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Pereira-Silva R, Teixeira-Pinto A, Neto FL, Martins I. μ-Opioid Receptor Activation at the Dorsal Reticular Nucleus Shifts Diffuse Noxious Inhibitory Controls to Hyperalgesia in Chronic Joint Pain in Male Rats. Anesthesiology 2024; 140:1176-1191. [PMID: 38381969 DOI: 10.1097/aln.0000000000004956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
BACKGROUND The dorsal reticular nucleus is a pain facilitatory area involved in diffuse noxious inhibitory control (DNIC) through opioidergic mechanisms that are poorly understood. The hypothesis was that signaling of μ-opioid receptors is altered in this area with prolonged chronic inflammatory pain and that this accounts for the loss of DNICs occurring in this condition. METHODS Monoarthritis was induced in male Wistar rats (n = 5 to 9/group) by tibiotarsal injection of complete Freund's adjuvant. The immunolabeling of µ-opioid receptors and the phosphorylated forms of µ-opioid receptors and cAMP response element binding protein was quantified. Pharmacologic manipulation of μ-opioid receptors at the dorsal reticular nucleus was assessed in DNIC using the Randall-Selitto test. RESULTS At 42 days of monoarthritis, μ-opioid receptor labeling decreased at the dorsal reticular nucleus, while its phosphorylated form and the phosphorylated cAMP response element binding protein increased. [d-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin acetate (DAMGO) enhanced DNIC analgesia in normal animals (means ± SD: pre-DNIC: 126.9 ± 7.0 g; DNIC - DAMGO: 147.5 ± 8.0 g vs. DNIC + DAMGO: 198.1 ± 19.3 g; P < 0.001), whereas it produced hyperalgesia in monoarthritis (pre-DNIC: 67.8 ± 7.5 g; DNIC - DAMGO: 70.6 ± 7.7 g vs. DNIC + DAMGO: 32.2 ± 2.6 g; P < 0.001). An ultra-low dose of naloxone, which prevents the excitatory signaling of the μ-opioid receptor, restored DNIC analgesia in monoarthritis (DNIC - naloxone: 60.0 ± 6.1 g vs. DNIC + naloxone: 98.0 ± 13.5 g; P < 0.001), compared to saline (DNIC - saline: 62.5 ± 5.2 g vs. DNIC + saline: 64.2 ± 3.8 g). When injected before DAMGO, it restored DNIC analgesia and decreased the phosphorylated cAMP response element binding protein in monoarthritis. CONCLUSIONS The dorsal reticular nucleus is likely involved in a facilitatory pathway responsible for DNIC hyperalgesia. The shift of μ-opioid receptor signaling to excitatory in this pathway likely accounts for the loss of DNIC analgesia in monoarthritis. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Raquel Pereira-Silva
- Institute for Research and Innovation in Health (i3S) of the University of Porto, Porto, Portugal; Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal; Department of Biomedicine - Unit of Experimental Biology, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Armando Teixeira-Pinto
- Sydney School of Public Health, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia; Centre for Kidney Research, Kids Research Institute, Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - Fani L Neto
- Institute for Research and Innovation in Health (i3S) of the University of Porto, Porto, Portugal; Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal; Department of Biomedicine - Unit of Experimental Biology, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Isabel Martins
- Institute for Research and Innovation in Health (i3S) of the University of Porto, Porto, Portugal; Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal; Department of Biomedicine - Unit of Experimental Biology, Faculty of Medicine, University of Porto, Porto, Portugal
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Hirsch SJ, Budig A, Husam S, Birklein F. Aged females unilaterally hypersensitize, lack descending inhibition, and overexpress alpha1D adrenergic receptors in a murine posttraumatic chronic pain model. Pain 2024:00006396-990000000-00533. [PMID: 38408277 DOI: 10.1097/j.pain.0000000000003197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 01/11/2024] [Indexed: 02/28/2024]
Abstract
ABSTRACT Vulnerability to chronic pain is found to depend on age and sex. Most patients with chronic pain are elderly women, especially with posttraumatic pain after bone fracture that prevails beyond the usual recovery period and develops into a complex regional pain syndrome (CRPS). There, a distal bone fracture seems to initiate a pathophysiological process with unknown mechanism. To investigate whether sex, age, and alpha adrenergic receptors also contribute to a CRPS-like phenotype in animals, we performed experiments on tibia-fractured mice. Those mice commonly are resilient to the development of a CRPS-like phenotype. However, we found them to be vulnerable to long-lasting pain after distal bone fracture when they were of old age. These mice expressed mechanical and thermal hypersensitivity, as well as weight-bearing and autonomic impairment following bone trauma, which persisted over 3 months. Site-specific and body side-specific glycinergic and α1D-noradrenergic receptor expression in the spinal cord and the contralateral locus coeruleus were misbalanced. Aged female tibia-fractured mice lost descending noradrenergic inhibition and displayed enhanced spinal activity on peripheral pressure stimuli. Together, changes in the noradrenergic, hence, glycinergic system towards excitation in the pain pathway-ascending and descending-might contribute to the development or maintenance of long-lasting pain. Conclusively, changes in the noradrenergic system particularly occur in aged female mice after trauma and might contribute to the development of long-lasting pain. Our data support the hypothesis that some patients with chronic pain would benefit from lowering the adrenergic/sympathetic tone or antagonizing α1(D).
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Affiliation(s)
- Silke J Hirsch
- Department of Neurology, Unimedizin Mainz, Mainz, Germany
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Cramer N, Ji Y, Kane MA, Pilli NR, Castro A, Posa L, Van Patten G, Masri R, Keller A. Elevated Serotonin in Mouse Spinal Dorsal Horn Is Pronociceptive. eNeuro 2023; 10:ENEURO.0293-23.2023. [PMID: 37945351 DOI: 10.1523/eneuro.0293-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 10/27/2023] [Accepted: 10/31/2023] [Indexed: 11/12/2023] Open
Abstract
Serotonergic neurons in the rostral ventral medulla (RVM) contribute to bidirectional control of pain through modulation of spinal and trigeminal nociceptive networks. Deficits in this pathway are believed to contribute to pathologic pain states, but whether changes in serotonergic mechanisms are pro- or antinociceptive is debated. We used a combination of optogenetics and fiber photometry to examine these mechanisms more closely. We find that optogenetic activation of RVM serotonergic afferents in the spinal cord of naive mice produces mechanical hypersensitivity and conditioned place aversion (CPA). Neuropathic pain, produced by chronic constriction injury of the infraorbital nerve (CCI-ION), evoked a tonic increase in serotonin (5HT) concentrations within the spinal trigeminal nucleus caudalis (SpVc), measured with liquid chromatography-tandem mass spectroscopy (LC-MS/MS). By contract, CCI-ION had no effect on the phasic serotonin transients in SpVc, evoked by noxious pinch, and measured with fiber photometry of a serotonin sensor. These findings suggest that serotonin release in the spinal cord is pronociceptive and that an increase in sustained serotonin signaling, rather than phasic or event driven increases, potentiate nociception in models of chronic pain.
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Affiliation(s)
- Nathan Cramer
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201
- University of Maryland - Medicine Institute for Neuroscience Discovery, University of Maryland School of Medicine, Baltimore, MD 21201
- Center to Advance Chronic Pain Research, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Yadong Ji
- Department of Advanced Oral Sciences and Therapeutics, University of Maryland School of Dentistry, Baltimore, MD 21201
| | - Maureen A Kane
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201
| | - Nageswara R Pilli
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201
| | - Alberto Castro
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Luca Posa
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Gabrielle Van Patten
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Radi Masri
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201
- Department of Advanced Oral Sciences and Therapeutics, University of Maryland School of Dentistry, Baltimore, MD 21201
- University of Maryland - Medicine Institute for Neuroscience Discovery, University of Maryland School of Medicine, Baltimore, MD 21201
- Center to Advance Chronic Pain Research, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Asaf Keller
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201
- University of Maryland - Medicine Institute for Neuroscience Discovery, University of Maryland School of Medicine, Baltimore, MD 21201
- Center to Advance Chronic Pain Research, University of Maryland School of Medicine, Baltimore, MD 21201
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Cramer N, Ji Y, Kane M, Pilli N, Posa L, Patten GV, Masri R, Keller A. Elevated serotonin in mouse spinal dorsal horn is pronociceptive. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.10.552838. [PMID: 37645759 PMCID: PMC10461991 DOI: 10.1101/2023.08.10.552838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Serotonergic neurons in the rostral ventral medulla (RVM) contribute to bidirectional control of pain through modulation of spinal and trigeminal nociceptive networks. Deficits in this pathway are believed to contribute to pathological pain states, but whether changes in serotonergic mechanisms are pro or anti-nociceptive are debated. We used a combination of optogenetics and fiber photometry to examine these mechanisms more closely. We find that optogenetic activation of RVM serotonergic afferents in the spinal cord of naïve mice produces mechanical hypersensitivity and conditioned place aversion. Neuropathic pain, produced by chronic constriction injury of the infraorbital nerve (CCI-ION), evoked a tonic increase in serotonin concentrations within the spinal trigeminal nucleus caudalis (SpVc), measured with liquid chromatography-tandem mass spectroscopy (LC-MS/MS). By contract, CCI-ION had no effect on the phasic serotonin transients in SpVc, evoked by noxious pinch, and measured with fiber photometry of a serotonin sensor. These findings suggest that serotonin release in the spinal cord is pronociceptive and that an increase is sustained serotonin signaling, rather than phasic or event driven increases, potentiate nociception in models of chronic pain.
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Affiliation(s)
- Nathan Cramer
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
- UM-MIND, University of Maryland School of Medicine, Baltimore, Maryland 21201
- Center to Advance Chronic Pain Research, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Yadong Ji
- Department of Advanced Oral Sciences and Therapeutics, University of Maryland School of Dentistry, Baltimore, Maryland 21201
| | - Maureen Kane
- Department of Pharmaceutical Sciences University of Maryland School of Pharmacy, Baltimore, Maryland 21201
| | - Nageswara Pilli
- Department of Pharmaceutical Sciences University of Maryland School of Pharmacy, Baltimore, Maryland 21201
| | - Luca Posa
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Gabrielle Van Patten
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Radi Masri
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
- Department of Advanced Oral Sciences and Therapeutics, University of Maryland School of Dentistry, Baltimore, Maryland 21201
- UM-MIND, University of Maryland School of Medicine, Baltimore, Maryland 21201
- Center to Advance Chronic Pain Research, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Asaf Keller
- Department of Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
- UM-MIND, University of Maryland School of Medicine, Baltimore, Maryland 21201
- Center to Advance Chronic Pain Research, University of Maryland School of Medicine, Baltimore, Maryland 21201
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Suto T, Kato D, Koibuchi I, Arai Y, Ohta J, Hiroki T, Obata H, Saito S. Rat model of attention-deficit hyperactivity disorder exhibits delayed recovery from acute incisional pain due to impaired descending noradrenergic inhibition. Sci Rep 2023; 13:5526. [PMID: 37016045 PMCID: PMC10073110 DOI: 10.1038/s41598-023-32512-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 03/28/2023] [Indexed: 04/06/2023] Open
Abstract
Chronic pain and attention-deficit hyperactivity disorder (ADHD) frequently coexist. However, the common pathology is still unclear. Attenuated noradrenergic endogenous analgesia can produce acute pain chronification, and dysfunction of noradrenergic systems in the nervous system is relevant to ADHD symptoms. Noxious stimuli-induced analgesia (NSIA) is measured to estimate noradrenergic endogenous analgesia in spontaneously hypertensive rats (SHR) as an ADHD model and control. Recovery of pain-related behaviors after paw incision was assessed. Contributions of noradrenergic systems were examined by in vivo microdialysis and immunohistochemistry. The SHR showed attenuated NSIA and needed a more extended period for recovery from acute pain. These results suggest ADHD patients exhibit acute pain chronification due to pre-existing attenuated noradrenergic endogenous analgesia. Immunohistochemistry suggests abnormal noradrenaline turnover and downregulation of the target receptor (alpha2a adrenoceptor). Standard ADHD treatment with atomoxetine restored NSIA and shortened the duration of hypersensitivity after the surgery in the SHR. NSIA protocol activated the locus coeruleus, the origin of spinal noradrenaline, of both strains, but only the control exhibited an increase in spinal noradrenaline. This result suggests dysfunction in the noradrenaline-releasing process and can be recognized as a novel mechanism of attenuation of noradrenergic endogenous analgesia.
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Affiliation(s)
- Takashi Suto
- Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan.
| | - Daiki Kato
- Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Ikuya Koibuchi
- Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Yuki Arai
- Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Jo Ohta
- Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Tadanao Hiroki
- Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
| | - Hideaki Obata
- Department of Anesthesiology, Saitama Medical Center, Saitama Medical University, 1981 Kamoda, Kawagoe, Saitama, 350-8550, Japan
| | - Shigeru Saito
- Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan
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