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McGlone JJ, Archer C, Henderson M. Interpretive review: Semiochemicals in domestic pigs and dogs. Front Vet Sci 2022; 9:967980. [PMID: 36387395 PMCID: PMC9640746 DOI: 10.3389/fvets.2022.967980] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 10/05/2022] [Indexed: 01/14/2024] Open
Abstract
This interpretive review includes discussion of the available scientific literature with interpretations by the authors. The broad field of semiochemicals can be confusing to scientists and consumers. This review attempts to summarize the known scientific studies for pig and dog semiochemicals while at the same time attempting to refine our use of terminology. The specific objectives of this interpretive review are to summarize and interpret much of the key scientific literature (but not the lay literature) on semiochemicals in pigs and dogs to include (1) definitions of semiochemicals and related molecules including pheromones, (2) to briefly summarize olfactory organs, and (3) and to examine the scientific literature for semiochemical mechanisms and applications in dogs and pigs (two domesticated species with known olfactory acuity). Dogs and pigs have olfactory features that are similar in that they both lack certain olfactory organs (Grueneberg ganglion and Septal Organ) and they have a small vomeronasal organ (VNO) without some major receptors that are found in other species. The primary olfactory organs for both pigs and dogs are the main olfactory epithelium and perhaps the trigeminal nerve. Several examples of pheromones activating the brain via the MOE or Trigeminal nerve rather than the VNO challenge the concept that the VNO is the site of pheromone sensing. We believe it is not appropriate to label something a pheromone when evidence is not available to show that it is a pheromone. We offer definitions for the terms semiochemicals, pheromones, interomones and others and then determine if the evidence is sufficient to call certain semiochemicals a pheromone. Here we review mixed, largely negative, scientific reports of the efficacy of some products labeled as "pheromones" that are more appropriately called semiochemicals. Interomones can have a more powerful effect on dog behavior and physiology than semiochemicals marketed as pheromones. Because marketing of semiochemicals is far ahead of the science, bringing some logic and uniformity to the field will benefit animals and hopefully cause less consumer confusion. Semiochemicals have the potential to offer powerful solutions to behavioral problems using more naturally occurring molecules.
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Affiliation(s)
- John J. McGlone
- Laboratory of Animal Behavior, Physiology and Welfare, Texas Tech University, Lubbock, TX, United States
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2
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From In Vitro Data to In Vivo Interspecies Danger Communication: A Study of Chemosensing via the Mouse Grueneberg Ganglion. Animals (Basel) 2022; 12:ani12030356. [PMID: 35158677 PMCID: PMC8833560 DOI: 10.3390/ani12030356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/26/2022] [Accepted: 01/27/2022] [Indexed: 12/10/2022] Open
Abstract
Simple Summary The mouse olfactory system is essential for danger detection with a critical role in the Grueneberg ganglion subsystem. This organ, which is localized at the tip of the nose, is implicated in the recognition of kairomones, or chemical cues released by predators which allow interspecies communication. These kairomones, which are present in the secretions of predators, will induce fear-related behaviours in mice. It is not yet known how the Grueneberg ganglion neurons can detect these molecules; however, three specific bitter taste receptors, known as TAS2Rs, that are present in the Grueneberg ganglion play a role in this detection. Here, using in vitro, ex vivo and in vivo experimental approaches, we identified two novel and potent sources of kairomones that are recognized by the mouse Grueneberg ganglion neurons, namely the biological secretions from the raccoon (Procyon lotor) and the skunk (Mephitis mephitis). Abstract In the wild, mice have developed survival strategies to detect volatile cues that warn them of potential danger. Specific olfactory neurons found in the Grueneberg ganglion olfactory subsystem can detect alarm pheromones emitted by stressed conspecifics, as well as kairomones involuntarily released by their predators. These volatile chemical cues allow intra- and interspecies communication of danger, respectively. Alarm pheromones, kairomones and bitter taste ligands share a common chemical motif containing sulfur or nitrogen. Interestingly, three specific bitter taste receptors (TAS2Rs) have been found in the Grueneberg ganglion neurons that are implicated in danger signalling pathways. We have recently developed a TAS2R–expressing heterologous system that mimics the Grueneberg ganglion neuron responses after kairomone stimulation. Here, we demonstrated by in vitro, ex vivo and in vivo experiments that the biological secretions from the raccoon (Procyon lotor) and the skunk (Mephitis mephitis) were acting as potent sources of kairomones. They activated the Grueneberg ganglion neurons and induced fear-related behaviours in mice. Identification of new sources of semiochemicals is a first step towards an understanding of the interspecies danger communication that takes place in the Grueneberg ganglion.
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Neural and Hormonal Basis of Opposite-Sex Preference by Chemosensory Signals. Int J Mol Sci 2021; 22:ijms22158311. [PMID: 34361077 PMCID: PMC8347621 DOI: 10.3390/ijms22158311] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 12/13/2022] Open
Abstract
In mammalian reproduction, sexually active males seek female conspecifics, while estrous females try to approach males. This sex-specific response tendency is called sexual preference. In small rodents, sexual preference cues are mainly chemosensory signals, including pheromones. In this article, we review the physiological mechanisms involved in sexual preference for opposite-sex chemosensory signals in well-studied laboratory rodents, mice, rats, and hamsters of both sexes, especially an overview of peripheral sensory receptors, and hormonal and central regulation. In the hormonal regulation section, we discuss potential rodent brain bisexuality, as it includes neural substrates controlling both masculine and feminine sexual preferences, i.e., masculine preference for female odors and the opposite. In the central regulation section, we show the substantial circuit regulating sexual preference and also the influence of sexual experience that innate attractants activate in the brain reward system to establish the learned attractant. Finally, we review the regulation of sexual preference by neuropeptides, oxytocin, vasopressin, and kisspeptin. Through this review, we clarified the contradictions and deficiencies in our current knowledge on the neuroendocrine regulation of sexual preference and sought to present problems requiring further study.
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Brechbühl J, Lopes AC, Wood D, Bouteiller S, de Vallière A, Verdumo C, Broillet MC. Age-dependent appearance of SARS-CoV-2 entry sites in mouse chemosensory systems reflects COVID-19 anosmia-ageusia symptoms. Commun Biol 2021; 4:880. [PMID: 34267318 PMCID: PMC8282876 DOI: 10.1038/s42003-021-02410-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 06/30/2021] [Indexed: 01/08/2023] Open
Abstract
COVID-19 pandemic has given rise to a collective scientific effort to study its viral causing agent SARS-CoV-2. Research is focusing in particular on its infection mechanisms and on the associated-disease symptoms. Interestingly, this environmental pathogen directly affects the human chemosensory systems leading to anosmia and ageusia. Evidence for the presence of the cellular entry sites of the virus, the ACE2/TMPRSS2 proteins, has been reported in non-chemosensory cells in the rodent’s nose and mouth, missing a direct correlation between the symptoms reported in patients and the observed direct viral infection in human sensory cells. Here, mapping the gene and protein expression of ACE2/TMPRSS2 in the mouse olfactory and gustatory cells, we precisely identify the virus target cells to be of basal and sensory origin and reveal the age-dependent appearance of viral entry-sites. Our results propose an alternative interpretation of the human viral-induced sensory symptoms and give investigative perspectives on animal models. Brechbühl et al characterise the gene and protein expression of ACE2/TMPRSS2 in the mouse olfactory and gustatory cells, which reveals that SARS-CoV-2 target cells are of basal and sensory origin. They also demonstrate an age-dependent appearance of viral entry-sites, which could inform the use of mouse models in the investigation of SARS-CoV-2 effects on olfaction.
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Affiliation(s)
- Julien Brechbühl
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Ana Catarina Lopes
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Dean Wood
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Sofiane Bouteiller
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Aurélie de Vallière
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Chantal Verdumo
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Marie-Christine Broillet
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
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5
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Manzini I, Schild D, Di Natale C. Principles of odor coding in vertebrates and artificial chemosensory systems. Physiol Rev 2021; 102:61-154. [PMID: 34254835 DOI: 10.1152/physrev.00036.2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The biological olfactory system is the sensory system responsible for the detection of the chemical composition of the environment. Several attempts to mimic biological olfactory systems have led to various artificial olfactory systems using different technical approaches. Here we provide a parallel description of biological olfactory systems and their technical counterparts. We start with a presentation of the input to the systems, the stimuli, and treat the interface between the external world and the environment where receptor neurons or artificial chemosensors reside. We then delineate the functions of receptor neurons and chemosensors as well as their overall I-O relationships. Up to this point, our account of the systems goes along similar lines. The next processing steps differ considerably: while in biology the processing step following the receptor neurons is the "integration" and "processing" of receptor neuron outputs in the olfactory bulb, this step has various realizations in electronic noses. For a long period of time, the signal processing stages beyond the olfactory bulb, i.e., the higher olfactory centers were little studied. Only recently there has been a marked growth of studies tackling the information processing in these centers. In electronic noses, a third stage of processing has virtually never been considered. In this review, we provide an up-to-date overview of the current knowledge of both fields and, for the first time, attempt to tie them together. We hope it will be a breeding ground for better information, communication, and data exchange between very related but so far little connected fields.
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Affiliation(s)
- Ivan Manzini
- Animal Physiology and Molecular Biomedicine, Justus-Liebig-University Gießen, Gießen, Germany
| | - Detlev Schild
- Institute of Neurophysiology and Cellular Biophysics, University Medical Center, University of Göttingen, Göttingen, Germany
| | - Corrado Di Natale
- Department of Electronic Engineering, University of Rome Tor Vergata, Rome, Italy
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The Grueneberg ganglion: signal transduction and coding in an olfactory and thermosensory organ involved in the detection of alarm pheromones and predator-secreted kairomones. Cell Tissue Res 2021; 383:535-548. [PMID: 33404842 DOI: 10.1007/s00441-020-03380-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 12/06/2020] [Indexed: 12/26/2022]
Abstract
In numerous mammalian species, the nose harbors several compartments populated by chemosensory cells. Among them, the Grueneberg ganglion (GG) located in the anterior nasal region comprises sensory neurons activated by given substances. In rodents, in which the GG has been best studied, these chemical cues mainly include heterocyclic compounds released by predators or by conspecifics. Since some of these substances evoke fear- or stress-associated responses, the GG is considered as a detector for alerting semiochemicals. In fact, certain behavioral and physiological reactions to alarm pheromones and predator-secreted kairomones are attenuated in the absence of a functional GG. Intriguingly, GG neurons are also stimulated by cool temperatures. Moreover, ambient temperatures modulate olfactory responsiveness in the GG, indicating that cross-talks exist between the transduction pathways mediating chemo- and thermosensory signaling in this organ. In this context, exploring the relevant molecular cascades has demonstrated that some chemosensory transduction elements are also crucial for thermosensory signaling in the GG. Finally, for further processing of sensory information, axons of GG neurons project to the olfactory bulb of the brain where they innervate distinct glomerular structures belonging to the enigmatic necklace glomeruli. In this review, the stimuli activating GG neurons as well as the underlying transduction pathways are summarized. Because these stimuli do not exclusively activate GG neurons but also other sensory cells, the biological relevance of the GG is discussed, with a special focus on the role of the GG in detecting alarm signals.
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7
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Zimmerman AD, Munger SD. Olfactory subsystems associated with the necklace glomeruli in rodents. Cell Tissue Res 2021; 383:549-557. [PMID: 33404845 DOI: 10.1007/s00441-020-03388-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 12/07/2020] [Indexed: 01/27/2023]
Abstract
The necklace glomeruli are a loosely defined group of glomeruli encircling the caudal main olfactory bulb in rodents. Initially defined by the expression of various immunohistochemical markers, they are now better understood in the context of the specialized chemosensory neurons of the main olfactory epithelium and Grueneberg ganglion that innervate them. It has become clear that the necklace region of the rodent main olfactory bulb is composed of multiple distinct groups of glomeruli, defined at least in part by their afferent inputs. In this review, we will explore the necklace glomeruli and the chemosensory neurons that innervate them.
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Affiliation(s)
- Arthur D Zimmerman
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, PO Box 100267, Gainesville, FL, 32610, USA
- Center for Smell and Taste, University of Florida, PO Box 100127, Gainesville, FL, 32610, USA
- Training Program in Chemosensory Science, University of Florida, PO Box 100127, Gainesville, FL, 32610, USA
| | - Steven D Munger
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, PO Box 100267, Gainesville, FL, 32610, USA.
- Center for Smell and Taste, University of Florida, PO Box 100127, Gainesville, FL, 32610, USA.
- Training Program in Chemosensory Science, University of Florida, PO Box 100127, Gainesville, FL, 32610, USA.
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Florida College of Medicine, PO Box 100266, Gainesville, FL, 32610, USA.
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The Grueneberg ganglion controls odor-driven food choices in mice under threat. Commun Biol 2020; 3:533. [PMID: 32973323 PMCID: PMC7518244 DOI: 10.1038/s42003-020-01257-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 09/01/2020] [Indexed: 12/23/2022] Open
Abstract
The ability to efficiently search for food is fundamental for animal survival. Olfactory messages are used to find food while being aware of the impending risk of predation. How these different olfactory clues are combined to optimize decision-making concerning food selection remains elusive. Here, we find that chemical danger cues drive the food selection in mice via the activation of a specific olfactory subsystem, the Grueneberg ganglion (GG). We show that a functional GG is required to decipher the threatening quality of an unfamiliar food. We also find that the increase in corticosterone, which is GG-dependent, enhances safe food preference acquired during social transmission. Moreover, we demonstrate that memory retrieval for food preference can be extinguished by activation of the GG circuitry. Our findings reveal a key function played by the GG in controlling contextual food responses and illustrate how mammalian organisms integrate environmental chemical stress to optimize decision-making. Julien Brechbühl et al. show that the Grueneberg ganglion olfactory subsystem is necessary for deciphering the threatening or safe qualities of unfamiliar food based on olfactory or social signals, respectively, in mice. These results highlight the role of this subsystem in optimizing decision-making strategies related to food preference by integrating environmental cues.
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Ramos MF, Baker J, Atzpodien EA, Bach U, Brassard J, Cartwright J, Farman C, Fishman C, Jacobsen M, Junker-Walker U, Kuper F, Moreno MCR, Rittinghausen S, Schafer K, Tanaka K, Teixeira L, Yoshizawa K, Zhang H. Nonproliferative and Proliferative Lesions of the Ratand Mouse Special Sense Organs(Ocular [eye and glands], Olfactory and Otic). J Toxicol Pathol 2018; 31:97S-214S. [PMID: 30158741 PMCID: PMC6108092 DOI: 10.1293/tox.31.97s] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Affiliation(s)
| | - Julia Baker
- Member of eye subgroup
- Charles River Laboratories, Inc., Frederick, MD, USA
| | | | - Ute Bach
- Member of eye subgroup
- Bayer AG, Wuppertal, Germany
| | | | | | | | - Cindy Fishman
- Member of eye subgroup
- Member of glands of the eye subgroup
- GlaxoSmithKline, King of Prussia, PA, USA
| | | | | | - Frieke Kuper
- Member of olfactory subgroup
- Retired; formerly The Netherlands Organization for Applied
Scientific Research (TNO), Zeist, the Netherlands
| | | | | | - Ken Schafer
- Member of eye subgroup
- Member of otic subgroup
- Vet Path Services, Inc., Mason, OH, USA
| | - Kohji Tanaka
- Member of eye subgroup
- Nippon Boehringer Ingelheim, Japan
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Homiack D, O'Cinneide E, Hajmurad S, Dohanich GP, Schrader LA. Effect of acute alarm odor exposure and biological sex on generalized avoidance and glutamatergic signaling in the hippocampus of Wistar rats. Stress 2018; 21:292-303. [PMID: 29916754 DOI: 10.1080/10253890.2018.1484099] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Post-traumatic stress disorder (PTSD) is characterized by the development of paradoxical memory disturbances including intrusive memories and amnesia for specific details of the traumatic experience. Despite evidence that women are at higher risk to develop PTSD, most animal research has focused on the processes by which male rodents develop adaptive fear memory. As such, the mechanisms contributing to sex differences in the development of PTSD-like memory disturbances are poorly understood. In this investigation, we exposed adult male and female Wistar rats to the synthetic alarm odor 2,4,5-trimethylthiazole (TMT) to assess development of generalized fear behavior and rapid modulation of glutamate uptake and signaling cascades associated with hippocampus-dependent long-term memory. We report that female Wistar rats exposed to alarm odor exhibit context discrimination impairments relative to TMT-exposed male rats, suggesting the intriguing possibility that females are at greater risk in developing generalized fear memories. Mechanistically, alarm odor exposure rapidly modulated signaling cascades consistent with activation of the CREB shut-off cascade in the male, but not the female hippocampus. Moreover, TMT exposure dampened glutamate uptake and affected expression of the glutamate transporter, GLT-1 in the hippocampus. Taken together, these results provide evidence for rapid sex-dependent modulation of CREB signaling in the hippocampus by alarm odor exposure which may contribute to the development of generalized fear.
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Affiliation(s)
- Damek Homiack
- a Neuroscience Program, Brain Institute , Tulane University , New Orleans , LA , USA
| | - Emma O'Cinneide
- a Neuroscience Program, Brain Institute , Tulane University , New Orleans , LA , USA
| | - Sema Hajmurad
- b Department of Cell and Molecular Biology , Tulane University , New Orleans , LA , USA
| | - Gary P Dohanich
- a Neuroscience Program, Brain Institute , Tulane University , New Orleans , LA , USA
- c Department of Psychology , Tulane University , New Orleans , LA , USA
| | - Laura A Schrader
- a Neuroscience Program, Brain Institute , Tulane University , New Orleans , LA , USA
- b Department of Cell and Molecular Biology , Tulane University , New Orleans , LA , USA
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Moine F, Brechbühl J, Nenniger Tosato M, Beaumann M, Broillet MC. Alarm pheromone and kairomone detection via bitter taste receptors in the mouse Grueneberg ganglion. BMC Biol 2018; 16:12. [PMID: 29347925 PMCID: PMC5774136 DOI: 10.1186/s12915-017-0479-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 12/28/2017] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND The mouse Grueneberg ganglion (GG) is an olfactory subsystem specialized in the detection of volatile heterocyclic compounds signalling danger. The signalling pathways transducing the danger signals are only beginning to be characterized. RESULTS Screening chemical libraries for compounds structurally resembling the already-identified GG ligands, we found a new category of chemicals previously identified as bitter tastants that initiated fear-related behaviours in mice depending on their volatility and evoked neuronal responses in mouse GG neurons. Screening for the expression of signalling receptors of these compounds in the mouse GG yielded transcripts of the taste receptors Tas2r115, Tas2r131, Tas2r143 and their associated G protein α-gustducin (Gnat3). We were further able to confirm their expression at the protein level. Challenging these three G protein-coupled receptors in a heterologous system with the known GG ligands, we identified TAS2R143 as a chemical danger receptor transducing both alarm pheromone and predator-derived kairomone signals. CONCLUSIONS These results demonstrate that similar molecular elements might be used by the GG and by the taste system to detect chemical danger signals present in the environment.
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Affiliation(s)
- Fabian Moine
- Department of Pharmacology and Toxicology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, CH-1011, Switzerland
| | - Julien Brechbühl
- Department of Pharmacology and Toxicology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, CH-1011, Switzerland
| | - Monique Nenniger Tosato
- Department of Pharmacology and Toxicology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, CH-1011, Switzerland
| | - Manon Beaumann
- Department of Pharmacology and Toxicology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, CH-1011, Switzerland
| | - Marie-Christine Broillet
- Department of Pharmacology and Toxicology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, CH-1011, Switzerland.
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Bumbalo R, Lieber M, Schroeder L, Polat Y, Breer H, Fleischer J. Grueneberg Glomeruli in the Olfactory Bulb are Activated by Odorants and Cool Temperature. Cell Mol Neurobiol 2016; 37:729-742. [PMID: 27488854 DOI: 10.1007/s10571-016-0408-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 07/19/2016] [Indexed: 01/18/2023]
Abstract
Neurons of the Grueneberg ganglion respond to cool temperatures as well as to distinct odorants and extend axonal processes to the olfactory bulb of the brain. Analyses of transgenic mice, in which Grueneberg ganglion neurons and their axons are labeled, revealed that these axons innervated nine distinct glomeruli distributed in a characteristic topographical pattern in dorsal, lateral, ventral, and medial regions of rather posterior areas in the bulb. To assess activation of these glomeruli (hereinafter designated as Grueneberg glomeruli) upon stimulation of Grueneberg ganglion neurons, mice were exposed to the odorant 2,3-dimethylpyrazine (2,3-DMP) and the expression of the activity-dependent marker c-Fos in juxtaglomerular cells of the relevant glomeruli was monitored. It was found that all of these glomeruli were activated, irrespective of their localization in the bulb. To verify that the activation of juxtaglomerular cells in Grueneberg glomeruli was indeed based on stimulation of Grueneberg ganglion neurons, the 2,3-DMP-induced responses in these glomeruli were investigated in mice lacking the cyclic nucleotide-gated channel CNGA3 which is critical for chemo- and thermosensory signal transduction in Grueneberg ganglion neurons. This approach revealed that elimination of CNGA3 led to a reduction of the odorant-induced activity in Grueneberg glomeruli, indicating that the activation of these glomeruli is based on a preceding stimulation of the Grueneberg ganglion. Analyzing whether Grueneberg glomeruli in the bulb might also process thermosensory information, it was found that upon exposure to coolness, Grueneberg glomeruli were activated. Investigating mice lacking CNGA3, the activation of these glomeruli by cool temperatures was attenuated.
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Affiliation(s)
- Rosolino Bumbalo
- Institute of Physiology, University of Hohenheim, Garbenstr. 30, 70599, Stuttgart, Germany
| | - Marilena Lieber
- Institute of Physiology, University of Hohenheim, Garbenstr. 30, 70599, Stuttgart, Germany
| | - Lisa Schroeder
- Institute of Physiology, University of Hohenheim, Garbenstr. 30, 70599, Stuttgart, Germany
| | - Yasemin Polat
- Institute of Physiology, University of Hohenheim, Garbenstr. 30, 70599, Stuttgart, Germany
| | - Heinz Breer
- Institute of Physiology, University of Hohenheim, Garbenstr. 30, 70599, Stuttgart, Germany
| | - Joerg Fleischer
- Institute of Physiology, University of Hohenheim, Garbenstr. 30, 70599, Stuttgart, Germany. .,Department of Animal Physiology, Institute of Biology/Zoology, Martin Luther University Halle-Wittenberg, Hoher Weg 8, 06120, Halle, Saale, Germany.
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Abstract
Olfaction enables most mammalian species to detect and discriminate vast numbers of chemical structures called odorants and pheromones. The perception of such chemical compounds is mediated via two major olfactory systems, the main olfactory system and the vomeronasal system, as well as minor systems, such as the septal organ and the Grueneberg ganglion. Distinct differences exist not only among species but also among individuals in terms of their olfactory sensitivity; however, little is known about the mechanisms that determine these differences. In research on the olfactory sensitivity of mammals, scientists thus depend in most cases on behavioral testing. In this article, we reviewed scientific studies performed on various mammalian species using different methodologies and target chemical substances. Human and non-human primates as well as rodents and dogs are the most frequently studied species. Olfactory threshold studies on other species do not exist with the exception of domestic pigs. Olfactory testing performed on seals, elephants, and bats focused more on discriminative abilities than on sensitivity. An overview of olfactory sensitivity studies as well as olfactory detection ability in most studied mammalian species is presented here, focusing on comparable olfactory detection thresholds. The basics of olfactory perception and olfactory sensitivity factors are also described.
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Abstract
Temperature perception has long been classified as a somesthetic function solely. However, in recent years several studies brought evidence that temperature perception also takes place in the olfactory system of rodents. Temperature has been described as an effective stimulus for sensory neurons of the Grueneberg ganglion located at the entrance of the nose. Here, we investigate whether a neuronal trace of temperature stimulation can be observed in the glomeruli and mitral cells of the olfactory bulb, using calcium imaging and fast line-scanning microscopy. We show in the Xenopus tadpole system that the γ-glomerulus, which receives input from olfactory neurons, is highly sensitive to temperature drops at the olfactory epithelium. We observed that thermo-induced activity in the γ-glomerulus is conveyed to the mitral cells innervating this specific neuropil. Surprisingly, a substantial number of thermosensitive mitral cells were also chemosensitive. Moreover, we report another unique feature of the γ-glomerulus: it receives ipsilateral and contralateral afferents. The latter fibers pass through the contralateral bulb, cross the anterior commissure, and then run to the ipsilateral olfactory bulb, where they target the γ-glomerulus. Temperature drops at the contralateral olfactory epithelium also induced responses in the γ-glomerulus and in mitral cells. Temperature thus appears to be a relevant physiological input to the Xenopus olfactory system. Each olfactory bulb integrates and codes temperature signals originating from receptor neurons of the ipsilateral and contralateral nasal cavities. Finally, temperature and chemical information is processed in shared cellular networks.
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Brechbühl J, Moine F, Tosato MN, Sporkert F, Broillet MC. Identification of pyridine analogs as new predator-derived kairomones. Front Neurosci 2015; 9:253. [PMID: 26283896 PMCID: PMC4517376 DOI: 10.3389/fnins.2015.00253] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 07/09/2015] [Indexed: 12/29/2022] Open
Abstract
In the wild, animals have developed survival strategies relying on their senses. The individual ability to identify threatening situations is crucial and leads to increase in the overall fitness of the species. Rodents, for example have developed in their nasal cavities specialized olfactory neurons implicated in the detection of volatile cues encoding for impending danger such as predator scents or alarm pheromones. In particular, the neurons of the Grueneberg ganglion (GG), an olfactory subsystem, are implicated in the detection of danger cues sharing a similar chemical signature, a heterocyclic sulfur- or nitrogen-containing motif. Here we used a “from the wild to the lab” approach to identify new molecules that are involuntarily emitted by predators and that initiate fear-related responses in the recipient animal, the putative prey. We collected urines from carnivores as sources of predator scents and first verified their impact on the blood pressure of the mice. With this approach, the urine of the mountain lion emerged as the most potent source of chemical stress. We then identified in this biological fluid, new volatile cues with characteristic GG-related fingerprints, in particular the methylated pyridine structures, 2,4-lutidine and its analogs. We finally verified their encoded danger quality and demonstrated their ability to mimic the effects of the predator urine on GG neurons, on mice blood pressure and in behavioral experiments. In summary, we were able to identify here, with the use of an integrative approach, new relevant molecules, the pyridine analogs, implicated in interspecies danger communication.
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Affiliation(s)
- Julien Brechbühl
- Department of Pharmacology and Toxicology, Faculty of Biology and Medicine, University of Lausanne Lausanne, Switzerland
| | - Fabian Moine
- Department of Pharmacology and Toxicology, Faculty of Biology and Medicine, University of Lausanne Lausanne, Switzerland
| | - Monique Nenniger Tosato
- Department of Pharmacology and Toxicology, Faculty of Biology and Medicine, University of Lausanne Lausanne, Switzerland
| | - Frank Sporkert
- University Center of Legal Medicine, Lausanne-Geneva Lausanne, Switzerland
| | - Marie-Christine Broillet
- Department of Pharmacology and Toxicology, Faculty of Biology and Medicine, University of Lausanne Lausanne, Switzerland
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Salazar I. The nasal cavity and its olfactory sensory territories. Front Neuroanat 2015; 9:31. [PMID: 25852492 PMCID: PMC4364257 DOI: 10.3389/fnana.2015.00031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 02/27/2015] [Indexed: 11/13/2022] Open
Affiliation(s)
- Ignacio Salazar
- Unit of Anatomy and Embryology, Department of Anatomy and Animal Production, Faculty of Veterinary, University of Santiago de Compostela Santiago de Compostela, Spain
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