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Karimi SA, Zahra FT, Martin LJ. IUPHAR review: Navigating the role of preclinical models in pain research. Pharmacol Res 2024; 200:107073. [PMID: 38232910 DOI: 10.1016/j.phrs.2024.107073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 01/09/2024] [Accepted: 01/11/2024] [Indexed: 01/19/2024]
Abstract
Chronic pain is a complex and challenging medical condition that affects millions of people worldwide. Understanding the underlying mechanisms of chronic pain is a key goal of preclinical pain research so that more effective treatment strategies can be developed. In this review, we explore nociception, pain, and the multifaceted factors that lead to chronic pain by focusing on preclinical models. We provide a detailed look into inflammatory and neuropathic pain models and discuss the most used animal models for studying the mechanisms behind these conditions. Additionally, we emphasize the vital role of these preclinical models in developing new pain-relief drugs, focusing on biologics and the therapeutic potential of NMDA and cannabinoid receptor antagonists. We also discuss the challenges of TRPV1 modulation for pain treatment, the clinical failures of neurokinin (NK)- 1 receptor antagonists, and the partial success story of Ziconotide to provide valuable lessons for preclinical pain models. Finally, we highlight the overall success and limitations of current treatments for chronic pain while providing critical insights into the development of more effective therapies to alleviate the burden of chronic pain.
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Affiliation(s)
- Seyed Asaad Karimi
- Department of Psychology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada
| | - Fatama Tuz Zahra
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Loren J Martin
- Department of Psychology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada; Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.
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Yoon YS, Hwang HJ, Kim JM, Chung KS, Jang SY, Heo SW, Lee SY, Kim SY, Song HA, Hong SJ, An HJ, Park SW, Im JJ, Oh DH, Lee AR, Lee KT. Antinociceptive and anti-inflammatory activity of DW-1021, the ionic complex of pelubiprofen and tramadol, in rodents. Biomed Pharmacother 2023; 163:114708. [PMID: 37121153 DOI: 10.1016/j.biopha.2023.114708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 04/04/2023] [Accepted: 04/12/2023] [Indexed: 05/02/2023] Open
Abstract
Although drugs such as acetaminophen, opioids, and nonsteroidal anti-inflammatory drugs (NSAIDs), are commonly used for pain management, the side effects of these drugs such as hepatotoxicity, nephrotoxicity, nausea, and vomiting, can not be neglected. Therefore, combinations of analgesics with different mechanisms raise the possibility of developing novel analgesics. Therefore, the aim of the present study was to evaluate whether DW-1021, the ionic complex of pelubiprofen (NSAID) and tramadol (opioid), has synergic antinociceptive and anti-inflammatory effects in nociceptive as well as inflammation-induced nociceptive models compared to pelubiprofen- or tramadol-only administration. Strong synergistic antinociceptive efficacy of DW-1021 was observed in the mouse writhing test and von Frey paw withdrawal threshold test in the carrageenan-induced rats. The hot plate test in mice and the Randall-Selitto mechanical paw pressure test in carrageenan-induced rats revealed that DW-1021 had a preferable effect on relieving pain to pelubiprofen, but not as much as tramadol. In the carrageenan-induced rats, DW-1021 had a more potent effect on reducing paw inflammation (paw volume, width, and thickness) via the suppression of PGE2 production than tramadol, but less than that of pelubiprofen. Taken together, our results suggest that the administration of DW-1021, a combination of pelubiprofen and tramadol, exerted a potent effect and can be used as a potential therapeutic agent for relieving pain and inflammation.
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Affiliation(s)
- Young-Seo Yoon
- Department of Pharmaceutical Biochemistry, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea; Department of Biomedical and Pharmaceutical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Han-Jun Hwang
- Department of Fundamental Pharmaceutical Science, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea; Department of Oriental Pharmaceutical Science, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Jae-Min Kim
- Department of Pharmaceutical Biochemistry, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea; Department of Biomedical and Pharmaceutical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Kyung-Sook Chung
- Department of Pharmaceutical Biochemistry, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Seo-Yun Jang
- Department of Pharmaceutical Biochemistry, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea; Department of Fundamental Pharmaceutical Science, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea
| | - So-Won Heo
- Department of Pharmaceutical Biochemistry, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea; Department of Biomedical and Pharmaceutical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Su-Yeon Lee
- Department of Pharmaceutical Biochemistry, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea; Department of Biomedical and Pharmaceutical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Soo-Yeon Kim
- Department of Pharmaceutical Biochemistry, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea; Department of Fundamental Pharmaceutical Science, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Hyeon-A Song
- Department of Pharmaceutical Biochemistry, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea; Department of Fundamental Pharmaceutical Science, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Seung-Jae Hong
- Department of Rheumatology, Kyung Hee University College of Medicine, Kyung Hee University Hospital, Seoul, Republic of Korea
| | - Hyo-Jin An
- Department of Oriental Pharmaceutical Science, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Sang-Wook Park
- Daewon Pharm. Co., Ltd., 520 Cheonhodae-ro, Gwangjin-gu, Seoul 04994, Republic of Korea
| | - Jhong-Jae Im
- Daewon Pharm. Co., Ltd., 520 Cheonhodae-ro, Gwangjin-gu, Seoul 04994, Republic of Korea
| | - Dong-Ho Oh
- Daewon Pharm. Co., Ltd., 520 Cheonhodae-ro, Gwangjin-gu, Seoul 04994, Republic of Korea
| | - Ah-Ram Lee
- Daewon Pharm. Co., Ltd., 520 Cheonhodae-ro, Gwangjin-gu, Seoul 04994, Republic of Korea
| | - Kyung-Tae Lee
- Department of Pharmaceutical Biochemistry, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea.
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Li M, Zhang K, Li T, Chen Y, Zang H, Hu Y, Yao W. Sciatic Nerve Block Combined with Flurbiprofen Inhibits Spinal Cord Inflammation and Improves Postoperative Pain in Rats with Plantar Incision. J Pain Res 2023; 16:1533-1546. [PMID: 37193359 PMCID: PMC10182802 DOI: 10.2147/jpr.s404226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 04/28/2023] [Indexed: 05/18/2023] Open
Abstract
Background and Purpose Peripheral nerve block is often used to relieve postoperative pain. But the effect of nerve block on inflammatory response is not fully understood. Spinal cord is the primary center of pain processing. This study is to investigate the effect of single sciatic nerve block on the inflammatory response of the spinal cord in rats with plantar incision and the combined effect with flurbiprofen. Methods The plantar incision was used to establish a postoperative pain model. Single sciatic nerve block, intravenous flurbiprofen or the combination of both were used for intervention. The sensory and motor functions after nerve block and incision were evaluated. The changes of IL-1β, IL-6, TNF-α, microglia and astrocytes in the spinal cord were examined by qPCR and immunofluorescence respectively. Results Sciatic nerve block with 0.5% ropivacaine in rats induced sensory block for 2h and motor block for 1.5h. In the rats with plantar incision, the single sciatic nerve block did not alleviate postoperative pain or inhibit the activation of spinal microglia and astrocytes, but the levels of IL-1β and IL-6 in spinal cord were decreased when the nerve block wore off. The combined effect of a single sciatic nerve block and intravenous flurbiprofen not only decreased the levels of IL-1β, IL-6, and TNF-α, but also relieved the pain and alleviated the activation of microglia and astrocytes. Conclusion The single sciatic nerve block cannot improve postoperative pain or inhibit the activation of spinal cord glial cells, but can reduce the expression of spinal inflammatory factors. Nerve block combined with flurbiprofen can inhibit spinal cord inflammation and improve postoperative pain. This study provides a reference for rational clinical application of nerve block.
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Affiliation(s)
- Meihong Li
- Hubei Key Laboratory of Geriatric Anesthesia and Perioperative Brain Health, and Wuhan Clinical Research Center for Geriatric Anesthesia, Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People’s Republic of China
| | - Kaiwen Zhang
- Hubei Key Laboratory of Geriatric Anesthesia and Perioperative Brain Health, and Wuhan Clinical Research Center for Geriatric Anesthesia, Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People’s Republic of China
| | - Ting Li
- Department of Anesthesiology, Zhongshan Hospital, Fudan University, Shanghai, 200032, People’s Republic of China
| | - Yuye Chen
- Hubei Key Laboratory of Geriatric Anesthesia and Perioperative Brain Health, and Wuhan Clinical Research Center for Geriatric Anesthesia, Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People’s Republic of China
| | - Hu Zang
- Hubei Key Laboratory of Geriatric Anesthesia and Perioperative Brain Health, and Wuhan Clinical Research Center for Geriatric Anesthesia, Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People’s Republic of China
| | - Yingjie Hu
- Hubei Key Laboratory of Geriatric Anesthesia and Perioperative Brain Health, and Wuhan Clinical Research Center for Geriatric Anesthesia, Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People’s Republic of China
| | - Wenlong Yao
- Hubei Key Laboratory of Geriatric Anesthesia and Perioperative Brain Health, and Wuhan Clinical Research Center for Geriatric Anesthesia, Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People’s Republic of China
- Correspondence: Wenlong Yao, Hubei Key Laboratory of Geriatric Anesthesia and Perioperative Brain Health, and Wuhan Clinical Research Center for Geriatric Anesthesia, Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People’s Republic of China, Tel +86 13720271159, Email
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Abboud C, Duveau A, Bouali-Benazzouz R, Massé K, Mattar J, Brochoire L, Fossat P, Boué-Grabot E, Hleihel W, Landry M. Animal models of pain: Diversity and benefits. J Neurosci Methods 2020; 348:108997. [PMID: 33188801 DOI: 10.1016/j.jneumeth.2020.108997] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 11/03/2020] [Accepted: 11/08/2020] [Indexed: 12/15/2022]
Abstract
Chronic pain is a maladaptive neurological disease that remains a major health problem. A deepening of our knowledge on mechanisms that cause pain is a prerequisite to developing novel treatments. A large variety of animal models of pain has been developed that recapitulate the diverse symptoms of different pain pathologies. These models reproduce different pain phenotypes and remain necessary to examine the multidimensional aspects of pain and understand the cellular and molecular basis underlying pain conditions. In this review, we propose an overview of animal models, from simple organisms to rodents and non-human primates and the specific traits of pain pathologies they model. We present the main behavioral tests for assessing pain and investing the underpinning mechanisms of chronic pathological pain. The validity of animal models is analysed based on their ability to mimic human clinical diseases and to predict treatment outcomes. Refine characterization of pathological phenotypes also requires to consider pain globally using specific procedures dedicated to study emotional comorbidities of pain. We discuss the limitations of pain models when research findings fail to be translated from animal models to human clinics. But we also point to some recent successes in analgesic drug development that highlight strategies for improving the predictive validity of animal models of pain. Finally, we emphasize the importance of using assortments of preclinical pain models to identify pain subtype mechanisms, and to foster the development of better analgesics.
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Affiliation(s)
- Cynthia Abboud
- Univ. Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, F-33000 Bordeaux, France; Univ. Bordeaux, CNRS, Institute for Neurodegenerative Diseases, IMN, UMR 5293, F-33000 Bordeaux, France; Faculty of Arts and Sciences, Holy Spirit University of Kaslik (USEK), Lebanon
| | - Alexia Duveau
- Univ. Bordeaux, CNRS, Institute for Neurodegenerative Diseases, IMN, UMR 5293, F-33000 Bordeaux, France
| | - Rabia Bouali-Benazzouz
- Univ. Bordeaux, CNRS, Institute for Neurodegenerative Diseases, IMN, UMR 5293, F-33000 Bordeaux, France
| | - Karine Massé
- Univ. Bordeaux, CNRS, Institute for Neurodegenerative Diseases, IMN, UMR 5293, F-33000 Bordeaux, France
| | - Joseph Mattar
- School of Medicine and Medical Sciences, Holy Spirit University of Kaslik (USEK), Lebanon
| | - Louison Brochoire
- Univ. Bordeaux, CNRS, Institute for Neurodegenerative Diseases, IMN, UMR 5293, F-33000 Bordeaux, France
| | - Pascal Fossat
- Univ. Bordeaux, CNRS, Institute for Neurodegenerative Diseases, IMN, UMR 5293, F-33000 Bordeaux, France
| | - Eric Boué-Grabot
- Univ. Bordeaux, CNRS, Institute for Neurodegenerative Diseases, IMN, UMR 5293, F-33000 Bordeaux, France
| | - Walid Hleihel
- School of Medicine and Medical Sciences, Holy Spirit University of Kaslik (USEK), Lebanon; Faculty of Arts and Sciences, Holy Spirit University of Kaslik (USEK), Lebanon
| | - Marc Landry
- Univ. Bordeaux, CNRS, Institute for Neurodegenerative Diseases, IMN, UMR 5293, F-33000 Bordeaux, France.
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Ilari S, Giancotti LA, Lauro F, Dagostino C, Gliozzi M, Malafoglia V, Sansone L, Palma E, Tafani M, Russo MA, Tomino C, Fini M, Salvemini D, Mollace V, Muscoli C. Antioxidant modulation of sirtuin 3 during acute inflammatory pain: The ROS control. Pharmacol Res 2020; 157:104851. [PMID: 32423865 DOI: 10.1016/j.phrs.2020.104851] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 04/18/2020] [Accepted: 04/19/2020] [Indexed: 12/11/2022]
Abstract
Oxidative stress induced post-translational protein modifications are associated with the development of inflammatory hypersensitivities. At least 90% of cellular reactive oxygen species (ROS) are produced in the mitochondria, where the mitochondrial antioxidant, manganese superoxide dismutase (MnSOD), is located. MnSOD's ability to reduce ROS is enhanced by the mitochondrial NAD+-dependent deacetylase sirtuin (SIRT3). SIRT3 can reduce ROS levels by deacetylating MnSOD and enhancing its ability to neutralize ROS or by enhancing the transcription of MnSOD and other oxidative stress-responsive genes. SIRT3 can be post-translationally modified through carbonylation which results in loss of activity. The contribution of post-translational SIRT3 modifications in central sensitization is largely unexplored. Our results reveal that SIRT3 carbonylation contributes to spinal MnSOD inactivation during carrageenan-induced thermal hyperalgesia in rats. Moreover, inhibiting ROS with natural and synthetic antioxidants, prevented SIRT3 carbonylation, restored the enzymatic activity of MnSOD, and blocked the development of thermal hyperalgesia. These results suggest that therapeutic strategies aimed at inhibiting post-translational modifications of SIRT3 may provide beneficial outcomes in pain states where ROS have been documented to play an important role in the development of central sensitization.
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Affiliation(s)
- Sara Ilari
- Institute of Research for Food Safety & Health (IRC-FSH), Department of Health Sciences, University "Magna Graecia" of Catanzaro, 88201 Catanzaro, Italy
| | - Luigino Antonio Giancotti
- Department of Pharmacology and Physiology and the Henry and Amelia Nasrallah Center for Neuroscience, Saint Louis University School of Medicine, 1402 South Grand Blvd, St. Louis, MO 63104, USA
| | - Filomena Lauro
- Institute of Research for Food Safety & Health (IRC-FSH), Department of Health Sciences, University "Magna Graecia" of Catanzaro, 88201 Catanzaro, Italy; Department of Pharmacology and Physiology and the Henry and Amelia Nasrallah Center for Neuroscience, Saint Louis University School of Medicine, 1402 South Grand Blvd, St. Louis, MO 63104, USA
| | - Concetta Dagostino
- Institute of Research for Food Safety & Health (IRC-FSH), Department of Health Sciences, University "Magna Graecia" of Catanzaro, 88201 Catanzaro, Italy
| | - Micaela Gliozzi
- Institute of Research for Food Safety & Health (IRC-FSH), Department of Health Sciences, University "Magna Graecia" of Catanzaro, 88201 Catanzaro, Italy
| | - Valentina Malafoglia
- Institute of Research for Food Safety & Health (IRC-FSH), Department of Health Sciences, University "Magna Graecia" of Catanzaro, 88201 Catanzaro, Italy; Institute for Research on Pain, ISAL Foundation, Torre Pedrera, RN, Italy
| | - Luigi Sansone
- Department of Cellular and Molecular Pathology, IRCCS San Raffaele Pisana, 00163 Rome, Italy
| | - Ernesto Palma
- Institute of Research for Food Safety & Health (IRC-FSH), Department of Health Sciences, University "Magna Graecia" of Catanzaro, 88201 Catanzaro, Italy
| | - Marco Tafani
- Department of Experimental Medicine, University of Rome "Sapienza", 00161 Rome, Italy
| | | | - Carlo Tomino
- Scientific Direction, IRCSS San Raffaele Pisana, 00163 Rome, Italy
| | - Massimo Fini
- Scientific Direction, IRCSS San Raffaele Pisana, 00163 Rome, Italy
| | - Daniela Salvemini
- Department of Pharmacology and Physiology and the Henry and Amelia Nasrallah Center for Neuroscience, Saint Louis University School of Medicine, 1402 South Grand Blvd, St. Louis, MO 63104, USA
| | - Vincenzo Mollace
- Institute of Research for Food Safety & Health (IRC-FSH), Department of Health Sciences, University "Magna Graecia" of Catanzaro, 88201 Catanzaro, Italy
| | - Carolina Muscoli
- Institute of Research for Food Safety & Health (IRC-FSH), Department of Health Sciences, University "Magna Graecia" of Catanzaro, 88201 Catanzaro, Italy.
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The Presence of High Levels of Circulating Trimethylamine N-Oxide Exacerbates Central and Peripheral Inflammation and Inflammatory Hyperalgesia in Rats Following Carrageenan Injection. Inflammation 2020; 42:2257-2266. [PMID: 31489527 DOI: 10.1007/s10753-019-01090-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Gut microbiota-derived metabolite trimethylamine N-oxide (TMAO) has recently been shown to promote inflammation in peripheral tissues and the central nervous system (CNS), contributing to the pathogenesis of various human diseases. Here, we examined whether the presence of high levels of circulating TMAO would influence central and peripheral inflammation and inflammatory hyperalgesia in a carrageenan (CG)-induced rat model of inflammation. Rats were treated with vehicle or TMAO in drinking water. After 2 weeks of treatment, rats received intraplantar injection of saline or CG into the hind paw. Acute nociception was unaltered in TMAO-treated rats that had elevated plasma TMAO. Following CG injection, TMAO-treated rats were significantly more sensitive to thermal and mechanical stimulation of the inflamed paw and displayed greater paw edema. Molecular studies revealed that CG injection induced increases in recruitment of neutrophils/macrophages in the paw and activation of microglia in the spinal cord, along with increased activation of nuclear factor (NF)-kB and production of proinflammatory mediators in both vehicle-treated rats and TMAO-treated rats. However, the increases in the above parameters were more pronounced in TMAO-treated rats. Moreover, TMAO treatment decreased protein levels of anti-inflammatory mediator regulator of G protein signaling (RGS)-10 in both saline-injected rats and CG-injected rats. These findings suggest that the presence of high levels of circulating TMAO downregulates anti-inflammatory mediator RGS10 in both peripheral tissues and the CNS, which may increase the susceptibility to inflammatory challenge-induced NF-kB activity, leading to greater increase in production of inflammatory mediators and consequent exacerbation of peripheral inflammation and inflammatory hyperalgesia.
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Li P, Zhang Q, Xiao Z, Yu S, Yan Y, Qin Y. Activation of the P2X 7 receptor in midbrain periaqueductal gray participates in the analgesic effect of tramadol in bone cancer pain rats. Mol Pain 2018; 14:1744806918803039. [PMID: 30198382 PMCID: PMC6176534 DOI: 10.1177/1744806918803039] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Background Cancer pain is a well-known serious complication in metastatic or terminal cancer patients. Current pain management remains unsatisfactory. The activation of spinal and supraspinal P2X7 receptors plays a crucial role in the induction and maintenance mechanisms of various kinds of acute or chronic pain. The midbrain periaqueductal gray is a vital supraspinal site of the endogenous descending pain-modulating system. Tramadol is a synthetic, centrally acting analgesic agent that exhibits considerable efficacy in clinically relieving pain. The purpose of this study was to determine whether the activation of P2X7 receptor in the ventrolateral region of the periaqueductal gray (vlPAG) participates in the analgesic mechanisms of tramadol on bone cancer pain in rats. The bone cancer pain rat model was established by intratibial cell inoculation of SHZ-88 mammary gland carcinoma cells. The analgesic effects of different doses of tramadol (10, 20, and 40 mg/kg) were assessed by measuring the mechanical withdrawal threshold and thermal withdrawal latency values in rats by using an electronic von Frey anesthesiometer and radiant heat stimulation, respectively. Alterations in the number of P2X7 receptor-positive cells and P2X7 protein levels in vlPAG were separately detected by using immunohistochemistry and Western blot assay. The effect of intra-vlPAG injection of A-740003 (100 nmol), a selective competitive P2X7 receptor antagonist, on the analgesic effect of tramadol was also observed. Results The expression of P2X7 receptor in the vlPAG on bone cancer pain rats was mildly elevated, and the tramadol (10, 20, and 40 mg/kg) dose dependently relieved pain-related behaviors in bone cancer pain rats and further upregulated the expression of P2X7 receptor in the vlPAG. The intra-vlPAG injection of A-740003 pretreatment partly but significantly antagonized the analgesic effect of tramadol on bone cancer pain rats. Conclusions The injection of tramadol can dose dependently elicit analgesic effect on bone cancer pain rats by promoting the expression of the P2X7 receptor in vlPAG.
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Affiliation(s)
- Pengtao Li
- 1 Graduate School, Zunyi Medical University, Zunyi, Guizhou, China
| | - Quan Zhang
- 2 Key Laboratory of Brain Science, Zunyi Medical University, Zunyi, Guizhou, China.,3 Research Center for Medicine and Biology, Zunyi Medical University, Zunyi, Guizhou, China
| | - Zhi Xiao
- 2 Key Laboratory of Brain Science, Zunyi Medical University, Zunyi, Guizhou, China.,3 Research Center for Medicine and Biology, Zunyi Medical University, Zunyi, Guizhou, China
| | - Shouyang Yu
- 2 Key Laboratory of Brain Science, Zunyi Medical University, Zunyi, Guizhou, China
| | - Yan Yan
- 2 Key Laboratory of Brain Science, Zunyi Medical University, Zunyi, Guizhou, China.,3 Research Center for Medicine and Biology, Zunyi Medical University, Zunyi, Guizhou, China
| | - Ying Qin
- 3 Research Center for Medicine and Biology, Zunyi Medical University, Zunyi, Guizhou, China
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