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Kerr PL, Gregg JM. The Roles of Endogenous Opioids in Placebo and Nocebo Effects: From Pain to Performance to Prozac. ADVANCES IN NEUROBIOLOGY 2024; 35:183-220. [PMID: 38874724 DOI: 10.1007/978-3-031-45493-6_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
Placebo and nocebo effects have been well documented for nearly two centuries. However, research has only relatively recently begun to explicate the neurobiological underpinnings of these phenomena. Similarly, research on the broader social implications of placebo/nocebo effects, especially within healthcare delivery settings, is in a nascent stage. Biological and psychosocial outcomes of placebo/nocebo effects are of equal relevance. A common pathway for such outcomes is the endogenous opioid system. This chapter describes the history of placebo/nocebo in medicine; delineates the current state of the literature related to placebo/nocebo in relation to pain modulation; summarizes research findings related to human performance in sports and exercise; discusses the implications of placebo/nocebo effects among diverse patient populations; and describes placebo/nocebo influences in research related to psychopharmacology, including the relevance of endogenous opioids to new lines of research on antidepressant pharmacotherapies.
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Affiliation(s)
- Patrick L Kerr
- West Virginia University School of Medicine-Charleston, Charleston, WV, USA.
| | - John M Gregg
- Department of Surgery, VTCSOM, Blacksburg, VA, USA
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Song I, Cho S, Nedeljkovic SS, Lee SR, Lee C, Kim J, Bai SJ. Role of VVZ-149, a Novel Analgesic Molecule, in the Affective Component of Pain: Results from an Exploratory Proof-of-Concept Study of Postoperative Pain following Laparoscopic and Robotic-Laparoscopic Gastrectomy. PAIN MEDICINE 2021; 22:2037-2049. [PMID: 33624798 DOI: 10.1093/pm/pnab066] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
OBJECTIVE VVZ-149 is a small molecule that both inhibits the glycine transporter type 2 and the serotonin receptor 5 hydroxytryptamine 2 A. In a randomized, parallel-group, and double-blind trial (NCT02844725), we investigated the analgesic efficacy and safety of VVZ-149 Injections, which is under clinical development as a single-use injectable product for treating moderate to severe postoperative pain. METHODS Sixty patients undergoing laparoscopic and robotic-laparoscopic gastrectomy were randomly assigned to receive a 10-hour intravenous infusion of VVZ-149 Injections or placebo, initiated approximately 1 hour before completion of surgical suturing. Major outcomes included pain intensity and opioid consumption via patient-controlled analgesia and rescue analgesia provided "as needed." The treatment efficacy of VVZ-149 was further examined in a subpopulation requiring early rescue medication, previously associated with the presence of high levels of preoperative negative affect in a prior Phase 2 study (NCT02489526). RESULTS Pain intensity was lower in the VVZ-149 (n = 30) than the placebo group (n = 29), reaching statistical significance at 4 hours post-emergence (P < .05), with a 29.5% reduction in opioid consumption for 24 hours and fewer demands for patient-controlled analgesia. In the rescued subgroup, VVZ-149 further reduced pain intensity (P < .05) with 32.6% less opioid consumption for 24 hours compared to placebo patients. CONCLUSIONS VVZ-149 demonstrated effective analgesia with reduced postoperative pain and opioid requirements. Consistent with the results from the previous Phase 2 study, patients with early rescue requirement had greater benefit from VVZ-149, supporting the hypothesis that VVZ-149 may alleviate the affective component of pain and mitigate excessive use of opioids postoperatively.
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Affiliation(s)
- Inkyung Song
- Department of Global Research and Development, Vivozon, Inc, West Windsor, New Jersey
| | - Sunyoung Cho
- Department of Global Research and Development, Vivozon, Inc, West Windsor, New Jersey
| | - Srdjan S Nedeljkovic
- Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Sang Rim Lee
- Department of Global Research and Development, Vivozon, Inc, West Windsor, New Jersey
| | - Chaewon Lee
- Department of Clinical Development, Vivozon, Inc, Seoul, Republic of Korea
| | - Jina Kim
- Department of Clinical Development, Vivozon, Inc, Seoul, Republic of Korea
| | - Sun Joon Bai
- Department of Global Research and Development, Vivozon, Inc, West Windsor, New Jersey.,Department of Anesthesiology and Pain Medicine, Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
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The Pelvic Girdle Pain deadlock: 2. Topics that, so far, have remained out of focus. Musculoskelet Sci Pract 2020; 48:102166. [PMID: 32560869 DOI: 10.1016/j.msksp.2020.102166] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 03/30/2020] [Accepted: 04/06/2020] [Indexed: 12/19/2022]
Abstract
INTRODUCTION In our preceding paper, we concluded that Pelvic Girdle Pain (PGP) should be taken seriously. Still, we do not know its causes. Literature reviews on treatment fail to reveal a consistent pattern, and there are patients who do not respond well to treatment. We designated the lack of progress in research and in the clinic as 'deadlock', and proposed a 'deconstruction' of PGP, that is to say, taking PGP apart into its relevant dimensions. PURPOSE We examine the proposition that PGP may emerge as local inflammation. Inflammation would be a new dimension to be taken into account, between biomechanics and psychology. To explore the consequences of this idea, we present four different topics that, so far, have remained out of focus. One: The importance of microtrauma. Two: Ways to counteract chronification. Three: The importance of sickness behaviour when systemic inflammation turns into neuroinflammation of the brain. And Four: The mainly emotional and cognitive nature of chronic pain, and how aberrant neuroinflammation may render chronic pain intractable. For intractable pain, sleep and stress management are promising treatment options. IMPLICATIONS The authors hope that the present paper helps to stimulate the flexible creativity that is required to deal with the biological and psychological impact of PGP. Measuring inflammatory mediators in PGP should be a research priority. It should be understood that the boundaries between biology and psychology are becoming blurred. Clinicians must frequently monitor pain, disability, and mood, and be ready to switch treatment whenever the patient does not improve.
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Kuner R, Kuner T. Cellular Circuits in the Brain and Their Modulation in Acute and Chronic Pain. Physiol Rev 2020; 101:213-258. [PMID: 32525759 DOI: 10.1152/physrev.00040.2019] [Citation(s) in RCA: 149] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Chronic, pathological pain remains a global health problem and a challenge to basic and clinical sciences. A major obstacle to preventing, treating, or reverting chronic pain has been that the nature of neural circuits underlying the diverse components of the complex, multidimensional experience of pain is not well understood. Moreover, chronic pain involves diverse maladaptive plasticity processes, which have not been decoded mechanistically in terms of involvement of specific circuits and cause-effect relationships. This review aims to discuss recent advances in our understanding of circuit connectivity in the mammalian brain at the level of regional contributions and specific cell types in acute and chronic pain. A major focus is placed on functional dissection of sub-neocortical brain circuits using optogenetics, chemogenetics, and imaging technological tools in rodent models with a view towards decoding sensory, affective, and motivational-cognitive dimensions of pain. The review summarizes recent breakthroughs and insights on structure-function properties in nociceptive circuits and higher order sub-neocortical modulatory circuits involved in aversion, learning, reward, and mood and their modulation by endogenous GABAergic inhibition, noradrenergic, cholinergic, dopaminergic, serotonergic, and peptidergic pathways. The knowledge of neural circuits and their dynamic regulation via functional and structural plasticity will be beneficial towards designing and improving targeted therapies.
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Affiliation(s)
- Rohini Kuner
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany; and Department of Functional Neuroanatomy, Institute for Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | - Thomas Kuner
- Institute of Pharmacology, Heidelberg University, Heidelberg, Germany; and Department of Functional Neuroanatomy, Institute for Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
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Abstract
Placebo effects influence symptom perceptions and treatment outcomes. Placebo effects can be explored in laboratory settings controlling for natural history and expectations. Such a mechanistic approach to neurological disorders has been implemented in the domain of chronic clinical pain and other neurological disorders. This article therefore focuses on definitions and historical notes related to placebo effects and mechanisms of placebo effects in chronic pain. Knowledge on mechanisms of placebo effects could inform current clinical practice for the treatment of neurological disorders by focusing on patients (and providers) expectations for outcome optimization.
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Affiliation(s)
- Luana Colloca
- Department of Pain Translational Symptoms Science, School of Nursing, University of Maryland, Baltimore, MD, United States; Center to Advance Chronic Pain Research, University of Maryland, Baltimore, MD, United States; Departments of Anesthesiology and Psychiatry, School of Medicine, University of Maryland, Baltimore, MD, United States.
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Zhang Y, Vakhtin AA, Jennings JS, Massaband P, Wintermark M, Craig PL, Ashford JW, Clark JD, Furst AJ. Diffusion tensor tractography of brainstem fibers and its application in pain. PLoS One 2020; 15:e0213952. [PMID: 32069284 PMCID: PMC7028272 DOI: 10.1371/journal.pone.0213952] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 02/02/2020] [Indexed: 12/13/2022] Open
Abstract
Evaluation of brainstem pathways with diffusion tensor imaging (DTI) and tractography may provide insights into pathophysiologies associated with dysfunction of key brainstem circuits. However, identification of these tracts has been elusive, with relatively few in vivo human studies to date. In this paper we proposed an automated approach for reconstructing nine brainstem fiber trajectories of pathways that might be involved in pain modulation. We first performed native-space manual tractography of these fiber tracts in a small normative cohort of participants and confirmed the anatomical precision of the results using existing anatomical literature. Second, region-of-interest pairs were manually defined at each extracted fiber's termini and nonlinearly warped to a standard anatomical brain template to create an atlas of the region-of-interest pairs. The resulting atlas was then transformed non-linearly into the native space of 17 veteran patients' brains for automated brainstem tractography. Lastly, we assessed the relationships between the integrity levels of the obtained fiber bundles and pain severity levels. Fractional anisotropy (FA) measures derived using automated tractography reflected the respective tracts' FA levels obtained via manual tractography. A significant inverse relationship between FA and pain levels was detected within the automatically derived dorsal and medial longitudinal fasciculi of the brainstem. This study demonstrates the feasibility of DTI in exploring brainstem circuitries involved in pain processing. In this context, the described automated approach is a viable alternative to the time-consuming manual tractography. The physiological and functional relevance of the measures derived from automated tractography is evidenced by their relationships with individual pain severities.
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Affiliation(s)
- Yu Zhang
- War Related Illness and Injury Study Center (WRIISC), VA Palo Alto Health Care System, Palo Alto, California, United States of America
| | - Andrei A. Vakhtin
- War Related Illness and Injury Study Center (WRIISC), VA Palo Alto Health Care System, Palo Alto, California, United States of America
- Psychiatry and Behavioral Sciences, Stanford University, Stanford, California, United States of America
| | - Jennifer S. Jennings
- War Related Illness and Injury Study Center (WRIISC), VA Palo Alto Health Care System, Palo Alto, California, United States of America
| | - Payam Massaband
- Radiology, VA Palo Alto Health Care System, Palo Alto, California, United States of America
| | - Max Wintermark
- Psychiatry and Behavioral Sciences, Stanford University, Stanford, California, United States of America
- Neuroradiology at Stanford University, Stanford, California, United States of America
| | - Patricia L. Craig
- Radiology, VA Palo Alto Health Care System, Palo Alto, California, United States of America
| | - J. Wesson Ashford
- War Related Illness and Injury Study Center (WRIISC), VA Palo Alto Health Care System, Palo Alto, California, United States of America
- Psychiatry and Behavioral Sciences, Stanford University, Stanford, California, United States of America
| | - J. David Clark
- Pain Clinic, VA Palo Alto Health Care System, Palo Alto, California, United States of America
- Anesthesiology, Perioperative and Pain Medicine, Stanford University, Stanford, California, United States of America
| | - Ansgar J. Furst
- War Related Illness and Injury Study Center (WRIISC), VA Palo Alto Health Care System, Palo Alto, California, United States of America
- Psychiatry and Behavioral Sciences, Stanford University, Stanford, California, United States of America
- Neurology and Neurological Sciences, Stanford University, Stanford, California, United States of America
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Sapio MR, Iadarola MJ, Loydpierson AJ, Kim JJ, Thierry-Mieg D, Thierry-Mieg J, Maric D, Mannes AJ. Dynorphin and Enkephalin Opioid Peptides and Transcripts in Spinal Cord and Dorsal Root Ganglion During Peripheral Inflammatory Hyperalgesia and Allodynia. THE JOURNAL OF PAIN 2020; 21:988-1004. [PMID: 31931229 DOI: 10.1016/j.jpain.2020.01.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 10/30/2019] [Accepted: 01/06/2020] [Indexed: 12/12/2022]
Abstract
Understanding molecular alterations associated with peripheral inflammation is a critical factor in selectively controlling acute and persistent pain. The present report employs in situ hybridization of the 2 opioid precursor mRNAs coupled with quantitative measurements of 2 peptides derived from the prodynorphin and proenkephalin precursor proteins: dynorphin A 1-8 and [Met5]-enkephalin-Arg6-Gly7-Leu8. In dorsal spinal cord ipsilateral to the inflammation, dynorphin A 1-8 was elevated after inflammation, and persisted as long as the inflammation was sustained. Qualitative identification by high performance liquid chromatography and gel permeation chromatography revealed the major immunoreactive species in control and inflamed extracts to be dynorphin A 1-8. In situ hybridization in spinal cord after administration of the inflammatory agent, carrageenan, showed increased expression of prodynorphin (Pdyn) mRNA somatotopically in medial superficial dorsal horn neurons. The fold increase in preproenkephalin mRNA (Penk) was comparatively lower, although the basal expression is substantially higher than Pdyn. While Pdyn is not expressed in the dorsal root ganglion (DRG) in basal conditions, it can be induced by nerve injury, but not by inflammation alone. A bioinformatic meta-analysis of multiple nerve injury datasets confirmed Pdyn upregulation in DRG across different nerve injury models. These data support the idea that activation of endogenous opioids, notably dynorphin, is a dynamic indicator of persistent pain states in spinal cord and of nerve injury in DRG. PERSPECTIVE: This is a systematic, quantitative assessment of dynorphin and enkephalin peptides and mRNA in dorsal spinal cord and DRG neurons in response to peripheral inflammation and axotomy. These studies form the foundational framework for understanding how endogenous spinal opioid peptides are involved in nociceptive circuit modulation.
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Affiliation(s)
- Matthew R Sapio
- Department of Perioperative Medicine, National Institutes of Health, Clinical Center, Bethesda, Maryland
| | - Michael J Iadarola
- Department of Perioperative Medicine, National Institutes of Health, Clinical Center, Bethesda, Maryland.
| | - Amelia J Loydpierson
- Department of Perioperative Medicine, National Institutes of Health, Clinical Center, Bethesda, Maryland
| | - Jenny J Kim
- Department of Perioperative Medicine, National Institutes of Health, Clinical Center, Bethesda, Maryland
| | - Danielle Thierry-Mieg
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland
| | - Jean Thierry-Mieg
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland
| | - Dragan Maric
- Flow and Imaging Cytometry Core Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Andrew J Mannes
- Department of Perioperative Medicine, National Institutes of Health, Clinical Center, Bethesda, Maryland
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miR-200a-3p modulates gene expression in comorbid pain and depression: Molecular implication for central sensitization. Brain Behav Immun 2019; 82:230-238. [PMID: 31479730 DOI: 10.1016/j.bbi.2019.08.190] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/18/2019] [Accepted: 08/26/2019] [Indexed: 12/20/2022] Open
Abstract
Chronic pain and depression are often comorbid exhibiting common clinical presentations and biological connections related to central nervous system sensitization. Epigenetic regulation of gene expression in the brain plays a crucial role in response to long-lasting stress and chronic pain, and microRNA imbalance in the prefrontal cortex (PFC) might be involved in central sensitization. Male Sprague Dawley rats were subjected to unpredictable chronic mild stress (UCMS) and spared nerve injury (SNI) to initiate depressive-like behavior and chronic pain behavior, respectively. The next-generation sequencing technique was employed to analyze PFC microRNAs in both the UCMS and SNI models. Rats exposed to either UCMS or SNI exhibited both depressive-like and chronic pain behaviors. Five specific microRNAs (miR-10a-5p, miR-182, miR-200a-3p, miR-200b-3p, and miR-429) were simultaneously down-regulated in the depressive-like and chronic pain models after 4 weeks of short-term stress. Gene ontology revealed that the 4-week period of stress enhanced neurogenesis. Only the miR-200a-3p level was continuously elevated under prolonged stress, suggesting roles of reduced neurogenesis, inflammatory activation, disturbed circadian rhythm, lipid metabolism, and insulin secretion in the co-existence of pain and depression. Thus we conclude that miR-200a-3p might be a specific biomarker of central sensitization in chronic pain and depression.
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Zamorano AM, Montoya P, Cifre I, Vuust P, Riquelme I, Kleber B. Experience-dependent neuroplasticity in trained musicians modulates the effects of chronic pain on insula-based networks - A resting-state fMRI study. Neuroimage 2019; 202:116103. [PMID: 31437550 DOI: 10.1016/j.neuroimage.2019.116103] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 07/02/2019] [Accepted: 08/14/2019] [Indexed: 10/26/2022] Open
Abstract
Recent resting-state fMRI studies associated extensive musical training with increased insula-based connectivity in large-scale networks involved in salience, emotion, and higher-order cognitive processes. Similar changes have also been found in chronic pain patients, suggesting that both types of experiences can have comparable effects on insula circuitries. Based on these observations, the current study asked the question whether, and if so in what way, different forms of experience-dependent neuroplasticity may interact. Here we assessed insula-based connectivity during fMRI resting-state between musicians and non-musicians both with and without chronic pain, and correlated the results with clinical pain duration and intensity. As expected, insula connectivity was increased in chronic pain non-musicians relative to healthy non-musicians (with cingulate cortex and supplementary motor area), yet no differences were found between chronic pain non-musicians and healthy musicians. In contrast, musicians with chronic pain showed decreased insula connectivity relative to both healthy musicians (with sensorimotor and memory regions) and chronic pain non-musicians (with the hippocampus, inferior temporal gyrus, and orbitofrontal cortex), as well as lower pain-related inferences with daily activities. Pain duration correlated positively with insula connectivity only in non-musicians, whereas pain intensity exhibited distinct relationships across groups. We conclude that although music-related sensorimotor training and chronic pain, taken in isolation, can lead to increased insula-based connectivity, their combination may lead to higher-order plasticity (metaplasticity) in chronic pain musicians, engaging brain mechanisms that can modulate the consequences of maladaptive experience-dependent neural reorganization (i.e., pain chronification).
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Affiliation(s)
- Anna M Zamorano
- Research Institute of Health Sciences (IUNICS-IdISBa), University of the Balearic Islands, Palma de Mallorca, Spain; Center for Neuroplasticity and Pain (CNAP), SMI, Department of Health Science and Technology, The Faculty of Medicine, Aalborg University, Denmark.
| | - Pedro Montoya
- Research Institute of Health Sciences (IUNICS-IdISBa), University of the Balearic Islands, Palma de Mallorca, Spain
| | - Ignacio Cifre
- University Ramon Llull, Blanquerna, FPCEE, Barcelona, Spain
| | - Peter Vuust
- Center for Music in the Brain, Department of Clinical Medicine, Aarhus University & The Royal Academy of Music, Aarhus/Aalborg, Denmark
| | - Inmaculada Riquelme
- Research Institute of Health Sciences (IUNICS-IdISBa), University of the Balearic Islands, Palma de Mallorca, Spain; Department of Nursing and Physiotherapy, University of the Balearic Islands, Palma de Mallorca, Spain
| | - Boris Kleber
- Center for Music in the Brain, Department of Clinical Medicine, Aarhus University & The Royal Academy of Music, Aarhus/Aalborg, Denmark; Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
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Discovery of endogenous opioid systems: what it has meant for the clinician's understanding of pain and its treatment. Pain 2017; 158:2290-2300. [DOI: 10.1097/j.pain.0000000000001043] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Tong W, Lu Z, Qin L, Mauck RL, Smith HE, Smith LJ, Malhotra NR, Heyworth MF, Caldera F, Enomoto-Iwamoto M, Zhang Y. Cell therapy for the degenerating intervertebral disc. Transl Res 2017; 181:49-58. [PMID: 27986604 PMCID: PMC5776755 DOI: 10.1016/j.trsl.2016.11.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 11/17/2016] [Accepted: 11/22/2016] [Indexed: 01/03/2023]
Abstract
Spinal conditions related to intervertebral disc (IVD) degeneration cost billions of dollars in the US annually. Despite the prevalence and soaring cost, there is no specific treatment that restores the physiological function of the diseased IVD. Thus, it is vital to develop new treatment strategies to repair the degenerating IVD. Persons with IVD degeneration without back pain or radicular leg pain often do not require any intervention. Only patients with severe back pain related to the IVD degeneration or biomechanical instability are likely candidates for cell therapy. The IVD progressively degenerates with age in humans, and strategies to repair the IVD depend on the stage of degeneration. Cell therapy and cell-based gene therapy aim to address moderate disc degeneration; advanced stage disease may require surgery. Studies involving autologous, allogeneic, and xenogeneic cells have all shown good survival of these cells in the IVD, confirming that the disc niche is an immunologically privileged site, permitting long-term survival of transplanted cells. All of the animal studies reviewed here reported some improvement in disc structure, and 2 studies showed attenuation of local inflammation. Among the 50 studies reviewed, 25 used some type of scaffold, and cell leakage is a consistently noted problem, though some studies showed reduced cell leakage. Hydrogel scaffolds may prevent cell leakage and provide biomechanical support until cells can become established matrix producers. However, these gels need to be optimized to prevent this leakage. Many animal models have been leveraged in this research space. Rabbit is the most frequently used model (28 of 50), followed by rat, pig, and dog. Sheep and goat IVDs resemble those of humans in size and in the absence of notochordal cells. Despite this advantage, there were only 2 sheep and 1 goat studies of 50 studies in this cohort. It is also unclear if a study in large animals is needed before clinical trials since some of the clinical trials proceeded without a study in large animals. No animal studies or clinical trials completely restored IVD structure. However, results suggest cause for optimism. In light of the fact that patients primarily seek medical care for back pain, attenuating local inflammation should be a priority in benchmarks for success. Clinicians generally agree that short-term back pain should be treated conservatively. When interventions are considered, the ideal therapy should also be minimally invasive and concurrent with other procedures such as discography or discectomy. Restoration of tissue structure and preservation of spinal motion are desirable.
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Affiliation(s)
- Wei Tong
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa; Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, P.R.China
| | - Zhouyu Lu
- Department of Physical Medicine & Rehabilitation, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa
| | - Ling Qin
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa
| | - Robert L Mauck
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa; Department of Physical Medicine & Rehabilitation, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa; Translational Musculoskeletal Research Center (TMRC), Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, Pa
| | - Harvey E Smith
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa; Translational Musculoskeletal Research Center (TMRC), Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, Pa
| | - Lachlan J Smith
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa; Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa
| | - Neil R Malhotra
- Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa
| | - Martin F Heyworth
- Research Service, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, Pa; Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa
| | - Franklin Caldera
- Department of Physical Medicine & Rehabilitation, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa
| | - Motomi Enomoto-Iwamoto
- Department of Surgery, Division of Orthopedic Surgery, Children's Hospital of Philadelphia, Philadelphia, Pa
| | - Yejia Zhang
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa; Department of Physical Medicine & Rehabilitation, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa; Translational Musculoskeletal Research Center (TMRC), Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, Pa.
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Deletion of the mu opioid receptor gene in mice reshapes the reward-aversion connectome. Proc Natl Acad Sci U S A 2016; 113:11603-11608. [PMID: 27671662 DOI: 10.1073/pnas.1601640113] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Connectome genetics seeks to uncover how genetic factors shape brain functional connectivity; however, the causal impact of a single gene's activity on whole-brain networks remains unknown. We tested whether the sole targeted deletion of the mu opioid receptor gene (Oprm1) alters the brain connectome in living mice. Hypothesis-free analysis of combined resting-state fMRI diffusion tractography showed pronounced modifications of functional connectivity with only minor changes in structural pathways. Fine-grained resting-state fMRI mapping, graph theory, and intergroup comparison revealed Oprm1-specific hubs and captured a unique Oprm1 gene-to-network signature. Strongest perturbations occurred in connectional patterns of pain/aversion-related nodes, including the mu receptor-enriched habenula node. Our data demonstrate that the main receptor for morphine predominantly shapes the so-called reward/aversion circuitry, with major influence on negative affect centers.
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