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McPherson KB, Ingram SL. Cellular and circuit diversity determines the impact of endogenous opioids in the descending pain modulatory pathway. Front Syst Neurosci 2022; 16:963812. [PMID: 36045708 PMCID: PMC9421147 DOI: 10.3389/fnsys.2022.963812] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 07/15/2022] [Indexed: 01/31/2023] Open
Abstract
The descending pain modulatory pathway exerts important bidirectional control of nociceptive inputs to dampen and/or facilitate the perception of pain. The ventrolateral periaqueductal gray (vlPAG) integrates inputs from many regions associated with the processing of nociceptive, cognitive, and affective components of pain perception, and is a key brain area for opioid action. Opioid receptors are expressed on a subset of vlPAG neurons, as well as on both GABAergic and glutamatergic presynaptic terminals that impinge on vlPAG neurons. Microinjection of opioids into the vlPAG produces analgesia and microinjection of the opioid receptor antagonist naloxone blocks stimulation-mediated analgesia, highlighting the role of endogenous opioid release within this region in the modulation of nociception. Endogenous opioid effects within the vlPAG are complex and likely dependent on specific neuronal circuits activated by acute and chronic pain stimuli. This review is focused on the cellular heterogeneity within vlPAG circuits and highlights gaps in our understanding of endogenous opioid regulation of the descending pain modulatory circuits.
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Affiliation(s)
- Kylie B. McPherson
- Division of Neuroscience and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari, Monserrato, Italy,Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, United States
| | - Susan L. Ingram
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, United States,*Correspondence: Susan L. Ingram
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Bagley EE, Ingram SL. Endogenous opioid peptides in the descending pain modulatory circuit. Neuropharmacology 2020; 173:108131. [PMID: 32422213 DOI: 10.1016/j.neuropharm.2020.108131] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 05/01/2020] [Accepted: 05/04/2020] [Indexed: 02/07/2023]
Abstract
The opioid epidemic has led to a serious examination of the use of opioids for the treatment of pain. Opioid drugs are effective due to the expression of opioid receptors throughout the body. These receptors respond to endogenous opioid peptides that are expressed as polypeptide hormones that are processed by proteolytic cleavage. Endogenous opioids are expressed throughout the peripheral and central nervous system and regulate many different neuronal circuits and functions. One of the key functions of endogenous opioid peptides is to modulate our responses to pain. This review will focus on the descending pain modulatory circuit which consists of the ventrolateral periaqueductal gray (PAG) projections to the rostral ventromedial medulla (RVM). RVM projections modulate incoming nociceptive afferents at the level of the spinal cord. Stimulation within either the PAG or RVM results in analgesia and this circuit has been studied in detail in terms of the actions of exogenous opioids, such as morphine and fentanyl. Further emphasis on understanding the complex regulation of endogenous opioids will help to make rational decisions with regard to the use of opioids for pain. We also include a discussion of the actions of endogenous opioids in the amygdala, an upstream brain structure that has reciprocal connections to the PAG that contribute to the brain's response to pain.
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Affiliation(s)
- Elena E Bagley
- Discipline of Pharmacology and Charles Perkins Centre, University of Sydney, NSW, 2006, Australia
| | - Susan L Ingram
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, 97239, USA.
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Poznański P, Lesniak A, Bujalska-Zadrozny M, Strzemecka J, Sacharczuk M. Bidirectional selection for high and low stress-induced analgesia affects G-protein activity. Neuropharmacology 2018; 144:37-42. [PMID: 30326238 DOI: 10.1016/j.neuropharm.2018.10.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 09/03/2018] [Accepted: 10/12/2018] [Indexed: 11/19/2022]
Abstract
Mice selected for high (HA) and low (LA) swim stress-induced analgesia (SSIA) are a unique model for studying the genetic background of this phenomenon. HA and LA miceshow substantial differences in the magnitude of the antinociceptive response to stress and when treated with exogenous opioids. However, the direct cause underplaying this distinctive feature has not yet been identified. The current study was designed to investigate the possibility that disturbances in G-protein signaling could explain the divergent response to opioid agonists. Supraspinal and spinal opioid sensitivity was assessed in vivo with intraperitoneal morphine and subsequent thermal stimulus exposure. The level of opioid receptor-mediated G-protein activation was investigated by means of DAMGO and morphine-stimulated [35S]GTPγS assay in the brain and spinal cord homogenates from HA and LA mice. Morphine (3-249 μmol/kg, i.p) was over 6 - and 3 - times more potent in HA than LA mice in the hot plate and tail-flick assays, respectively. Additionally, HA mice showed elevated β - endorphin levels in the brain. Enhanced efficacy of agonist-stimulated [35S]GTPγS binding was detected in opioid receptor-rich limbic regions of HA mice like the hypothalamus and hippocampus. Increased G-protein activity also emerged in the thalamus, periaqueductal gray matter and prefrontal cortex. In conclusion, the magnitude of the antinociceptive response to opioids in HA and LA mice is correlated with alterations in G-protein activation in brain regions responsible for integration and descending modulation of nociceptive information as well as at sites governing the emotional response to stressful stimuli.
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Affiliation(s)
- Piotr Poznański
- Department of Genomics, Institute of Genetics and Animal Breeding, Polish Academy of Sciences, Jastrzebiec, Poland
| | - Anna Lesniak
- Faculty of Pharmacy with the Laboratory Medicine Division, Department of Pharmacodynamics, Medical University of Warsaw, Centre for Preclinical Research and Technology, Warsaw, Poland
| | - Magdalena Bujalska-Zadrozny
- Faculty of Pharmacy with the Laboratory Medicine Division, Department of Pharmacodynamics, Medical University of Warsaw, Centre for Preclinical Research and Technology, Warsaw, Poland
| | - Joanna Strzemecka
- Institute of Health Sciences, Pope John Paul II State School of Higher Education, Biala Podlaska, Poland
| | - Mariusz Sacharczuk
- Faculty of Pharmacy with the Laboratory Medicine Division, Department of Pharmacodynamics, Medical University of Warsaw, Centre for Preclinical Research and Technology, Warsaw, Poland; Department of Genomics, Institute of Genetics and Animal Breeding, Polish Academy of Sciences, Jastrzebiec, Poland; Department of Internal Medicine, Hypertension and Vascular Diseases, Medical University of Warsaw, Warsaw, Poland.
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Wu B, Ni J, Zhang C, Fu P, Yue J, Yang L. Changes in spinal cord met-enkephalin levels and mechanical threshold values of pain after pulsed radio frequency in a spared nerve injury rat model. Neurol Res 2013; 34:408-14. [PMID: 22643086 DOI: 10.1179/1743132812y.0000000026] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Affiliation(s)
- Baishan Wu
- Department of Pain Management Beijing Xuanwu Hospital Capital Medical UniversityBeijing, China
| | - Jiaxiang Ni
- Department of Pain Management Beijing Xuanwu Hospital Capital Medical UniversityBeijing, China
| | - Chunlei Zhang
- Department of Pain Management Beijing Xuanwu Hospital Capital Medical UniversityBeijing, China
| | - Paul Fu
- Wayne State University School of MedicineDetroit, MI, USA
| | - Jianning Yue
- Department of Pain Management Beijing Xuanwu Hospital Capital Medical UniversityBeijing, China
| | - Liqiang Yang
- Department of Pain Management Beijing Xuanwu Hospital Capital Medical UniversityBeijing, China
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Butler RK, Finn DP. Stress-induced analgesia. Prog Neurobiol 2009; 88:184-202. [PMID: 19393288 DOI: 10.1016/j.pneurobio.2009.04.003] [Citation(s) in RCA: 435] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Revised: 03/15/2009] [Accepted: 04/15/2009] [Indexed: 12/21/2022]
Abstract
For over 30 years, scientists have been investigating the phenomenon of pain suppression upon exposure to unconditioned or conditioned stressful stimuli, commonly known as stress-induced analgesia. These studies have revealed that individual sensitivity to stress-induced analgesia can vary greatly and that this sensitivity is coupled to many different phenotypes including the degree of opioid sensitivity and startle response. Furthermore, stress-induced analgesia is influenced by age, gender, and prior experience to stressful, painful, or other environmental stimuli. Stress-induced analgesia is mediated by activation of the descending inhibitory pain pathway. Pharmacological and neurochemical studies have demonstrated involvement of a large number of neurotransmitters and neuropeptides. In particular, there are key roles for the endogenous opioid, monoamine, cannabinoid, gamma-aminobutyric acid and glutamate systems. The study of stress-induced analgesia has enhanced our understanding of the fundamental physiology of pain and stress and can be a useful approach for uncovering new therapeutic targets for the treatment of pain and stress-related disorders.
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Affiliation(s)
- Ryan K Butler
- Department of Pharmacology and Therapeutics, NCBES Neuroscience Cluster and Centre for Pain Research, National University of Ireland, Galway, University Road, Galway, Ireland
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Hsu CT, Liu IM, Cheng JT. Increase of beta-endorphin biosynthesis in the adrenal gland of streptozotocin-induced diabetic rats. Neurosci Lett 2002; 318:57-60. [PMID: 11796185 DOI: 10.1016/s0304-3940(01)02473-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Opioid plays an important role in the regulation of glucose homeostasis in diabetic rats lacking insulin. The present study investigated the changes of beta-endorphin biosynthesis in the adrenal medulla of streptozotocin-induced diabetic rats (STZ-diabetic rats) by determination of the gene expression of pro-opiomelanocortin (POMC) and the amount of beta-endorphin. Expression of the distinct mRNA that encodes proteins of POMC was studied using reverse transcription combined with polymerase chain reaction (RT-PCR). Results of RT-PCR demonstrated that the mRNA level of POMC in the adrenal gland markedly increased in STZ-diabetic rats as compared with that in normal rats. The content of beta-endorphin-like immunoreactivity (BER) in the adrenal medulla, determined by enzyme-linked immunosorbent assay, was actually higher in diabetic rats with insulin deficiency. Normalization of the plasma glucose concentration in STZ-diabetic rats with exogenous insulin or phlorizin, an inhibitor of the renal tubular glucose transport, reversed the mRNA level of POMC in the adrenal gland after 4 days of treatment. A similar decrease of BER amount also observed in the adrenal medulla of STZ-diabetic rats received the same treatment with exogenous insulin or phlorizin. Therefore, correction of hyperglycemia in STZ-diabetic rats could reverse the higher gene expression of POMC in the adrenal gland. These results suggest that hyperglycemia is responsible for the increase of POMC gene expression to enhance beta-endorphin biosynthesis in the adrenal gland of STZ-diabetic rats.
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Affiliation(s)
- Chao-Tien Hsu
- Division of Neuroscience and Neuropathology, Graduate School of Medicine, China Medical College, Taichung City, 40401 Taiwan
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Wiedenmayer CP, Barr GA. Mu opioid receptors in the ventrolateral periaqueductal gray mediate stress-induced analgesia but not immobility in rat pups. Behav Neurosci 2000; 114:125-36. [PMID: 10718268 DOI: 10.1037/0735-7044.114.1.125] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Rat pups become immobile and analgesic when exposed to an adult male rat. The aim of this study was to determine whether these reactions are under the control of endogenous opioids and to determine the role of the midbrain periaqueductal gray (PAG), which mediates stress-induced immobility and analgesia in adult animals. In Experiment 1, 14-day-old rats were injected systemically with the general opioid receptor antagonist naltrexone (1 mg/kg), which blocked male-induced analgesia to thermal stimulation but did not affect immobility. In Experiment 2, the selective mu opioid receptor antagonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP; 50 or 100 ng/200 nl) was microinjected into the ventrolateral and lateral PAG. CTOP suppressed male-induced analgesia when injected into the ventrolateral PAG. Male-induced immobility was not affected by CTOP. Male proximity therefore seems to induce analgesia in rat pups by releasing endogenous opioids that bind to mu opioid receptors in the ventrolateral PAG.
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Affiliation(s)
- C P Wiedenmayer
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute, New York 10032, USA.
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Metaksa EE, Zakharova LA, Koptelov OV, Koroleva NA, Yankovskii OG. Influence of bone marrow hexapeptides (myelopeptides) on antibody production and algesthesia in mice and the dependence of these effects on naloxone. Bull Exp Biol Med 1995. [DOI: 10.1007/bf02445904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Vasilenko AM, Yanovskii OG, Koptelov OV, Metaksa EE, Zakharova LA. Correlation of pain sensitivity and the humoral immune response in mice during thermal stimulation. Bull Exp Biol Med 1995. [DOI: 10.1007/bf02445902] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Siegfried B, Frischknecht HR, Nunes de Souza RL. An ethological model for the study of activation and interaction of pain, memory and defensive systems in the attacked mouse. Role of endogenous opioids. Neurosci Biobehav Rev 1990; 14:481-90. [PMID: 2287485 DOI: 10.1016/s0149-7634(05)80071-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The present work reviews neurochemical, physiological and behavioral data recorded from the attacked mouse and integrates them into a model of coping mechanisms during social conflict. More specifically, the possible relationships between systems of pain, memory and defense are presented, with special emphasis on the role of endogenous opioid peptides (EOPs). In recipients of attack, decreased beta-endorphin-like immunoreactivity and changes in opiate and benzodiazepine binding characteristics are found in structures of the brain defensive system. EOPs mediate the social conflict-induced increase of dopamine synthesis in the periaqueductal grey and frontal cortex. Social conflict analgesia in attacked mice is under the control of central opioid and nonopioid (e.g., benzodiazepine, glutamate) mechanisms, and is modified by experience (e.g., long-term analgesic reaction; tolerance). EOPs and pain-inhibitory mechanisms participate in the organization of behavioral defense, recuperative behavior and the memory of attack experience. The data are considered in relation to the perceptual-defensive-recuperative model of fear and pain, forwarded by Bolles and Fanselow.
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Affiliation(s)
- B Siegfried
- Institute of Pharmacology, University of Zurich, Switzerland
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Abstract
This paper is the twelfth installment of our annual review of the research published during 1989 involving the behavioral, nonanalgesic, effects of the endogenous opiate peptides. The specific topics this year include stress; tolerance and dependence; eating; drinking; gastrointestinal and renal functions; mental illness; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical-related activity; locomotor activity; sex, development, pregnancy, and aging; immunological responses; and other behavior.
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Affiliation(s)
- G A Olson
- Department of Psychology, University of New Orleans, LA 70148
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