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Park M, Koh CS, Chang H, Kim TJ, Mun W, Chang JW, Jung HH. Low-frequency (5-Hz) stimulation of ventrolateral periaqueductal gray modulates the descending serotonergic system in the peripheral neuropathic pain. Pain 2024; 165:1774-1783. [PMID: 38422490 DOI: 10.1097/j.pain.0000000000003185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 11/15/2023] [Indexed: 03/02/2024]
Abstract
ABSTRACT Neuropathic pain is a type of chronic pain that entails severe prolonged sensory dysfunctions caused by a lesion of the somatosensory system. Many of those suffering from the condition do not experience significant improvement with existing medications, resulting in various side effects. In this study, Sprague-Dawley male rats were used, and long-term deep brain stimulation of the ventrolateral periaqueductal gray was conducted in a rat model of spared nerve injury. We found that 5-Hz deep brain stimulation effectively modulated mechanical allodynia and induced neuronal activation in the rostral ventromedial medulla, restoring impaired descending serotonergic system. At the spinal level, glial cells were still activated but only the 5-HT1a receptor in the spinal cord was activated, implying its inhibitory role in mechanical allodynia. This study found that peripheral neuropathy caused dysfunction in the descending serotonergic system, and prolonged stimulation of ventrolateral periaqueductal gray can modulate the pathway in an efficient manner. This work would provide new opportunities for the development of targeted and effective treatments for this debilitating disease, possibly giving us lower chances of side effects from repeated high-frequency stimulation or long-term use of medication.
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Affiliation(s)
- Minkyung Park
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Republic of Korea
- Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Chin Su Koh
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Heesue Chang
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Republic of Korea
- Department of Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Tae Jun Kim
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Republic of Korea
- Department of Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Wonki Mun
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Republic of Korea
- Department of Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jin Woo Chang
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Republic of Korea
- Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Hyun Ho Jung
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Republic of Korea
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Lyubashina OA, Sivachenko IB, Sushkevich BM, Busygina II. Opposing effects of 5-HT1A receptor agonist buspirone on supraspinal abdominal pain transmission in normal and visceral hypersensitive rats. J Neurosci Res 2023; 101:1555-1571. [PMID: 37331003 DOI: 10.1002/jnr.25222] [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: 02/14/2023] [Revised: 05/11/2023] [Accepted: 05/28/2023] [Indexed: 06/20/2023]
Abstract
The serotonergic 5-HT1A receptors are implicated in the central mechanisms of visceral pain, but their role in these processes is controversial. Considering existing evidences for organic inflammation-triggered neuroplastic changes in the brain serotonergic circuitry, the ambiguous contribution of 5-HT1A receptors to supraspinal control of visceral pain in normal and post-inflammatory conditions can be assumed. In this study performed on male Wistar rats, we used microelectrode recording of the caudal ventrolateral medulla (CVLM) neuron responses to colorectal distension (CRD) and electromyography recording of CRD-evoked visceromotor reactions (VMRs) to evaluate post-colitis changes in the effects of 5-HT1A agonist buspirone on supraspinal visceral nociceptive transmission. In rats recovered from trinitrobenzene sulfonic acid colitis, the CRD-induced CVLM neuronal excitation and VMRs were increased compared with those in healthy animals, revealing post-inflammatory intestinal hypersensitivity. Intravenous buspirone (2 and 4 mg/kg) under urethane anesthesia dose-dependently suppressed CVLM excitatory neuron responses to noxious CRD in healthy rats, but caused dose-independent increase in the already enhanced nociceptive activation of CVLM neurons in post-colitis animals, losing also its normally occurring faciliatory effect on CRD-evoked inhibitory medullary neurotransmission and suppressive action on hemodynamic reactions to CRD. In line with this, subcutaneous injection of buspirone (2 mg/kg) in conscious rats, which attenuated CRD-induced VMRs in controls, further increased VMRs in hypersensitive animals. The data obtained indicate a shift from anti- to pronociceptive contribution of 5-HT1A-dependent mechanisms to supraspinal transmission of visceral nociception in intestinal hypersensitivity conditions, arguing for the disutility of buspirone and possibly other 5-HT1A agonists for relieving post-inflammatory abdominal pain.
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Affiliation(s)
- Olga A Lyubashina
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology of the Russian Academy of Sciences, Saint Petersburg, Russia
| | - Ivan B Sivachenko
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology of the Russian Academy of Sciences, Saint Petersburg, Russia
| | - Boris M Sushkevich
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology of the Russian Academy of Sciences, Saint Petersburg, Russia
| | - Irina I Busygina
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology of the Russian Academy of Sciences, Saint Petersburg, Russia
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Nakamura S, Nonaka T, Yoshida K, Yamada T, Yamamoto T. Neuropeptide W, an endogenous NPBW1 and NPBW2 ligand, produced an analgesic effect via activation of the descending pain modulatory system during a rat formalin test. Mol Pain 2021; 17:1744806921992187. [PMID: 33573476 PMCID: PMC7887691 DOI: 10.1177/1744806921992187] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 12/11/2020] [Accepted: 01/07/2021] [Indexed: 12/25/2022] Open
Abstract
Neuropeptide W (NPW) messenger ribonucleic acid (mRNA) and NPBW1 and/or NPBW2 mRNA are expressed in the descending pain inhibitory system. In the present study, we examined whether NPW microinjected into the descending pain inhibitory system, such as the periaqueductal gray (PAG), locus coeruleus (LC), and rostral ventromedial medulla (RVM), produces an analgesic effect using a rat formalin test. Microinjections of NPW into the PAG ipsilateral and contralateral to the formalin-injected side, LC ipsilateral and contralateral to the formalin-injected side, and RVM produced an analgesic effect. In the RVM study, the analgesic effect was antagonized by WAY100135, a 5-HT1A antagonist, and enhanced by prazosin, an α1 antagonist, and SB269970, a 5-HT7 antagonist. Naloxone, an opioid antagonist, also antagonized the effect of NPW in the RVM study. In the ipsilateral LC study, the analgesic effect was antagonized by WAY100135, idazoxan, an α2 antagonist, and naloxone and was enhanced by prazosin and SB269970. In the contralateral LC study, the analgesic effect was antagonized by prazosin, idazoxan, SB269970, and naloxone. The analgesic effect was antagonized by WAY100135, SB269970, idazoxan, and naloxone in the ipsilateral and contralateral PAG studies. These findings strongly suggest that NPBW1/W2 activation by NPW microinjection into the RVM, LC, and PAG affect the descending pain modulatory system and produce anti-nociceptive and pro-nociceptive effects in the rat formalin test.
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Affiliation(s)
- Shingo Nakamura
- Department of Anesthesiology, School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Takahiro Nonaka
- Department of Anesthesiology, School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Koji Yoshida
- Department of Anesthesiology, School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Toshihiko Yamada
- Department of Anesthesiology, School of Medical Science, Kumamoto University, Kumamoto, Japan
| | - Tatsuo Yamamoto
- Department of Anesthesiology, School of Medical Science, Kumamoto University, Kumamoto, Japan
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Panteleev SS, Sivachenko IB, Lyubashina OA. The Buspirone-dependent Abdominal Pain Transmission Within the Nucleus Tractus Solitarius in the Rat. Neuroscience 2020; 452:326-334. [PMID: 33248152 DOI: 10.1016/j.neuroscience.2020.11.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/22/2020] [Accepted: 11/18/2020] [Indexed: 01/07/2023]
Abstract
Buspirone, a partial agonist of the 5-HT1aR, due to potential antinociceptive properties can be useful for abdominal pain treatment in IBS patients. Pain-related effects of buspirone can be mediated by the 5-HT1aRs, located within the nucleus tractus solitarius. The 5-HT1aR involvement in pain transmission within the NTS is unclear. The objective of our study was to evaluate the involvement of the 5-HT1aR in abdominal pain transmission within the NTS. Using a model of abdominal pain on urethane-anesthetized rats, two types of NTS pain-related neurons responding to the noxious colorectal distension (CRD) with excitatory and inhibitory sustained patterns of evoked activity were revealed. Buspirone (1.0-4.0 mg kg-1, iv) has complex time- and dose-depended action on the CRD-induced NTS neuron responses. Buspirone inhibits the responses of the excitatory neurons and inverts the responses of the inhibitory pain-related neurons but at a dose of 4.0 buspirone, the effect on NTS pain-related neurons attenuates. The inhibitory effect of buspirone on the CRD-evoked responses of the excitatory NTS neurons is completely blocked by an intra-cerebroventricular administration of buspirone agonist WAY100,635. The inhibitory responses do not change by this agonist. The inhibitory action of buspirone is mediated by supraspinal 5-HT1a receptors however, its excitatory effect on inhibitory neurons does not dependents on these receptors. We proposed that the NTS pain-related neurons could be involved in anti- or pronociceptive effects of buspirone on abdominal pain.
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Affiliation(s)
- Sergey S Panteleev
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, Saint-Petersburg 199034, Russia.
| | - Ivan B Sivachenko
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, Saint-Petersburg 199034, Russia.
| | - Olga A Lyubashina
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology of the Russian Academy of Sciences, 6 Nab. Makarova, Saint-Petersburg 199034, Russia; Department of Neuropharmacology, Valdman Institute of Pharmacology, First Saint-Petersburg Pavlov State Medical University, 6/8 Lev Tolstoy Street, Saint-Petersburg 197022, Russia.
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Panteleev SS, Sivachenko IB, Lyubashina OA. The central effects of buspirone on abdominal pain in rats. Neurogastroenterol Motil 2018; 30:e13431. [PMID: 30101506 DOI: 10.1111/nmo.13431] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 06/08/2018] [Accepted: 06/24/2018] [Indexed: 12/28/2022]
Abstract
BACKGROUND Buspirone, a partial agonist of the 5-HT1a receptor (5-HT1a R), owing to potential antinociceptive properties may be useful in treatment of abdominal pain in IBS patients. The pain-related effects of buspirone are mediated via the 5-HT1a Rs, specifically located within the ventrolateral medulla (VLM). The most animal studies of the 5-HT1a R involvement in pain control have been carried out with somatic behavioral tests. The 5-HT1a R contribution in visceral pain transmission within the VLM is unclear. The objective of our study was to evaluate the 5-HT1a R contribution in abdominal pain transmission within the VLM. METHODS Using animal model of abdominal pain (urethane-anaesthetized rats), based on the noxious colorectal distension (CRD) as pain stimulus we studied effects of buspirone (1.0-4.0 mg kg-1 , iv) on the CRD-induced VLM neuron and blood pressure responses as markers of abdominal pain before and after the 5-HT1a R blockade by antagonist, WAY 100,635. RESULTS The CRD induced a significant increase in VLM neuron activity up to 201.5 ± 18.0% and depressor reactions up to 68 ± 1.8% of baseline. Buspirone (1.0-4.0 mg kg-1 , iv) resulted in an inhibition of the CRD-induced neuron responses which were changed inversely with dose increase and decreased depressor reactions directly with dose increase. These effects were antagonized by intracerebroventricular WAY 100,635. CONCLUSION Buspirone exerts complex biphasic action on the pain-related VLM neuron activity inversely depending on dose. The final effect of buspirone depends on the functional balance between of activation the pre- and postsynaptic 5-HT1a Rs in mediating pain control networks.
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Affiliation(s)
- S S Panteleev
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology, Russian Academy of Sciences, Saint Petersburg, Russia.,Department of Neuropharmacology, Valdman Institute of Pharmacology, First Saint-Petersburg Pavlov State Medical University, Saint Petersburg, Russia
| | - I B Sivachenko
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology, Russian Academy of Sciences, Saint Petersburg, Russia
| | - O A Lyubashina
- Laboratory of Cortico-Visceral Physiology, Pavlov Institute of Physiology, Russian Academy of Sciences, Saint Petersburg, Russia.,Department of Neuropharmacology, Valdman Institute of Pharmacology, First Saint-Petersburg Pavlov State Medical University, Saint Petersburg, Russia
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Tavares LRR, Baptista-de-Souza D, Canto-de-Souza A. Activation of 5-HT2C (but not 5-HT1A) receptors in the amygdala enhances fear-induced antinociception: Blockade with local 5-HT2C antagonist or systemic fluoxetine. Neuropharmacology 2018; 135:376-385. [DOI: 10.1016/j.neuropharm.2018.03.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 03/05/2018] [Accepted: 03/06/2018] [Indexed: 12/28/2022]
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Lyubashina OA, Busygina II, Panteleev SS, Nozdrachev AD. Antinociceptive effect of the agonist of 5-HT1A receptors buspirone in the model of abdominal pain in dogs. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2017; 473:46-49. [PMID: 28508197 DOI: 10.1134/s0012496617020119] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 12/12/2016] [Indexed: 01/16/2023]
Abstract
We have demonstrated that activation of 5-HT1A receptors with buspirone promotes visceral analgesia in awake dogs. The administration of 0.035 mg/kg (i.m.) of the drug caused depression of viscero-motor (contraction of the abdominal muscles) and pressor (increase in the heart rate) responses to noxious distension of the large intestine. An increase in the dose to 0.07 and 0.14 mg/kg did not enhance the antinociceptive effect of buspirone but triggered basal tachycardia. The obtained results provide evidence of the inhibitory role of 5-HT1A receptors in modulating visceral pain sensitivity and the possibility of an exciting effect of their activation on the cardiovascular system.
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Affiliation(s)
- O A Lyubashina
- Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia.
| | - I I Busygina
- Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia
| | - S S Panteleev
- Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia
| | - A D Nozdrachev
- Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia
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Kannampalli P, Sengupta JN. Role of principal ionotropic and metabotropic receptors in visceral pain. J Neurogastroenterol Motil 2015; 21:147-58. [PMID: 25843070 PMCID: PMC4398235 DOI: 10.5056/jnm15026] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 02/24/2015] [Accepted: 03/26/2015] [Indexed: 12/13/2022] Open
Abstract
Visceral pain is the most common form of pain caused by varied diseases and a major reason for patients to seek medical consultation. It also leads to a significant economic burden due to workdays lost and reduced productivity. Further, long-term use of non-specific medications is also associated with side effects affecting the quality of life. Despite years of extensive research and the availability of several therapeutic options, management of patients with chronic visceral pain is often inadequate, resulting in frustration for both patients and physicians. This is, most likely, because the mechanisms associated with chronic visceral pain are different from those of acute pain. Accumulating evidence from years of research implicates several receptors and ion channels in the induction and maintenance of central and peripheral sensitization during chronic pain states. Understanding the specific role of these receptors will facilitate to capitalize on their unique properties to augment the therapeutic efficacy while at the same time minimizing unwanted side effects. The aim of this review is to provide a concise review of the recent literature that reports on the role of principal ionotropic receptors and metabotropic receptors in the modulation visceral pain. We also include an overview of the possibility of these receptors as potential new targets for the treatment of chronic visceral pain conditions.
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Affiliation(s)
- Pradeep Kannampalli
- Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jyoti N Sengupta
- Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, WI, USA
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Wang GD, Wang XY, Zou F, Qu M, Liu S, Fei G, Xia Y, Needleman BJ, Mikami DJ, Wood JD. Mast cell expression of the serotonin1A receptor in guinea pig and human intestine. Am J Physiol Gastrointest Liver Physiol 2013. [PMID: 23518679 DOI: 10.1152/ajpgi.00421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Serotonin [5-hydroxytryptamine (5-HT)] is released from enterochromaffin cells in the mucosa of the small intestine. We tested a hypothesis that elevation of 5-HT in the environment of enteric mast cells might degranulate the mast cells and release mediators that become paracrine signals to the enteric nervous system, spinal afferents, and secretory glands. Western blotting, immunofluorescence, ELISA, and pharmacological analysis were used to study expression of 5-HT receptors by mast cells in the small intestine and action of 5-HT to degranulate the mast cells and release histamine in guinea pig small intestine and segments of human jejunum discarded during Roux-en-Y gastric bypass surgeries. Mast cells in human and guinea pig preparations expressed the 5-HT1A receptor. ELISA detected spontaneous release of histamine in guinea pig and human preparations. The selective 5-HT1A receptor agonist 8-hydroxy-PIPAT evoked release of histamine. A selective 5-HT1A receptor antagonist, WAY-100135, suppressed stimulation of histamine release by 5-HT or 8-hydroxy-PIPAT. Mast cell-stabilizing drugs, doxantrazole and cromolyn sodium, suppressed the release of histamine evoked by 5-HT or 8-hydroxy-PIPAT in guinea pig and human preparations. Our results support the hypothesis that serotonergic degranulation of enteric mast cells and release of preformed mediators, including histamine, are mediated by the 5-HT1A serotonergic receptor. Association of 5-HT with the pathophysiology of functional gastrointestinal disorders (e.g., irritable bowel syndrome) underlies a question of whether selective 5-HT1A receptor antagonists might have therapeutic application in disorders of this nature.
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Affiliation(s)
- Guo-Du Wang
- Dept. of Physiology and Cell Biology, College of Medicine and Public Health, The Ohio State Univ., 304 Hamilton Hall, 1645 Neil Ave., Columbus, OH 43210, USA
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Wang GD, Wang XY, Zou F, Qu M, Liu S, Fei G, Xia Y, Needleman BJ, Mikami DJ, Wood JD. Mast cell expression of the serotonin1A receptor in guinea pig and human intestine. Am J Physiol Gastrointest Liver Physiol 2013; 304:G855-63. [PMID: 23518679 PMCID: PMC3652070 DOI: 10.1152/ajpgi.00421.2012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Serotonin [5-hydroxytryptamine (5-HT)] is released from enterochromaffin cells in the mucosa of the small intestine. We tested a hypothesis that elevation of 5-HT in the environment of enteric mast cells might degranulate the mast cells and release mediators that become paracrine signals to the enteric nervous system, spinal afferents, and secretory glands. Western blotting, immunofluorescence, ELISA, and pharmacological analysis were used to study expression of 5-HT receptors by mast cells in the small intestine and action of 5-HT to degranulate the mast cells and release histamine in guinea pig small intestine and segments of human jejunum discarded during Roux-en-Y gastric bypass surgeries. Mast cells in human and guinea pig preparations expressed the 5-HT1A receptor. ELISA detected spontaneous release of histamine in guinea pig and human preparations. The selective 5-HT1A receptor agonist 8-hydroxy-PIPAT evoked release of histamine. A selective 5-HT1A receptor antagonist, WAY-100135, suppressed stimulation of histamine release by 5-HT or 8-hydroxy-PIPAT. Mast cell-stabilizing drugs, doxantrazole and cromolyn sodium, suppressed the release of histamine evoked by 5-HT or 8-hydroxy-PIPAT in guinea pig and human preparations. Our results support the hypothesis that serotonergic degranulation of enteric mast cells and release of preformed mediators, including histamine, are mediated by the 5-HT1A serotonergic receptor. Association of 5-HT with the pathophysiology of functional gastrointestinal disorders (e.g., irritable bowel syndrome) underlies a question of whether selective 5-HT1A receptor antagonists might have therapeutic application in disorders of this nature.
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Affiliation(s)
- Guo-Du Wang
- 1Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio;
| | - Xi-Yu Wang
- 1Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio;
| | - Fei Zou
- 1Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio;
| | - Meihua Qu
- 1Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio;
| | - Sumei Liu
- 1Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio;
| | - Guijun Fei
- 1Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio;
| | - Yun Xia
- 1Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio; ,2Department of Anesthesiology, College of Medicine, The Ohio State University, Columbus, Ohio; and
| | - Bradley J. Needleman
- 3Department of Surgery, College of Medicine, The Ohio State University, Columbus, Ohio
| | - Dean J. Mikami
- 3Department of Surgery, College of Medicine, The Ohio State University, Columbus, Ohio
| | - Jackie D. Wood
- 1Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio;
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Central α-adrenoceptors contribute to mustard oil-induced central sensitization in the rat medullary dorsal horn. Neuroscience 2013; 236:244-52. [PMID: 23333675 DOI: 10.1016/j.neuroscience.2013.01.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 12/22/2012] [Accepted: 01/03/2013] [Indexed: 11/22/2022]
Abstract
Our previous studies have demonstrated that application of the inflammatory irritant mustard oil (MO) to the tooth pulp produces trigeminal central sensitization that includes increases in mechanoreceptive field size and responses to noxious stimuli and decrease in activation threshold in brainstem nociceptive neurons of trigeminal subnucleus caudalis (the medullary dorsal horn, MDH). The aim of the present study was to test if central noradrenergic processes are involved in the central sensitization of MDH neurons and if α1-adrenoceptors or α2-adrenoceptors or both are involved. In urethane/α-chloralose-anesthetized rats, the activity of extracellularly recorded and functionally identified single nociceptive neurons in the MDH was studied. Continuous intrathecal (i.t.) superfusion of the adrenergic modulator guanethidine and α-adrenoceptor blocker phentolamine or selective α1-adrenoceptor antagonist prazosin over the medulla strongly attenuated all three MO-induced parameters of central sensitization in the MDH nociceptive neurons, compared to phosphate-buffered saline (as vehicle control). In contrast, i.t. superfusion of the selective α2-adrenoceptor antagonist yohimbine had little effect on the mechanoreceptive field expansion and the decreased mechanical activation threshold, and indeed facilitated responses to noxious stimuli of sensitized nociceptive neurons. Superfusion of each of the four chemicals alone did not affect baseline nociceptive neuronal properties. These findings provide the first documentation of the involvement of central noradrenergic processes in MDH in the development of the central sensitization, and that α1- and α2-adrenoceptors may be differentially involved.
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