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Amato E, Taroc EZM, Forni PE. Illuminating the Terminal Nerve: Uncovering the Link between GnRH-1 and Olfactory Development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.31.555770. [PMID: 37693459 PMCID: PMC10491181 DOI: 10.1101/2023.08.31.555770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
During embryonic development, the olfactory placode (OP) generates migratory neurons, including olfactory pioneer neurons, cells of the terminal nerve (TN), Gonadotropin-releasing hormone-1 (GnRH-1) neurons, and other uncharacterized neurons. Pioneer neurons from the olfactory placode induce olfactory bulb morphogenesis. In mice, GnRH-1 neurons appear in the olfactory system around mid-gestation and migrate via the terminal nerve axons to different brain regions. The GnRH-1 neurons are crucial in controlling the hypothalamic-pituitary-gonadal (HPG) axis. Kallmann syndrome is characterized by impaired olfactory system development, defective olfactory bulbs, defective secretion of GnRH-1, and infertility. The precise mechanistic link between the olfactory system and GnRH-1 development remains unclear. Studies in humans and mice highlight the importance of the Prokineticin-2/Prokineticin-Receptor-2 (Prokr2) signaling pathway in olfactory bulb morphogenesis and GnRH-1 neuronal migration. Prokr2 loss-of-function mutations can cause Kallmann syndrome, and hence the Prokr2 signaling pathway represents a unique model to decipher the olfactory/GnRH-1 connection. We discovered that Prokr2 is expressed in the TN neurons during the critical period of GnRH-1 neuron formation, migration, and induction of olfactory bulb morphogenesis. Single-cell RNA sequencing identified that the TN is formed by neurons that are distinct from the olfactory neurons. The TN neurons express multiple genes associated with KS. Our study suggests that the aberrant development of pioneer/TN neurons might cause the KS spectrum. Key Points 1) Pioneer or terminal nerve neurons play a crucial role in initiating the development of the olfactory bulbs. We found that the Prokineticin Receptor-2 gene, associated with Kallmann syndrome, is expressed by the olfactory pioneer/terminal nerve neurons.2) We genetically traced, isolated, and conducted Single-cell RNA sequencing on terminal nerve neurons of rodents. This analysis revealed a significant enrichment of gene expression related to Kallmann syndrome.3) Our study indicates that the investigation of Pioneer/terminal nerve neurons should be a pivotal focal point for comprehending developmental defects affecting olfactory and GnRH-1 systems.
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Dhawan SS, Yedavalli V, Massoud TF. Atavistic and vestigial anatomical structures in the head, neck, and spine: an overview. Anat Sci Int 2023:10.1007/s12565-022-00701-7. [PMID: 36680662 DOI: 10.1007/s12565-022-00701-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Accepted: 12/27/2022] [Indexed: 01/22/2023]
Abstract
Organisms may retain nonfunctional anatomical features as a consequence of evolutionary natural selection. Resultant atavistic and vestigial anatomical structures have long been a source of perplexity. Atavism is when an ancestral trait reappears after loss through an evolutionary change in previous generations, whereas vestigial structures are remnants that are largely or entirely functionless relative to their original roles. While physicians are cognizant of their existence, atavistic and vestigial structures are rarely emphasized in anatomical curricula and can, therefore, be puzzling when discovered incidentally. In addition, the literature is replete with examples of the terms atavistic and vestigial being used interchangeably without careful distinction between them. We provide an overview of important atavistic and vestigial structures in the head, neck, and spine that can serve as a reference for anatomists and clinical neuroscientists. We review the literature on atavistic and vestigial anatomical structures of the head, neck, and spine that may be encountered in clinical practice. We define atavistic and vestigial structures and employ these definitions consistently when classifying anatomical structures. Pertinent anatomical structures are numerous and include human tails, plica semilunaris, the vomeronasal organ, levator claviculae, and external ear muscles, to name a few. Atavistic and vestigial structures are found throughout the head, neck, and spine. Some, such as human tails and branchial cysts may be clinically symptomatic. Literature reports indicate that their prevalence varies across populations. Knowledge of atavistic and vestigial anatomical structures can inform diagnoses, prevent misrecognition of variation for pathology, and guide clinical interventions.
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Affiliation(s)
- Siddhant Suri Dhawan
- Department of Bioengineering, Schools of Engineering and Medicine, Stanford University, Stanford, USA
| | - Vivek Yedavalli
- Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, USA
| | - Tarik F Massoud
- Division of Neuroimaging and Neurointervention, and Stanford Initiative for Multimodality Neuro-Imaging in Translational Anatomy Research (SIMITAR), Department of Radiology, Stanford University School of Medicine, Stanford, USA. .,Center for Academic Medicine, Radiology MC: 5659; 453 Quarry Road, Palo Alto, CA, 94304, USA.
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Kurihara S, Tei M, Hata J, Mori E, Fujioka M, Matsuwaki Y, Otori N, Kojima H, Okano HJ. MRI tractography reveals the human olfactory nerve map connecting the olfactory epithelium and olfactory bulb. Commun Biol 2022; 5:843. [PMID: 36068329 PMCID: PMC9448749 DOI: 10.1038/s42003-022-03794-y] [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: 08/30/2021] [Accepted: 08/03/2022] [Indexed: 11/16/2022] Open
Abstract
The olfactory nerve map describes the topographical neural connections between the olfactory epithelium in the nasal cavity and the olfactory bulb. Previous studies have constructed the olfactory nerve maps of rodents using histological analyses or transgenic animal models to investigate olfactory nerve pathways. However, the human olfactory nerve map remains unknown. Here, we demonstrate that high-field magnetic resonance imaging and diffusion tensor tractography can be used to visualize olfactory sensory neurons while maintaining their three-dimensional structures. This technique allowed us to evaluate the olfactory sensory neuron projections from the nasal cavities to the olfactory bulbs and visualize the olfactory nerve maps of humans, marmosets and mice. The olfactory nerve maps revealed that the dorsal-ventral and medial-lateral axes were preserved between the olfactory epithelium and olfactory bulb in all three species. Further development of this technique might allow it to be used clinically to facilitate the diagnosis of olfactory dysfunction. Combined high-field MRI and DTI analyses in post-mortem mouse, marmoset, and human samples provide insight into the neural connections between nasal cavities and olfactory bulbs.
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Affiliation(s)
- Sho Kurihara
- Department of Otorhinolaryngology, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan.
| | - Masayoshi Tei
- Department of Otorhinolaryngology, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan
| | - Junichi Hata
- Division of Regenerative Medicine, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan.,Graduate School of Human Health Sciences, Tokyo Metropolitan University, 7-2-10 Higashi-Ogu Arakawa-ku, Tokyo, 116-8551, Japan
| | - Eri Mori
- Department of Otorhinolaryngology, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan
| | - Masato Fujioka
- Department of Molecular Genetics, Kitasato University School of Medicine, 1-15-1 Kitasato Minami-ku Sagamihara-shi, Kanagawa, 252-0373, Japan.,Department of Otorhinolaryngology, Head and Neck Surgery, Keio University School of Medicine, 35 Shinanomachi Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Yoshinori Matsuwaki
- Department of Otorhinolaryngology, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan
| | - Nobuyoshi Otori
- Department of Otorhinolaryngology, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan
| | - Hiromi Kojima
- Department of Otorhinolaryngology, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan
| | - Hirotaka James Okano
- Division of Regenerative Medicine, The Jikei University School of Medicine, 3-25-8 Nishishimbashi Minato-ku, Tokyo, 105-8471, Japan.
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AlMatrouk A, Lemons K, Ogura T, Lin W. Modification of the Peripheral Olfactory System by Electronic Cigarettes. Compr Physiol 2021; 11:2621-2644. [PMID: 34661289 DOI: 10.1002/cphy.c210007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Electronic cigarettes (e-cigs) are used by millions of adolescents and adults worldwide. Commercial e-liquids typically contain flavorants, propylene glycol, and vegetable glycerin with or without nicotine. These chemical constituents are detected and evaluated by chemosensory systems to guide and modulate vaping behavior and product choices of e-cig users. The flavorants in e-liquids are marketing tools. They evoke sensory percepts of appealing flavors through activation of chemical sensory systems to promote the initiation and sustained use of e-cigs. The vast majority of flavorants in e-liquids are volatile odorants, and as such, the olfactory system plays a dominant role in perceiving these molecules that enter the nasal cavity either orthonasally or retronasally during vaping. In addition to flavorants, e-cig aerosol contains a variety of by-products generated through heating the e-liquids, including odorous irritants, toxicants, and heavy metals. These harmful substances can directly and adversely impact the main olfactory epithelium (MOE). In this article, we first discuss the olfactory contribution to e-cig flavor perception. We then provide information on MOE cell types and their major functions in olfaction and epithelial maintenance. Olfactory detection of flavorants, nicotine, and odorous irritants and toxicants are also discussed. Finally, we discuss the cumulated data on modification of the MOE by flavorant exposure and toxicological impacts of formaldehyde, acrolein, and heavy metals. Together, the information presented in this overview may provide insight into how e-cig exposure may modify the olfactory system and adversely impact human health through the alteration of the chemosensory factor driving e-cig use behavior and product selections. © 2021 American Physiological Society. Compr Physiol 11:2621-2644, 2021.
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Affiliation(s)
- Abdullah AlMatrouk
- General Department of Criminal Evidence, Forensic Laboratories, Ministry of Interior, Farwaniyah, Kuwait.,Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland, USA
| | - Kayla Lemons
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, North Carolina, USA.,Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland, USA
| | - Tatsuya Ogura
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland, USA
| | - Weihong Lin
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland, USA
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The Microvillar and Solitary Chemosensory Cells as the Novel Targets of Infection of SARS-CoV-2 in Syrian Golden Hamsters. Viruses 2021; 13:v13081653. [PMID: 34452517 PMCID: PMC8402700 DOI: 10.3390/v13081653] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/11/2021] [Accepted: 08/18/2021] [Indexed: 12/11/2022] Open
Abstract
Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019, suffer from respiratory and non-respiratory symptoms. Among these symptoms, the loss of smell has attracted considerable attention. The objectives of this study were to determine which cells are infected, what happens in the olfactory system after viral infection, and how these pathologic changes contribute to olfactory loss. For this purpose, Syrian golden hamsters were used. First, we verified the olfactory structures in the nasal cavity of Syrian golden hamsters, namely the main olfactory epithelium, the vomeronasal organ, and their cellular components. Second, we found angiotensin-converting enzyme 2 expression, a receptor protein of SARS-CoV-2, in both structures and infections of supporting, microvillar, and solitary chemosensory cells. Third, we observed pathological changes in the infected epithelium, including reduced thickness of the mucus layer, detached epithelia, indistinct layers of epithelia, infiltration of inflammatory cells, and apoptotic cells in the overall layers. We concluded that a structurally and functionally altered microenvironment influences olfactory function. We observed the regeneration of the damaged epithelium, and found multilayers of basal cells, indicating that they were activated and proliferating to reconstitute the injured epithelium.
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Lanfranchi A. Hormonal Contraception and Violent Death: The Physiological and Psychological Links. Front Behav Neurosci 2021; 15:667563. [PMID: 34393733 PMCID: PMC8363127 DOI: 10.3389/fnbeh.2021.667563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 07/13/2021] [Indexed: 11/26/2022] Open
Abstract
In the past decade, two large prospective cohort studies of British and American women have been conducted which found a statistically significant increase in the risk of violent death in ever-users of hormonal contraceptives. Research on the effects of hormonal contraceptives upon the behaviors of intimate partners and on the physiology of women using hormonal contraceptives has provided insight into the possible basis for the resulting increase in violent death. This review examines the changes that are potential contributors to the reported increase.
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Affiliation(s)
- Angela Lanfranchi
- Department of Surgery, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ, United States.,Breast Cancer Prevention Institute, Whitehouse Station, NJ, United States
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Popov SV, Kamchatnov PR, Sturov NV, Bogdanets SA. [Modern studies of the role of the vomeronasal system in the perception of pheromones and their impact on social and sexual behavior]. Zh Nevrol Psikhiatr Im S S Korsakova 2020; 119:143-147. [PMID: 31994528 DOI: 10.17116/jnevro2019119121143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The vomeronasal system (VNS) provides regulation of a wide range of autonomic and affective functions, behavioral reactions in response to the specific chemical stimuli pheromones secreted by mammals, including humans. The results of experimental studies confirming the existence of VNS and explaining the basic mechanisms of its functioning are presented. The results of studies of healthy volunteers, explaining the effect of pheromones on a number of functions of the human body, are considered.
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Affiliation(s)
- S V Popov
- Peoples' Friendship University of Russia, Moscow, Russia
| | - P R Kamchatnov
- Pirogov Russian National Research Medical University, Moscow, Russia
| | - N V Sturov
- Peoples' Friendship University of Russia, Moscow, Russia
| | - S A Bogdanets
- Medical Center Yuzhnyy 'Vascular clinic', Moscow, Russia
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Zoological terms in the human histological nomenclature Terminologia Histologica. What we think, what we know, and what we think we know. Biologia (Bratisl) 2019. [DOI: 10.2478/s11756-019-00356-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Stoyanov GS, Matev BK. Samuel Thomas von Sömmerring's Contributions on the Cranial Nerves and Vomeronasal Organ. Cureus 2018; 10:e2859. [PMID: 30148012 PMCID: PMC6107037 DOI: 10.7759/cureus.2859] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Samuel Thomas von Sömmerring (January 28th, 1755, Thorn, then Royal Prussia, now Torun Poland – March 2nd, 1830, Frankfurt am Main, then a free city, now Germany) was one of the most respected Germanic scientists of his time. Whilst working on his philosophy doctorate (Ph.D.) thesis, when he was only 23 years old (circa 1778), Sömmerring proposed a new classification for the arrangement of the cranial nerves, based on the order in which they become visible on the surface of the brain. Amongst his many other anatomical studies worthy of notice, in 1809 Sömmerring began studying the human olfactory system. During this period, he published a detailed text with sketches, being the first to describe in detail the human vomeronasal organ (VNO), working in parallel with Jacobsen, whose name has been synonymous with the VNO, despite denying its existence in man. Nonetheless, Sömmerring's contributions are numerous. Some of his other works include the description of the structure of the female skeleton and how it differs from the male and the first description of the Pterodactyl in 1812, with which he has been epitomized in modern times and denoted due to his erroneous concepts on it. Even though he studied a wide range of subjects from medical to political, most of his work has been overlooked or forgotten but it is important to understand the range of his contributions.
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Affiliation(s)
- George S Stoyanov
- General and Clinical Pathology/Forensic Medicine and Deontology, Medical University, Varna, BGR
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