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Cell and Tissue Research Jun 2021Detection and discrimination of odorants by the olfactory system plays a pivotal role in animal survival. Olfactory-based behaviors must be adapted to an ever-changing... (Review)
Review
Detection and discrimination of odorants by the olfactory system plays a pivotal role in animal survival. Olfactory-based behaviors must be adapted to an ever-changing environment. Part of these adaptations includes changes of odorant detection by olfactory sensory neurons localized in the olfactory epithelium. It is now well established that internal signals such as hormones, neurotransmitters, or paracrine signals directly affect the electric activity of olfactory neurons. Furthermore, recent data have shown that activity-dependent survival of olfactory neurons is important in the olfactory epithelium. Finally, as olfactory neurons are directly exposed to environmental toxicants and pathogens, the olfactory epithelium also interacts closely with the immune system leading to neuroimmune modulations. Here, we review how detection of odorants can be modulated in the vertebrate olfactory epithelium. We choose to focus on three cellular types of the olfactory epithelium (the olfactory sensory neuron, the sustentacular and microvillar cells) to present the diversity of modulation of the detection of odorant in the olfactory epithelium. We also present some of the growing literature on the importance of immune cells in the functioning of the olfactory epithelium, although their impact on odorant detection is only just beginning to be unravelled.
Topics: Animals; Humans; Olfactory Mucosa; Olfactory Receptor Neurons; Receptors, Odorant; Smell
PubMed: 33961125
DOI: 10.1007/s00441-021-03467-y -
Scientific Reports Apr 2016Intestinal epithelium development is dramatically impaired in germfree rodents, but the consequences of the absence of microbiota have been overlooked in other...
Intestinal epithelium development is dramatically impaired in germfree rodents, but the consequences of the absence of microbiota have been overlooked in other epithelia. In the present study, we present the first description of the bacterial communities associated with the olfactory epithelium and explored differences in olfactory epithelium characteristics between germfree and conventional, specific pathogen-free, mice. While the anatomy of the olfactory epithelium was not significantly different, we observed a thinner olfactory cilia layer along with a decreased cellular turn-over in germfree mice. Using electro-olfactogram, we recorded the responses of olfactory sensitive neuronal populations to various odorant stimulations. We observed a global increase in the amplitude of responses to odorants in germfree mice as well as altered responses kinetics. These changes were associated with a decreased transcription of most olfactory transduction actors and of olfactory xenobiotic metabolising enzymes. Overall, we present here the first evidence that the microbiota modulates the physiology of olfactory epithelium. As olfaction is a major sensory modality for most animal species, the microbiota may have an important impact on animal physiology and behaviour through olfaction alteration.
Topics: Animals; Behavior, Animal; Gene Expression; Germ-Free Life; Mice; Mice, Inbred C3H; Microscopy, Electron, Transmission; Odorants; Olfactory Mucosa; RNA, Ribosomal, 16S; Smell
PubMed: 27089944
DOI: 10.1038/srep24687 -
Pharmaceutical Patent Analyst Jan 2014The neuroepithelium has been used as an experimental model to find biological markers for neuropsychiatric disease diagnosis. Patent information permits understanding of... (Review)
Review
The neuroepithelium has been used as an experimental model to find biological markers for neuropsychiatric disease diagnosis. Patent information permits understanding of the state of the art of neuroepithelium in neuropsychiatric disease diagnosis, as well as the identification of trends in research and development on this theme. In this article, we discuss diverse methods for obtaining primary cultures of olfactory neurons obtained by animal dissection or by postmortem biopsy of human cadavers. The principal owners of patents related to olfactory neuroepithelia are universities such as John Hopkins and Bristol-Myers Squibb. The USA has the most research lines and approved patents in the world, while Rutgers, the State University of New Jersey, provides composition and methods related to the diagnoses and treatment of neuropsychiatric disorders.
Topics: Animals; Cell Physiological Phenomena; Humans; Mental Disorders; Neurons; Olfactory Mucosa; Patents as Topic
PubMed: 24354978
DOI: 10.4155/ppa.13.68 -
International Forum of Allergy &... Mar 2022The olfactory cleft (OC) comprising the olfactory epithelium (OE) is the most important anatomical location for olfactory function. Endoscopic sinus surgery (ESS) is...
BACKGROUND
The olfactory cleft (OC) comprising the olfactory epithelium (OE) is the most important anatomical location for olfactory function. Endoscopic sinus surgery (ESS) is used to treat diseases related to the OC and improve olfactory dysfunction. However, iatrogenic OE injury occasionally occurs. Comprehensive knowledge of the olfactory region is required to avoid damage to the OE during endoscopic procedures.
METHODS
Immunohistochemistry was performed on olfactory mucosa obtained from the unaffected side of olfactory neuroblastoma surgical specimens. The OE was defined as the epithelium containing mature olfactory sensory neurons (OSNs). The distribution and cell kinetics of the OE were examined.
RESULTS
The OE was selectively localized to the anterior two-thirds of the superior turbinate (ST) and in the nasal septum (NS) just opposite to the ST; the OE was not detected within the mucosa of the superior meatus. The density of mature OSNs was high at the ethmoid tegmen but gradually decreased with distance from the ethmoid tegmen. The extent of cell death and proliferation was relatively even across the OE. Analysis of airflow profiles revealed that resection of inferior ST does not decrease airflow to the OC.
CONCLUSION
The results indicate that the distribution and degree of differentiation of mature OSNs are heterogenous throughout the OE. Epithelial resection of the anterior or superior ST has the potential to damage olfactory function. Resection of the inferior or posterior ST or widening of the superior meatus is a safer alternative that does not damage mature OSNs or alter airflow to the OC.
Topics: Cell Death; Cell Differentiation; Humans; Olfactory Mucosa; Olfactory Receptor Neurons; Smell
PubMed: 34538025
DOI: 10.1002/alr.22885 -
Brazilian Journal of Otorhinolaryngology 2022Olfactory epithelium biopsy has been useful for studying diverse otorhinolaryngological and neurological diseases, including the potential to better understand the...
INTRODUCTION
Olfactory epithelium biopsy has been useful for studying diverse otorhinolaryngological and neurological diseases, including the potential to better understand the pathophysiology behind COVID-19 olfactory manifestations. However, the safety and efficacy of the technique for obtaining human olfactory epithelium are still not fully established.
OBJECTIVE
This study aimed to determine the safety and efficacy of harvesting olfactory epithelium cells, nerve bundles, and olfactory epithelium proper for morphological analysis from the superior nasal septum.
METHODS
During nasal surgery, 22 individuals without olfactory complaints underwent olfactory epithelium biopsies from the superior nasal septum. The efficacy of obtaining olfactory epithelium, verification of intact olfactory epithelium and the presence of nerve bundles in biopsies were assessed using immunofluorescence. Safety for the olfactory function was tested psychophysically using both unilateral and bilateral tests before and 1 month after the operative procedure.
RESULTS
Olfactory epithelium was found in 59.1% of the subjects. Of the samples, 50% were of the quality necessary for morphological characterization and 90.9% had nerve bundles. There was no difference in the psychophysical scores obtained in the bilateral olfactory test (University of Pennsylvania Smell Identification Test [UPSIT®]) between means before biopsy: 32.3 vs. postoperative: 32.5, p = 0.81. Also, no significant decrease occurred in unilateral testing (mean unilateral test scores 6 vs. 6.2, p = 0.46). None out of the 56 different odorant identification significantly diminished (p > 0.05).
CONCLUSION
The technique depicted for olfactory epithelium biopsy is highly effective in obtaining neuronal olfactory tissue, but it has moderate efficacy in achieving samples useful for morphological analysis. Olfactory sensitivity remained intact.
Topics: Biopsy; COVID-19; Humans; Nasal Septum; Neurons; Olfaction Disorders; Olfactory Mucosa; Smell
PubMed: 34144902
DOI: 10.1016/j.bjorl.2021.05.008 -
Annals of Anatomy = Anatomischer... Sep 2010Olfactory acuity differs among animal species depending on age and dependence on smell. However, the attendant functional anatomy has not been elucidated. We sought to...
Olfactory acuity differs among animal species depending on age and dependence on smell. However, the attendant functional anatomy has not been elucidated. We sought to determine the functional structure of the olfactory mucosa in suckling and adult dog and sheep. Mucosal samples harvested from ethmoturbinates were analyzed qualitatively and quantitatively. In both species, the olfactory mucosa comprised olfactory, supporting and basal cells, and a lamina propria containing bundles of olfactory cell axons, Bowman's glands and vascular elements. The olfactory cells terminated apically with an expanded knob, from which cilia projected in a radial fashion from its base and in form of a tuft from its apex in the dog and the sheep respectively. Olfactory cilia per knob were more numerous in the dog (19 ± 3) compared to the sheep (7 ± 2) (p<0.05). In the dog, axonal bundles exhibited one to two centrally located capillaries and the bundles were of greater diameters (73.3 ± 10.3 μm) than those of the sheep (50.6 ± 6.8 μm), which had no capillaries. From suckling to adulthood in the dog, the packing density of the olfactory and supporting cells increased by 22.5% and 12.6% respectively. Surprisingly in the sheep, the density of the olfactory cells decreased by 26.2% while that of the supportive cells showed no change. Overall epithelial thickness reached 72.5 ± 2.9 μm in the dog and 56.8 ± 3.1 μm in the sheep. These observations suggest that the mucosa is better structurally refined during maturation in the dog than in the sheep.
Topics: Animals; Axons; Cilia; Dogs; Mice; Olfactory Mucosa; Sheep; Smell
PubMed: 20801626
DOI: 10.1016/j.aanat.2010.07.004 -
Journal of Neuroscience Research Oct 2001The existence of stem cells in the CNS raises issues concerning the ability of nervous tissues to regenerate in the adult mammal and provides new perspectives on the... (Review)
Review
The existence of stem cells in the CNS raises issues concerning the ability of nervous tissues to regenerate in the adult mammal and provides new perspectives on the treatment of degenerative disease and traumatic injury of the nervous system. These cells have a relatively limited range of locations within the nervous system and include cells of the rostral migratory stream, hippocampus, retina, and olfactory epithelium. The olfactory epithelium has been studied as a model of adult neuronal regeneration, with neuronal precursor/basal cells serving as the olfactory "stem cells." The identification of factors that promote neuronal proliferation or regeneration within the olfactory epithelium can provide clues to the process of adult mammalian nervous system repair and treatment. Multiple factors have been examined that appear to influence the proliferation and subsequent maturation of basal cells. These factors include nerve growth factor, fibroblast growth factor-2, epidermal growth factor, and insulin/insulin-like growth factor-1. Recently, two amidated neuropeptides, neuropeptide Y (NPY) and pituitary adenylate cyclase-activating polypeptide (PACAP38), identified in the olfactory epithelium have been shown to promote dramatically neuronal proliferation. The effects of NPY and PACAP suggest that amidated neuropeptides may serve a broad developmental and regenerative role in the mammalian olfactory epithelium.
Topics: Amides; Animals; Cell Division; Neuropeptide Y; Neuropeptides; Olfactory Mucosa; Pituitary Adenylate Cyclase-Activating Polypeptide; Stem Cells
PubMed: 11598996
DOI: 10.1002/jnr.1191 -
European Archives of... Sep 2016To develop a new therapeutic method to treat olfactory deficits, we investigated the engraftment and regenerative effects of transplanted bone marrow stromal cells...
To develop a new therapeutic method to treat olfactory deficits, we investigated the engraftment and regenerative effects of transplanted bone marrow stromal cells (BMSCs) on damaged rat olfactory mucosa. To induce olfactory nerve degeneration, one side of the olfactory mucosa of Sprague-Dawley rats was damaged via Triton X-100 irrigation. Phosphate-buffered saline containing syngeneic BMSCs was injected into the olfactory mucosa for transplantation. PKH fluorescent cell dye labeling of BMSCs was used to monitor the transplanted cells. After transplantation of BMSCs, the thickness and regeneration of olfactory mucosa were analyzed using hematoxylin-eosin (H&E) staining. S100 immunohistochemical staining was used to measure nerve sheath regeneration. The increase in NGF (nerve growth factor) level in the olfactory mucosa was measured by Western blot analysis. Transplanted bone marrow stromal cells were engrafted to the lamia propria of damaged mucosa. The mean time for normalization of thickness and morphological recovery of the olfactory mucosa was 4 weeks in the therapeutic group and 9 weeks in the control group. S100 immunoreactivity was higher on the BMSC-treated side than on the control side. During regeneration, the expression of NGF increased in the olfactory mucosa of the experimental group. Based on these results, BMSC transplantation accelerated regeneration of olfactory mucosa damaged by Triton X-100, and NGF may be essential to this regenerative process.
Topics: Animals; Male; Mesenchymal Stem Cell Transplantation; Nerve Growth Factor; Nerve Regeneration; Olfactory Mucosa; Rats; Rats, Sprague-Dawley
PubMed: 26940801
DOI: 10.1007/s00405-016-3957-x -
Seminars in Cell Biology Feb 1994Proliferation, differentiation and death of olfactory neurons occur continually, even in adult animals. New data suggest that growth factors regulate the rate of cell... (Review)
Review
Proliferation, differentiation and death of olfactory neurons occur continually, even in adult animals. New data suggest that growth factors regulate the rate of cell proliferation. Early growth of olfactory axons in embryonic development is accompanied by the migration of epithelial cells from the olfactory placode toward the presumptive olfactory bulb. Maturation and ciliogenesis at the dendritic end of the cell is apparently dependent on a signal(s) from the bulb. The total life span of the neuron depends on maintenance of contact with the bulb. Olfactory life span is normally variable but is curtailed substantially in the absence of the bulb.
Topics: Animals; Axons; Cell Death; Cell Differentiation; Cell Division; Dendrites; Embryonic and Fetal Development; Epidermal Growth Factor; Olfactory Mucosa; Olfactory Receptor Neurons; Transforming Growth Factor alpha
PubMed: 8186394
DOI: 10.1006/scel.1994.1002 -
Archives of Histology and Cytology 1989The immunohistochemical localization of nervous system-specific proteins and cytokeratin in the olfactory mucosa is described mainly in humans and guinea pigs.... (Review)
Review
The immunohistochemical localization of nervous system-specific proteins and cytokeratin in the olfactory mucosa is described mainly in humans and guinea pigs. Immunoreactivity for neuron-specific enolase (NSE) was demonstrated in olfactory receptor cells including their dendrite and axon. Immunoreactivity for neurofilament protein (NFP) was contained in the dendrite and perikaryon of the olfactory cells, but not in the axon. Immunoreactivity for spot-35 protein, a kind of neuron-specific proteins was selectively localized in several flask-shaped cells of the olfactory epithelium only in the guinea pig. These spot-35 protein-positive cells were suspected of being microvillar cells, considered the second type of receptor cells dispersed in the olfactory epithelium. Immunoreactivity for glia-specific S-100 protein was demonstrated in the Bowman's glands as well as Schwann cells associated with the olfactory nerves in the lamina propria. Supporting cells were not immunolabelled with any antisera against nervous system-specific proteins. Cytokeratin, a useful marker for epithelial cells, was expressed exclusively in basal cells. Axotomy of olfactory nerves induced the disappearance of the olfactory receptor cells with NSE immunoreactivity 3 days after the operation. Regenerating cells showing NSE immunoreactivity were first recognized in the lower portion of the epithelium within 7 days. The epithelium was completely repaired 3-4 weeks later and came to contain many NSE-reactive mature receptor cells. Bromodeoxyuridine (BrdU), administered during regeneration of the olfactory epithelium, was immunohistochemically detected in the cells of the layer above the basal cell layer, but not in the latter itself. This result does not support the general contention that the receptor cells originate from the basal cells.
Topics: Animals; Calbindin 1; Calbindins; Calcium-Binding Proteins; Guinea Pigs; Humans; Immunohistochemistry; Intermediate Filament Proteins; Nerve Regeneration; Nerve Tissue Proteins; Olfactory Mucosa; Phosphopyruvate Hydratase; S100 Calcium Binding Protein G; S100 Proteins
PubMed: 2510793
DOI: 10.1679/aohc.52.suppl_375