1
|
Yin JB, Lu YC, Li F, Zhang T, Ding T, Hu HQ, Chen YB, Guo HW, Kou ZZ, Zhang MM, Yuan J, Chen T, Li H, Cao BZ, Dong YL, Li YQ. Morphological investigations of endomorphin-2 and spinoparabrachial projection neurons in the spinal dorsal horn of the rat. Front Neuroanat 2022; 16:1072704. [PMID: 36506871 PMCID: PMC9726772 DOI: 10.3389/fnana.2022.1072704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 11/07/2022] [Indexed: 11/24/2022] Open
Abstract
It has been proved that endomorphin-2 (EM2) produced obvious analgesic effects in the spinal dorsal horn (SDH), which existed in our human bodies with remarkable affinity and selectivity for the μ-opioid receptor (MOR). Our previous study has demonstrated that EM2 made synapses with the spinoparabrachial projection neurons (PNs) in the SDH and inhibited their activities by reducing presynaptic glutamate release. However, the morphological features of EM2 and the spinoparabrachial PNs in the SDH have not been completely investigated. Here, we examined the morphological features of EM2 and the spinoparabrachial PNs by using triple fluorescence and electron microscopic immunohistochemistry. EM2-immunoreactive (-ir) afferents directly contacted with the spinoparabrachial PNs in lamina I of the SDH. Immunoelectron microscopy (IEM) were used to confirm that these contacts were synaptic connections. It was also observed that EM2-ir axon terminals contacting with spinoparabrachial PNs in lamina I contained MOR, substance P (SP) and vesicular glutamate transporter 2 (VGLUT2). In lamina II, MOR-ir neurons were observed to receive direct contacts from EM2-ir varicosities. The synaptic connections among EM2, MOR, SP, VGLUT2, and the spinoparabrachial PNs were also confirmed by IEM. In sum, our results supply morphological evidences for the analgesic effects of EM2 on the spinoparabrachial PNs in the SDH.
Collapse
Affiliation(s)
- Jun-Bin Yin
- Department of Human Anatomy, K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, China,Department of Neurology, The 960th Hospital of Joint Logistics Support, PLA, Jinan, China,State Key Laboratory of Military Medical Psychology, The Fourth Military Medical University, Xi’an, China
| | - Ya-Cheng Lu
- Department of Human Anatomy, K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, China
| | - Fei Li
- Department of Human Anatomy, K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, China
| | - Ting Zhang
- Department of Human Anatomy, K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, China
| | - Tan Ding
- Institute of Orthopedics, Xijing Hospital, The Fourth Military Medical University, Xi’an, China
| | - Huai-Qiang Hu
- Department of Neurology, The 960th Hospital of Joint Logistics Support, PLA, Jinan, China,State Key Laboratory of Military Medical Psychology, The Fourth Military Medical University, Xi’an, China
| | - Ying-Biao Chen
- Department of Human Anatomy, Fujian Health College, Fuzhou, China
| | - Hong-Wei Guo
- Department of Neurology, The 960th Hospital of Joint Logistics Support, PLA, Jinan, China
| | - Zhen-Zhen Kou
- Department of Human Anatomy, K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, China
| | - Ming-Ming Zhang
- Department of Human Anatomy, K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, China
| | - Jun Yuan
- Department of Neurology, The 960th Hospital of Joint Logistics Support, PLA, Jinan, China
| | - Tao Chen
- Department of Human Anatomy, K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, China
| | - Hui Li
- Department of Human Anatomy, K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, China
| | - Bing-Zhen Cao
- Department of Neurology, The 960th Hospital of Joint Logistics Support, PLA, Jinan, China
| | - Yu-Lin Dong
- Department of Human Anatomy, K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, China,Yu-Lin Dong,
| | - Yun-Qing Li
- Department of Human Anatomy, K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi’an, China,*Correspondence: Yun-Qing Li,
| |
Collapse
|
2
|
Maletz SN, Reid BT, Varga AG, Levitt ES. Nucleus Tractus Solitarius Neurons Activated by Hypercapnia and Hypoxia Lack Mu Opioid Receptor Expression. Front Mol Neurosci 2022; 15:932189. [PMID: 35898697 PMCID: PMC9309891 DOI: 10.3389/fnmol.2022.932189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 06/14/2022] [Indexed: 11/30/2022] Open
Abstract
Impaired chemoreflex responses are a central feature of opioid-induced respiratory depression, however, the mechanism through which mu opioid receptor agonists lead to diminished chemoreflexes is not fully understood. One brainstem structure involved in opioid-induced impairment of chemoreflexes is the nucleus of the solitary tract (NTS), which contains a population of neurons that express mu opioid receptors. Here, we tested whether caudal NTS neurons activated during the chemoreflex challenge express mu opioid receptors and overlap with neurons activated by opioids. Using genetic labeling of mu opioid receptor-expressing neurons and cFos immunohistochemistry as a proxy for neuronal activation, we examined the distribution of activated NTS neurons following hypercapnia, hypoxia, and morphine administration. The main finding was that hypoxia and hypercapnia primarily activated NTS neurons that did not express mu opioid receptors. Furthermore, concurrent administration of morphine with hypercapnia induced cFos expression in non-overlapping populations of neurons. Together these results suggest an indirect effect of opioids within the NTS, which could be mediated through mu opioid receptors on afferents and/or inhibitory interneurons.
Collapse
Affiliation(s)
- Sebastian N. Maletz
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, United States
| | - Brandon T. Reid
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, United States
| | - Adrienn G. Varga
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, United States
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, United States
| | - Erica S. Levitt
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, United States
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, United States
- *Correspondence: Erica S. Levitt ; orcid.org/0000-0002-3634-6594
| |
Collapse
|
3
|
Lu YC, Yin JB, Bai Y, Li X, Zhang T, Yang J, Yi XN, Zhang MM, Li YQ. Morphological Features of Endomorphin-2-immunoreactive Ultrastructures in the Dorsal Root Ganglion and Spinal Dorsal Horn of the Rat. J Chem Neuroanat 2022; 125:102142. [DOI: 10.1016/j.jchemneu.2022.102142] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 01/24/2023]
|
4
|
Hsieh YL, Yang CC, Yang NP. Ultra-Low Frequency Transcutaneous Electrical Nerve Stimulation on Pain Modulation in a Rat Model with Myogenous Temporomandibular Dysfunction. Int J Mol Sci 2021; 22:ijms22189906. [PMID: 34576074 PMCID: PMC8465049 DOI: 10.3390/ijms22189906] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 09/11/2021] [Accepted: 09/12/2021] [Indexed: 12/22/2022] Open
Abstract
Masticatory myofascial pain (MMP) is one of the most common causes of chronic orofacial pain in patients with temporomandibular disorders. To explore the antinociceptive effects of ultra-low frequency transcutaneous electrical nerve stimulation (ULF-TENS) on alterations of pain-related biochemicals, electrophysiology and jaw-opening movement in an animal model with MMP, a total of 40 rats were randomly and equally assigned to four groups; i.e., animals with MMP receiving either ULF-TENS or sham treatment, as well as those with sham-MMP receiving either ULF-TENS or sham treatment. MMP was induced by electrically stimulated repetitive tetanic contraction of masticatory muscle for 14 days. ULF-TENS was then performed at myofascial trigger points of masticatory muscles for seven days. Measurable outcomes included maximum jaw-opening distance, prevalence of endplate noise (EPN), and immunohistochemistry for substance P (SP) and μ-opiate receptors (MOR) in parabrachial nucleus and c-Fos in rostral ventromedial medulla. There were significant improvements in maximum jaw-opening distance and EPN prevalence after ULF-TENS in animals with MMP. ULF-TENS also significantly reduced SP overexpression, increased MOR expression in parabrachial nucleus, and increased c-Fos expression in rostral ventromedial medulla. ULF-TENS may represent a novel and applicable therapeutic approach for improvement of orofacial pain induced by MMP.
Collapse
Affiliation(s)
- Yueh-Ling Hsieh
- Department of Physical Therapy, Graduate Institute of Rehabilitation Science, China Medical University, Taichung 406040, Taiwan;
- Correspondence: ; Tel.: +886-4-22053366 (ext. 7312)
| | - Chen-Chia Yang
- Kao-An Physical Medicine and Rehabilitation Clinic, Taichung 406040, Taiwan;
| | - Nian-Pu Yang
- Department of Physical Therapy, Graduate Institute of Rehabilitation Science, China Medical University, Taichung 406040, Taiwan;
| |
Collapse
|
5
|
Ramirez JM, Burgraff NJ, Wei AD, Baertsch NA, Varga AG, Baghdoyan HA, Lydic R, Morris KF, Bolser DC, Levitt ES. Neuronal mechanisms underlying opioid-induced respiratory depression: our current understanding. J Neurophysiol 2021; 125:1899-1919. [PMID: 33826874 DOI: 10.1152/jn.00017.2021] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Opioid-induced respiratory depression (OIRD) represents the primary cause of death associated with therapeutic and recreational opioid use. Within the United States, the rate of death from opioid abuse since the early 1990s has grown disproportionally, prompting the classification as a nationwide "epidemic." Since this time, we have begun to unravel many fundamental cellular and systems-level mechanisms associated with opioid-related death. However, factors such as individual vulnerability, neuromodulatory compensation, and redundancy of opioid effects across central and peripheral nervous systems have created a barrier to a concise, integrative view of OIRD. Within this review, we bring together multiple perspectives in the field of OIRD to create an overarching viewpoint of what we know, and where we view this essential topic of research going forward into the future.
Collapse
Affiliation(s)
- Jan-Marino Ramirez
- Department of Neurological Surgery, University of Washington, Seattle, Washington.,Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Nicholas J Burgraff
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Aguan D Wei
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Nathan A Baertsch
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Adrienn G Varga
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida.,Center for Respiratory Research and Rehabilitation, Department of Physical Therapy, University of Florida, Gainesville, Florida
| | - Helen A Baghdoyan
- Department of Psychology, University of Tennessee, Knoxville, Tennessee.,Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Ralph Lydic
- Department of Psychology, University of Tennessee, Knoxville, Tennessee.,Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Kendall F Morris
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Donald C Bolser
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida
| | - Erica S Levitt
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida.,Center for Respiratory Research and Rehabilitation, Department of Physical Therapy, University of Florida, Gainesville, Florida
| |
Collapse
|
6
|
Zhang T, Zhang N, Zhang R, Zhao W, Chen Y, Wang Z, Xu B, Zhang M, Shi X, Zhang Q, Guo Y, Xiao J, Chen D, Fang Q. Preemptive intrathecal administration of endomorphins relieves inflammatory pain in male mice via inhibition of p38 MAPK signaling and regulation of inflammatory cytokines. J Neuroinflammation 2018; 15:320. [PMID: 30442166 PMCID: PMC6236886 DOI: 10.1186/s12974-018-1358-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 11/02/2018] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Preemptive administration of analgesic drugs reduces perceived pain and prolongs duration of antinociceptive action. Whereas several lines of evidence suggest that endomorphins, the endogenous mu-opioid agonists, attenuate acute and chronic pain at the spinal level, their preemptive analgesic effects remain to be determined. In this study, we evaluated the anti-allodynic activities of endomorphins and explored their mechanisms of action after preemptive administration in a mouse model of inflammatory pain. METHODS The anti-allodynic activities of preemptive intrathecal administration of endomorphin-1 and endomorphin-2 were investigated in complete Freund's adjuvant (CFA)-induced inflammatory pain model and paw incision-induced postoperative pain model. The modulating effects of endomorphins on the expression of p38 mitogen-activated protein kinase (p38 MAPK) and inflammatory mediators in dorsal root ganglion (DRG) of CFA-treated mice were assayed by real-time reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, or immunofluorescence staining. RESULTS Preemptive intrathecal injection of endomorphins dose-dependently attenuated CFA-induced mechanical allodynia via the mu-opioid receptor and significantly reversed paw incision-induced allodynia. In addition, CFA-caused increase of phosphorylated p38 MAPK in DRG was dramatically reduced by preemptive administration of endomorphins. Repeated intrathecal application of the specific p38 MAPK inhibitor SB203580 reduced CFA-induced mechanical allodynia as well. Further RT-PCR assay showed that endomorphins regulated the mRNA expression of inflammatory cytokines in DRGs induced by peripheral inflammation. CONCLUSIONS Our findings reveal a novel mechanism by which preemptive treatment of endomorphins attenuates inflammatory pain through regulating the production of inflammatory cytokines in DRG neurons via inhibition of p38 MAPK phosphorylation.
Collapse
Affiliation(s)
- Ting Zhang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, and Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, 199 Donggang West Road, Lanzhou, 730000, People's Republic of China
| | - Nan Zhang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, and Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, 199 Donggang West Road, Lanzhou, 730000, People's Republic of China
| | - Run Zhang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, and Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, 199 Donggang West Road, Lanzhou, 730000, People's Republic of China
| | - Weidong Zhao
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, and Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, 199 Donggang West Road, Lanzhou, 730000, People's Republic of China
| | - Yong Chen
- Department of Neurology, School of Medicine, Duke University, Durham, North Carolina, 27710, USA
| | - Zilong Wang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, and Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, 199 Donggang West Road, Lanzhou, 730000, People's Republic of China
| | - Biao Xu
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, and Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, 199 Donggang West Road, Lanzhou, 730000, People's Republic of China
| | - Mengna Zhang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, and Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, 199 Donggang West Road, Lanzhou, 730000, People's Republic of China
| | - Xuerui Shi
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, and Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, 199 Donggang West Road, Lanzhou, 730000, People's Republic of China
| | - Qinqin Zhang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, and Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, 199 Donggang West Road, Lanzhou, 730000, People's Republic of China
| | - Yuanyuan Guo
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, and Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, 199 Donggang West Road, Lanzhou, 730000, People's Republic of China
| | - Jian Xiao
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, and Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, 199 Donggang West Road, Lanzhou, 730000, People's Republic of China
| | - Dan Chen
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, and Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, 199 Donggang West Road, Lanzhou, 730000, People's Republic of China
| | - Quan Fang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, and Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, 199 Donggang West Road, Lanzhou, 730000, People's Republic of China.
| |
Collapse
|
7
|
Matus-Ortega ME, Leff Gelman P, Calva-Nieves JC, Flores-Zamora A, Salazar-Juárez A, Torner-Aguilar CA, Gamba G, De Los Heros P, Peng B, Pintar JE, Gompf HS, Allen CN, Antón-Palma B. Mexneurin is a novel precursor of peptides in the central nervous system of rodents. FEBS Lett 2017; 591:1627-1636. [PMID: 28504339 DOI: 10.1002/1873-3468.12679] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 04/19/2017] [Accepted: 05/10/2017] [Indexed: 12/29/2022]
Abstract
Endomorphins (EMs) have been proposed as the endogenous ligand agonists of the μ-opioid receptor; however, no propeptide precursor protein for EMs has been identified. Here, to identify the presumed precursor of EMs, we designed an immunoscreening assay using specific affinity-purified rabbit antisera raised against synthetic EMs in a whole-mouse brain cDNA library. Following this approach, we identify a DNA sequence encoding a protein precursor, which we name proMexneurin, that contains three different peptide sequences: Mexneurin-1 (an EM-like peptide), Mexneurin-2, and Mexneurin-3, a peptide which appears to be unrelated to EMs. RT-PCR analysis and in situ hybridization reveal a widespread distribution of proMexneurin mRNA throughout the mouse brain. Both Mexneurin-1 and Mexneurin-3 peptides display biological activities in the mouse CNS.
Collapse
Affiliation(s)
- Maura E Matus-Ortega
- Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Ciudad de México, México
| | | | - Juan C Calva-Nieves
- Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Ciudad de México, México
| | - Anabel Flores-Zamora
- Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Ciudad de México, México
| | | | | | - Gerardo Gamba
- Molecular Physiology Unit, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Paola De Los Heros
- Dirección de Investigación, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Bonnie Peng
- Department of Neuroscience and Cell Biology, Rutgers Biomedical and Health Sciences, Newark, NJ, USA
| | - John E Pintar
- Department of Neuroscience and Cell Biology, Rutgers Biomedical and Health Sciences, Newark, NJ, USA
| | - Heinrich S Gompf
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, USA
| | - Charles N Allen
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, USA
| | - Benito Antón-Palma
- Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Ciudad de México, México
| |
Collapse
|
8
|
MCRT, a chimeric peptide based on morphiceptin and PFRTic-NH2, regulates the depressor effects induced by endokinin A/B. Eur J Pharmacol 2016; 792:33-37. [DOI: 10.1016/j.ejphar.2016.10.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 10/21/2016] [Accepted: 10/21/2016] [Indexed: 01/13/2023]
|
9
|
Kou ZZ, Wan FP, Bai Y, Li CY, Hu JC, Zhang GT, Zhang T, Chen T, Wang YY, Li H, Li YQ. Decreased Endomorphin-2 and μ-Opioid Receptor in the Spinal Cord Are Associated with Painful Diabetic Neuropathy. Front Mol Neurosci 2016; 9:80. [PMID: 27656127 PMCID: PMC5013037 DOI: 10.3389/fnmol.2016.00080] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Accepted: 08/24/2016] [Indexed: 12/17/2022] Open
Abstract
Painful diabetic neuropathy (PDN) is one of the most common complications in the early stage of diabetes mellitus (DM). Endomorphin-2 (EM2) selectively activates the μ-opioid receptor (MOR) and subsequently induces antinociceptive effects in the spinal dorsal horn. However, the effects of EM2-MOR in PDN have not yet been clarified in the spinal dorsal horn. Therefore, we aimed to explore the role of EM2-MOR in the pathogenesis of PDN. The main findings were the following: (1) streptozotocin (STZ)-induced diabetic rats exhibited hyperglycemia, body weight loss and mechanical allodynia; (2) in the spinal dorsal horn, the expression levels of EM2 and MOR decreased in diabetic rats; (3) EM2 protein concentrations decreased in the brain, lumbar spinal cord and cerebrospinal fluid (CSF) in diabetic rats but were unchanged in the plasma; (4) the frequency but not the amplitude of spontaneous excitatory postsynaptic currents (sEPSCs) was significantly higher in diabetic rats than in control rats; and (5) intrathecal injection of EM2 for 14 days in the early stage of PDN partially alleviated mechanical allodynia and reduced MOR expression in diabetic rats. Our results demonstrate that the EM2-MOR signal may be involved in the early stage of PDN.
Collapse
Affiliation(s)
- Zhen-Zhen Kou
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Fa-Ping Wan
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Yang Bai
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Chun-Yu Li
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Jia-Chen Hu
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Guo-Tao Zhang
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Ting Zhang
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Tao Chen
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Ya-Yun Wang
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Hui Li
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Yun-Qing Li
- Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical UniversityXi'an, China; Collaborative Innovation Center for Brain Science, Fudan UniversityShanghai, China
| |
Collapse
|
10
|
Watanabe N, Piché M, Hotta H. Types of skin afferent fibers and spinal opioid receptors that contribute to touch-induced inhibition of heart rate changes evoked by noxious cutaneous heat stimulation. Mol Pain 2015; 11:4. [PMID: 25884917 PMCID: PMC4335417 DOI: 10.1186/s12990-015-0001-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 01/26/2015] [Indexed: 12/04/2022] Open
Abstract
Background In anesthetized rats and conscious humans, a gentle touch using a soft disc covered with microcones (with a texture similar to that of a finger), but not with a flat disc, inhibits nociceptive somatocardiac reflexes. Such an inhibitory effect is most reliably evoked when touch is applied to the skin ipsilateral and closest to nociceptive inputs. However, the mechanism of this inhibition is not completely elucidated. We aimed to clarify the types of cutaneous afferent fibers and spinal opioid receptors that contribute to antinociceptive effects of microcone touch. Results The present study comprised two experiments with urethane-anesthetized rats. In the first experiment, unitary activity of skin afferent fibers was recorded from the saphenous nerve, and responses to a 10-min touch using a microcone disc and a flat disc (control) were compared. Greater discharge rate during microcone touch was observed in low-threshold mechanoreceptive Aδ and C afferent units, whereas many Aβ afferents responded similarly to the two types of touch. In the second experiment, the effect of an intrathecal injection of opioid receptor antagonists on the inhibitory effects of microcone touch on heart rate responses to noxious heat stimulation was examined. The magnitude of the heart rate response was significantly reduced by microcone touch in rats that received saline or naltrindole (δ-opioid receptor antagonist) injections. However, such an inhibition was not observed in rats that received naloxone (non-selective opioid receptor antagonist) or Phe-Cys-Tyr-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP; μ-opioid receptor antagonist) injections. Conclusions Microcone touch induced greater responses of low-threshold mechanoreceptive Aδ and C afferent units than control touch. The antinociceptive effect of microcone touch was abolished by intrathecal injection of μ-opioid receptor antagonist. These results suggest that excitation of low-threshold mechanoreceptive Aδ and C afferents produces the release of endogenous μ-opioid ligands in the spinal cord, resulting in the inhibition of nociceptive transmission that contributes to somatocardiac reflexes.
Collapse
Affiliation(s)
- Nobuhiro Watanabe
- Department of Autonomic Neuroscience, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo, 173-0015, Japan.
| | - Mathieu Piché
- Department of Chiropractic, Université du Québec à Trois-Rivières, 3351 Boul. Des Forges, C.P 500, Trois-Rivières, Québec, G9A 5H7, Canada.
| | - Harumi Hotta
- Department of Autonomic Neuroscience, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo, 173-0015, Japan.
| |
Collapse
|
11
|
Wu XN, Zhang T, Qian NS, Guo XD, Yang HJ, Huang KB, Luo GQ, Xiang W, Deng WT, Dai GH, Peng KR, Pan SY. Antinociceptive effects of endomorphin-2: suppression of substance P release in the inflammatory pain model rat. Neurochem Int 2015; 82:1-9. [PMID: 25661513 DOI: 10.1016/j.neuint.2015.01.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Revised: 01/02/2015] [Accepted: 01/13/2015] [Indexed: 12/13/2022]
Abstract
Endomorphin-2 (EM2) and Substance P (SP) exert suppressive and facilitative influences upon nociception, respectively. Although EM2 and SP were often co-expressed in single neurons in dorsal root ganglion (DRG), it is still unknown if and how the nociception-suppressive influences of EM2 might be exerted upon nociception-facilitative effects of SP in the DRG neurons. We examined these issues in the inflammatory pain model rats produced by subcutaneous injection of the complete Freund's adjuvant into the hind paw. The paw withdrawal threshold for mechanical allodynia was measured. Changes of EM2 and SP release were estimated by measuring intrathecal levels of EM2 and SP through in vivo microdialysis analysis of cerebrospinal fluid. The mechanical allodynia was dose-dependently attenuated by intrathecal injection of EM2 or a neurokinin-1 receptor antagonist, and facilitated by intrathecal injection of SP or a mu-opioid receptor (MOR) antagonist. Importantly, intrathecal level of SP was found to be lowered by intrathecal injection of EM2. Morphologically, colocalization of EM2-, MOR- and SP-immunoreactivity in single DRG neurons was observed by immunofluorescent histochemistry, and co-expression of EM2 and SP in large, dense-cored presynaptic vesicles in primary afferents, as well as localization of MOR on pre- and postsynaptic membrane in spinal dorsal horn, was also confirmed electron miscroscopically. Thus, the results indicated that analgesic influences of EM2 upon inflammatory pain might be exerted through suppression of SP release, supporting the assumptions that binding of EM2 to presynaptic MOR might induce such effects.
Collapse
Affiliation(s)
- Xiao-Na Wu
- Department of Neurology, Nanfang Hospital of Southern Medical University, Guangzhou 510515, China; Department of Neurology, Guangzhou General Hospital of Guangzhou Military Command, Guangzhou 510010, China
| | - Tao Zhang
- Department of Orthopaedics, Guangzhou General Hospital of Guangzhou Military Command, Guangzhou 510010, China
| | - Nian-Song Qian
- Department of Oncology Unit 2, PLA General Hospital, Beijing 100853, China
| | - Xiao-Dong Guo
- Department of Neurosurgery, The 153th Hospital of PLA, Zhengzhou 450042, China
| | - Hong-Jun Yang
- Department of Neurology, Guangzhou General Hospital of Guangzhou Military Command, Guangzhou 510010, China
| | - Kai-Bin Huang
- Department of Neurology, Nanfang Hospital of Southern Medical University, Guangzhou 510515, China
| | - Gao-Quan Luo
- Department of Neurology, Guangzhou General Hospital of Guangzhou Military Command, Guangzhou 510010, China
| | - Wei Xiang
- Department of Neurology, Nanfang Hospital of Southern Medical University, Guangzhou 510515, China; Department of Neurology, Guangzhou General Hospital of Guangzhou Military Command, Guangzhou 510010, China
| | - Wen-Ting Deng
- Department of Neurology, Nanfang Hospital of Southern Medical University, Guangzhou 510515, China
| | - Guang-Hai Dai
- Department of Oncology Unit 2, PLA General Hospital, Beijing 100853, China.
| | - Kai-Run Peng
- Department of Neurology, Guangzhou General Hospital of Guangzhou Military Command, Guangzhou 510010, China.
| | - Su-Yue Pan
- Department of Neurology, Nanfang Hospital of Southern Medical University, Guangzhou 510515, China.
| |
Collapse
|
12
|
Li MY, Wu ZY, Lu YC, Yin JB, Wang J, Zhang T, Dong YL, Wang F. Connections between EM2-containing terminals and GABA/μ-opioid receptor co-expressing neurons in the rat spinal trigeminal caudal nucleus. Front Neural Circuits 2014; 8:125. [PMID: 25386121 PMCID: PMC4208411 DOI: 10.3389/fncir.2014.00125] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 09/29/2014] [Indexed: 01/15/2023] Open
Abstract
Endomorphin-2 (EM2) demonstrates a potent antinociceptive effect via the μ-opioid receptor (MOR). To provide morphological evidence for the pain control effect of EM2, the synaptic connections between EM2-immunoreactive (IR) axonal terminals and γ-amino butyric acid (GABA)/MOR co-expressing neurons in lamina II of the spinal trigeminal caudal nucleus (Vc) were investigated in the rat. Dense EM2-, MOR- and GABA-IR fibers and terminals were mainly observed in lamina II of the Vc. Within lamina II, GABA- and MOR-neuronal cell bodies were also encountered. The results of immunofluorescent histochemical triple-staining showed that approximately 14.2 or 18.9% of GABA-IR or MOR-IR neurons also showed MOR- or GABA-immunopositive staining in lamina II; approximately 45.2 and 36.1% of the GABA-IR and MOR-IR neurons, respectively, expressed FOS protein in their nuclei induced by injecting formalin into the left lower lip of the mouth. Most of the GABA/MOR, GABA/FOS, and MOR/FOS double-labeled neurons made close contacts with EM2-IR fibers and terminals. Immuno-electron microscopy confirmed that the EM2-IR terminals formed synapses with GABA-IR or MOR-IR dendritic processes and neuronal cell bodies in lamina II of the Vc. These results suggest that EM2 might participate in pain transmission and modulation by binding to MOR-IR and GABAergic inhibitory interneuron in lamina II of the Vc to exert inhibitory effect on the excitatory interneuron in lamina II and projection neurons in laminae I and III.
Collapse
Affiliation(s)
- Meng-Ying Li
- Department of Nutrition and Food Hygiene, The Fourth Military Medical University Xi'an, China
| | - Zhen-Yu Wu
- Department of Anatomy, Histology and Embryology, K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Ya-Cheng Lu
- Department of Anatomy, Histology and Embryology, K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Jun-Bin Yin
- Department of Anatomy, Histology and Embryology, K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Jian Wang
- Department of Anatomy, Histology and Embryology, K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Ting Zhang
- Department of Anatomy, Histology and Embryology, K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Yu-Lin Dong
- Department of Anatomy, Histology and Embryology, K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China
| | - Feng Wang
- Department of Nutrition and Food Hygiene, The Fourth Military Medical University Xi'an, China
| |
Collapse
|
13
|
Kawabe T, Ueyama T, Hano T, Sapru HN. Cardiovascular responses to microinjections of endomorphin-2 into the nucleus of the solitary tract are attenuated in the spontaneously hypertensive rat. Clin Exp Hypertens 2014; 37:197-206. [DOI: 10.3109/10641963.2014.933969] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Tetsuya Kawabe
- Center for Educational Research and Development, Wakayama Medical University, Wakayama, Japan,
| | - Takashi Ueyama
- Department of Anatomy and Cell Biology, Wakayama Medical University, Wakayama, Japan, and
| | - Takuzo Hano
- Center for Educational Research and Development, Wakayama Medical University, Wakayama, Japan,
| | - Hreday N. Sapru
- Department of Neurological Surgery, Rutgers New Jersey Medical School, Newark, NJ, USA
| |
Collapse
|
14
|
Gyires K, Zádori ZS. Brain neuropeptides in gastric mucosal protection. Curr Opin Pharmacol 2014; 19:24-30. [PMID: 24971914 DOI: 10.1016/j.coph.2014.06.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 05/29/2014] [Accepted: 06/01/2014] [Indexed: 01/15/2023]
Abstract
The centrally induced gastroprotective effect of neuropeptides has been intensively studied. Besides many similarities, however, differences can also be observed in their gastroprotective actions. The gastroprotective dose-response curve proved to be either sigmoid, or bell-shaped. Additional gastrointestinal effects of neuropeptides can contribute to their mucosal protective effect. Part of the neuropeptides induces gastroprotection by peripheral administration as well. Besides vagal nerve the sympathetic nervous system may also be involved in conveying the central effect to the periphery. Better understanding of the complex mechanism of the maintenance of gastric mucosal integrity may result in the development of new strategy to enhance gastric mucosal resistance against injury.
Collapse
Affiliation(s)
- Klára Gyires
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, Semmelweis University, Nagyvárad tér 4, 1089, Budapest, Hungary.
| | - Zoltán S Zádori
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, Semmelweis University, Nagyvárad tér 4, 1089, Budapest, Hungary
| |
Collapse
|
15
|
Luo DS, Huang J, Dong YL, Wu ZY, Wei YY, Lu YC, Wang YY, Yanagawa Y, Wu SX, Wang W, Li YQ. Connections between EM2- and SP-containing terminals and GABAergic neurons in the mouse spinal dorsal horn. Neurol Sci 2014; 35:1421-7. [PMID: 24718557 DOI: 10.1007/s10072-014-1774-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 03/25/2014] [Indexed: 12/22/2022]
Abstract
Endomorphin-2 (EM2) demonstrates a potent antinociceptive effect in pain modulation. To investigate the potential interactions of EM2- and substance P (SP)-containing primary afferents and γ-amino butyric acid (GABA)-containing interneurons in lamina II in nociceptive transmission, connections between EM2- and SP-containing terminals and GABAergic neurons in the spinal dorsal horn were studied. Double-immunofluorescent labeling showed that approximately 62.3 % of EM2-immunoreactive neurons exhibited SP-immunostaining, and 76.9 % of SP-immunoreactive neurons demonstrated EM2-immunoreactivities in the dorsal root ganglion (DRG). Dense double-labeled EM2- and SP-immunoreactivities were mainly observed in lamina II of the lumbar dorsal horn. Furthermore, triple-immunofluorescent labeling results revealed that EM2 and SP double-labeled terminals overlapped with GABAergic neurons. Immuno-electron microscopy confirmed that the EM2- or SP-immunoreactive terminals formed synapses with GABA-immunoreactive dendrites in lamina II of the lumbar dorsal horn. During noxious information transmission induced by formalin plantar injection, GABAergic neurons expressing FOS in their nuclei were contacted with EM2- or SP-immunoreactive terminals. These results suggest that the interactions between EM2- and SP-containing terminals and GABAergic interneurons in the lamina II influence pain transmission and modulation in the spinal dorsal horn.
Collapse
Affiliation(s)
- Dao-Shu Luo
- Department of Anatomy, Histology and Embryology, Basic Medical College, Fujian Medical University, Fuzhou, 350004, China
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Stuth EAE, Stucke AG, Zuperku EJ. Effects of anesthetics, sedatives, and opioids on ventilatory control. Compr Physiol 2013; 2:2281-367. [PMID: 23720250 DOI: 10.1002/cphy.c100061] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
This article provides a comprehensive, up to date summary of the effects of volatile, gaseous, and intravenous anesthetics and opioid agonists on ventilatory control. Emphasis is placed on data from human studies. Further mechanistic insights are provided by in vivo and in vitro data from other mammalian species. The focus is on the effects of clinically relevant agonist concentrations and studies using pharmacological, that is, supraclinical agonist concentrations are de-emphasized or excluded.
Collapse
Affiliation(s)
- Eckehard A E Stuth
- Medical College of Wisconsin, Anesthesia Research Service, Zablocki VA Medical Center, Milwaukee, Wisconsin, USA.
| | | | | |
Collapse
|
17
|
Brancati SB, Zádori ZS, Németh J, Gyires K. Substance P induces gastric mucosal protection at supraspinal level via increasing the level of endomorphin-2 in rats. Brain Res Bull 2013; 91:38-45. [PMID: 23328537 DOI: 10.1016/j.brainresbull.2013.01.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 01/04/2013] [Accepted: 01/07/2013] [Indexed: 02/02/2023]
Abstract
The aim of the present study was to analyze the potential role of substance P (SP) in gastric mucosal defense and to clarify the receptors and mechanisms that may be involved in it. Gastric ulceration was induced by oral administration of acidified ethanol in male Wistar rats. Mucosal levels of calcitonin gene-related peptide (CGRP) and somatostatin were determined by radioimmunoassay. For analysis of gastric motor activity the rubber balloon method was used. We found that central (intracerebroventricular) injection of SP (9.3-74 pmol) dose-dependently inhibited the formation of ethanol-induced ulcers, while intravenously injected SP (0.37-7.4 nmol/kg) had no effect. The mucosal protective effect of SP was inhibited by pretreatment with neurokinin 1-, neurokinin 2-, neurokinin 3- and μ-opioid receptor antagonists, while δ- and κ-opioid receptor antagonists had no effect. Endomorphin-2 antiserum also antagonized the SP-induced mucosal protection. In the gastroprotective dose range SP failed to influence the gastric motor activity. Inhibition of muscarinic cholinergic receptors, or the synthesis of nitric oxide or prostaglandins significantly reduced the effect of SP. In addition, centrally injected SP reversed the ethanol-induced reduction of gastric mucosal CGRP content. It can be concluded, that SP may induce gastric mucosal protection initiated centrally. Its protective effect is likely to be mediated by endomorphin-2, and vagal nerve may convey the centrally initiated protection to the periphery, where both prostaglandins, nitric oxide and CGRP are involved in mediating this effect.
Collapse
Affiliation(s)
- Serena B Brancati
- Department of Pharmaceutical Sciences - Pharmacology Section, University of Catania, Viale A. Doria 6, 95125 Catania, Italy
| | | | | | | |
Collapse
|
18
|
Fechir M, Breimhorst M, Kritzmann S, Geber C, Schlereth T, Baier B, Birklein F. Naloxone inhibits not only stress-induced analgesia but also sympathetic activation and baroreceptor-reflex sensitivity. Eur J Pain 2012; 16:82-92. [DOI: 10.1016/j.ejpain.2011.06.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- M. Fechir
- Department of Neurology; University Medical Center of the Johannes Gutenberg-University Mainz; Langenbeckstrasse 1; D-55101; Mainz; Germany
| | - M. Breimhorst
- Department of Neurology; University Medical Center of the Johannes Gutenberg-University Mainz; Langenbeckstrasse 1; D-55101; Mainz; Germany
| | - S. Kritzmann
- Department of Neurology; University Medical Center of the Johannes Gutenberg-University Mainz; Langenbeckstrasse 1; D-55101; Mainz; Germany
| | - C. Geber
- Department of Neurology; University Medical Center of the Johannes Gutenberg-University Mainz; Langenbeckstrasse 1; D-55101; Mainz; Germany
| | - T. Schlereth
- Department of Neurology; University Medical Center of the Johannes Gutenberg-University Mainz; Langenbeckstrasse 1; D-55101; Mainz; Germany
| | - B. Baier
- Department of Neurology; University Medical Center of the Johannes Gutenberg-University Mainz; Langenbeckstrasse 1; D-55101; Mainz; Germany
| | - F. Birklein
- Department of Neurology; University Medical Center of the Johannes Gutenberg-University Mainz; Langenbeckstrasse 1; D-55101; Mainz; Germany
| |
Collapse
|
19
|
The dipeptidyl peptidase IV (CD26, EC 3.4.14.5) inhibitor vildagliptin is a potent antihyperalgesic in rats by promoting endomorphin-2 generation in the spinal cord. Eur J Pharmacol 2011; 650:195-9. [DOI: 10.1016/j.ejphar.2010.09.060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 09/09/2010] [Accepted: 09/20/2010] [Indexed: 12/17/2022]
|
20
|
Hui R, Wang W, Chen T, Lü BC, Li H, Zhang T, Wu SX, Li YQ. Origins of endomorphin-2 immunopositive fibers and terminals in the spinal dorsal horn of the rat. Neuroscience 2010; 169:422-30. [PMID: 20457220 DOI: 10.1016/j.neuroscience.2010.05.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 05/02/2010] [Accepted: 05/03/2010] [Indexed: 01/06/2023]
Abstract
Endomorphin 2 (EM2) plays essential roles in regulating nociceptive transmission within the spinal dorsal horn, where EM2-immunopositive (EM2-IP) fibers and terminals are densely encountered. However, the origins of these EM2-IP structures are still obscure. Unilateral primary sensory afferents disruption (lumbar 3-6 dorsal roots rhizotomy) significantly decreased the density of EM2-IP fibers and terminals in the superficial laminae (laminae I and II) on the ipsilateral but not contralateral lumbar dorsal horn (LDH). Spinal hemisection at the 7th thoracic (T7) segment down-regulated bilateral EM2 expression, with a higher influence on the ipsilateral side of the LDH. Unilateral L3-6 dorsal roots rhizotomy combined with spinal transection but not with hemisection at T7 level completely obliterated EM2-IP fibers and terminals on the rhizotomized-side of the LDH. Disruption of bilateral (exposure to the primary afferent neurotoxin, capsaicin) primary sensory afferents combined with spinal hemisection at T7 decreased the EM2-IP density bilaterally but could obliterate it on neither side of the LDH. While in capsaicin plus transection rats, EM2 was depleted symmetrically and completely. In the colchicine treated rats, no EM2-IP neuronal cell bodies could be detected in the spinal gray matter. After injecting tetramethyl rhodamine dextran-amine (TMR) into the LDH, some of the TMR retrogradely labeled neurons in the nucleus tractus solitarii (NTS) showed EM2-immunoreactivities. The present results indicate that EM2-IP fibers and terminals in the spinal dorsal horn originate from the ipsilateral primary afferents and bilateral descending fibers from NTS.
Collapse
Affiliation(s)
- R Hui
- Department of Anatomy, Histology & Embryology, K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an 710032, PR China
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Sex differences in the activation of the spinoparabrachial circuit by visceral pain. Physiol Behav 2009; 97:205-12. [PMID: 19275905 DOI: 10.1016/j.physbeh.2009.02.037] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 02/23/2009] [Accepted: 02/24/2009] [Indexed: 12/16/2022]
Abstract
Women are more sensitive to most noxious visceral stimuli, both in terms of intensity and frequency. The spinoparabrachial (spino-PBn) pathway is an essential neural circuit for the central relay of viscerosensitive information, but studies characterizing the anatomical and physiological characteristics of this pathway have only been conducted in males. Sex differences in the anatomical and/or physiological organization of the spino-PBn may contribute to the sexually dimorphic incidence rate for visceral pain syndromes. Retrograde labeling and colorectal distention (CRD) induced Fos expression was used to delineate the spino-PBn circuit in male and cycling female Sprague-Dawley rats. The ability of morphine to suppress CRD evoked responses was also examined. Neurons retrogradely labeled from the PBn were localized primarily within the superficial dorsal horn and sacral parasympathetic nucleus of the L5-S1 spinal cord. While no sex differences were noted in either the distribution of spino-PBn neurons or in CRD-induced Fos expression, significantly greater Fos expression was noted specifically in spino-PBn neurons in males compared to females. Morphine selectively attenuated Fos expression in spino-PBn neurons in males, but not females. Subsequent anatomical studies showed significantly reduced mu opioid receptor protein levels and radioligand binding within the PBn of females in comparison to males. Together, these data indicate that there are profound sex differences in how a noxious visceral stimulus and opiates engage the spino-PBn pathway, which may account for the observed clinical differences in visceral pain sensitivity and morphine antinociception.
Collapse
|
22
|
Abstract
This paper is the thirtieth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2007 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.
Collapse
Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, 65-30 Kissena Blvd.,Flushing, NY 11367, United States.
| |
Collapse
|
23
|
Szemenyei E, Barna I, Mergl Z, Keresztes A, Darula Z, Kató E, Tóth G, Rónai AZ. Detection of a novel immunoreactive endomorphin 2-like peptide in rat brain extracts. ACTA ACUST UNITED AC 2008; 148:54-61. [DOI: 10.1016/j.regpep.2008.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Revised: 02/11/2008] [Accepted: 03/04/2008] [Indexed: 10/22/2022]
|
24
|
Scanlin HL, Carroll EA, Jenkins VK, Balkowiec A. Endomorphin-2 is released from newborn rat primary sensory neurons in a frequency- and calcium-dependent manner. Eur J Neurosci 2008; 27:2629-42. [PMID: 18513316 DOI: 10.1111/j.1460-9568.2008.06238.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recent evidence indicates that endomorphins, endogenous mu-opioid receptor (MOR) agonists, modulate synaptic transmission in both somatic and visceral sensory pathways. Here we show that endomorphin-2 (END-2) is expressed in newborn rat dorsal root ganglion (DRG) and nodose-petrosal ganglion complex (NPG) neurons, and rarely co-localizes with brain-derived neurotrophic factor (BDNF). In order to examine activity-dependent release of END-2 from neurons, we established a model using dispersed cultures of DRG and NPG cells activated by patterned electrical field stimulation. To detect release of END-2, we developed a novel rapid capture enzyme-linked immunosorbent assay (ELISA), in which END-2 capture antibody was added to neuronal cultures shortly before their electrical stimulation. The conventional assay was effective at reliably detecting END-2 only when the cells were stimulated in the presence of CTAP, a MOR-selective antagonist. This suggests that the strength of the novel assay is related primarily to rapid capture of released END-2 before it binds to endogenous MORs. Using the rapid capture ELISA, we found that stimulation protocols known to induce plastic changes at sensory synapses were highly effective at releasing END-2. Removal of extracellular calcium or blocking voltage-activated calcium channels significantly reduced the release. Together, our data provide the first evidence that END-2 is expressed by newborn DRG neurons of all sizes found in this age group, and can be released from these, as well as from NPG neurons, in an activity-dependent manner. These results point to END-2 as a likely mediator of activity-dependent plasticity in sensory pathways.
Collapse
Affiliation(s)
- Heather L Scanlin
- Department of Integrative Biosciences, Oregon Health and Science University, Portland, OR 97239, USA
| | | | | | | |
Collapse
|