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Gong HS, Pan JP, Guo F, Wu MM, Dong L, Li Y, Rong WF. Sodium oligomannate activates the enteroendocrine-vagal afferent pathways in APP/PS1 mice. Acta Pharmacol Sin 2024:10.1038/s41401-024-01293-w. [PMID: 38702501 DOI: 10.1038/s41401-024-01293-w] [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: 10/06/2023] [Accepted: 04/15/2024] [Indexed: 05/06/2024] Open
Abstract
Enteroendocrine cells (EECs) and vagal afferent neurons constitute functional sensory units of the gut, which have been implicated in bottom-up modulation of brain functions. Sodium oligomannate (GV-971) has been shown to improve cognitive functions in murine models of Alzheimer's disease (AD) and recently approved for the treatment of AD patients in China. In this study, we explored whether activation of the EECs-vagal afferent pathways was involved in the therapeutic effects of GV-971. We found that an enteroendocrine cell line RIN-14B displayed spontaneous calcium oscillations due to TRPA1-mediated calcium entry; perfusion of GV-971 (50, 100 mg/L) concentration-dependently enhanced the calcium oscillations in EECs. In ex vivo murine jejunum preparation, intraluminal infusion of GV-971 (500 mg/L) significantly increased the spontaneous and distension-induced discharge rate of the vagal afferent nerves. In wild-type mice, administration of GV-971 (100 mg· kg-1 ·d-1, i.g. for 7 days) significantly elevated serum serotonin and CCK levels and increased jejunal afferent nerve activity. In 7-month-old APP/PS1 mice, administration of GV-971 for 12 weeks significantly increased jejunal afferent nerve activity and improved the cognitive deficits in behavioral tests. Sweet taste receptor inhibitor Lactisole (0.5 mM) and the TRPA1 channel blocker HC-030031 (10 µM) negated the effects of GV-971 on calcium oscillations in RIN-14B cells as well as on jejunal afferent nerve activity. In APP/PS1 mice, co-administration of Lactisole (30 mg ·kg-1 ·d-1, i.g. for 12 weeks) attenuated the effects of GV-971 on serum serotonin and CCK levels, vagal afferent firing, and cognitive behaviors. We conclude that GV-971 activates sweet taste receptors and TRPA1, either directly or indirectly, to enhance calcium entry in enteroendocrine cells, resulting in increased CCK and 5-HT release and consequent increase of vagal afferent activity. GV-971 might activate the EECs-vagal afferent pathways to modulate cognitive functions.
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Affiliation(s)
- Hua-Shan Gong
- Songjiang Research Institute, Shanghai Songjiang District Central Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 201600, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Jing-Pei Pan
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Fei Guo
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Mei-Mei Wu
- Songjiang Research Institute, Shanghai Songjiang District Central Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 201600, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Li Dong
- Songjiang Research Institute, Shanghai Songjiang District Central Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 201600, China
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Yang Li
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, 200040, China.
| | - Wei-Fang Rong
- Songjiang Research Institute, Shanghai Songjiang District Central Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 201600, China.
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
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Mulak A, Larauche M, Biraud M, Million M, Rivier J, Taché Y. Selective agonists of somatostatin receptor subtype 1 or 2 injected peripherally induce antihyperalgesic effect in two models of visceral hypersensitivity in mice. Peptides 2015; 63:71-80. [PMID: 25451334 PMCID: PMC4385413 DOI: 10.1016/j.peptides.2014.10.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 10/27/2014] [Accepted: 10/28/2014] [Indexed: 02/08/2023]
Abstract
Somatostatin interacts with five G-protein-coupled receptor (sst1-5). Octreotide, a stable sst2≫3≥5 agonist, exerts a visceral anti-hyperalgesic effect in experimental and clinical studies. Little is known on the receptor subtypes involved. We investigated the influence of the stable sst1-5 agonist, ODT8-SST and selective receptor subtype peptide agonists (3 or 10μg/mouse) injected intraperitoneally (ip) on visceral hypersensitivity in mice induced by repeated noxious colorectal distensions (four sets of three CRD, each at 55mmHg) or corticotropin-releasing factor receptor 1 agonist, cortagine given between two sets of graded CRD (15, 30, 45, and 60mmHg, three times each pressure). The mean visceromotor response (VMR) was assessed using a non-invasive manometry method and values were expressed as percentage of the VMR to the 1st set of CRD baseline or to the 60mmHg CRD, respectively. ODT8-SST (10μg) and the sst2 agonist, S-346-011 (3 and 10μg) prevented mechanically induced visceral hypersensitivity in the three sets of CRD, the sst1 agonist (10μg) blocked only the 2nd set and showed a trend at 3μg while the sst4 agonist had no effect. The selective sst2 antagonist, S-406-028 blocked the sst2 agonist but not the sst1 agonist effect. The sst1 agonist (3 and 10μg) prevented cortagine-induced hypersensitivity to CRD at each pressure while the sst2 agonist at 10μg reduced it. These data indicate that in addition to sst2, the sst1 agonist may provide a novel promising target to alleviate visceral hypersensitivity induced by mechanoreceptor sensitization and more prominently, stress-related visceral nociceptive sensitization.
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Affiliation(s)
- Agata Mulak
- Department of Medicine, CURE: Digestive Diseases Research Center and Oppenheimer Family Center for Neurobiology of Stress, Digestive Diseases Division at the University of California Los Angeles and VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA; Department of Gastroenterology and Hepatology, Wroclaw Medical University, Wroclaw, Poland
| | - Muriel Larauche
- Department of Medicine, CURE: Digestive Diseases Research Center and Oppenheimer Family Center for Neurobiology of Stress, Digestive Diseases Division at the University of California Los Angeles and VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Mandy Biraud
- Department of Medicine, CURE: Digestive Diseases Research Center and Oppenheimer Family Center for Neurobiology of Stress, Digestive Diseases Division at the University of California Los Angeles and VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Mulugeta Million
- Department of Medicine, CURE: Digestive Diseases Research Center and Oppenheimer Family Center for Neurobiology of Stress, Digestive Diseases Division at the University of California Los Angeles and VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Jean Rivier
- The Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, CA, USA
| | - Yvette Taché
- Department of Medicine, CURE: Digestive Diseases Research Center and Oppenheimer Family Center for Neurobiology of Stress, Digestive Diseases Division at the University of California Los Angeles and VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA.
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3
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Acupuncture for visceral pain: neural substrates and potential mechanisms. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2014; 2014:609594. [PMID: 25614752 PMCID: PMC4295157 DOI: 10.1155/2014/609594] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 12/13/2014] [Accepted: 12/13/2014] [Indexed: 12/17/2022]
Abstract
Visceral pain is the most common form of pain caused by varied diseases and a major reason for patients to seek medical consultation. Despite much advances, the pathophysiological mechanism is still poorly understood comparing with its somatic counterpart and, as a result, the therapeutic efficacy is usually unsatisfactory. Acupuncture has long been used for the management of numerous disorders in particular pain and visceral pain, characterized by the high therapeutic benefits and low adverse effects. Previous findings suggest that acupuncture depresses pain via activation of a number of neurotransmitters or modulators including opioid peptides, serotonin, norepinephrine, and adenosine centrally and peripherally. It endows us, by advancing the understanding of the role of ion channels and gut microbiota in pain process, with novel perspectives to probe the mechanisms underlying acupuncture analgesia. In this review, after describing the visceral innervation and the relevant afferent pathways, in particular the ion channels in visceral nociception, we propose three principal mechanisms responsible for acupuncture induced benefits on visceral pain. Finally, potential topics are highlighted regarding the future studies in this field.
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Reed DE, Blackshaw LA. Inhibition of visceral nociceptors. Front Pharmacol 2014; 5:72. [PMID: 24782775 PMCID: PMC3995067 DOI: 10.3389/fphar.2014.00072] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 03/27/2014] [Indexed: 12/12/2022] Open
Affiliation(s)
- David E Reed
- Neurogastroenterolohy Group, Centre for Digestive Diseases, Blizard Institute, Queen Mary University of London London, UK
| | - L Ashley Blackshaw
- Neurogastroenterolohy Group, Centre for Digestive Diseases, Blizard Institute, Queen Mary University of London London, UK
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Grider JS, Ackerman WE. Opioid-induced hyperalgesia and tolerance: understanding opioid side effects. Expert Rev Clin Pharmacol 2014; 1:291-7. [PMID: 24422653 DOI: 10.1586/17512433.1.2.291] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Opioid-induced pain or opioid tolerance should be considered when opioid therapy fails to provide expected analgesic effects or when there is unexplainable pain exacerbation following opioid treatment. As a result, an increase in the opioid dosage may not be the solution to ineffective opioid therapy for chronic pain management. A decrease in the opioid mass may actually provide pain relief in many instances. At one time, it was anticipated that opioid-induced pain was related to upregulation of NMDA receptors with a downregulation of mu receptors. However, there is growing evidence to suggest the opioid receptor-based hyperalgesic mechanism may be directly modulated by the NMDA receptor. Furthermore, the mechanism that causes opioid tolerance may be the same mechanism that causes opioid-induced pain. Current evidence suggests that opioid-induced pain sensitivity could be prevented by interrupting the cellular and molecular changes associated with the development of opioid tolerance. Continued research may lead the way to a new period in which patients prone to opioid-induced pain could be identified, allowing one to tailor pharmacologic pain therapy to each patient.
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Affiliation(s)
- Jay S Grider
- Assistant Professor, University of Kentucky, College of Medicine, Department of Anesthesiology, 800 Rose Street Suite, N 201, Lexington, KY 40536, USA. ; www.mc.uky.edu/anesthesiology
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Yang J, Zhao J, Jiang W, Nakaguchi T, Kunwald P, Grundy D, Gregersen H. Neurogenic adaptation contributes to the afferent response to mechanical stimulation. Am J Physiol Gastrointest Liver Physiol 2012; 302:G1025-34. [PMID: 22345553 DOI: 10.1152/ajpgi.00513.2010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This study aimed to characterize the effect of mechanical stimuli on mesenteric afferent nerve signaling in the isolated rat jejunum in vitro. This was done to determine the effect of mechanical stresses and strains relative to nonmechanical parameters (neurogenic adaptation). Mechanical stimulations were applied to a segment of jejunum from 15 rats using ramp distension with water at three rates of distension, a relaxation test (volume maintained constant from initial pressure of 20 or 40 mmHg), and a creep test (pressure maintained constant). Circumferential stress and strain and the spike rate increase ratio were calculated for evaluation of afferent nerve activity during the mechanical stimulations. Ramp distension evoked two distinct phases of afferent nerve signaling as a function of circumferential stress or strain. Changing the volume distension rate did not change the stress-strain relationship, but faster distension rate increased the afferent firing rate (P < 0.05). In the stress relaxation test, the spike rate declined faster and to a greater extent than the stress. In the creep test, the spike rate declined, despite a small increase in the strain. Three classes of mechanosensitive single-afferent units (low, wide dynamic range, and high threshold units) showed different response profiles against stress and strain. Low-threshold units exhibited a near linear relationship against the strain (R(2) = 0.8095), whereas high-threshold units exhibited a linear profile against the stress (R(2) = 0.9642). The afferent response is sensitive to the distension speed and to the stress and strain level during distension. However, the afferent nerve response is not a simple function of either stress or strain. Nonmechanical time-dependent adaptive responses other than those related to viscoelasticity also play a role.
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Affiliation(s)
- J Yang
- Mech-Sense, Aalborg Hospital, Aalborg, Denmark
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Rasmussen BA, Breen DM, Luo P, Cheung GWC, Yang CS, Sun B, Kokorovic A, Rong W, Lam TKT. Duodenal activation of cAMP-dependent protein kinase induces vagal afferent firing and lowers glucose production in rats. Gastroenterology 2012; 142:834-843.e3. [PMID: 22245844 DOI: 10.1053/j.gastro.2011.12.053] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 12/23/2011] [Accepted: 12/27/2011] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS The duodenum senses nutrients to maintain energy and glucose homeostasis, but little is known about the signaling and neuronal mechanisms involved. We tested whether duodenal activation of adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase A (PKA) is sufficient and necessary for cholecystokinin (CCK) signaling to trigger vagal afferent firing and regulate glucose production. METHODS In rats, we selectively activated duodenal PKA and evaluated changes in glucose kinetics during the pancreatic (basal insulin) pancreatic clamps and vagal afferent firing. The requirement of duodenal PKA signaling in glucose regulation was evaluated by inhibiting duodenal activation of PKA in the presence of infusion of the intraduodenal PKA agonist (Sp-cAMPS) or CCK1 receptor agonist (CCK-8). We also assessed the involvement of a neuronal network and the metabolic impact of duodenal PKA activation in rats placed on high-fat diets. RESULTS Intraduodenal infusion of Sp-cAMPS activated duodenal PKA and lowered glucose production, in association with increased vagal afferent firing in control rats. The metabolic and neuronal effects of duodenal Sp-cAMPS were negated by coinfusion with either the PKA inhibitor H89 or Rp-CAMPS. The metabolic effect was also negated by coinfusion with tetracaine, molecular and pharmacologic inhibition of NR1-containing N-methyl-d-aspartate (NMDA) receptors within the dorsal vagal complex, or hepatic vagotomy in rats. Inhibition of duodenal PKA blocked the ability of duodenal CCK-8 to reduce glucose production in control rats, whereas duodenal Sp-cAMPS bypassed duodenal CCK resistance and activated duodenal PKA and lowered glucose production in rats on high-fat diets. CONCLUSIONS We identified a neural glucoregulatory function of duodenal PKA signaling.
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Affiliation(s)
- Brittany A Rasmussen
- Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
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8
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Wang YP, Sun BY, Li Q, Dong L, Zhang GH, Grundy D, Rong WF. Hyperpolarization-activated cyclic nucleotide-gated cation channel subtypes differentially modulate the excitability of murine small intestinal afferents. World J Gastroenterol 2012; 18:522-31. [PMID: 22363118 PMCID: PMC3280397 DOI: 10.3748/wjg.v18.i6.522] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2011] [Revised: 06/21/2011] [Accepted: 06/28/2011] [Indexed: 02/06/2023] Open
Abstract
AIM: To assess the role of hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channels in regulating the excitability of vagal and spinal gut afferents.
METHODS: The mechanosensory response of mesenteric afferent activity was measured in an ex vivo murine jejunum preparation. HCN channel activity was recorded through voltage and current clamp in acutely dissociated dorsal root ganglia (DRG) and nodose ganglia (NG) neurons retrogradely labeled from the small intestine through injection of a fluorescent marker (DiI). The isoforms of HCN channels expressed in DRG and NG neurons were examined by immunohistochemistry.
RESULTS: Ramp distension of the small intestine evoked biphasic increases in the afferent nerve activity, reflecting the activation of low- and high-threshold fibers. HCN blocker CsCl (5 mmol/L) preferentially inhibited the responses of low-threshold fibers to distension and showed no significant effects on the high-threshold responses. The effect of CsCl was mimicked by the more selective HCN blocker ZD7288 (10 μmol/L). In 71.4% of DiI labeled DRG neurons (n = 20) and 90.9% of DiI labeled NG neurons (n = 10), an inward current (Ih current) was evoked by hyperpolarization pulses which was fully eliminated by extracellular CsCl. In neurons expressing Ih current, a typical “sag” was observed upon injection of hyperpolarizing current pulses in current-clamp recordings. CsCl abolished the sag entirely. In some DiI labeled DRG neurons, the Ih current was potentiated by 8-Br-cAMP, which had no effect on the Ih current of DiI labeled NG neurons. Immunohistochemistry revealed differential expression of HCN isoforms in vagal and spinal afferents, and HCN2 and HCN3 seemed to be the dominant isoform in DRG and NG, respectively.
CONCLUSION: HCNs differentially regulate the excitability of vagal and spinal afferent of murine small intestine.
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Stengel A, Taché Y. Activation of somatostatin 2 receptors in the brain and the periphery induces opposite changes in circulating ghrelin levels: functional implications. Front Endocrinol (Lausanne) 2012; 3:178. [PMID: 23335913 PMCID: PMC3542632 DOI: 10.3389/fendo.2012.00178] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 12/17/2012] [Indexed: 12/26/2022] Open
Abstract
Somatostatin is an important modulator of neurotransmission in the central nervous system and acts as a potent inhibitor of hormone and exocrine secretion and regulator of cell proliferation in the periphery. These pleiotropic actions occur through interaction with five G protein-coupled somatostatin receptor subtypes (sst(1) (-) (5)) that are widely expressed in the brain and peripheral organs. The characterization of somatostatin's effects can be investigated by pharmacological or genetic approaches using newly developed selective sst agonists and antagonists and mice lacking specific sst subtypes. Recent evidence points toward a divergent action of somatostatin in the brain and in the periphery to regulate circulating levels of ghrelin, an orexigenic hormone produced by the endocrine X/A-like cells in the rat gastric mucosa. Somatostatin interacts with the sst(2) in the brain to induce an increase in basal ghrelin plasma levels and counteracts the visceral stress-related decrease in circulating ghrelin. By contrast, stimulation of peripheral somatostatin-sst(2) signaling results in the inhibition of basal ghrelin release and mediates the postoperative decrease in circulating ghrelin. The peripheral sst(2)-mediated reduction of plasma ghrelin is likely to involve a paracrine action of D cell-derived somatostatin acting on sst(2) bearing X/A-like ghrelin cells in the gastric mucosa. The other member of the somatostatin family, named cortistatin, in addition to binding to sst(1) (-) (5) also directly interacts with the ghrelin receptor and therefore may simultaneously modulate ghrelin release and actions at target sites bearing ghrelin receptors representing a link between the ghrelin and somatostatin systems.
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Affiliation(s)
- Andreas Stengel
- Division Psychosomatic Medicine and Psychotherapy, Department of Medicine, Obesity Center Berlin, Charité, Universitätsmedizin BerlinBerlin, Germany
- *Correspondence: Andreas Stengel, Division Psychosomatic Medicine and Psychotherapy, Department of Medicine, Obesity Center Berlin, Charité, Universitätsmedizin Berlin, Luisenstr. 13a, 10117 Berlin, Germany. e-mail: ; Yvette Taché, Digestive Diseases Division, CURE: Digestive Diseases Research Center, Center for Neurobiology of Stress and Women’s Health, Department of Medicine, VA Greater Los Angeles Health Care System, University of California at Los Angeles, CURE Building 115, Room 117, 11301 Wilshire Boulevard, Los Angeles, CA 90073, USA. e-mail:
| | - Yvette Taché
- Digestive Diseases Division, CURE: Digestive Diseases Research Center, Center for Neurobiology of Stress and Women’s Health, Department of Medicine, VA Greater Los Angeles Health Care System, University of California at Los AngelesLos Angeles, CA, USA
- *Correspondence: Andreas Stengel, Division Psychosomatic Medicine and Psychotherapy, Department of Medicine, Obesity Center Berlin, Charité, Universitätsmedizin Berlin, Luisenstr. 13a, 10117 Berlin, Germany. e-mail: ; Yvette Taché, Digestive Diseases Division, CURE: Digestive Diseases Research Center, Center for Neurobiology of Stress and Women’s Health, Department of Medicine, VA Greater Los Angeles Health Care System, University of California at Los Angeles, CURE Building 115, Room 117, 11301 Wilshire Boulevard, Los Angeles, CA 90073, USA. e-mail:
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Moncayo R. Reflections on the theory of "silver bullet" octreotide tracers: implications for ligand-receptor interactions in the age of peptides, heterodimers, receptor mosaics, truncated receptors, and multifractal analysis. EJNMMI Res 2011; 1:9. [PMID: 22214590 PMCID: PMC3251005 DOI: 10.1186/2191-219x-1-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 07/26/2011] [Indexed: 12/25/2022] Open
Abstract
The classical attitude of Nuclear Medicine practitioners on matters of peptide-receptor interactions has maintained an intrinsic monogamic character since many years. New advances in the field of biochemistry and even in clinical Nuclear Medicine have challenged this type of thinking, which prompted me to work on this review. The central issue of this paper will be the use of somatostatin analogs, i.e., octreotide, in clinical imaging procedures as well as in relation to neuroendocirne tumors. Newly described characteristics of G-protein coupled receptors such as the formation of receptor mosaics will be discussed. A small section will enumerate the regulatory processes found in the cell membrane. Possible new interpretations, other than tumor detection, based on imaging procedures with somatostatin analogs will be presented. The readers will be taken to situations such as inflammation, nociception, mechanosensing, chemosensing, fibrosis, taste, and vascularity where somatostatin is involved. Thyroid-associated orbitopathy will be used as a model for the development of multi-agent therapeutics. The final graphical summary depicts the multifactorial properties of ligand binding.
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Affiliation(s)
- Roy Moncayo
- Department of Nuclear Medicine, Medical University of Innsbruck, Innsbruck, Austria.
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11
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Experimental models of visceral pain. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2010; 617:115-54. [PMID: 20336418 DOI: 10.1007/978-1-60327-323-7_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Visceral pain models are used to study afferent nerve traffic during noxious stimulation at the level of the visceral organ. This chapter provides details on several in vitro and in vivo models of organs in the gastrointestinal and genitourinary tract that use electrophysiological recordings of afferent nerve fibres in order to directly characterize stimulus-response relationships. These models can also be used to investigate stimulus-response patterns during physiological (nonpainful) stimulation of the visceral organs or during exposure to pathological stimuli, such as inflammatory mediators during inflammation of the visceral organ.
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Abstract
PURPOSE OF REVIEW Somatostatin influences motility, secretion, and absorption and often has in vivo a modulating, indirect effect on target cells in the gastrointestinal tract. Knowledge on tissue-specific expression of the five somatostatin receptors (SSTRs), their capacities for internalization and downregulation, their subtype-specific intracellular messengers, and the possibility of forming functionally distinct homodimers or heterodimers, has further complicated the actual in-vivo mechanism of action of somatostatin. This review reports recent in-vivo and in-vitro studies on somatostatin effects on the gastrointestinal tract and pancreas, most of them using a new engineered animal model able to define specific roles of somatostatin and/or its receptor subtypes. RECENT FINDINGS SSTR2 knockout mice showed normal circulating gastrin and unchanged acid output, suggesting a high degree of plasticity behind gastric acid secretion. Intestinal inflammation significantly increased somatostatin mRNA in SSTR2 null compared to wild type suggesting that somatostatin mediates inflammation also in SSTR2 null mice. In pancreatic islets of SSTR1-5 null mice no variations of islet size, cellular organization or glucagon or insulin content was shown when compared with null SSTRs and control mice. SUMMARY Although none of the recent findings produced on somatostatin seem ready to be considered for clinical application, recent developments of animal models such as SSTR knockout mice have highlighted promising results to better understand the direct and indirect effects of somatostatin on gastrointestinal tract functions.
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Affiliation(s)
- Vito Domenico Corleto
- Digestive and Liver Disease, II School of Medicine, University La Sapienza, Rome, Italy.
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13
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Beyak MJ. Visceral afferents - determinants and modulation of excitability. Auton Neurosci 2009; 153:69-78. [PMID: 19674942 DOI: 10.1016/j.autneu.2009.07.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Revised: 07/13/2009] [Accepted: 07/20/2009] [Indexed: 02/06/2023]
Abstract
An essential property of visceral sensory afferents is to be able to alter their firing properties in response to changes in the microenvironment at the level of the sensory ending. Significant progress has been made in recent years in understanding the ionic mechanisms of the regulation of afferent neuronal excitability, and in identifying the mechanisms by which this can be altered. This article will review some of the recent developments in the state of knowledge regarding mechanisms of increased excitability after inflammation, and pharmacological modulation of excitability, concentrating on afferent nerves innervating the GI tract and urinary bladder.
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Affiliation(s)
- Michael J Beyak
- Department of Medicine, Queen's University, GIDRU Wing, Kingston General Hospital, 76 Stuart St, Kingston, ON, Canada K7L 2V7.
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Van Op den Bosch J, Adriaensen D, Van Nassauw L, Timmermans JP. The role(s) of somatostatin, structurally related peptides and somatostatin receptors in the gastrointestinal tract: a review. ACTA ACUST UNITED AC 2009; 156:1-8. [PMID: 19362110 DOI: 10.1016/j.regpep.2009.04.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Accepted: 04/05/2009] [Indexed: 12/19/2022]
Abstract
Extensive functional and morphological research has demonstrated the pivotal role of somatostatin (SOM) in the regulation of a wide variety of gastrointestinal activities. In addition to its profound inhibitory effects on gastrointestinal motility and exocrine and endocrine secretion processes along the entire gastrointestinal tract, SOM modulates several organ-specific activities. In contrast to these well-known SOM-dependent effects, knowledge on the SOM receptors (SSTR) involved in these effects is much less conclusive. Experimental data on the identities of the SSTRs, although species- and tissue-dependent, point towards the involvement of multiple receptor subtypes in the vast majority of gastrointestinal SOM-mediated effects. Recent evidence demonstrating the role of SOM in intestinal pathologies has extended the interest of gastrointestinal research in this peptide even further. More specifically, SOM is supposed to suppress intestinal inflammatory responses by interfering with the extensive bidirectional communication between mucosal mast cells and neurons. This way, SOM not only acts as a powerful inhibitor of the inflammatory cascade at the site of inflammation, but exerts a profound antinociceptive effect through the modulation of extrinsic afferent nerve fibres. The combination of these physiological and pathological activities opens up new opportunities to explore the potential of stable SOM analogues in the treatment of GI inflammatory pathologies.
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Affiliation(s)
- Joeri Van Op den Bosch
- Laboratory of Cell Biology & Histology, Department of Veterinary Sciences, University of Antwerp, Antwerp, Belgium
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15
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Basic and clinical aspects of gastrointestinal pain. Pain 2009; 141:191-209. [PMID: 19155134 DOI: 10.1016/j.pain.2008.12.011] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 09/29/2008] [Accepted: 12/03/2008] [Indexed: 12/12/2022]
Abstract
The gastrointestinal (GI) tract is a system of organs within multicellular animals which facilitates the ingestion, digestion, and absorption of food with subsequent defecation of waste. A complex arrangement of nerves and ancillary cells contributes to the sensorimotor apparatus required to subserve such essential functions that are with the exception of the extreme upper and lower ends of the GI tract normally subconscious. However, it also has the potential to provide conscious awareness of injury. Although this function can be protective, when dysregulated, particularly on a chronic basis, the same system can lead to considerable morbidity. The anatomical and molecular basis of gastrointestinal nociception, conditions associated with chronic unexplained visceral pain, and developments in treatment are presented in this review.
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The role of metabotropic glutamate receptor mGlu5 in control of micturition and bladder nociception. Neurosci Lett 2009; 450:12-7. [DOI: 10.1016/j.neulet.2008.11.026] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Revised: 10/18/2008] [Accepted: 11/11/2008] [Indexed: 11/24/2022]
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Grundy D. Ainsley Iggo's early recordings from C fibre vagal afferents supplying the gut. Exp Physiol 2008; 93:1170-3. [PMID: 18945759 DOI: 10.1113/expphysiol.2007.038984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- David Grundy
- Department of Biomedical Science, The University of Sheffield, Western Bank, Sheffield S10 3RA, UK.
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Mechanical hyperalgesia is attenuated by local administration of octreotide in pristane-induced arthritis in Dark-Agouti rats. Life Sci 2008; 83:732-8. [PMID: 18930069 DOI: 10.1016/j.lfs.2008.09.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 09/12/2008] [Accepted: 09/16/2008] [Indexed: 01/22/2023]
Abstract
AIMS The Dark-Agouti (DA) rat is very susceptible to pristane-induced arthritis (PIA) and represents a suitable model for rheumatoid arthritis. In the present study, we examined the pain sensitivity and the effect of local administration of octreotide (OCT) on mechanical hyperalgesia in PIA DA rats. MAIN METHODS Arthritis was induced by intradermal injection of pristane (300 microl). The mechanical withdrawal threshold (MWT) and heat withdrawal latency (HWL) were used to evaluate the pain sensitivity. In addition, we recorded the discharge firings in the tibial nerve sensory C-fibers innervating the inflamed toe joints of arthritic DA rats. KEY FINDINGS Two weeks after injection of pristane, all DA rats developed severe arthritis. This symptom was associated with a decreased MWT (78.50+/-5.68 mN before pristane injection, 19.50+/-6.27 mN on day 14 after pristane injection), indicating a mechanical hyperalgesia in PIA. In contrast, HWL was comparable before and after pristane injection (10.25+/-0.70 s before injection; 9.45+/-1.23 s on day 14 after injection). Local injection of OCT markedly increased MWT and relieved the hyperalgesia in PIA. In addition, OCT significantly decreased the discharge rate of afferent C units evoked by both non-noxious and noxious joint movements. SIGNIFICANCE Taken together, the results demonstrate that mechanical hyperalgesia, but not thermal hyperalgesia is associated with PIA and that the mechanical hyperalgesia and the discharge of afferent C units are attenuated by local administration of OCT. These observations provide evidence for a novel therapeutic strategy for pain control in rheumatoid arthritis.
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Somatostatin inhibits activation of dorsal cutaneous primary afferents induced by antidromic stimulation of primary afferents from an adjacent thoracic segment in the rat. Brain Res 2008; 1229:61-71. [PMID: 18640104 DOI: 10.1016/j.brainres.2008.06.111] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 06/30/2008] [Accepted: 06/30/2008] [Indexed: 01/17/2023]
Abstract
To investigate the effect of somatostatin on the cross-excitation between adjacent primary afferent terminals in the rats, we recorded single unit activity from distal cut ends of dorsal cutaneous branches of the T10 and T12 spinal nerves in response to antidromic stimulation of the distal cut end of the T11 dorsal root in the presence and absence of somatostatin and its receptor antagonist applied to the receptive field of the recorded nerve. Afferent fibers were classified based upon their conduction velocity. Mean mechanical thresholds decreased and spontaneous discharge rates increased significantly in C and Adelta but not Abeta fibers of the T10 and T12 spinal nerves in both male and female rats following antidromic electrical stimulation (ADES) of the dorsal root from adjacent spinal segment (DRASS) indicating cross-excitation of thin fiber afferents. The cross-excitation was not significantly different between male and female rats. Microinjection of somatostatin into the receptive field of recorded units inhibited the cross-excitation. This inhibitory effect, in turn, was reversed by the somatostation receptor antagonist cyclo-somatostatin (c-SOM). Application of c-SOM alone followed by ADES of DRASS significantly decreased the mechanical thresholds and increased the discharge rates of C and Adelta fibers, indicating that endogenous release of somatostatin plays a tonic inhibitory role on the cross-excitation between peripheral nerves. These results suggest that somatostatin could inhibit the cross-excitation involved in peripheral hyperalgesia and have a peripheral analgesic effect.
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Van Op den Bosch J, Lantermann K, Torfs P, Van Marck E, Van Nassauw L, Timmermans JP. Distribution and expression levels of somatostatin and somatostatin receptors in the ileum of normal and acutely Schistosoma mansoni-infected SSTR2 knockout/lacZ knockin mice. Neurogastroenterol Motil 2008; 20:798-807. [PMID: 18298437 DOI: 10.1111/j.1365-2982.2008.01088.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We recently described the widespread expression of somatostatin (SOM) receptors (SSTRs) in the non-inflamed and inflamed murine ileum. Surprisingly, no significant changes were observed in the SSTR2 expression during intestinal inflammation. These data, combined with several recent independent lines of investigation, raised some question about the long presumed central role of SSTR2 in the SOM-mediated effects in the physiological and pathological activity of the gastrointestinal (GI) tract. To further unravel the role of SSTR2 in GI physiology, we studied the expression of SOM and SSTRs in the normal and inflamed SSTR2 knockout/lacZ knockin (SSTR2(-/-)) ileum. The SSTR2(-/-) ileum was characterized by a widespread distribution of multiple SSTR subtypes in non-inflamed and inflamed conditions. Moreover, the absence of SSTR2 did not induce any compensatory effect in the distribution pattern or expression level of any of the other SSTR subtypes. In contrast, the amount of SOM mRNA was significantly lower in SSTR2(-/-) ileum than that in wild type animals. Quantitative analysis revealed a decreased number of SOM-expressing neurons in both enteric plexuses of the knockout animals, implying a possible link between the number of SOM-expressing enteric neurons and the expression of SSTR2 in the enteric nervous system. In conclusion, these data show that a reconsideration of the role of SSTR2 in the GI somatostatinergic effects is in order and further corroborate recent data on the role of other SSTR subtypes in the inflammatory effects of SOM during intestinal inflammation.
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Affiliation(s)
- J Van Op den Bosch
- Laboratory of Cell Biology & Histology, Department of Veterinary Sciences, University of Antwerp, Antwerp, Belgium
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Zeyda T, Hochgeschwender U. Null mutant mouse models of somatostatin and cortistatin, and their receptors. Mol Cell Endocrinol 2008; 286:18-25. [PMID: 18206294 DOI: 10.1016/j.mce.2007.11.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 08/25/2007] [Accepted: 11/28/2007] [Indexed: 01/08/2023]
Abstract
Somatostatin (somatotropin release inhibitory factor, SRIF) and the related cortistatin (CST) are multifunctional peptide molecules attributed with neurohormone, neurotransmitter/modulator, and autocrine/paracrine actions. The physiological responses of SRIF and CST are mediated by five widely distributed G protein-coupled receptors (sst1-5) which have been implicated in regulating numerous biological processes. Much of the information on the effects of somatostatin has been gained through pharmacological studies with analogs and antagonists. The possibility of targeted mutagenesis in the mouse has resulted, over the last 10 years, in the generation of mouse models which genetically lack somatostatin ligands or receptors. We will review here the mouse models generated, the studies undertaken with them, and what has been learned so far.
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Affiliation(s)
- T Zeyda
- John A. Burns School of Medicine, Honolulu, HI, USA
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Modulation of visceral nociceptive pathways. Curr Opin Pharmacol 2007; 7:593-7. [DOI: 10.1016/j.coph.2007.09.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Revised: 09/17/2007] [Accepted: 09/17/2007] [Indexed: 02/06/2023]
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