1
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Hebert SV, Green MA, Mashaw SA, Brouillette WD, Nguyen A, Dufrene K, Shelvan A, Patil S, Ahmadzadeh S, Shekoohi S, Kaye AD. Assessing Risk Factors and Comorbidities in the Treatment of Chronic Pain: A Narrative Review. Curr Pain Headache Rep 2024; 28:525-534. [PMID: 38558165 DOI: 10.1007/s11916-024-01249-z] [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] [Accepted: 03/19/2024] [Indexed: 04/04/2024]
Abstract
PURPOSE OF REVIEW Chronic pain affects a significant portion of the population globally, making it a leading cause of disability. Understanding the multifaceted nature of chronic pain, its various types, and the intricate relationship it shares with risk factors, comorbidities, and mental health issues like depression and anxiety is critical for comprehensive patient care. Factors such as socioeconomic status (SES), age, gender, and obesity collectively add layers of complexity to chronic pain experiences and pose management challenges. RECENT FINDINGS Low SES presents barriers to effective pain care, while gender differences and the prevalence of chronic pain in aging adults emphasize the need for tailored approaches. The association between chronic pain and physical comorbidities like cardiovascular disease, chronic obstructive pulmonary disease (COPD), and diabetes mellitus reveals shared risk factors and further highlights the importance of integrated treatment strategies. Chronic pain and mental health are intricately linked through biochemical mechanisms, profoundly affecting overall quality of life. This review explores pharmacologic treatment for chronic pain, particularly opioid analgesia, with attention to the risk of substance misuse and the ongoing opioid epidemic. We discuss the potential role of medical cannabis as an alternative treatment with a nuanced perspective on its impact on opioid use. Addressing the totality and complexity of pain states is crucial to individualizing chronic pain management. With different types of pain having different underlying mechanisms, considerations should be made when approaching their treatment. Moreover, the synergistic relationship that pain states can have with other comorbidities further complicates chronic pain conditions.
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Affiliation(s)
- Sage V Hebert
- School of Medicine, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, 71103, USA
| | - Melanie A Green
- School of Medicine, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, 71103, USA
| | - Sydney A Mashaw
- School of Medicine, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, 71103, USA
| | - William D Brouillette
- School of Medicine, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, 71103, USA
| | - Angela Nguyen
- School of Medicine, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, 71103, USA
| | - Kylie Dufrene
- School of Medicine, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, 71103, USA
| | - Anitha Shelvan
- Department of Anesthesiology, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, 71103, USA
| | - Shilpadevi Patil
- Department of Anesthesiology, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, 71103, USA
| | - Shahab Ahmadzadeh
- Department of Anesthesiology, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, 71103, USA
| | - Sahar Shekoohi
- Department of Anesthesiology, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, 71103, USA.
| | - Alan D Kaye
- Department of Anesthesiology, Louisiana State University Health Sciences Center Shreveport, Shreveport, LA, 71103, USA
- Department of Pharmacology, Louisiana State University Health Sciences Center at Shreveport, Toxicology, and Neurosciences, Shreveport, LA, 71103, USA
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2
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Garland EL, Froeliger B, Zeidan F, Partin K, Howard MO. The downward spiral of chronic pain, prescription opioid misuse, and addiction: cognitive, affective, and neuropsychopharmacologic pathways. Neurosci Biobehav Rev 2013; 37:2597-607. [PMID: 23988582 DOI: 10.1016/j.neubiorev.2013.08.006] [Citation(s) in RCA: 159] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 08/15/2013] [Indexed: 12/19/2022]
Abstract
Prescription opioid misuse and addiction among chronic pain patients are emerging public health concerns of considerable significance. Estimates suggest that more than 10% of chronic pain patients misuse opioid analgesics, and the number of fatalities related to nonmedical or inappropriate use of prescription opioids is climbing. Because the prevalence and adverse consequences of this threat are increasing, there is a pressing need for research that identifies the biobehavioral risk chain linking chronic pain, opioid analgesia, and addictive behaviors. To that end, the current manuscript draws upon current neuropsychopharmacologic research to provide a conceptual framework of the downward spiral leading to prescription opioid misuse and addiction among chronic pain patients receiving opioid analgesic pharmacotherapy. Addictive use of opioids is described as the outcome of a cycle initiated by chronic pain and negative affect and reinforced by opioidergic-dopamingeric interactions, leading to attentional hypervigilance for pain and drug cues, dysfunctional connectivity between self-referential and cognitive control networks in the brain, and allostatic dysregulation of stress and reward circuitry. Implications for clinical practice are discussed; multimodal, mindfulness-oriented treatment is introduced as a potentially effective approach to disrupting the downward spiral and facilitating recovery from chronic pain and opioid addiction.
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Affiliation(s)
- Eric L Garland
- Supportive Oncology & Survivorship Program, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, United States; College of Social Work, University of Utah, Salt Lake City, UT, United States.
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3
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Pappas SS, Kennedy T, Goudreau JL, Lookingland KJ. Opioid-mediated regulation of A11 diencephalospinal dopamine neurons: pharmacological evidence of activation by morphine. Neuropharmacology 2011; 61:614-21. [PMID: 21605572 DOI: 10.1016/j.neuropharm.2011.05.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 04/30/2011] [Accepted: 05/03/2011] [Indexed: 11/17/2022]
Abstract
Dopamine (DA) neurons of the A11 diencephalospinal system represent the sole source of DA innervation to the spinal cord in mice, serving neuromodulatory roles in the processing of nociceptive input and movement. These neurons originate in the dorso-caudal diencephalon and project axons unilaterally throughout the rostrocaudal extent of the spinal cord, terminating predominantly in the dorsal horn. The density of A11 DA axon terminals in the lumbar region is greater in males compared to females, while in both sexes the activity of neurons terminating in the thoracic spinal cord is greater than those terminating in the lumbar region. The present study was designed to test the hypothesis that A11 DA neurons are activated by opioids. To test this hypothesis, male and female mice were systemically treated with agonists or antagonists acting at the μ-opioid receptor, and spinal cord concentrations of DA and its metabolite DOPAC were determined in the thoracic and lumbar spinal cord using high performance liquid chromatography coupled with electrochemical detection. Systemic administration of the μ-opioid agonist morphine led to a dose- and time-dependent increase in spinal cord DOPAC/DA ratio (an estimate of DA neuronal activity) in both male and female mice, with greater changes occurring in the lumbar segment. Blockade of opioid receptors with the opioid antagonist naloxone reversed the stimulatory effects of morphine on A11 DA neurons in both male and female mice, but had little to no effect on the activity of these neurons when administered alone. Present findings are consistent with the conclusion that spinal cord-projecting axon terminals of A11 DA neurons are activated by opioids in both male and female mice, most likely through a dis-inhibitory mechanism.
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Affiliation(s)
- Samuel S Pappas
- Department of Physiology, Michigan State University, East Lansing, MI 48824, USA
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4
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Vogel Z, Nah SY, Saya D, Levy R, Attali B, Barg J. Signal Transduction of Opiate Receptors in Spinal Cord Cells. ACTA ACUST UNITED AC 2008. [DOI: 10.3109/15569549409006485] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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5
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Rahman W, Dashwood MR, Fitzgerald M, Aynsley-Green A, Dickenson AH. Postnatal development of multiple opioid receptors in the spinal cord and development of spinal morphine analgesia. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1998; 108:239-54. [PMID: 9693800 DOI: 10.1016/s0165-3806(98)00054-6] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The postnatal ontogeny of mu, delta and kappa opioid receptor binding sites in the spinal cord of rat pups at various postnatal days was determined using in vitro autoradiographical methods. The functional effect of spinal morphine was also assessed using in vivo electrophysiological methods in rats at P14, P21 and adults (P56). Both mu and kappa opioid receptor binding-sites are present from P0 and spread relatively diffusely throughout the spinal cord. Overall binding peaks at P7 and subsequently decreases to adult levels with the mu opioid receptor binding sites regressing to become denser in the superficial dorsal horn. delta Opioid receptor binding was first seen at P7, and no distinction between superficial and deeper laminae was seen. In the adult, the relative proportions of the opiate receptors in the superficial dorsal horn are 63%, 22% and 15%, for mu, delta and kappa receptor binding sites, respectively. C-fibre evoked dorsal horn neuronal responses recorded from anaesthetized rat pups were highly sensitive to spinal morphine at P21, (EC50 0.005 microgram), compared to the adult (EC50 0.9 microgram). However, the EC50 (0.2 microgram) at P14 was greater than at P21 despite the fact that mu receptor binding was greater at P14. Opioid receptor binding is developmentally regulated and undergoes substantial postnatal reorganization. However, the number of mu receptor binding sites appears not to be the only determinant of functional sensitivity to spinal morphine. Other factors, such as coupling of the receptors are likely to be important.
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MESH Headings
- Analgesics/pharmacology
- Analgesics, Opioid/pharmacology
- Animals
- Autoradiography
- Benzeneacetamides
- Dose-Response Relationship, Drug
- Electrophysiology
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
- Enkephalin, D-Penicillamine (2,5)-
- Enkephalins/pharmacology
- Male
- Morphine/pharmacology
- Nerve Fibers/chemistry
- Nerve Fibers/drug effects
- Nerve Fibers/physiology
- Pyrrolidines/pharmacology
- Radioligand Assay
- Rats
- Rats, Sprague-Dawley
- Receptors, Opioid/agonists
- Receptors, Opioid/analysis
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/analysis
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/analysis
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/analysis
- Spinal Cord/chemistry
- Spinal Cord/drug effects
- Spinal Cord/growth & development
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Affiliation(s)
- W Rahman
- Dept. of Pharmacology, University College London, UK
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6
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Thorn SA, Herrero JF, Headley PM. Stimulus intensity and the comparative efficacy of mu- and kappa-opioid agonists on nociceptive spinal reflexes in the rat. Brain Res 1994; 663:352-6. [PMID: 7874523 DOI: 10.1016/0006-8993(94)91286-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The influence of stimulus intensity was tested on the relative spinal efficacy of intravenously administered mu- (fentanyl) and kappa-opioid (U-50,488) agonists. Spinal reflexes were generated by different intensities of noxious electrical stimuli in alpha-chloralose anaesthetized, spinalized rats. Both drugs became less effective as the intensity of C-fibre generated responses was increased, but U-50,488 retained the ability to reduce responses to the same degree as fentanyl. The effects were naloxone reversible. The results indicate that kappa-opioid receptor activation has similar potential for spinal analgesia as does activation of mu-opioid receptors.
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Affiliation(s)
- S A Thorn
- Department of Physiology, University of Bristol, School of Medical Sciences, University Walk, UK
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7
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Collin E, Bourgoin S, Ferhat L, Hamon M, Cesselin F. Kappa-opioid receptor stimulation abolishes mu- but not delta-mediated inhibitory control of spinal Met-enkephalin release. Neurosci Lett 1992; 134:238-42. [PMID: 1317026 DOI: 10.1016/0304-3940(92)90525-c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The possible opioid control through delta, mu and kappa receptors of the spinal release of Met-enkephalin-like material (MELM) was investigated in halothane-anaesthetized rats. The intrathecal perfusion of the delta agonist DTLET (10 microM) or the mu agonist DAGO (10 microM) resulted in a marked inhibition of MELM release, which could be prevented by the selective antagonists naltrindole and naloxone, respectively. Although the kappa agonist U 50488 H (10 microM) was inactive per se, it completely suppressed the inhibitory effect of DAGO, without affecting that of DTLET. As the selective kappa antagonist norbinaltorphimine blocked the action of U 50488 H, it can be concluded that kappa receptors modulate the mu- (but not the delta-) mediated feed back control of spinal enkephalinergic neurones.
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MESH Headings
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer
- Analgesics/pharmacology
- Animals
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
- Enkephalin, Methionine/metabolism
- Enkephalins/administration & dosage
- Enkephalins/pharmacology
- Indoles/pharmacology
- Injections, Spinal
- Male
- Morphinans/pharmacology
- Naloxone/pharmacology
- Naltrexone/analogs & derivatives
- Neurons/drug effects
- Neurons/physiology
- Oligopeptides/administration & dosage
- Oligopeptides/pharmacology
- Pyrrolidines/administration & dosage
- Pyrrolidines/pharmacology
- Rats
- Rats, Inbred Strains
- Receptors, Opioid/drug effects
- Receptors, Opioid/physiology
- Receptors, Opioid, delta
- Receptors, Opioid, kappa
- Receptors, Opioid, mu
- Spinal Cord/drug effects
- Spinal Cord/physiology
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Affiliation(s)
- E Collin
- INSERM U 288, Faculté de Médecine Pitié-Salpêtrière, Paris, France
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8
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Besse D, Lombard MC, Besson JM. Autoradiographic distribution of mu, delta and kappa opioid binding sites in the superficial dorsal horn, over the rostrocaudal axis of the rat spinal cord. Brain Res 1991; 548:287-91. [PMID: 1651143 DOI: 10.1016/0006-8993(91)91134-m] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The purpose of this study was to use [3H]DAMGO, [3H]DTLET and [3H]EKC in the presence of 100 nM DAMGO and 100 nM DTLET, combined with a quantitative autoradiography to analyse the different proportions and the rostrocaudal distribution of mu, delta and kappa opioid binding sites in the superficial layers (laminae I and II) of the cervical (C6-C8), thoracic (T5-T7), lumbar (L3-L5) and sacral (S2-S3) dorsal horn of the rat. The proportions of the three main types of opioid binding sites, assessed by autoradiography in laminae I and II, were found homogeneous at each segmental level considered: 70.4-74.3%, 18.4-20.3% and 7.3-9.5% for mu, delta, kappa sites, respectively. The physiological relevance of these data is discussed.
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MESH Headings
- Animals
- Autoradiography
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
- Enkephalins/metabolism
- Ethylketocyclazocine/metabolism
- Kinetics
- Oligopeptides/metabolism
- Rats
- Rats, Inbred Strains
- Receptors, Opioid/analysis
- Receptors, Opioid/metabolism
- Receptors, Opioid, delta
- Receptors, Opioid, kappa
- Receptors, Opioid, mu
- Spinal Cord/anatomy & histology
- Spinal Cord/metabolism
- Tritium
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Affiliation(s)
- D Besse
- Unité de Recherche de Neurophysiologie Pharmacologique (INSERM, Unité 161) and Laboratoire de Physiopharmacologie de la Douleur (EPHE), Paris, France
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9
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Gouardères C, Beaudet A, Zajac JM, Cros J, Quirion R. High resolution radioautographic localization of [125I]FK-33-824-labelled mu opioid receptors in the spinal cord of normal and deafferented rats. Neuroscience 1991; 43:197-209. [PMID: 1717884 DOI: 10.1016/0306-4522(91)90427-p] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Recent data have shown that [125I]D-Ala2, MePhe4, Met(o)ol5-enkephalin (FK-33-824) is a highly selective and specific mu opioid receptor ligand [Moyse et al. (1986) Peptides 7, 351-355]. This probe was used here to investigate the detailed radioautographic distribution of mu sites at various levels of the spinal cord. [125I]FK-33-824 binding sites were localized by both tritium-sensitive film and liquid emulsion radioautography in the spinal cord of naive and deafferented rats. In naive animals, high densities of mu sites were apparent within laminae I-II at all levels of the dorsal horn, with higher levels of labelling seen in layer IIi as compared to IIo in the lumbar segment. Laminae III-IV contained about half the quantities of binding observed in superficial layers. Relatively high densities of sites were also seen over lamina VI in the upper cervical cord and throughout Clarke's column. Within the latter, [125I]FK-33-824 binding clearly spared the large perikarya of the spinocerebellar neurons. In the ventral horn, [125I]FK-33-824 binding was mainly concentrated in layer IX, at the level of cervical and lumbar enlargements. Labelled sites were confined to the neuropil, mostly sparing the soma of motoneurons. Significant decreases in [125I]FK-33-824 binding in laminae I-II (55%) and III-IV (28%) were detected four days following cervical (C3-C7) or lumbar (L1-L6) rhizotomies. These decrements were most evident at seven days post-lesion at C3-C7 levels (93 and 76% in laminae I-II and III-IV, respectively) and recovered slightly thereafter up to 28 days post-lesion. In contrast, dorsal rhizotomies did not influence mu labelling in either the ventral horn or Clarke's column. These results confirm the association of mu opioid binding sites with dorsal primary afferent fibres and demonstrate the presence of mu sites in Clarke's column and lamina IX of the ventral horn. These findings suggest that endogenous opioids in the spinal cord play a role in sensory motor integration as well as in the modulation of primary nociceptive inputs.
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Affiliation(s)
- C Gouardères
- Douglas Hospital Research Centre, McGill University, Verdun, Quebec, Canada
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10
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Wang XJ, Wang XH, Han JS. Cholecystokinin octapeptide antagonized opioid analgesia mediated by mu- and kappa- but not delta-receptors in the spinal cord of the rat. Brain Res 1990; 523:5-10. [PMID: 1976419 DOI: 10.1016/0006-8993(90)91629-u] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Intrathecal (ith) injection of cholecystokinin octapeptide (CCK-8) to the rat with single dose of 4 or 40 ng, or successive doses from 0.1 to 1 microgram at 10 min intervals produced neither analgesia nor hyperalgesia. However, the analgesia produced by ith injection of PL017, a specific mu-receptor agonist or 66A-078, a specific kappa-receptor agonist could be markedly antagonized by CCK-8 at a dose as small as 4 ng. In contrast, analgesia produced by ith injection of delta-agonist DPDPE could not be blocked by CCK-8 even at a dose as high as 40 ng. Since the effect of CCK-8 could be totally reversed by the CCK receptor antagonist proglumide, this effect is most probably mediated by CCK receptors.
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Affiliation(s)
- X J Wang
- Department of Physiology, Beijing Medical University, People's Republic of China
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11
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Besse D, Lombard MC, Zajac JM, Roques BP, Besson JM. Pre- and postsynaptic distribution of mu, delta and kappa opioid receptors in the superficial layers of the cervical dorsal horn of the rat spinal cord. Brain Res 1990; 521:15-22. [PMID: 2169958 DOI: 10.1016/0006-8993(90)91519-m] [Citation(s) in RCA: 255] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Highly selective tritiated ligands and quantitative autoradiography have been used to study mu, delta and kappa binding sites in the dorsal horn of the rat spinal cord. We have measured the proportions of the 3 main types of opioid binding sites in the superficial layers of the cervical dorsal horn (laminae I and II). The proportions of mu, delta and kappa sites were 70 +/- 4%, 23 +/- 2% and 7 +/- 1%, respectively, over the whole C4-T2 extent. Similar percentages were encountered at the level of each individual segment from C4 to T2. Eight days after a unilateral dorsal rhizotomy C4-T2, dramatic decreases were seen on the ipsilateral side to the lesion by comparison to the intact side. In the C7 segment, these decreases were 76 +/- 1%, 61 +/- 1% and 53 +/- 3% for mu, delta and kappa binding sites, respectively. The C7 segment can be considered as completely deafferented, so we attribute the residual values to postsynaptic binding whereas the decrease can be attributed to a loss of the presynaptic sites. These results are discussed with respect to the contribution of pre- and postsynaptic depressive effects of opiates on the transmission of noxious messages at the level of the dorsal horn.
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Affiliation(s)
- D Besse
- Unité de Recherche de Neurophysiologie Pharmacologique (I.N.S.E.R.M., Unité 161), Paris, France
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12
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Traynor JR, Hunter JC, Rodriguez RE, Hill RG, Hughes J. Delta-opioid receptor binding sites in rodent spinal cord. Br J Pharmacol 1990; 100:319-23. [PMID: 2165837 PMCID: PMC1917433 DOI: 10.1111/j.1476-5381.1990.tb15802.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
1. The delta-opioid receptor agonist [D-Pen2,D-Pen5]enkephalin showed an antinociceptive effect in the mouse tail-flick test, following intrathecal administration. This action was reversed by naloxone and by the selective delta-opioid receptor antagonist ICI 174864. 2. High affinity, saturable binding of [3H]-[D-Pen2,D-Pen5]enkephalin has been demonstrated in spinal cord homogenates from guinea-pig, hamster, rat and both adult and young (18-20 g) mice. The binding was shown by autoradiography to be concentrated in the superficial laminae of the dorsal horn. 3. Competition studies confirmed that the binding of [3H]-[D-Pen2,D-Pen5]enkephalin was to the delta-opioid site. However, anomalies were seen with displacement assays using mu-ligands, which may suggest some common high affinity site for delta- and mu-opioid receptor agonists in the spinal cord. 4. The results add further evidence for a role of the delta-opioid receptor in spinally-mediated antinociception.
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MESH Headings
- Analgesics
- Animals
- Autoradiography
- Binding, Competitive/drug effects
- Cricetinae
- Enkephalin, D-Penicillamine (2,5)-
- Enkephalins/pharmacology
- Guinea Pigs
- In Vitro Techniques
- Injections, Spinal
- Male
- Mesocricetus
- Mice
- Mice, Inbred Strains
- Naloxone/pharmacology
- Psychomotor Performance/drug effects
- Rats
- Rats, Inbred Strains
- Reaction Time/drug effects
- Receptors, Opioid/metabolism
- Receptors, Opioid, delta
- Receptors, Opioid, mu
- Spinal Cord/metabolism
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Affiliation(s)
- J R Traynor
- Department of Chemistry, Loughborough University, Leics
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13
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Dixon DM, Traynor JR. Formation of [Leu5]enkephalin from dynorphin A(1-8) by rat central nervous tissue in vitro. J Neurochem 1990; 54:1379-85. [PMID: 1968961 DOI: 10.1111/j.1471-4159.1990.tb01972.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
[3H]Dynorphin A(1-8) is readily metabolised by rat lumbosacral spinal cord tissue in vitro, affording a variety of products including a significant amount (20% recovered activity) of [3H][Leu5]enkephalin. In the presence of the peptidase inhibitors bestatin, captopril, thiorphan, and leucyl-leucine, [3H][Leu5]enkephalin was the major metabolic product, accounting for 60% of recovered activity. Production of [3H][Leu5]enkephalin was seen across all gross brain regions. The enzyme responsible for the cleavage has an optimal substrate length of 8-13 amino acids and is inhibited by N-[1-(RS)-carboxy-2-phenylethyl]-Ala-Ala-Phe-p-aminobenzoate, a site-directed inhibitor of the metalloendopeptidase EC 3.4.24.15. However the enzymic breakdown also has properties in common with involvement of endo-oligopeptidase A. Possible consequences of the formation of [Leu5]-enkephalin from the smaller dynorphins are discussed.
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Affiliation(s)
- D M Dixon
- Department of Chemistry, University of Technology, Loughborough, Leicester, England
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14
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James IF, Bettaney J, Perkins MN, Ketchum SB, Dray A. Opioid receptor ligands in the neonatal rat spinal cord: binding and in vitro depression of the nociceptive responses. Br J Pharmacol 1990; 99:503-8. [PMID: 2158845 PMCID: PMC1917323 DOI: 10.1111/j.1476-5381.1990.tb12958.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
1. Opioid receptors in the neonatal rat spinal cord have been characterized by measurements of ligand binding to crude membrane fractions and by functional tests on the nociceptive spinal response in a spinal cord-tail preparation in vitro. 2. There were high affinity binding sites for [3H]-[D-Ala2, MePhe4, Gly(ol)5]enkephalin (DAGOL), [3H]-U69593, and [3H]-ethylketocyclazocine (EKC) on spinal cord membranes from neonatal rats. Hill slopes for binding of [3H]-DAGOL and [3H]-U69593 were close to unity. The Hill slope for binding of [3H]-EKC was less than unity, even after its interactions at mu-receptors had been blocked with 100 nM unlabelled DAGOL. Binding sites for [3H]-[D-Pen2, D-Pen5]enkephalin (DPDPE) could not be detected. 3. In competition assays U50488 was as potent as PD117302 and U69593 in competition for either [3H]-U69593 or [3H]-EKC binding sites. Hill slopes for a range of competing ligands at [3H]-DAGOL or [3H]-U69593 sites were close to unity. Hill slopes for competition at [3H]-EKC sites were less than one. 4. In the spinal cord-tail preparation from neonatal rats, opioid receptor agonists depressed spinal nociceptive responses evoked by application of capsaicin or heat to the tail. The order of potency was DAGOL greater than U69593 = PD117302 greater than morphine greater than U50488 = [D-Pen2, L-Pen5]enkephalin (DPLPE). 5. The antagonist naloxone was about equally potent against DAGOL, morphine and DPLPE, and about ten times less potent against U69593 and PD117302. The effects of U50488 were much less sensitive to blockade by naloxone than the effects of PD11703 or U69593. The Kappa antagonist, nor-binaltorphimine was equipotent against all three Kappa agonists. 6. The absence of delta-binding sites, and the low potency and relatively high sensitivity to naloxone suggest that DPLPE could be working at mu-receptors in the neonatal rat spinal cord. 7. The binding assays show that U50488 has the same affinity as PD1 17302 and U69593 for Kappa-receptors, yet it was less effective in the depression of nociceptive responses. This may be because U50488 has a relatively low efficacy at Kappa-receptors. It is possible that at high concentrations U50488 activates receptors not affected by other Kappa-ligands. These additional receptors may be non-opioid receptors (hence the insensitivity to naloxone), or they could be a subtype of Kappa-opioid receptor.
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MESH Headings
- Animals
- Animals, Newborn
- Benzeneacetamides
- Cyclazocine/analogs & derivatives
- Cyclazocine/metabolism
- Cyclazocine/pharmacology
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
- Enkephalin, D-Penicillamine (2,5)-
- Enkephalins/metabolism
- Enkephalins/pharmacology
- Ethylketocyclazocine
- In Vitro Techniques
- Kinetics
- Ligands
- Morphine/pharmacology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Naloxone/pharmacology
- Narcotics/pharmacology
- Nociceptors/drug effects
- Pyrrolidines/pharmacology
- Rats
- Receptors, Opioid/drug effects
- Receptors, Opioid/metabolism
- Receptors, Opioid, delta
- Receptors, Opioid, kappa
- Spinal Cord/metabolism
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Affiliation(s)
- I F James
- Sandoz Institute for Medical Research, London
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15
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Allerton CA, Smith JA, Hunter JC, Hill RG, Hughes J. Correlation of ontogeny with function of [3H]U69593 labelled kappa opioid binding sites in the rat spinal cord. Brain Res 1989; 502:149-57. [PMID: 2555025 DOI: 10.1016/0006-8993(89)90470-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In this study, we have used a variety of in vitro and in vivo techniques to demonstrate the presence, and examine the function, of [3H]U69593 binding sites in the spinal cord of the 9-16-day-old rat in comparison to the adult. Equilibrium binding of [3H]U69593 to homogenates of adult rat spinal cord revealed a single population of non-interacting sites with a maximum binding capacity of 10.4 +/- 1.4 fmol/mg protein and an apparent equilibrium dissociation constant of 2.31 +/- 0.47 nM while in 9-16-day-old cord these parameters were 57.0 +/- 9.4 fmol/mg protein and 2.28 +/- 0.22 nM, respectively. The total binding capacity per cord was 95.8 +/- 8.3 and 121.8 +/- 7.7 fmol/cord for adult and immature rat, respectively. Competition studies using receptor-selective opioid ligands showed that these sites were kappa opioid in nature. Autoradiographical techniques demonstrated a uniform distribution of these sites over transverse sections of 9-16-day-old rat cord. In vitro electrophysiology was performed on spinal cord slice preparations from the 9-16-day-old rat. U69593 (100 nM-1 microM) had no effect on passive membrane properties but produced a naloxone-reversible depression of both spontaneous and electrically evoked activity in dorsal horn neurones. Direct intrathecal injection of U69593 (0.3-10.0 micrograms/animal) into 9-16-day-old rats produced a dose-dependent, naloxone-reversible, antinociception when measured using the paw-pressure test. In conclusion, we have shown that, in contrast to the adult, the spinal cord of the 9-16-day-old rat has a significantly higher concentration of [3H]U69593 binding sites which have functional in vitro and in vivo correlates.
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Affiliation(s)
- C A Allerton
- Parke-Davis Research Unit, Addenbrookes Hospital Site, Cambridge, U.K
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16
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Attali B, Saya D, Vogel Z. Kappa-opiate agonists inhibit adenylate cyclase and produce heterologous desensitization in rat spinal cord. J Neurochem 1989; 52:360-9. [PMID: 2536070 DOI: 10.1111/j.1471-4159.1989.tb09130.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The nature of the opiate modulation of adenylate cyclase following acute and chronic agonist exposure has been investigated in rat spinal cord. Using membranes of both adult rat spinal cord and spinal cord-dorsal root ganglion cocultures, we found that kappa-opiate receptors are negatively coupled to adenylate cyclase. The kappa-opiate agonists (e.g., U50488) inhibit significantly and dose-dependently the basal and the forskolin-stimulated cyclase activities, whereas mu and delta agonists are ineffective. The regulatory action is stereospecific and requires the presence of GTP. EGTA treatment of the plasma membranes abolished the effect of kappa-opiate agonists on the basal cyclase activity, and this inhibitory effect could not be restored by subsequent addition of Ca2+. The EGTA treatment did not affect the kappa agonist inhibition of the forskolin-stimulated cyclase. The results also show that following chronic exposure of cultured cells to etorphine or U50488, there is a loss of kappa agonist inhibition of the cyclase. Moreover, this desensitization process appears to be heterologous, because alpha 2-adrenergic agonists (e.g., clonidine or norepinephrine) and the muscarinic agonist (carbachol) exhibited significantly lower potency for inhibiting cyclase activity when compared to untreated cultures. This pattern of heterologous desensitization suggests that chronic exposure to kappa opiates leads to alterations in postreceptor regulatory components, possibly GTP-binding proteins.
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MESH Headings
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer
- Adenylyl Cyclase Inhibitors
- Adenylyl Cyclases/metabolism
- Animals
- Benzomorphans/pharmacology
- Cell Membrane/physiology
- Cells, Cultured
- Colforsin/pharmacology
- Egtazic Acid/pharmacology
- Etorphine/pharmacology
- Ganglia, Spinal/drug effects
- Ganglia, Spinal/physiology
- Guanosine Triphosphate/pharmacology
- Guanylyl Imidodiphosphate/pharmacology
- Male
- Pyrrolidines/pharmacology
- Rats
- Rats, Inbred Strains
- Receptors, Opioid/drug effects
- Receptors, Opioid/physiology
- Receptors, Opioid, kappa
- Sodium/pharmacology
- Sodium Fluoride/pharmacology
- Spinal Cord/drug effects
- Spinal Cord/physiology
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Affiliation(s)
- B Attali
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
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