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Clarkson JM, Martin JE, McKeegan DEF. A review of methods used to kill laboratory rodents: issues and opportunities. Lab Anim 2022; 56:419-436. [PMID: 35611553 DOI: 10.1177/00236772221097472] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Rodents are the most widely used species for scientific purposes. A critical pre-requisite of their use, based on utilitarian ethical reasoning, is the provision of a humane death when necessary for scientific or welfare grounds. Focussing on the welfare challenges presented by current methods, we critically evaluate the literature, consider emerging methodologies that may have potential for refinement and highlight knowledge gaps for future research. The evidence supports the conclusion that scientists and laboratory personnel should seek to avoid killing laboratory rodents by exposing them to carbon dioxide (CO2), unless exploiting its high-throughput advantage. We suggest that stakeholders and policymakers should advocate for the removal of CO2 from existing guidelines, instead making its use conditionally acceptable with justification for additional rationale for its application. With regards to physical methods such as cervical dislocation, decapitation and concussion, major welfare concerns are based on potential inaccuracy in application and their susceptibility to high failure rates. There is a need for independent quality-controlled training programmes to facilitate optimal success rates and the development of specialist tools to improve outcomes and reliability. Furthermore, we highlight questions surrounding the inconsistent inclusion criteria and acceptability of physical methods in international regulation and/or guidance, demonstrating a lack of cohesion across countries and lack of a comprehensive 'gold standard' methodology. We encourage better review of new data and championing of open access scientific resources to advocate for best practice and enable significant changes to policy and legislation to improve the welfare of laboratory rodents at killing.
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Affiliation(s)
- Jasmine M Clarkson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, UK
| | - Jessica E Martin
- The Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, UK
| | - Dorothy E F McKeegan
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, UK
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2
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Lötsch J, Oertel BG, Felden L, Nöth U, Deichmann R, Hummel T, Walter C. Central encoding of the strength of intranasal chemosensory trigeminal stimuli in a human experimental pain setting. Hum Brain Mapp 2020; 41:5240-5254. [PMID: 32870583 PMCID: PMC7670645 DOI: 10.1002/hbm.25190] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 08/10/2020] [Accepted: 08/11/2020] [Indexed: 12/29/2022] Open
Abstract
An important measure in pain research is the intensity of nociceptive stimuli and their cortical representation. However, there is evidence of different cerebral representations of nociceptive stimuli, including the fact that cortical areas recruited during processing of intranasal nociceptive chemical stimuli included those outside the traditional trigeminal areas. Therefore, the aim of this study was to investigate the major cerebral representations of stimulus intensity associated with intranasal chemical trigeminal stimulation. Trigeminal stimulation was achieved with carbon dioxide presented to the nasal mucosa. Using a single-blinded, randomized crossover design, 24 subjects received nociceptive stimuli with two different stimulation paradigms, depending on the just noticeable differences in the stimulus strengths applied. Stimulus-related brain activations were recorded using functional magnetic resonance imaging with event-related design. Brain activations increased significantly with increasing stimulus intensity, with the largest cluster at the right Rolandic operculum and a global maximum in a smaller cluster at the left lower frontal orbital lobe. Region of interest analyses additionally supported an activation pattern correlated with the stimulus intensity at the piriform cortex as an area of special interest with the trigeminal input. The results support the piriform cortex, in addition to the secondary somatosensory cortex, as a major area of interest for stimulus strength-related brain activation in pain models using trigeminal stimuli. This makes both areas a primary objective to be observed in human experimental pain settings where trigeminal input is used to study effects of analgesics.
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Affiliation(s)
- Jörn Lötsch
- Institute of Clinical PharmacologyGoethe – UniversityFrankfurt am MainGermany
- Fraunhofer Institute for Molecular Biology and Applied Ecology IMEBranch for Translational Medicine and Pharmacology TMPFrankfurt am MainGermany
| | - Bruno G. Oertel
- Institute of Clinical PharmacologyGoethe – UniversityFrankfurt am MainGermany
| | - Lisa Felden
- Institute of Clinical PharmacologyGoethe – UniversityFrankfurt am MainGermany
| | - Ulrike Nöth
- Brain Imaging CenterGoethe – UniversityFrankfurt am MainGermany
| | - Ralf Deichmann
- Brain Imaging CenterGoethe – UniversityFrankfurt am MainGermany
| | - Thomas Hummel
- Smell & Taste Clinic, Department of OtorhinolaryngologyTU DresdenDresdenGermany
| | - Carmen Walter
- Institute of Clinical PharmacologyGoethe – UniversityFrankfurt am MainGermany
- Fraunhofer Institute for Molecular Biology and Applied Ecology IMEBranch for Translational Medicine and Pharmacology TMPFrankfurt am MainGermany
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3
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Mangelsdorf I, Schröder K, Escher SE, Kolossa-Gehring M, Debiak M. Risk assessment for irritating chemicals - Derivation of extrapolation factors. Int J Hyg Environ Health 2020; 232:113668. [PMID: 33333487 DOI: 10.1016/j.ijheh.2020.113668] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 11/19/2020] [Accepted: 11/24/2020] [Indexed: 02/06/2023]
Abstract
Irritation of the eyes and the upper respiratory tract are important endpoints for setting guide values for chemicals. To optimize the use of the often-limited data, we analysed controlled human exposure studies (CHS) with 1-4 h inhalation of the test substance, repeated dose inhalation studies in rodents, and Alarie-Tests and derived extrapolation factors (EF) for exposure duration, inter- and intraspecies differences. For the endpoint irritating effects in the respiratory tract in rodents, geometric mean (GM) values of 1.9 were obtained for the EF for subacute→subchronic (n = 16), 2.1 for subchronic→chronic (n = 40), and 2.9 for subacute→chronic (n = 10) extrapolation. Based on these data we suggest an EF of 2 for subchronic→chronic and of 4 for subacute→chronic extrapolation. In CHS, exposure concentration determines the effects rather than exposure duration. Slight reversible effects during 4 h exposure indicate that an EF of 1 can be considered for assessing chronic exposures. To assess species extrapolation, 10 chemicals were identified with both, reliable rat inhalation studies and CHS. The GM of the ratio between the No Observed Adverse Effect Concentration (NOAEC) in rats and humans was 2.3 and increased to 3.6 when expanding the dataset to all available EF (n = 25). Based on these analyses, an EF of 3 is suggested to extrapolate from a NOAEC in a chronic rat study to a NOAEC in a CHS. The analysis of EFs for the extrapolation from a 50% decrease in respiratory frequency in the Alarie test in mice (RD50) to a NOAEC in a CHS resulted in a GM of 40, for both, the reliable (n = 11) and the overall dataset (n = 19). We propose to use the RD50 from the Alarie test for setting guide values and to use 40 as EF. Efs for intraspecies differences in the human population must account for susceptible persons, most importantly for persons with chemical intolerance (CI), who show subjective signs of irritation at low concentrations. The limited data available do not justify to deviate from an EF of 10 - 20 as currently used in different regulatory settings.
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Affiliation(s)
- Inge Mangelsdorf
- Toxicology Consulting, Hamburg, Germany; Fraunhofer Institute for Toxicology and Experimental Medicine, Hannover, Germany.
| | - Katrin Schröder
- Fraunhofer Institute for Toxicology and Experimental Medicine, Hannover, Germany
| | - Sylvia E Escher
- Fraunhofer Institute for Toxicology and Experimental Medicine, Hannover, Germany
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Panneton WM, Gan Q. The Mammalian Diving Response: Inroads to Its Neural Control. Front Neurosci 2020; 14:524. [PMID: 32581683 PMCID: PMC7290049 DOI: 10.3389/fnins.2020.00524] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 04/27/2020] [Indexed: 01/03/2023] Open
Abstract
The mammalian diving response (DR) is a remarkable behavior that was first formally studied by Laurence Irving and Per Scholander in the late 1930s. The DR is called such because it is most prominent in marine mammals such as seals, whales, and dolphins, but nevertheless is found in all mammals studied. It consists generally of breathing cessation (apnea), a dramatic slowing of heart rate (bradycardia), and an increase in peripheral vasoconstriction. The DR is thought to conserve vital oxygen stores and thus maintain life by directing perfusion to the two organs most essential for life-the heart and the brain. The DR is important, not only for its dramatic power over autonomic function, but also because it alters normal homeostatic reflexes such as the baroreceptor reflex and respiratory chemoreceptor reflex. The neurons driving the reflex circuits for the DR are contained within the medulla and spinal cord since the response remains after the brainstem transection at the pontomedullary junction. Neuroanatomical and physiological data suggesting brainstem areas important for the apnea, bradycardia, and peripheral vasoconstriction induced by underwater submersion are reviewed. Defining the brainstem circuit for the DR may open broad avenues for understanding the mechanisms of suprabulbar control of autonomic function in general, as well as implicate its role in some clinical states. Knowledge of the proposed diving circuit should facilitate studies on elite human divers performing breath-holding dives as well as investigations on sudden infant death syndrome (SIDS), stroke, migraine headache, and arrhythmias. We have speculated that the DR is the most powerful autonomic reflex known.
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Affiliation(s)
- W. Michael Panneton
- Department of Pharmacological and Physiological Science, School of Medicine, Saint Louis University, St. Louis, MO, United States
| | - Qi Gan
- Department of Pharmacological and Physiological Science, School of Medicine, Saint Louis University, St. Louis, MO, United States
- Department of Pediatrics, School of Medicine, Saint Louis University, St. Louis, MO, United States
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Gudziol H, Guntinas-Lichius O. Electrophysiologic assessment of olfactory and gustatory function. HANDBOOK OF CLINICAL NEUROLOGY 2020; 164:247-262. [PMID: 31604551 DOI: 10.1016/b978-0-444-63855-7.00016-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This chapter reviews approaches for assessing human and gustatory function using electrophysiologic methods. Its focus is on changes in electrical signals, including summated generator potentials that occur after nasal or oral stimulation. In the first part of the review, we describe tools available to the clinician for assessing olfactory and nasotrigeminal function, including modern electroencephalography (EEG) analysis of brain responses both in the time domain and in the time-frequency (TF) domain. Particular attention is paid to chemosensory event-related potentials (CSERPs) and their potential use in medical-legal cases. Additionally, we focus on the changes of summated generator potentials from the olfactory and respiratory nasal epithelium that could provide new diagnostic insights. In the second part, we describe gustatory event-related potentials (gCSERPs) obtained using a relatively new computer controlled gustometer. A device for presenting different pulses of electrical current to the tongue is also described, with weaker pulses likely reflecting gCSERPs and stronger ones trigeminal CSERPs. Finally, summated generator potentials from the surface of the tongue during gustatory stimulation are described that may prove useful for examining peripheral taste function.
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Affiliation(s)
- Hilmar Gudziol
- Department of Otorhinolaryngology, University Hospital, Jena, Germany.
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Marquardt N, Feja M, Hünigen H, Plendl J, Menken L, Fink H, Bert B. Euthanasia of laboratory mice: Are isoflurane and sevoflurane real alternatives to carbon dioxide? PLoS One 2018; 13:e0203793. [PMID: 30199551 PMCID: PMC6130864 DOI: 10.1371/journal.pone.0203793] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 08/28/2018] [Indexed: 01/17/2023] Open
Abstract
In the European Union (EU) millions of laboratory mice are used and killed for experimental and other scientific purposes each year. Although controversially discussed, the use of carbon dioxide (CO2) is still permitted for killing rodents according to the Directive 2010/63/EU. Within the scope of refinement, our aim was to investigate if isoflurane and sevoflurane are an appropriate alternative killing method to CO2 in mice. Different concentrations of CO2 (filling rates of 20%, 60%, 100%; CO2 20, 60, 100), isoflurane (Iso 2%, 5%) and sevoflurane (Sevo 4.8%, 8%) were compared in two mouse strains (NMRI, C57Bl/6J) using a broad spectrum of behavioral parameters, including the approach-avoidance test, and analyzing blood for stress parameters (glucose, adrenaline, noradrenaline). We focused in our study on the period from the beginning of the gas inlet to loss of consciousness, as during this period animals are able to perceive pain and distress. Our results show that only higher concentrations of CO2 (CO2 60, 100) and isoflurane (5%) induced surgical tolerance within 300 s in both strains, with CO2 100 being the fastest acting inhalant anesthetic. The potency of halogenated ethers depended on the mouse strain, with C57Bl/6J being more susceptible than NMRI mice. Behavioral analysis revealed no specific signs of distress, e. g. stress-induced grooming, and pain, i. e. audible vocalizations, for all inhalant gases. However, adrenaline and noradrenaline plasma concentrations were increased, especially in NMRI mice exposed to CO2 in high concentrations, whereas we did not observe such increase in animals exposed to isoflurane or sevoflurane. Escape latencies in the approach-avoidance test using C57Bl/6J mice did not differ between the three inhalant gases, however, some animals became recumbent during isoflurane and sevoflurane but not during CO2 exposure. The rise in catecholamine concentrations suggests that CO2 exposure might be linked to a higher stress response compared to isoflurane and sevoflurane exposure, although we did not observe a behavioral correlate for that. Follow-up studies investigating other fast-acting stress hormones and central anxiety circuits are needed to confirm our findings.
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Affiliation(s)
- Nicole Marquardt
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Malte Feja
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
- * E-mail:
| | - Hana Hünigen
- Institute of Veterinary Anatomy, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Johanna Plendl
- Institute of Veterinary Anatomy, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Lena Menken
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Heidrun Fink
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Bettina Bert
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
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Oleszkiewicz A, Meusel T, Güpfert M, Westermann B, Hummel T, Welge-Lüssen A. Olfactory deficits decrease the time resolution for trigeminal lateralization. Int J Psychophysiol 2017; 121:18-21. [PMID: 28918916 DOI: 10.1016/j.ijpsycho.2017.09.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 04/27/2017] [Accepted: 09/07/2017] [Indexed: 11/19/2022]
Abstract
OBJECTIVES To date the temporal resolution of the detection of almost simultaneously applied intranasal trigeminal stimuli is unknown. The aim of our study was to examine this temporal resolution in an/hyposmic subjects, who are known to have reduced trigeminal sensitivity and compare it with healthy controls. METHODS Participants were 20 posttraumatic an/hyposmic patients, and 23 healthy controls (matched with regard to sex and age). Olfactory function was tested psychophysically using the Sniffin´ Sticks test battery. Bilateral trigeminal stimulation was carried out using a birhinal high-precision olfactometer. The trigeminal stimulus used was CO₂ 60% v/v, the interstimulus interval ranged from 28 to 32s, stimulus duration was 200ms. Time-lags tested between right and left side of stimulation were at 40, 80, 120, 160 and 200ms. Subjects raised their left or right hand to indicate the side on which the stimulus had been perceived first. RESULTS In both groups the accuracy in the trigeminal lateralization task increased with the time-lag but normosmic subjects significantly outperformed an/hyposmics in the 200ms time-lag condition. Normosmics significantly exceeded 50% chance level at the time-lag of 80ms, whereas an/hyposmics were only able to score above chance starting from 120ms time-lag. Lateralization scores significantly decreased with age. CONCLUSIONS At a time lag of 200ms intranasal trigeminal stimuli can be lateralized. The reduced trigeminal sensitivity in patients with anosmia or hyposmia leads to an increased time lag required for correct perception of intranasal, almost simultaneously, applied stimuli.
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Affiliation(s)
- A Oleszkiewicz
- Smell and Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany; Institute of Psychology, University of Wroclaw, Wroclaw, Poland.
| | - T Meusel
- Department of Otorhinolaryngology, Head and Neck Surgery, University of Erlangen Medical School, Erlangen, Germany
| | - M Güpfert
- Department of Otorhinolaryngology, Head and Neck Surgery, University of Basel, Basel, Switzerland
| | - B Westermann
- Department of Neurosurgery, University of Basel, Basel, Switzerland
| | - T Hummel
- Smell and Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany
| | - A Welge-Lüssen
- Department of Otorhinolaryngology, Head and Neck Surgery, University of Basel, Basel, Switzerland
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8
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Frie J, Bartocci M, Lagercrantz H, Kuhn P. Cortical Responses to Alien Odors in Newborns: An fNIRS Study. Cereb Cortex 2017; 28:3229-3240. [DOI: 10.1093/cercor/bhx194] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Accepted: 07/13/2017] [Indexed: 11/13/2022] Open
Affiliation(s)
- Jakob Frie
- Neonatal Research Unit, Department of Women’s and Children’s Health, Karolinska Institute, Stockholm, Sweden
- Department of Neonatal Medicine, Astrid Lindgren Children’s Hospital, Karolinska University Hospital, Stockholm, Sweden
| | - Marco Bartocci
- Neonatal Research Unit, Department of Women’s and Children’s Health, Karolinska Institute, Stockholm, Sweden
- Department of Neonatal Medicine, Astrid Lindgren Children’s Hospital, Karolinska University Hospital, Stockholm, Sweden
| | - Hugo Lagercrantz
- Neonatal Research Unit, Department of Women’s and Children’s Health, Karolinska Institute, Stockholm, Sweden
| | - Pierre Kuhn
- Neonatal Research Unit, Department of Women’s and Children’s Health, Karolinska Institute, Stockholm, Sweden
- Service de Médecine et Réanimation du Nouveau-né, Hôpital de Hautepierre, Centre Hospitalier Universitaire de Strasbourg, France
- Institut de Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique et Unistra, Strasbourg, France
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Evaluation of Low versus High Volume per Minute Displacement CO₂ Methods of Euthanasia in the Induction and Duration of Panic-Associated Behavior and Physiology. Animals (Basel) 2016; 6:ani6080045. [PMID: 27490573 PMCID: PMC4997270 DOI: 10.3390/ani6080045] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 06/21/2016] [Accepted: 07/12/2016] [Indexed: 11/17/2022] Open
Abstract
Current recommendations for the use of CO ₂ as a euthanasia agent for rats require the use of gradual fill protocols (such as 10% to 30% volume displacement per minute) in order to render the animal insensible prior to exposure to levels of CO ₂ that are associated with pain. However, exposing rats to CO ₂ , concentrations as low as 7% CO ₂ are reported to cause distress and 10%-20% CO ₂ induces panic-associated behavior and physiology, but loss of consciousness does not occur until CO ₂ concentrations are at least 40%. This suggests that the use of the currently recommended low flow volume per minute displacement rates create a situation where rats are exposed to concentrations of CO ₂ that induce anxiety, panic, and distress for prolonged periods of time. This study first characterized the response of male rats exposed to normoxic 20% CO ₂ for a prolonged period of time as compared to room air controls. It demonstrated that rats exposed to this experimental condition displayed clinical signs consistent with significantly increased panic-associated behavior and physiology during CO ₂ exposure. When atmospheric air was then again delivered, there was a robust increase in respiration rate that coincided with rats moving to the air intake. The rats exposed to CO ₂ also displayed behaviors consistent with increased anxiety in the behavioral testing that followed the exposure. Next, this study assessed the behavioral and physiologic responses of rats that were euthanized with 100% CO ₂ infused at 10%, 30%, or 100% volume per minute displacement rates. Analysis of the concentrations of CO ₂ and oxygen in the euthanasia chamber and the behavioral responses of the rats suggest that the use of the very low flow volume per minute displacement rate (10%) may prolong the duration of panicogenic ranges of ambient CO ₂ , while the use of the higher flow volume per minute displacement rate (100%) increases agitation. Therefore, of the volume displacement per minute rates evaluated, this study suggests that 30% minimizes the potential pain and distress experienced by the animal.
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Lötsch J, Dimova V, Ultsch A, Lieb I, Zimmermann M, Geisslinger G, Oertel BG. A small yet comprehensive subset of human experimental pain models emerging from correlation analysis with a clinical quantitative sensory testing protocol in healthy subjects. Eur J Pain 2015; 20:777-89. [PMID: 26492152 DOI: 10.1002/ejp.803] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/06/2015] [Indexed: 11/11/2022]
Abstract
BACKGROUND Picturing the complexity of pain in human experimental settings has increased the predictivity for clinical pain but requires increasingly complex test batteries. This raises problems in studies in which time is objectively limited, for example by the course of action of an analgesic drug. We addressed the selection of a small yet comprehensive set of pain tests for the use in such a situation. METHOD Nineteen different pain measures from 'classical' pain models (n = 9) and a clinically established QST-pain test battery (n = 10), were obtained from 72 healthy volunteers (34 men). The nonparametric correlation structure among the various pain measures was analysed using Ward clustering. RESULTS Four clusters emerged, each consisting of highly correlated pain measures. The pain model groups emerged comprised (I) pain thresholds and tolerances to blunt pressure or electrical pain; (II) pain thresholds to thermal stimuli; (III) pain measures obtained following application of punctate mechanical, intranasal CO2 chemical or cutaneous laser heat stimuli; and (IV) detection thresholds to thermal stimuli. The first three clusters agreed with an immediate mechanistic interpretation as reflecting C-fibre mediated pain, thermal pain and Aδ-fibre mediated pain, respectively, whereas the last cluster contained non-painful measures and was disregarded. CONCLUSIONS When basing a selection of a small comprehensive set of pain models on the assumption that highly correlated pain measures account for redundant results and therefore, one member of each group suffices an economic yet comprehensive pain study, results suggest inclusion of established C-fibre, Aδ-fibre mediated and thermal pain measures.
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Affiliation(s)
- J Lötsch
- Institute of Clinical Pharmacology, Goethe - University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.,Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany
| | - V Dimova
- Institute of Clinical Pharmacology, Goethe - University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.,Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - A Ultsch
- DataBionics Research Group, University of Marburg, Hans-Meerwein-Straße, 35032, Marburg, Germany
| | - I Lieb
- Institute of Clinical Pharmacology, Goethe - University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - M Zimmermann
- DataBionics Research Group, University of Marburg, Hans-Meerwein-Straße, 35032, Marburg, Germany
| | - G Geisslinger
- Institute of Clinical Pharmacology, Goethe - University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.,Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany
| | - B G Oertel
- Institute of Clinical Pharmacology, Goethe - University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.,Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany
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Walter C, Dimova V, Bu J, Parnham MJ, Oertel BG, Lötsch J. Inverted Perceptual Judgment of Nociceptive Stimuli at Threshold Level following Inconsistent Cues. PLoS One 2015; 10:e0132069. [PMID: 26147732 PMCID: PMC4493070 DOI: 10.1371/journal.pone.0132069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 06/09/2015] [Indexed: 11/18/2022] Open
Abstract
Objective The perception of pain is susceptible to modulation by psychological and contextual factors. It has been shown that subjects judge noxious stimuli as more painful in a respective suggestive context, which disappears when the modifying context is resolved. However, a context in which subjects judge the painfulness of a nociceptive stimulus in exactly the opposite direction to that of the cues has never been shown so far. Methods Nociceptive stimuli (300 ms intranasal gaseous CO2) at the individual pain threshold level were applied after a visual cue announcing the stimulus as either “no pain”, merely a “stimulus”, or “pain”. Among the stimuli at threshold level, other CO2 stimuli that were clearly below or above pain threshold were randomly interspersed. These were announced beforehand in 12 subjects randomly with correct or incorrect cues, i.e., clearly painful or clearly non-painful stimuli were announced equally often as not painful or painful. By contrast, in a subsequent group of another 12 subjects, the stimuli were always announced correctly with respect to the evoked pain. Results The random and often incorrect announcement of stimuli clearly below or above pain threshold caused the subjects to rate the stimuli at pain-threshold level in the opposite direction of the cue, i.e., when the stimuli were announced as “pain” significantly more often than as non-painful and vice versa (p < 10-4). By contrast, in the absence of incongruence between announcement and perception of the far-from-threshold stimuli, stimuli at pain threshold were rated in the cued direction. Conclusions The present study revealed the induction of associations incongruent with a given message in the perception of pain. We created a context of unreliable cues whereby subjects perceived the stimulus opposite to that suggested by a prior cue, i.e., potentially nociceptive stimuli at pain threshold level that were announced as painful were judged as non-painful and vice versa. These findings are consistent with reported data on the effects of distrust on non-painful cognitive responses.
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Affiliation(s)
- Carmen Walter
- Institute of Clinical Pharmacology, Goethe—University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - Violeta Dimova
- Institute of Clinical Pharmacology, Goethe—University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
- Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - Julia Bu
- Institute of Clinical Pharmacology, Goethe—University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - Michael J. Parnham
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany
| | - Bruno G. Oertel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany
| | - Jörn Lötsch
- Institute of Clinical Pharmacology, Goethe—University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany
- * E-mail:
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Lötsch J, Oertel BG, Ultsch A. Human models of pain for the prediction of clinical analgesia. Pain 2014; 155:2014-21. [PMID: 25020003 DOI: 10.1016/j.pain.2014.07.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 07/02/2014] [Accepted: 07/03/2014] [Indexed: 12/31/2022]
Abstract
Human experimental pain models are widely used to study drug effects under controlled conditions. However, efforts to improve both animal and human experimental model selection, on the basis of increased understanding of the underlying pathophysiological pain mechanisms, have been disappointing, with poor translation of results to clinical analgesia. We have developed an alternative approach to the selection of suitable pain models that can correctly predict drug efficacy in particular clinical settings. This is based on the analysis of successful or unsuccessful empirical prediction of clinical analgesia using experimental pain models. We analyzed statistically the distribution of published mutual agreements or disagreements between drug efficacy in experimental and clinical pain settings. Significance limits were derived by random permutations of agreements. We found that a limited subset of pain models predicts a large number of clinically relevant pain settings, including efficacy against neuropathic pain for which novel analgesics are particularly needed. Thus, based on empirical evidence of agreement between drugs for their efficacy in experimental and clinical pain settings, it is possible to identify pain models that reliably predict clinical analgesic drug efficacy in cost-effective experimental settings.
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Affiliation(s)
- Jörn Lötsch
- Institute of Clinical Pharmacology, Goethe-University, Frankfurt am Main, Germany; Fraunhofer Project Group Translational Medicine and Pharmacology (IME-TMP), Frankfurt am Main, Germany.
| | - Bruno G Oertel
- Fraunhofer Project Group Translational Medicine and Pharmacology (IME-TMP), Frankfurt am Main, Germany
| | - Alfred Ultsch
- Data Bionics Research Group, University of Marburg, Marburg, Germany
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Panneton WM, Gan Q. Direct reticular projections of trigeminal sensory fibers immunoreactive to CGRP: potential monosynaptic somatoautonomic projections. Front Neurosci 2014; 8:136. [PMID: 24926231 PMCID: PMC4046267 DOI: 10.3389/fnins.2014.00136] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 05/14/2014] [Indexed: 11/30/2022] Open
Abstract
Few trigeminal sensory fibers project centrally beyond the trigeminal sensory complex, with only projections of fibers carried in its sensory anterior ethmoidal (AEN) and intraoral nerves described. Fibers of the AEN project into the brainstem reticular formation where immunoreactivity against substance P and CGRP are found. We investigated whether the source of these peptides could be from trigeminal ganglion neurons by performing unilateral rhizotomies of the trigeminal root and looking for absence of label. After an 8–14 days survival, substance P immunoreactivity in the trigeminal sensory complex was diminished, but we could not conclude that the sole source of this peptide in the lateral parabrachial area and lateral reticular formation arises from primary afferent fibers. Immunoreactivity to CGRP after rhizotomy however was greatly diminished in the trigeminal sensory complex, confirming the observations of others. Moreover, CGRP immunoreactivity was nearly eliminated in fibers in the lateral parabrachial area, the caudal ventrolateral medulla, both the peri-ambiguus and ventral parts of the rostral ventrolateral medulla, in the external formation of the nucleus ambiguus, and diminished in the caudal pressor area. The nearly complete elimination of CGRP in the lateral reticular formation after rhizotomy suggests this peptide is carried in primary afferent fibers. Moreover, the arborization of CGRP immunoreactive fibers in these areas mimics that of direct projections from the AEN. Since electrical stimulation of the AEN induces cardiorespiratory adjustments including an apnea, peripheral vasoconstriction, and bradycardia similar to those seen in the mammalian diving response, we suggest these perturbations of autonomic behavior are enhanced by direct somatic primary afferent projections to these reticular neurons. We believe this to be first description of potential direct somatoautonomic projections to brainstem neurons regulating autonomic activity.
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Affiliation(s)
- W Michael Panneton
- Department of Pharmacological and Physiological Science, St. Louis University Medical School , St. Louis, MO, USA
| | - Qi Gan
- Department of Pharmacological and Physiological Science, St. Louis University Medical School , St. Louis, MO, USA
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14
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Schütz M, Oertel BG, Heimann D, Doehring A, Walter C, Dimova V, Geisslinger G, Lötsch J. Consequences of a human TRPA1 genetic variant on the perception of nociceptive and olfactory stimuli. PLoS One 2014; 9:e95592. [PMID: 24752136 PMCID: PMC4005389 DOI: 10.1371/journal.pone.0095592] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 03/28/2014] [Indexed: 01/13/2023] Open
Abstract
Background TRPA1 ion channels are involved in nociception and are also excited by pungent odorous substances. Based on reported associations of TRPA1 genetics with increased sensitivity to thermal pain stimuli, we therefore hypothesized that this association also exists for increased olfactory sensitivity. Methods Olfactory function and nociception was compared between carriers (n = 38) and non-carriers (n = 43) of TRPA1 variant rs11988795 G>A, a variant known to enhance cold pain perception. Olfactory function was quantified by assessing the odor threshold, odor discrimination and odor identification, and by applying 200-ms pulses of H2S intranasal. Nociception was assessed by measuring pain thresholds to experimental nociceptive stimuli (blunt pressure, electrical stimuli, cold and heat stimuli, and 200-ms intranasal pulses of CO2). Results Among the 11 subjects with moderate hyposmia, carriers of the minor A allele (n = 2) were underrepresented (34 carriers among the 70 normosmic subjects; p = 0.049). Moreover, carriers of the A allele discriminated odors significantly better than non-carriers (13.1±1.5 versus 12.3±1.6 correct discriminations) and indicated a higher intensity of the H2S stimuli (29.2±13.2 versus 21±12.8 mm VAS, p = 0.006), which, however, could not be excluded to have involved a trigeminal component during stimulation. Finally, the increased sensitivity to thermal pain could be reproduced. Conclusions The findings are in line with a previous association of a human TRPA1 variant with nociceptive parameters and extend the association to the perception of odorants. However, this addresses mainly those stimulants that involve a trigeminal component whereas a pure olfactory effect may remain disputable. Nevertheless, findings suggest that future TRPA1 modulating drugs may modify the perception of odorants.
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Affiliation(s)
- Michael Schütz
- Institute of Clinical Pharmacology, Goethe - University, Frankfurt am Main, Germany
| | - Bruno G. Oertel
- Institute of Clinical Pharmacology, Goethe - University, Frankfurt am Main, Germany
- Fraunhofer Institute of Molecular Biology and Applied Ecology - Project Group Translational Medcine and Pharmacology (IME-TMP), Frankfurt am Main, Germany
| | - Dirk Heimann
- Institute of Clinical Pharmacology, Goethe - University, Frankfurt am Main, Germany
| | - Alexandra Doehring
- Institute of Clinical Pharmacology, Goethe - University, Frankfurt am Main, Germany
| | - Carmen Walter
- Institute of Clinical Pharmacology, Goethe - University, Frankfurt am Main, Germany
| | - Violeta Dimova
- Institute of Clinical Pharmacology, Goethe - University, Frankfurt am Main, Germany
| | - Gerd Geisslinger
- Institute of Clinical Pharmacology, Goethe - University, Frankfurt am Main, Germany
- Fraunhofer Institute of Molecular Biology and Applied Ecology - Project Group Translational Medcine and Pharmacology (IME-TMP), Frankfurt am Main, Germany
| | - Jörn Lötsch
- Institute of Clinical Pharmacology, Goethe - University, Frankfurt am Main, Germany
- Fraunhofer Institute of Molecular Biology and Applied Ecology - Project Group Translational Medcine and Pharmacology (IME-TMP), Frankfurt am Main, Germany
- * E-mail:
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15
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Panneton WM. The mammalian diving response: an enigmatic reflex to preserve life? Physiology (Bethesda) 2014; 28:284-97. [PMID: 23997188 DOI: 10.1152/physiol.00020.2013] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The mammalian diving response is a remarkable behavior that overrides basic homeostatic reflexes. It is most studied in large aquatic mammals but is seen in all vertebrates. Pelagic mammals have developed several physiological adaptations to conserve intrinsic oxygen stores, but the apnea, bradycardia, and vasoconstriction is shared with those terrestrial and is neurally mediated. The adaptations of aquatic mammals are reviewed here as well as the neural control of cardiorespiratory physiology during diving in rodents.
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Affiliation(s)
- W Michael Panneton
- Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, MO, USA.
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16
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Lötsch J, Hummel T, Warskulat U, Coste O, Häussinger D, Geisslinger G, Tegeder I. Congenital taurine deficiency in mice is associated with reduced sensitivity to nociceptive chemical stimulation. Neuroscience 2013; 259:63-70. [PMID: 24321512 DOI: 10.1016/j.neuroscience.2013.11.037] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 11/04/2013] [Accepted: 11/20/2013] [Indexed: 01/06/2023]
Abstract
The amino acid taurine is required for development and functioning of the central and peripheral nervous system where it exerts osmoregulatory, neuromodulatory and anti-apoptotic actions. It is subject to cellular import by the taurine transporter slc6a6. Absence of the transporter and consequently, absence of taurine leads to several neurologic deficits and sensory losses. In a slc6a6 knock-out mouse model, consequences of congenital taurine deficiency were assessed in nociceptive sensory processes. The formalin assay, hot plate assay, and summated generator potentials in response to local nociceptive stimulation with gaseous CO2 were applied. Reduced responsiveness of slc6a6(-/-) mice to nociceptive stimulation was observed in particular to chemical nociceptive stimuli. Scl6a6 knock-out mice spent significantly less time licking the formalin injected paw and displayed smaller amplitudes of the nociceptive nasal mucosa potentials than wild-type mice (p=0.002 and 0.01 respectively). In contrast, withdrawal latencies on a hot plate did not significantly differ, suggesting that intracellular taurine deficits lead in particular to a hyposensitivity of nociceptive sensory neurons sensitive to noxious chemical stimulation. As hereditary absence of taurine affects biological processes of anatomical structure development, the altered nociceptive responses likely reflect consequences of compromised peripheral nervous system development.
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Affiliation(s)
- J Lötsch
- Institute of Clinical Pharmacology, Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany; Fraunhofer Institute of Molecular Biology and Applied Ecology-Project Group Translational Medicine and Pharmacology (IME-TMP), Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany.
| | - T Hummel
- Smell & Taste Clinic, Department of Otorhinolaryngology, University of Dresden Medical School, Fetscherstr. 74, D-01307 Dresden, Germany
| | - U Warskulat
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich Heine University, Moorenstraße 5, D-40225 Düsseldorf, Germany
| | - O Coste
- Institute of Clinical Pharmacology, Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
| | - D Häussinger
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich Heine University, Moorenstraße 5, D-40225 Düsseldorf, Germany
| | - G Geisslinger
- Institute of Clinical Pharmacology, Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany; Fraunhofer Institute of Molecular Biology and Applied Ecology-Project Group Translational Medicine and Pharmacology (IME-TMP), Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
| | - I Tegeder
- Institute of Clinical Pharmacology, Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany
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17
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Jürgens TP, Reetz R, May A. No relevant modulation of TRPV1-mediated trigeminal pain by intranasal carbon dioxide in healthy humans. J Headache Pain 2013; 14:33. [PMID: 23574808 PMCID: PMC3630066 DOI: 10.1186/1129-2377-14-33] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Accepted: 03/12/2013] [Indexed: 11/27/2022] Open
Abstract
Background Nasal insufflation of CO2 has been shown to exert antinociceptive respectively antihyperalgesic effects in animal pain models using topical capsaicin with activation of TRPV1-receptor positive nociceptive neurons. Clinical benefit from CO2 inhalation in patients with craniofacial pain caused by a putative activation of TRPV1 receptor positive trigeminal neurons has also been reported. These effects are probably mediated via an activation of TRPV1 receptor - positive neurons in the nasal mucosa with subsequent central inhibitory effects (such as conditioned pain modulation). In this study, we aimed to examine the effects of intranasal CO2 on a human model of craniofacial pain elicited by nasal application of capsaicin. Methods In a first experiment, 48 healthy volunteers without previous craniofacial pain received intranasal capsaicin to provoke trigeminal pain elicited by activation of TRVP1 positive nociceptive neurons. Then, CO2 or air was insufflated alternatingly into the nasal cavity at a flow rate of 1 l/min for 60 sec each. In the subsequent experiment, all participants were randomized into 2 groups of 24 each and received either continuous nasal insufflation of CO2 or placebo for 18:40 min after nociceptive stimulation with intranasal capsaicin. In both experiments, pain was rated on a numerical rating scale every 60 sec. Results Contrary to previous animal studies, the effects of CO2 on experimental trigeminal pain were only marginal. In the first experiment, CO2 reduced pain ratings only minimally by 5.3% compared to air if given alternatingly with significant results for the main factor GROUP (F1,47 = 4.438; p = 0.041) and the interaction term TIME*GROUP (F2.6,121.2 = 3.3; p = 0.029) in the repeated-measures ANOVA. However, these effects were abrogated after continuous insufflation of CO2 or placebo with no significant changes for the main factors or the interaction term. Conclusions Although mild modulatory effects of low-flow intranasal CO2 could be seen in this human model of TRPV-1 mediated activation of nociceptive trigeminal neurons, utility is limited as observed changes in pain ratings are clinically non-significant.
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Affiliation(s)
- Tim P Jürgens
- Department of Systems Neuroscience, University Medical Centre Hamburg-Eppendorf, Martinistr, 52, Hamburg, D-20246, Germany.
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18
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Daiber P, Genovese F, Schriever VA, Hummel T, Möhrlen F, Frings S. Neuropeptide receptors provide a signalling pathway for trigeminal modulation of olfactory transduction. Eur J Neurosci 2012. [PMID: 23205840 DOI: 10.1111/ejn.12066] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The mammalian olfactory epithelium contains olfactory receptor neurons and trigeminal sensory endings. The former mediate odor detection, the latter the detection of irritants. The two apparently parallel chemosensory systems are in reality interdependent in various well-documented ways. Psychophysical studies have shown that virtually all odorants can act as irritants, and that most irritants have an odor. Thus, the sensory perception of odorants and irritants is based on simultaneous input from the two systems. Moreover, functional interactions between the olfactory system and the trigeminal system exist on both peripheral and central levels. Here we examine the impact of trigeminal stimulation on the odor response of olfactory receptor neurons. Using an odorant with low trigeminal potency (phenylethyl alcohol) and a non-odorous irritant (CO(2) ), we have explored this interaction in psychophysical experiments with human subjects and in electroolfactogram (EOG) recordings from rats. We have demonstrated that simultaneous activation of the trigeminal system attenuates the perception of odor intensity and distorts the EOG response. On the molecular level, we have identified a route for this cross-modal interaction. The neuropeptide calcitonin-gene related peptide (CGRP), which is released from trigeminal sensory fibres upon irritant stimulation, inhibits the odor response of olfactory receptor neurons. CGRP receptors expressed by these neurons mediate this neuromodulatory effect. This study demonstrates a site of trigeminal-olfactory interaction in the periphery. It reveals a pathway for trigeminal impact on olfactory signal processing that influences odor perception.
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Affiliation(s)
- Philipp Daiber
- Department of Molecular Physiology, Centre for Organismal Studies, Heidelberg University, Heidelberg, Germany
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19
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Nasal-to-CNS drug delivery: where are we now and where are we heading? An industrial perspective. Ther Deliv 2012; 3:195-208. [PMID: 22834197 DOI: 10.4155/tde.11.149] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Delivery of drug therapeutics across the blood-brain barrier is a challenging task for pharmaceutical scientists. Nasal-to-CNS drug delivery has shown promising results in preclinical efficacy models and investigatory human clinical trials. The further development of this technology with respect to the establishment of valid, predictable preclinical species models, translatable pharmacokinetic-pharmacodynamic relationships and definition of toxicology impact will help attract additional pharmaceutical investment in this drug-delivery approach. Further discoveries in nasal nanotechnology, targeted delivery devices and diagnostic olfactory imaging will serve to fuel the advancements in this area of drug delivery.
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20
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Lötsch J, Walter C, Felden L, Nöth U, Deichmann R, Oertel BG. The human operculo-insular cortex is pain-preferentially but not pain-exclusively activated by trigeminal and olfactory stimuli. PLoS One 2012; 7:e34798. [PMID: 22496865 PMCID: PMC3320628 DOI: 10.1371/journal.pone.0034798] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Accepted: 03/07/2012] [Indexed: 12/29/2022] Open
Abstract
Increasing evidence about the central nervous representation of pain in the brain suggests that the operculo-insular cortex is a crucial part of the pain matrix. The pain-specificity of a brain region may be tested by administering nociceptive stimuli while controlling for unspecific activations by administering non-nociceptive stimuli. We applied this paradigm to nasal chemosensation, delivering trigeminal or olfactory stimuli, to verify the pain-specificity of the operculo-insular cortex. In detail, brain activations due to intranasal stimulation induced by non-nociceptive olfactory stimuli of hydrogen sulfide (5 ppm) or vanillin (0.8 ppm) were used to mask brain activations due to somatosensory, clearly nociceptive trigeminal stimulations with gaseous carbon dioxide (75% v/v). Functional magnetic resonance (fMRI) images were recorded from 12 healthy volunteers in a 3T head scanner during stimulus administration using an event-related design. We found that significantly more activations following nociceptive than non-nociceptive stimuli were localized bilaterally in two restricted clusters in the brain containing the primary and secondary somatosensory areas and the insular cortices consistent with the operculo-insular cortex. However, these activations completely disappeared when eliminating activations associated with the administration of olfactory stimuli, which were small but measurable. While the present experiments verify that the operculo-insular cortex plays a role in the processing of nociceptive input, they also show that it is not a pain-exclusive brain region and allow, in the experimental context, for the interpretation that the operculo-insular cortex splay a major role in the detection of and responding to salient events, whether or not these events are nociceptive or painful.
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Affiliation(s)
- Jörn Lötsch
- Pharmazentrum Frankfurt/ZAFES, Institute of Clinical Pharmacology, Goethe - University, Frankfurt am Main, Germany.
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21
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Huart C, Legrain V, Hummel T, Rombaux P, Mouraux A. Time-frequency analysis of chemosensory event-related potentials to characterize the cortical representation of odors in humans. PLoS One 2012; 7:e33221. [PMID: 22427997 PMCID: PMC3302858 DOI: 10.1371/journal.pone.0033221] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Accepted: 02/09/2012] [Indexed: 11/19/2022] Open
Abstract
Background The recording of olfactory and trigeminal chemosensory event-related potentials (ERPs) has been proposed as an objective and non-invasive technique to study the cortical processing of odors in humans. Until now, the responses have been characterized mainly using across-trial averaging in the time domain. Unfortunately, chemosensory ERPs, in particular, olfactory ERPs, exhibit a relatively low signal-to-noise ratio. Hence, although the technique is increasingly used in basic research as well as in clinical practice to evaluate people suffering from olfactory disorders, its current clinical relevance remains very limited. Here, we used a time-frequency analysis based on the wavelet transform to reveal EEG responses that are not strictly phase-locked to onset of the chemosensory stimulus. We hypothesized that this approach would significantly enhance the signal-to-noise ratio of the EEG responses to chemosensory stimulation because, as compared to conventional time-domain averaging, (1) it is less sensitive to temporal jitter and (2) it can reveal non phase-locked EEG responses such as event-related synchronization and desynchronization. Methodology/Principal Findings EEG responses to selective trigeminal and olfactory stimulation were recorded in 11 normosmic subjects. A Morlet wavelet was used to characterize the elicited responses in the time-frequency domain. We found that this approach markedly improved the signal-to-noise ratio of the obtained EEG responses, in particular, following olfactory stimulation. Furthermore, the approach allowed characterizing non phase-locked components that could not be identified using conventional time-domain averaging. Conclusion/Significance By providing a more robust and complete view of how odors are represented in the human brain, our approach could constitute the basis for a robust tool to study olfaction, both for basic research and clinicians.
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Affiliation(s)
- Caroline Huart
- Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium.
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22
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Mettam JJ, McCrohan CR, Sneddon LU. Characterisation of chemosensory trigeminal receptors in the rainbow trout, Oncorhynchus mykiss: responses to chemical irritants and carbon dioxide. J Exp Biol 2012; 215:685-93. [DOI: 10.1242/jeb.060350] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
SUMMARY
Trigeminally innervated, mechanically sensitive chemoreceptors (M) were previously identified in rainbow trout, Oncorhynchus mykiss, but it is not known whether these receptors are responsive only to noxious, chemical irritants or have a general chemosensory function. This study aimed to characterise the stimulus–response properties of these receptors in comparison with polymodal nociceptors (P). Both P and M gave similar response profiles to acetic acid concentrations. The electrophysiological properties were similar between the two different afferent types. To determine whether the receptors have a nociceptive function, a range of chemical stimulants was applied to these receptors, including non-noxious stimuli such as ammonium chloride, bile, sodium bicarbonate and alarm pheromone, and potentially noxious chemical irritants such as acetic acid, carbon dioxide, low pH, citric acid, citric acid phosphate buffer and sodium chloride. Only irritant stimuli evoked a response, confirming their nociceptive function. All receptor afferents tested responded to carbon dioxide (CO2) in the form of mineral water or soda water. The majority responded to 1% acetic acid, 2% citric acid, citric acid phosphate buffer (pH 3) and 5.0 mol l–1 NaCl. CO2 receptors have been characterised in the orobranchial cavity and gill arches in fish; however, this is the first time that external CO2 receptors have been identified on the head of a fish. Because the fish skin is in constant contact with the aqueous environment, contaminants with a low pH or hypercapnia may stimulate the nociceptive system in fish.
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Affiliation(s)
- Jessica J. Mettam
- University of Liverpool, School of Biological Sciences, Liverpool L69 7ZB, UK
| | - Catherine R. McCrohan
- University of Manchester, Faculty of Life Sciences, AV Hill Building, Manchester M13 9PT, UK
| | - Lynne U. Sneddon
- University of Liverpool, School of Biological Sciences, Liverpool L69 7ZB, UK
- University of Chester, Biological Sciences, Chester CH1 4BJ, UK
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Lötsch J, Walter C, Felden L, Preibisch C, Nöth U, Martin T, Anti S, Deichmann R, Oertel BG. Extended cortical activations during evaluating successive pain stimuli. Soc Cogn Affect Neurosci 2011; 7:698-707. [PMID: 21768205 DOI: 10.1093/scan/nsr042] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Comparing pain is done in daily life and involves short-term memorizing and attention focusing. This event-related functional magnetic resonance imaging study investigated the short-term brain activations associated with the comparison of pain stimuli using a delayed discrimination paradigm. Fourteen healthy young volunteers compared two successive pain stimuli administered at a 10 s interval to the same location at the nasal mucosa. Fourteen age- and sex-matched subjects received similar pain stimuli without performing the comparison task. With the comparison task, the activations associated with the second pain stimulus were significantly greater than with the first stimulus in the anterior insular cortex and the primary somatosensory area. This was observed on the background of a generally increased stimulus-associated brain activation in the presence of the comparison task that included regions of the pain matrix (insular cortex, primary and secondary somatosensory area, midcingulate cortex, supplemental motor area) and regions associated with attention, decision making, working memory and body recognition (frontal and temporal gyri, inferior parietal lobule, precuneus, lingual cortices). This data provides a cerebral correlate for the role of pain as a biological alerting system that gains the subject's attention and then dominates most other perceptions and activities involving pain-specific and non-pain-specific brain regions.
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Affiliation(s)
- Jörn Lötsch
- Pharmazentrum Frankfurt/ZAFES, Institute of Clinical Pharmacology, Goethe-University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany.
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Melzner J, Bitter T, Guntinas-Lichius O, Gottschall R, Walther M, Gudziol H. Comparison of the orthonasal and retronasal detection thresholds for carbon dioxide in humans. Chem Senses 2011; 36:435-41. [PMID: 21398414 DOI: 10.1093/chemse/bjr013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Several studies have investigated the orthonasal detection threshold for carbon dioxide (CO(2)) in humans. The aim of current study was to investigate whether 24 healthy young subjects exhibited differences of CO(2) detection thresholds during orthonasal or retronasal stimulation. As nasal mucosa is believed to desensitize to CO(2) concentrations at or below 4% (v/v) during expiration, the second aim of the study was to explore the influence during nasal versus oral breathing on the detection thresholds. CO(2) stimuli of varying concentrations and a duration of 1000 ms were applied with an air-dilution olfactometer in either the anterior nasal cavity or the nasopharynx during nasal respectively oral breathing. In these 4 conditions, the mean CO(2) detection thresholds using the staircase forced-choice procedure were between 3.9% and 5.3% (v/v). Statistical analysis revealed a significant difference between orthonasal and retronasal stimulation. The CO(2) detection threshold was lower in retronasal stimulation. The nasopharyngeal mucosa is more sensitive to perithreshold CO(2) stimuli than the nasal mucosa. The breathing route had no influence on the detection thresholds. The results of this study indicate that the natural contact of the nasal mucosa with approximately 4% (v/v) CO(2) during nasal expiration does not influence CO(2) detection thresholds.
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Affiliation(s)
- Johannes Melzner
- Department of Otorhinolaryngology, University Hospital Jena, Germany.
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25
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Topographical differences in distribution and responsiveness of trigeminal sensitivity within the human nasal mucosa. Pain 2011; 151:516-521. [PMID: 20817356 DOI: 10.1016/j.pain.2010.08.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 08/01/2010] [Accepted: 08/10/2010] [Indexed: 11/21/2022]
Abstract
The study was designed to provide a topographical map of the sensitivity of the human nasal respiratory epithelium towards trigeminal chemosensory stimuli. As an electrophysiological measure of intranasal trigeminal activation at the level of the epithelium, we used the so-called negative mucosa potential (NMP), a measure that represents the sum of generator potentials of trigeminal receptor neurons after chemical stimulation. Sixty subjects participated (30 men and 30 women; mean age 23.5 years). Measurements were made in response to stimulation with menthol, CO(2), ethanol, and cinnamaldehyde, which are known to activate trigeminal receptors to various degrees. Recordings of the NMP were made from five intranasal sites: the anterior septum, the posterior septum, the tip of the middle turbinate, the tip of the lower turbinate, and the lateral side wall of the posterior nasal cavity. The recording electrode was positioned under endoscopic control. The largest NMP amplitudes were recorded at the anterior septum in response to stimulation with CO(2). Comparing all recording sites, significant differences were observed between responses at the posterior septum and the lateral side wall of the posterior nasal cavity in response to stimulation by ethanol, menthol, and CO(2). These findings suggest that the presence of topographical and chemosensory differences in the responsiveness of the nasal mucosa to irritants.
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Tzabazis AZ, Niv SH, Manering NA, Klyukinov M, Cuellar JM, Bhatnagar A, Yeomans DC. Trigeminal antihyperalgesic effect of intranasal carbon dioxide. Life Sci 2010; 87:36-41. [PMID: 20561904 DOI: 10.1016/j.lfs.2010.05.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2010] [Revised: 04/28/2010] [Accepted: 05/13/2010] [Indexed: 10/19/2022]
Abstract
AIMS Clinical studies demonstrate attenuation of trigeminal-related pain states such as migraine by intranasal CO(2) application. This study investigated the underlying mechanisms of this observation and its potential use to reverse trigeminal pain and hypersensitivity. MAIN METHODS We used a behavioral rat model of capsaicin-induced trigeminal thermal hyperalgesia, intranasal CO2 application and several pharmacologic agents such as carbonic anhydrase, acid-sensing ion channels (ASICs), and TRPV1 blocker as well as acidic buffer solutions to investigate and mimic the underlying mechanism. KEY FINDINGS Intranasal CO(2) application produced a robust dose-dependent antihyperalgesic effect in rats that lasted at least one hour. Blockade of nasal carbonic anhydrase with a dorzolamide solution (Trusopt ophthalmic solution) showed only a non-significant decrease of the antihyperalgesic effect of intranasal CO(2) application. Pharmacologic blockade of ASICs or TRPV(1) receptor significantly attenuated the antihyperalgesic effect of CO(2) application. The effect of intranasal CO(2) application could be mimicked by application of pH 4, but not pH 5, buffer solution to the nasal mucosa. As with CO(2) application, the antihyperalgesic effect of intranasal pH 4 buffer was blocked by nasal application of antagonists to ASICs and TRPV(1) receptors. SIGNIFICANCE Our results indicate that intranasal CO(2) application results in a subsequent attenuation of trigeminal nociception, mediated by protonic activation of TRPV(1) and ASIC channels. A potential central mechanism for this attenuation is discussed. The antihyperalgesic effects of intranasal CO(2) application might be useful for the treatment of trigeminal pain states.
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Affiliation(s)
- Alexander Z Tzabazis
- Department of Anesthesia, Stanford University, 300 Pasteur Drive, Stanford, CA 94305-5117, USA.
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Monsé C, Broding HC, Hoffmeyer F, Jettkant B, Berresheim H, Brüning T, Bünger J, Sucker K. Use of a calibration gas generator for irritation threshold assessment and as supplement of dynamic dilution olfactometry. Chem Senses 2010; 35:523-30. [PMID: 20507921 DOI: 10.1093/chemse/bjq046] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Human odor and mucosal membrane irritation thresholds are used as criteria for assessing air quality in occupational and environmental settings. Unfortunately, reported threshold values still differ by several orders of magnitude rendering most standard compilations of little practical utility. Thus, in view of the need to repeat odor threshold measurements with a reliable methodology, a new technical approach based on original equipment manufacturer integrated solutions is presented. To test applicability, a calibration gas generator was used to continuously generate a fixed odor vapor concentration. Different dilution steps were realized by coupling to a purchasable olfactometer. Comparison with the "standard," that is, odor stimulus supply via sample bags revealed good correspondence. As a second step, the calibration gas generator was used to generate rapid changes in stimulus concentration between consecutive trials. Irritation thresholds were measured with an ascending series of ammonia concentrations generated from an aqueous solution. The obtained thresholds lay within the range previously reported. The introduced technology enables quick and reliable odor stimulus generation and provides flexibility in choosing the optimal start concentration, the step-size between dilutions, and the range of stimulus concentrations. Errors from usage of rotameters or sample bags can be avoided.
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Affiliation(s)
- Christian Monsé
- Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr-University Bochum (IPA), Bürkle-de-la-Camp-Platz 1, Bochum, Germany.
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28
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Abstract
Dynamics, or how stimulation occurs over time, influences the somatosensory impact of volatile chemicals. Within an experimental session, sensation waxes with steady presentation over seconds to minutes, may reach a plateau, and then may fade. Long-term occupational exposure can desensitize the trigeminal system. Short- and long-term dynamics might be mediated by different mechanisms. For brief intranasal exposures (i.e., up to about 10 seconds), studies have systematically manipulated both time (duration of exposure) and concentration to maintain a fixed perceived intensity or a fixed level of detection. A simple mass integration model describes the trade-off between concentration and time quite well: a fixed-ratio increase in duration compensates for a fixed-ratio decrease in concentration. However, for most compounds, more than a two-fold increase in duration are required to compensate for cutting concentration in half. For example, for ethanol, an increase in duration of about six-fold are required. For such compounds that display highly imperfect integration, a fixed number of molecules might have a much greater sensory impact when presented over 0.2 seconds than over 0.5 seconds. Nasal chemesthesis may be temporally sluggish compared to olfaction, but fine-grained dynamics still matter. Time-intensity ratings of nasal irritation from dynamic stimuli also support this conclusion. Although integration is generally imperfect, compounds vary widely in how far they fall short of perfect time-concentration trading. Current studies use a structure-activity approach to determine how molecular parameters correlate with how well a compound integrates over time.
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Affiliation(s)
- Paul M Wise
- Monell Chemical Senses Center, Philadelphia, Pennsylvania 19104, USA.
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29
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Albrecht J, Kopietz R, Linn J, Sakar V, Anzinger A, Schreder T, Pollatos O, Brückmann H, Kobal G, Wiesmann M. Activation of olfactory and trigeminal cortical areas following stimulation of the nasal mucosa with low concentrations of S(-)-nicotine vapor--an fMRI study on chemosensory perception. Hum Brain Mapp 2009; 30:699-710. [PMID: 18381635 PMCID: PMC6870617 DOI: 10.1002/hbm.20535] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Revised: 12/06/2007] [Accepted: 12/07/2007] [Indexed: 11/09/2022] Open
Abstract
Applied to the nasal mucosa in low concentrations, nicotine vapor evokes odorous sensations (mediated by the olfactory system) whereas at higher concentrations nicotine vapor additionally produces burning and stinging sensations in the nose (mediated by the trigeminal system). The objective of this study was to determine whether intranasal stimulation with suprathreshold concentrations of S(-)-nicotine vapor causes brain activation in olfactory cortical areas or if trigeminal cortical areas are also activated. Individual olfactory detection thresholds for S(-)-nicotine were determined in 19 healthy occasional smokers using a computer-controlled air-dilution olfactometer. Functional magnetic resonance images were acquired using a 1.5T MR scanner with applications of nicotine in concentrations at or just above the individual's olfactory detection threshold. Subjects reliably perceived the stimuli as being odorous. Accordingly, activation of brain areas known to be involved in processing of olfactory stimuli was identified. Although most of the subjects never or only rarely observed a burning or painful sensation in the nose, brain areas associated with the processing of painful stimuli were activated in all subjects. This indicates that the olfactory and trigeminal systems are activated during perception of nicotine and it is not possible to completely separate olfactory from trigeminal effects by lowering the concentration of the applied nicotine. In conclusion, even at low concentrations that do not consistently lead to painful sensations, intranasally applied nicotine activates both the olfactory and the trigeminal system.
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Affiliation(s)
- Jessica Albrecht
- Department of Neuroradiology, Ludwig-Maximilians-University Munich, Munich, Germany.
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Lin W, Ogura T, Margolskee RF, Finger TE, Restrepo D. TRPM5-Expressing Solitary Chemosensory Cells Respond to Odorous Irritants. J Neurophysiol 2008; 99:1451-60. [DOI: 10.1152/jn.01195.2007] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Inhaled airborne irritants elicit sensory responses in trigeminal nerves innervating the nasal epithelium, leading to protective reflexes. The sensory mechanisms involved in the detection of odorous irritants are poorly understood. We identified a large population of solitary chemosensory cells expressing the transient receptor potential channel M5 (TRPM5) using transgenic mice where the promoter of TRPM5 drives the expression of green fluorescent protein (GFP). Most of these solitary chemosensory cells lie in the anterior nasal cavity. These GFP-labeled solitary chemosensory cells exhibited immunoreactivity for synaptobrevin-2, a vesicle-associated membrane protein important for synaptic transmission. Concomitantly, we found trigeminal nerve fibers apposed closely to the solitary chemosensory cells, indicating potential transmission of sensory information to trigeminal fibers. In addition, stimulation of the nasal cavity with high concentrations (0.5–5 mM) of a variety of odorants elicited event-related potentials (ERPs) in areas rich in TRPM5-expressing solitary chemosensory cells. Furthermore, odorous chemicals and trigeminal stimuli induced changes in intracellular Ca2+ levels in isolated TRPM5-expressing solitary chemosensory cells in a concentration-dependent manner. Together, our data show that the TRPM5-expressing cells respond to a variety of chemicals at high exposure levels typical of irritants and are positioned in the nasal cavity appropriately to monitor inhaled air quality.
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Cometto-Muñiz JE, Cain WS, Abraham MH, Sánchez-Moreno R. Concentration-detection functions for eye irritation evoked by homologous n-alcohols and acetates approaching a cut-off point. Exp Brain Res 2007; 182:71-9. [PMID: 17503026 DOI: 10.1007/s00221-007-0966-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Accepted: 04/16/2007] [Indexed: 02/06/2023]
Abstract
We measured the concentration-detection (i.e., psychometric) functions for the eye irritation evoked by three homologous n-alcohols (1-nonanol, 1-decanol and 1-undecanol) and two homologous acetates (nonyl and decyl acetate). A vapor delivery device based on a dynamic dilution of stimuli in nitrogen served to present various concentrations of each compound, including the undiluted vapor, to the subjects (n >or= 26). Delivered concentrations were quantified by gas chromatography. Detection probability (P) was assessed via a three-alternative, forced-choice procedure and quantified on a scale ranging from P = 0.0 (chance detection) to P = 1.0 (perfect detection). Flow rate to the eye equaled 2.5 l/min and time of exposure was 6 s. The functions for 1-undecanol and decyl acetate plateaued at P approximately 0.5 and P approximately 0.25, respectively, such that further increases in concentration failed to increase detection notably. Thus, both series reached a break point, or cut-off, in the detection of ocular irritation. The present outcome provides additional evidence that the cut-off does not rest on the low vapor concentration of the homolog but, more likely, on the homolog exceeding a critical molecular dimension(s), which prevents it from interacting effectively with the appropriate receptors.
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Affiliation(s)
- J Enrique Cometto-Muñiz
- Chemosensory Perception Laboratory, Department of Surgery (Otolaryngology), University of California, San Diego, 9500 Gilman Dr., Mail Code 0957, La Jolla, CA 92093-0957, USA.
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Renner B, Clarke G, Grattan T, Beisel A, Mueller C, Werner U, Kobal G, Brune K. Caffeine accelerates absorption and enhances the analgesic effect of acetaminophen. J Clin Pharmacol 2007; 47:715-26. [PMID: 17442681 DOI: 10.1177/0091270007299762] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The aim of this study was to determine the analgesic effect of acetaminophen compared to a combination of both caffeine and acetaminophen or caffeine alone using tonic and phasic pain stimulation. Twenty-four subjects were treated orally with 1000 mg acetaminophen, 130 mg caffeine, and a combination of both in a 4-way crossover, double-blind, placebo-controlled study. Pharmacokinetics and analgesic effects were assessed by means of an experimental pain model based on pain-related cortical potentials after phasic stimulation of the nasal mucosa with CO(2) and based on pain ratings after tonic stimulation with dry air. Analgesic effects of acetaminophen and acetaminophen plus caffeine but not caffeine alone caused a significant reduction of pain-related cortical potentials beginning 30 minutes after medication. The combination demonstrated an enhanced effect throughout the observation time up to 3 hours. Caffeine accelerated acetaminophen absorption, indicated by enhanced early AUCs. Significant analgesic effects of the combination on tonic pain ratings were found throughout the observation time as compared to acetaminophen and placebo. In this study, caffeine enhanced and prolonged the analgesic activity of acetaminophen.
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Affiliation(s)
- Bertold Renner
- University of Erlangen-Nuremberg, Department of Experimental and Clinical Pharmacology and Toxicology, Krankenhausstr. 9, D-91054 Erlangen, Germany.
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Scheibe M, Zahnert T, Hummel T. Topographical differences in the trigeminal sensitivity of the human nasal mucosa. Neuroreport 2006; 17:1417-20. [PMID: 16932150 DOI: 10.1097/01.wnr.0000224764.61959.e8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The aim of the study was to investigate differences in the distribution of intranasal trigeminal receptors in humans using an electrophysiological measure of trigeminally induced activation, the negative mucosa potential. A total of 29 young, healthy volunteers participated, results were on the basis of data from 18 participants. The trigeminal irritant CO2 was presented using a computer-controlled olfactometer. Negative mucosa potential recording sites included the anterior olfactory cleft, the anterior septum, and the lower turbinate. Lowest amplitudes of the negative mucosa potential were found in the olfactory cleft, maximum amplitudes at the septum. Intranasal measurements of CO2 concentrations suggested that these differences were not due to the intranasal distribution of CO2. These results are compatible with the idea that the trigeminal system acts as a sentinel of the human airways.
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Affiliation(s)
- Mandy Scheibe
- Smell & Taste Clinic, Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany
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Smeets MAM, Bulsing PJ, van Rooden S, Steinmann R, de Ru JA, Ogink NWM, van Thriel C, Dalton PH. Odor and Irritation Thresholds for Ammonia: A Comparison between Static and Dynamic Olfactometry. Chem Senses 2006; 32:11-20. [PMID: 17003100 DOI: 10.1093/chemse/bjl031] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Odor and lateralization (irritation) thresholds (LTs) for ammonia vapor were measured using static and dynamic olfactometry. The purpose of the study was to explore the test-retest reliability and comparability of dynamic olfactometry methodology, generally used to determine odor thresholds following European Committee for Standardization guidelines in the context of odor regulations to outside emissions, with static olfactometry. Within a 2-week period, odor and LTs for ammonia were obtained twice for each method for 24 females. No significant differences between methods were found: mean odor detection thresholds (ODTs) were 2.6 parts per million (ppm) for either method (P = 0.96), and mean LTs were 31.7 and 60.9 ppm for the static and dynamic method, respectively (P = 0.07). Test-retest reliability was higher for the dynamic than for the static method (r = 0.61 vs. 0.14 for ODTs and r = 0.86 vs. 0.45 for LTs). The choice of optimal method for any application, however, depends not only on psychometric factors but also on practical factors such as physicochemical properties of the compound, availability of equipment and expertise, task efficiency, and costs.
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Affiliation(s)
- Monique A M Smeets
- Department of Clinical and Health Psychology, Utrecht University, P.O. Box 80.140, 3508 TC Utrecht, the Netherlands.
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Cometto-Muñiz JE, Cain WS, Abraham MH, Sánchez-Moreno R. Chemical Boundaries for Detection of Eye Irritation in Humans from Homologous Vapors. Toxicol Sci 2006; 91:600-9. [PMID: 16543295 DOI: 10.1093/toxsci/kfj157] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In a series of experiments, we looked at a "cutoff" effect for the detection of eye irritation from neat vapors of homologous n-alkylbenzenes and 2-ketones. Stimuli comprised pentyl, hexyl, and heptyl benzene, 2-dodecanone, and 2-tridecanone, presented to each eye at 4 and 8 l/min for 6 sec, using a three-alternative forced-choice procedure against blanks. Detection probability corrected for chance (i.e., detectability) decreased with carbon chain length such that heptyl benzene and 2-tridecanone were virtually undetectable, irrespective of flow rate to the eye. Heating both stimuli sources to 37 degrees C (body temperature) from 23 degrees C (room temperature) increased vapor concentration by 5.0 and 6.9 times, respectively, for heptyl benzene and 2-tridecanone. Still, both chemicals failed to show increased detection for 13 of the 21 participants. In addition, plots of experimentally measured and calculated eye irritation thresholds as a function of carbon chain length for each series indicated that, based on the trend, the concentration of the two cutoff homologs at 37 degrees C should have been high enough to allow detection. Taken together, the results suggest that these cutoffs rest on limitations related to the dimension of the molecules rather than on limitations related to their vapor concentration. For example, the stimulus molecule could exceed the size that allows it to fit into the receptor pocket of a receptive protein. Plots of calculated molecular dimensions across homologous alkylbenzenes, from ethyl to dodecylbenzene, and across 2-ketones, from 2-octanone to 2-octadecanone, provided additional support to the above conclusion.
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Affiliation(s)
- J Enrique Cometto-Muñiz
- Chemosensory Perception Laboratory, Department of Surgery (Otolaryngology), University of California, San Diego, La Jolla, California 92093-0957, USA.
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Abstract
Two experiments examined the trade-off between concentration and stimulus duration in nasal lateralization of n-ethyl alcohol. In nasal lateralization, a common measure of irritation threshold, subjects receive chemical vapor in one nostril and clean air in the other. Subjects try to determine which nostril received the chemical. Within experimental runs, subjects received fixed concentrations (1650-5000 ppm) of ethanol, and duration was varied to find the shortest, lateralizable stimulus. In Experiment 1, a small group of subjects was tested intensively to obtain stable individual data. In Experiment 2, a larger group was studied using more rapid methods. In both cases, subjects could lateralize increasingly weaker concentrations with longer stimulus presentations. Hence integration occurred. However, more than a twofold increase in duration was required to compensate for a twofold decrease in concentration to maintain threshold lateralization. These results suggest that an imperfect, mass-integrator model can describe short-term integration of nasal lateralization of ethanol.
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Affiliation(s)
- Paul M Wise
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104-3308, USA.
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Wise PM, Canty TM, Wysocki CJ. Temporal integration of nasal irritation from ammonia at threshold and supra-threshold levels. Toxicol Sci 2005; 87:223-31. [PMID: 15976196 DOI: 10.1093/toxsci/kfi229] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Two experiments examined integration of perceived irritation over short-term (approximately 100-4000 ms) delivery of ammonia into the nasal cavity of human subjects. Experiment 1 examined trade-offs between time and concentration at threshold level by means of nasal lateralization, a common measure of irritation threshold. Within experimental sessions, the duration of a fixed-concentration stimulus varied to determine the shortest, detectable pulse. Subjects could lateralize increasingly weaker concentrations with longer stimulus presentations. Experiment 2 examined an analogous trade-off for supra-threshold irritation. Subjects rated irritation from presentations of ammonia that varied both in concentration and in duration. Rated intensity for a given concentration increased with stimulus duration. Hence integration occurred at both threshold and supra-threshold levels. However, more than a twofold increase in duration was required to compensate for a twofold decrease in concentration to maintain threshold lateralization or a fixed level of perceived intensity. These results suggest that an imperfect mass-integrator model may be able to describe short-term integration of nasal irritation from ammonia at both the threshold and supra-threshold levels.
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Affiliation(s)
- Paul M Wise
- Monell Chemical Senses Center, Philadelphia, Pennsylvania, 19104-3308, USA.
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