not affected; nevertheless, a long-lasting after-discharge appeared. The addition of 2-amino-5 phosphonovaleric acid (AP5), an NMDA receptor antagonist, abolished the MR without changing the after-discharge. The absence of DRR and MR facilitated single action potentials in the dorsal and ventral roots that persisted even in low Ca2+ concentrations. The results suggest that firing interneurons could send their axons through the dorsal roots. These interneurons could activate motoneurons producing individual spikes recorded in the ventral roots. Identifying these interneurons and the persistence of their neuronal connectivity in adulthood remains to be established.
Collapse
Affiliation(s)
| | | | - Carmen Toro-Castillo
- Department of Translational Bioengineering, CUCEI, University of Guadalajara, Guadalajara 44430, México
| | - Braniff De la Torre
- Department of Translational Bioengineering, CUCEI, University of Guadalajara, Guadalajara 44430, México
| | - Irene Aguilar-García
- Department of Molecular and Genomics, CUCS, University of Guadalajara, Guadalajara 44340, México
| | - Jonatan Alpirez
- Department of Neuroscience, CUCS, University of Guadalajara, Guadalajara 44340, México
| | - Luis Castillo
- Basic Center, Autonomous University of Aguascalientes, Aguascalientes 20131, México
| | | |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
Sousa M, Szucs P, Lima D, Aguiar P. The pronociceptive dorsal reticular nucleus contains mostly tonic neurons and shows a high prevalence of spontaneous activity in block preparation. J Neurophysiol 2014; 111:1507-18. [PMID: 24431401 DOI: 10.1152/jn.00440.2013] [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] [Indexed: 11/22/2022] Open
Abstract
Despite the importance and significant clinical impact of understanding information processing in the nociceptive system, the functional properties of neurons in many parts of this system are still unknown. In this work we performed whole cell patch-clamp recording in rat brain stem blocks to characterize the electrophysiological properties of neurons in the dorsal reticular nucleus (DRt), a region known to be involved in pronociceptive modulation. We also compared properties of DRt neurons with those in the adjacent parvicellular reticular nucleus and in neighboring regions outside the reticular formation. We found that neurons in the DRt and parvicellular reticular nucleus had similar electrophysiological properties and exhibited mostly toniclike firing patterns, whereas neurons outside the reticular formation showed a larger diversity of firing patterns. Interestingly, more than one-half of the neurons also showed spontaneous activity. While the general view of the reticular formation, being a loosely associated mesh of groups of neurons with diverse function, and earlier reports suggests more electrophysiological heterogeneity, we showed that this is indeed not the case. Our results indicate that functional difference of neurons in the reticular formation may mostly be determined by their connectivity profiles and not by their intrinsic electrophysiological properties. The dominance of tonic neurons in the DRt supports previous conclusions that these neurons encode stimulus intensity through their firing frequency, while the high prevalence of spontaneous activity most likely shapes nociceptive modulation by this brain stem region.
Collapse
Affiliation(s)
- Mafalda Sousa
- Instituto de Biologia Molecular e Celular, Porto, Portugal
| | | | | | | |
Collapse
|
4
|
Staud R. The important role of CNS facilitation and inhibition for chronic pain. ACTA ACUST UNITED AC 2013; 8:639-646. [PMID: 24489609 DOI: 10.2217/ijr.13.57] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Multiple studies have demonstrated that the pain experience among individuals is highly variable. Even under circumstances where the tissue injuries are similar, individual pain experiences may vary drastically. However, this individual difference in pain sensitivity is not only related to sensitivity of peripheral pain receptors, but also to variability in CNS pain processing. Peripheral impulses derived from tissue receptors undergo modification in dorsal horn neurons that can either result in inhibition or facilitation of pain. Such influences are particularly apparent in inflammation where not only peripheral, but also central, pain modulatory mechanisms can significantly increase nociceptive pain. Emotional state, level of anxiety, attention and distraction, memories, stress, fatigue and many other factors can either increase or reduce the pain experience. Increasing evidence suggests that 'bottom-up' and 'top-down' modulatory circuits within the spinal cord and brain play an important role in pain processing, which can profoundly affect the experience of pain.
Collapse
Affiliation(s)
- Roland Staud
- Division of Rheumatology & Clinical Immunology, University of Florida, PO Box 100221, Gainesville, FL 32610-0221, USA, Tel.: +1 352 273 9681
| |
Collapse
|
5
|
Electrophysiological study of supraspinal input and spinal output of cat's subnucleus reticularis dorsalis (SRD) neurons. PLoS One 2013; 8:e60686. [PMID: 23544161 PMCID: PMC3609786 DOI: 10.1371/journal.pone.0060686] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 03/03/2013] [Indexed: 11/19/2022] Open
Abstract
This work addressed the study of subnucleus reticularis dorsalis (SRD) neurons in relation to their supraspinal input and the spinal terminating sites of their descending axons. SRD extracellular unitary recordings from anesthetized cats aimed to specifically test, 1) the rostrocaudal segmental level reached by axons of spinally projecting (SPr) neurons collateralizing or not to or through the ipsilateral nucleus reticularis gigantocellularis (NRGc), 2) whether SPr fibers bifurcate to the thalamus, and 3) the effects exerted on SRD cells by electrically stimulating the locus coeruleus, the periaqueductal grey, the nucleus raphe magnus, and the mesencephalic locomotor region. From a total of 191 SPr fibers tested to cervical 2 (Ce2), thoracic 5 (Th5) and lumbar5 (Lu5) stimulation, 81 ended between Ce2 and Th5 with 39 of them branching to or through the NRGc; 21/49 terminating between Th5 and Lu5 collateralized to or through the same nucleus, as did 34/61 reaching Lu5. The mean antidromic conduction velocity of SPr fibers slowed in the more proximal segments and increased with terminating distance along the cord. None of the 110 axons tested sent collaterals to the thalamus; instead thalamic stimulation induced long-latency polysynaptic responses in most cells but also short-latency, presumed monosynaptic, in 7.9% of the tested neurons (18/227). Antidromic and orthodromic spikes were elicited from the locus coeruleus and nucleus raphe magnus, but exclusively orthodromic responses were observed following stimulation of the periaqueductal gray or mesencephalic locomotor region. The results suggest that information from pain-and-motor-related supraspinal structures converge on SRD cells that through SPr axons having conduction velocities tuned to their length may affect rostral and caudal spinal cord neurons at fixed delays, both directly and in parallel through different descending systems. The SRD will thus play a dual functional role by simultaneously regulating dorsal horn ascending noxious information and pain-related motor responses.
Collapse
|
6
|
Ossipov MH. The perception and endogenous modulation of pain. SCIENTIFICA 2012; 2012:561761. [PMID: 24278716 PMCID: PMC3820628 DOI: 10.6064/2012/561761] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 11/19/2012] [Indexed: 06/02/2023]
Abstract
Pain is often perceived an unpleasant experience that includes sensory and emotional/motivational responses. Accordingly, pain serves as a powerful teaching signal enabling an organism to avoid injury, and is critical to survival. However, maladaptive pain, such as neuropathic or idiopathic pain, serves no survival function. Genomic studies of individuals with congenital insensitivity to pain or paroxysmal pain syndromes considerable increased our understanding of the function of peripheral nociceptors, and especially of the roles of voltage-gated sodium channels and of nerve growth factor (NGF)/TrkA receptors in nociceptive transduction and transmission. Brain imaging studies revealed a "pain matrix," consisting of cortical and subcortical regions that respond to noxious inputs and can positively or negatively modulate pain through activation of descending pain modulatory systems. Projections from the periaqueductal grey (PAG) and the rostroventromedial medulla (RVM) to the trigeminal and spinal dorsal horns can inhibit or promote further nociceptive inputs. The "pain matrix" can explain such varied phenomena as stress-induced analgesia, placebo effect and the role of expectation on pain perception. Disruptions in these systems may account for the existence idiopathic pan states such as fibromyalgia. Increased understanding of pain modulatory systems will lead to development of more effective therapeutics for chronic pain.
Collapse
Affiliation(s)
- Michael H. Ossipov
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
| |
Collapse
|
7
|
Reyns N, Derambure P, Duhamel A, Bourriez JL, Blond S, Houdayer E. Motor cortex stimulation modulates defective central beta rhythms in patients with neuropathic pain. Clin Neurophysiol 2012; 124:761-9. [PMID: 23151426 DOI: 10.1016/j.clinph.2012.10.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 10/16/2012] [Accepted: 10/17/2012] [Indexed: 11/18/2022]
Abstract
OBJECTIVE Motor cortex stimulation therapy (MCS) is increasingly used to control refractory neuropathic pain. Post-movement beta synchronization (PMBS) is defined as a sharp increase in beta-frequency electroencephalographic power following movement offset and may reflect sensorimotor cortex inhibition induced, at least in part, by cortical processing of movement-related sensory afferent inputs. PMBS pattern is then often altered in case of neuropathic pain. The main objective of the present study was to test the hypothesis that implanted MCS modulates PMBS in patients presenting with neuropathic pain. METHODS Using a high-resolution, 128-electrode electroencephalographic system, we recorded and compared, before and during MCS, PMBS patterns during brisk, unilateral right and left index finger extension in 8 patients presenting with neuropathic pain. RESULTS The pre-operative PMBS patterns were altered in all cases. MCS increased the spatial distribution and amplitude of PMBS in most of cases and restored maximum-intensity of PMBS contralateral to the painful body side. These modifications appeared significantly correlated with the analgesic effect of MCS. CONCLUSION This study provides evidence of central beta rhythms neuromodulation induced by MCS. SIGNIFICANCE The restoration by MCS of defective cortical inhibition in patients with neuropathic pain is evoked.
Collapse
Affiliation(s)
- Nicolas Reyns
- Department of Functional Neurosurgery, FRE 3291 CNRS, Université Lille Nord de France, France.
| | | | | | | | | | | |
Collapse
|
8
|
Streff A, Michaux G, Anton F. Internal validity of inter-digital web pinching as a model for perceptual diffuse noxious inhibitory controls-induced hypoalgesia in healthy humans. Eur J Pain 2012; 15:45-52. [DOI: 10.1016/j.ejpain.2010.05.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 04/16/2010] [Accepted: 05/20/2010] [Indexed: 10/19/2022]
|
9
|
Panneton WM, Gan Q, Livergood RS. A trigeminoreticular pathway: implications in pain. PLoS One 2011; 6:e24499. [PMID: 21957454 PMCID: PMC3177822 DOI: 10.1371/journal.pone.0024499] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Accepted: 08/11/2011] [Indexed: 01/18/2023] Open
Abstract
Neurons in the caudalmost ventrolateral medulla (cmVLM) respond to noxious stimulation. We previously have shown most efferent projections from this locus project to areas implicated either in the processing or modulation of pain. Here we show the cmVLM of the rat receives projections from superficial laminae of the medullary dorsal horn (MDH) and has neurons activated with capsaicin injections into the temporalis muscle. Injections of either biotinylated dextran amine (BDA) into the MDH or fluorogold (FG)/fluorescent microbeads into the cmVLM showed projections from lamina I and II of the MDH to the cmVLM. Morphometric analysis showed the retrogradely-labeled neurons were small (area 88.7 µm(2)±3.4) and mostly fusiform in shape. Injections (20-50 µl) of 0.5% capsaicin into the temporalis muscle and subsequent immunohistochemistry for c-Fos showed nuclei labeled in the dorsomedial trigeminocervical complex (TCC), the cmVLM, the lateral medulla, and the internal lateral subnucleus of the parabrachial complex (PBil). Additional labeling with c-Fos was seen in the subnucleus interpolaris of the spinal trigeminal nucleus, the rostral ventrolateral medulla, the superior salivatory nucleus, the rostral ventromedial medulla, and the A1, A5, A7 and subcoeruleus catecholamine areas. Injections of FG into the PBil produced robust label in the lateral medulla and cmVLM while injections of BDA into the lateral medulla showed projections to the PBil. Immunohistochemical experiments to antibodies against substance P, the substance P receptor (NK1), calcitonin gene regulating peptide, leucine enkephalin, VRL1 (TPRV2) receptors and neuropeptide Y showed that these peptides/receptors densely stained the cmVLM. We suggest the MDH- cmVLM projection is important for pain from head and neck areas. We offer a potential new pathway for regulating deep pain via the neurons of the TCC, the cmVLM, the lateral medulla, and the PBil and propose these areas compose a trigeminoreticular pathway, possibly the trigeminal homologue of the spinoreticulothalamic pathway.
Collapse
Affiliation(s)
- W Michael Panneton
- Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, Missouri, United States of America.
| | | | | |
Collapse
|
10
|
Robbins A, Schmitt D, Winterson BJ, Meng ID. Chronic morphine increases Fos-positive neurons after concurrent cornea and tail stimulation. Headache 2011; 52:262-73. [PMID: 21929659 DOI: 10.1111/j.1526-4610.2011.01999.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The aim of the present study was to examine the effect of chronic morphine exposure on diffuse noxious inhibitory controls in a large population of neurons throughout the medullary dorsal horn, as assessed using immunocytochemistry for c-Fos protein. BACKGROUND Overuse of medications, including the opioids, to treat migraine headache can lead to progressively more frequent headaches. In addition, chronic daily headache sufferers and chronic opioid users both lack the inhibition of pain produced by noxious stimulation of a distal body region, often referred to as diffuse noxious inhibitory controls. METHODS In urethane anesthetized rats, Fos-positive neurons were quantified in chronic morphine and vehicle-treated animals following 52°C noxious thermal stimulation of the cornea with and without the application of a spatially remote noxious stimulus (placement of the tail in 55°C water). RESULTS When compared to chronic morphine-treated animals that did not receive the spatially remote noxious stimulus, chronic morphine-treated animals given corneal stimulation along with the spatially remote noxious stimulus demonstrated a 163% increase (P < .05) in the number of Fos-positive neurons in the superficial laminae of the medullary dorsal horn and a 682% increase (P < .01) in deep laminae that was restricted to the side ipsilateral to the applied stimulus. In contrast, no significant difference was found in Fos-like immunoreactivity in vehicle-treated animals given concurrent cornea and tail stimulation or only cornea stimulation in either superficial or deep laminae. CONCLUSIONS It is proposed that an increase in descending facilitation and subsequent loss of diffuse noxious inhibitory controls contributes to the development of medication overuse headache.
Collapse
Affiliation(s)
- Ashlee Robbins
- Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, Biddeford, ME, USA
| | | | | | | |
Collapse
|
11
|
Soto C, Canedo A. Intracellular recordings of subnucleus reticularis dorsalis neurones revealed novel electrophysiological properties and windup mechanisms. J Physiol 2011; 589:4383-401. [PMID: 21746779 DOI: 10.1113/jphysiol.2011.212464] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Aδ- and/or C-fibre nociceptive inputs drive subnucleus reticularis dorsalis (SRD) neurones projecting to a variety of regions including the spinal cord and the nucleus reticularis gigantocellularis (NRGc), but their electrophysiological properties are largely unknown. Here we intracellularly recorded the SRD neuronal responses to injection of polarising current pulses as well as to electrical stimulation of the cervical spinal posterior quadrant (PQ) and the NRGc. Three different classes of neurones with distinct electrophysiological properties were found: type I were characterised by the absence of a fast postspike hyperpolarisation, type II by the presence of a postspike hyperpolarisation followed by a depolarisation resembling low threshold calcium spikes (LTSs), and type III (lacking LTSs) had a fast postspike hyperpolarisation deinactivating A-like potassium channels leading to enlarged interspike intervals. All three classes generated depolarising sags to hyperpolarising current pulses and showed 3-4.5 Hz subthreshold oscillatory activity leading to windup when intracellularly injecting low-frequency repetitive depolarising pulses as well as in response to 0.5-2 Hz NRGc and PQ electrical stimulation. About half of the 132 sampled neurones responded antidromically to NRGc stimulation with more than 65% of the NRGc-antidromic cells, pertaining to all three types, also responding antidromically to PQ stimulation. NRGc stimulation induced exclusively excitatory first-synaptic-responses whilst PQ stimulation induced first-response excitation in most cases, but inhibitory postsynaptic potentials in a few type II and type III neurones not projecting to the spinal cord that also displayed cumulative inhibitory effects (inverse windup). The results show that SRD cells (i) can actively regulate different temporal firing patterns due to their intrinsic electrophysiological properties, (ii) generate windup upon gradual membrane depolarisation produced by low-frequency intracellular current injection and by C-fibre tonic input, both processes leading subthreshold oscillations to threshold, and (iii) collateralise to the NRGc and the spinal cord, potentially providing simultaneous regulation of ascending noxious information and motor reactions to pain.
Collapse
Affiliation(s)
- Cristina Soto
- A. Canedo: Health Research Institute (IDIS), Department of Physiology, Faculty of Medicine, 15704 Santiago de Compostela, Spain.
| | | |
Collapse
|
12
|
Ossipov MH, Dussor GO, Porreca F. Central modulation of pain. J Clin Invest 2010; 120:3779-87. [PMID: 21041960 DOI: 10.1172/jci43766] [Citation(s) in RCA: 697] [Impact Index Per Article: 49.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
It has long been appreciated that the experience of pain is highly variable between individuals. Pain results from activation of sensory receptors specialized to detect actual or impending tissue damage (i.e., nociceptors). However, a direct correlation between activation of nociceptors and the sensory experience of pain is not always apparent. Even in cases in which the severity of injury appears similar, individual pain experiences may vary dramatically. Emotional state, degree of anxiety, attention and distraction, past experiences, memories, and many other factors can either enhance or diminish the pain experience. Here, we review evidence for "top-down" modulatory circuits that profoundly change the sensory experience of pain.
Collapse
Affiliation(s)
- Michael H Ossipov
- Department of Pharmacology, University of Arizona, Tucson, Arizona 85724, USA
| | | | | |
Collapse
|
13
|
Michaux G, Anton F, Erpelding N, Streff A. Comments on "Recommendations on terminology and practice of psychophysical DNIC testing" by Yarnitsky et al., 14 (4), 339. Eur J Pain 2010; 14:1068-9; author reply 1070. [PMID: 21070958 DOI: 10.1016/j.ejpain.2010.05.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Revised: 05/21/2010] [Accepted: 05/23/2010] [Indexed: 11/28/2022]
|
14
|
A quantitative comparison of BOLD fMRI responses to noxious and innocuous stimuli in the human spinal cord. Neuroimage 2010; 50:1408-15. [DOI: 10.1016/j.neuroimage.2010.01.043] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 12/07/2009] [Accepted: 01/13/2010] [Indexed: 11/22/2022] Open
|
15
|
Noseda R, Monconduit L, Constandil L, Chalus M, Villanueva L. Central nervous system networks involved in the processing of meningeal and cutaneous inputs from the ophthalmic branch of the trigeminal nerve in the rat. Cephalalgia 2008; 28:813-24. [PMID: 18498395 DOI: 10.1111/j.1468-2982.2008.01588.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
This study analysed the organization of central nervous system networks involved in the processing of meningeal inputs in the male, Sprague-Dawley rat. We injected the anterograde tracer, biotin dextran, into areas of the medullary trigeminal nucleus caudalis (Sp5C), which receive inputs from the ophthalmic division of the trigeminal nerve. Double-labelling immunohistochemical studies were then performed to compare calcitonin gene-related peptide (CGRP) or serotonin 1D (5HT1(D)) receptor distributions in the areas innervated by Sp5C neurons. Dense, topographically organized intratrigeminal connections were observed. Sp5C neurons projected to the commissural subnucleus of the solitary tract, A5 cell group region/superior salivatory nucleus, lateral periaqueductal grey matter, inferior colliculus and parabrachial nuclei. Trigeminothalamic afferents were restricted to the posterior group and ventroposteromedial thalamic nuclei. Some of these areas are also immunoreactive for 5HT1(D) and CGRP and thus remain potential central targets of triptan molecules and other antimigraine drugs.
Collapse
|
16
|
Abstract
Damage to a nerve should only lead to sensory loss. While this is common, the incidence of spontaneous pain, allodynia and hyperalgesia indicate marked changes in the nervous system that are possible compensations for the loss of normal function that arises from the sensory loss. Neuropathic pain arises from changes in the damaged nerve which then alter function in the spinal cord and the brain and lead to plasticity in areas adjacent to those directly influenced by the neuropathy. The peripheral changes drive central compensations so that the mechanisms involved are multiple and located at a number of sites. Nerve damage increases the excitability of both the damaged and undamaged nerve fibres, neuromas and the cell bodies in the dorsal root ganglion. These peripheral changes are substrates for the ongoing pain and the efficacy of excitability blockers such as carbamazepine, lamotrigine and mexiletine, all anti-convulsants. A better understanding of ion channels at the sites of injury has shown important roles of particular sodium, potassium and calcium channels in the genesis of neuropathic pain. Within the spinal cord, increases in the activity of calcium channels and the receptors for glutamate, especially the N-methyl-D-aspartate (NMDA) receptor, trigger wind-up and central hyperexcitability. Increases in transmitter release, neuronal excitability and receptive field size result from the damage to the peripheral nerves. Ketamine and gabapentin/pregabalin, again with anti-convulsant activity, may interact with these mechanisms. Ketamine acts on central spinal mechanisms of excitability whereas gabapentin acts on a subunit of calcium channels that is responsible for the release of pain transmitters into the spinal cord. In addition to these spinal mechanisms of hyperexcitability, spinal cells participate in a spinal-supraspinal loop that involves parts of the brain involved in affective responses to pain but also engages descending excitatory and inhibitory systems that use the monoamines. These pathways become more active after nerve injury and are the site of action of anti-depressants. This chapter reviews the evidence and mechanisms of drugs, both anti-depressants and anti-convulsants, that are believed to be effective in pain control, with a major emphasis on the neuropathic state.
Collapse
Affiliation(s)
- A H Dickenson
- Dept. Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
| | | |
Collapse
|
17
|
Sukhotinsky I, Reiner K, Govrin-Lippmann R, Belenky M, Lu J, Hopkins DA, Saper CB, Devor M. Projections from the mesopontine tegmental anesthesia area to regions involved in pain modulation. J Chem Neuroanat 2006; 32:159-78. [PMID: 17049433 DOI: 10.1016/j.jchemneu.2006.08.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2006] [Revised: 08/25/2006] [Accepted: 08/30/2006] [Indexed: 11/19/2022]
Abstract
Pentobarbital microinjected into a restricted locus in the upper brainstem induces a general anesthesia-like state characterized by atonia, loss of consciousness, and pain suppression as assessed by loss of nocifensive response to noxious stimuli. This locus is the mesopontine tegmental anesthesia area (MPTA). Although anesthetic agents directly influence spinal cord nociceptive processing, antinociception during intracerebral microinjection indicates that they can also act supraspinally. Using neuroanatomical tracing methods we show that the MPTA has multiple descending projections to brainstem and spinal areas associated with pain modulation. Most prominent is a massive projection to the rostromedial medulla, a nodal region for descending pain modulation. Together with the periaqueductal gray (PAG), the MPTA is the major mesopontine input to this region. Less dense projections target the PAG, the locus coeruleus and pericoerulear areas, and dorsal and ventral reticular nuclei of the caudal medulla. The MPTA also has modest direct projections to the trigeminal nuclear complex and to superficial layers of the dorsal horn. Double anterograde and retrograde labeling at the light and electron microscopic levels shows that MPTA neurons with descending projections synapse directly on spinally projecting cells of rostromedial medulla. The prominence of the MPTA's projection to the rostromedial medulla suggests that, like the PAG, it may exert antinociceptive actions via this bulbospinal relay.
Collapse
Affiliation(s)
- I Sukhotinsky
- Department of Cell and Animal Biology, Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
| | | | | | | | | | | | | | | |
Collapse
|
18
|
Medullary control of nociceptive transmission: Reciprocal dual communication with the spinal cord. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.ddmec.2006.09.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
19
|
Leite-Almeida H, Valle-Fernandes A, Almeida A. Brain projections from the medullary dorsal reticular nucleus: an anterograde and retrograde tracing study in the rat. Neuroscience 2006; 140:577-95. [PMID: 16563637 DOI: 10.1016/j.neuroscience.2006.02.022] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Revised: 02/06/2006] [Accepted: 02/10/2006] [Indexed: 11/28/2022]
Abstract
In the last 15 years a role has been ascribed for the medullary dorsal reticular nucleus as a supraspinal pain modulating area. The medullary dorsal reticular nucleus is reciprocally connected with the spinal dorsal horn, is populated mainly by nociceptive neurons and regulates spinal nociceptive processing. Here we analyze the distribution of brain projections from the medullary dorsal reticular nucleus using the iontophoretic administration of the anterograde tracer biotinylated-dextran amine and the retrograde tracer cholera toxin subunit B. Fibers and terminal boutons labeled from the medullary dorsal reticular nucleus were located predominately in the brainstem, although extending also to the forebrain. In the medulla oblongata, anterograde labeling was observed in the orofacial motor nuclei, inferior olive, caudal ventrolateral medulla, rostral ventromedial medulla, nucleus tractus solitarius and most of the reticular formation. Labeling at the pons-cerebellum level was present in the locus coeruleus, A5 and A7 noradrenergic cell groups, parabrachial and deep cerebellar nuclei, whereas in the mesencephalon it was located in the periaqueductal gray matter, deep mesencephalic, oculomotor and anterior pretectal nuclei, and substantia nigra. In the diencephalon, fibers and terminal boutons were found mainly in the parafascicular, ventromedial, and posterior thalamic nuclei and in the arcuate, lateral, posterior, peri- and paraventricular hypothalamic areas. Telencephalic labeling was consistent but less intense and concentrated in the septal nuclei, globus pallidus and amygdala. The well-known role of the medullary dorsal reticular nucleus in nociception and its pattern of brain projections in rats suggests that the nucleus is possibly implicated in the modulation of: (i) the ascending nociceptive transmission involved in the motivational-affective dimension of pain; (ii) the endogenous supraspinal pain control system centered in the periaqueductal gray matter-rostral ventromedial medulla-spinal cord circuitry; (iii) the motor reactions associated with pain.
Collapse
Affiliation(s)
- H Leite-Almeida
- Life and Health Sciences Research Institute, School of Health Sciences, University of Minho, CP-II, Piso 3, Campus de Gualtar, 4710-057 Braga, Portugal
| | | | | |
Collapse
|
20
|
Travers JB, Yoo JE, Chandran R, Herman K, Travers SP. Neurotransmitter phenotypes of intermediate zone reticular formation projections to the motor trigeminal and hypoglossal nuclei in the rat. J Comp Neurol 2005; 488:28-47. [PMID: 15912497 DOI: 10.1002/cne.20604] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Numerous studies suggest an essential role for the intermediate (IRt) and parvocellular (PCRt) reticular formation (RF) in consummatory ingestive responses. Although the IRt and PCRt contain a large proportion of neurons with projections to the oromotor nuclei, these areas of the RF are heterogeneous with respect to neurotransmitter phenotypes. Glutamatergic, GABAergic, cholinergic, and nitrergic neurons are all found in the PCRt and IRt, but the projections of neurons with these phenotypes to the motor trigeminal (mV) and hypoglossal nucleus (mXII) has not been fully evaluated. In the present study, after small injections of Fluorogold (FG) into mV and mXII, sections were processed immunohistochemically to detect retrogradely labeled FG neurons in combination with the synthetic enzymes for nitric oxide (nitric oxide synthase) or acetylcholine (choline acetyltransferase) or in situ hybridization for the synthetic enzyme for GABA (GAD65/67) or the brainstem vesicular transporter for glutamate (VGLUT2). In three additional cases, FG injections were made into one motor nucleus and cholera toxin (subunit b) injected in the other to determine the presence of dual projection neurons. Premotor neurons to mXII (pre-mXII) were highly concentrated in the IRt. In contrast, there were nearly equal proportions of premotor-trigeminal neurons (pre-mV) in the IRt and PCRt. A high proportion of pre-oromotor neurons were positive for VGLUT2 (pre-mXII: 68%; pre-mV: 53%) but GABAergic projections were differentially distributed with a greater projection to mV (25%) compared to mXII (8%). Significant populations of cholinergic and nitrergic neurons overlapped pre-oromotor neurons, but there was sparse double-labeling (<10%). The IRt also contained a high proportion of neurons that projected to both mV and MXII. These different classes of premotor neurons in the IRt and PCRt provide a substrate for the rhythmic activation of lingual and masticatory muscles.
Collapse
Affiliation(s)
- Joseph B Travers
- College of Dentistry, Ohio State University, Section of Oral Biology, Columbus, 43210, USA.
| | | | | | | | | |
Collapse
|
21
|
Simpson JI, Hulscher HC, Sabel-Goedknegt E, Ruigrok TJH. Between in and out: linking morphology and physiology of cerebellar cortical interneurons. PROGRESS IN BRAIN RESEARCH 2005; 148:329-40. [PMID: 15661201 DOI: 10.1016/s0079-6123(04)48026-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We used the juxtacellular recording and labeling technique of Pinault (1996) in the uvula/nodulus of the ketamine anesthetized rat in an attempt to link different patterns of spontaneous activity with different types of morphologically identified cerebellar cortical interneurons. Cells displaying a somewhat irregular, syncopated cadence of spontaneous activity averaging 4-10 Hz could, upon successful entrainment and visualization, be morphologically identified as Golgi cells. Spontaneously firing cells with a highly or fairly regular firing rate of 10-35 Hz turned out to be unipolar brush cells. We also found indications that other types of cerebellar cortical neurons might also be distinguished on the basis of the characteristics of their spontaneous firing. Comparison of the interspike interval histograms of spontaneous activity obtained in the anaesthetized rat with those obtained in the awake rabbit points to a way whereby the behaviorally related modulation of specific types of interneurons can be studied. In particular, the spontaneous activity signatures of Golgi cells and unipolar brush cells anatomically identified in the uvula/nodulus of the anaesthetized rat are remarkably similar to the spontaneous activity patterns of some units we have recorded in the flocculus of the awake rabbit. The spontaneous activity patterns of at least some types of cerebellar interneurons clearly have the potential to serve as identifying signatures in behaving animals.
Collapse
Affiliation(s)
- J I Simpson
- Department of Physiology & Neuroscience, NYU Medical School, 550 First Avenue, New York, NY 10016, USA.
| | | | | | | |
Collapse
|
22
|
Corrêa SAL, Zupanc GKH. Re-evaluation of the afferent connections of the pituitary in the weakly electric fish Apteronotus leptorhynchus: an in vitro tract-tracing study. J Comp Neurol 2004; 470:39-49. [PMID: 14755524 DOI: 10.1002/cne.20009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The pituitary plays a key role in the interaction between the brain and the endocrine system. We re-examined the afferent connections of the pituitary in the weakly electric fish Apteronotus leptorhynchus using the in vitro application of dextran-tetramethylrhodamine to the pituitary. The resultant retrograde labeling was analyzed. Application of the tracer to the rostral part, but not the caudal part, of the pituitary labels hypothalamic cells in the anterior division of the periventricular nucleus, the suprachiasmatic nucleus, and the nucleus tuberis lateralis pars anterior. Application of the tracer to either the rostral or caudal parts of the pituitary labels hypothalamic cells in the posterior division of the periventricular nucleus (RPPp), the nucleus hypothalamus caudalis (Hc), the nucleus hypothalamus anterioris, the ventral hypothalamic nucleus, and the central nucleus of the inferior lobe. Furthermore, cells in the rostral two-thirds of the brainstem reticular formation (RF) project to the entire rostrocaudal extent of the pituitary. The largest projections to the pituitary are from Hc, PPp, and RF. Of the cells in Hc that project to the pituitary, almost all (96%) are small and the remainder are medium-sized. Of the cells in PPp that project to the pituitary, about half are small or medium-sized (44% and 56%, respectively). In Hc and PPp, about one-third to one-half of the cells that project to the pituitary are markedly elongated. The cells in RF that project to the pituitary are small (4%), medium-sized (89%), or large (7%) and about four-fifths of these cells are markedly elongated. With regard to the RF projections, the pituitary may receive copies of motor instructions and sensory information supplied by collaterals of the descending and ascending projection systems of RF cells. Thus, the ongoing motor activity of the animal and the ensuing sensory feedback from this activity could directly influence the pituitary.
Collapse
Affiliation(s)
- Sônia A L Corrêa
- School of Biological Sciences, University of Manchester, Manchester M13 9PT, United Kingdom.
| | | |
Collapse
|