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Rufenacht KE, Asson AJ, Hossain K, Santoro SW. The influence of olfactory experience on the birthrates of olfactory sensory neurons with specific odorant receptor identities. Genesis 2024; 62:e23611. [PMID: 38888221 PMCID: PMC11189617 DOI: 10.1002/dvg.23611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 05/31/2024] [Accepted: 06/03/2024] [Indexed: 06/20/2024]
Abstract
Olfactory sensory neurons (OSNs) are one of a few neuron types that are generated continuously throughout life in mammals. The persistence of olfactory sensory neurogenesis beyond early development has long been thought to function simply to replace neurons that are lost or damaged through exposure to environmental insults. The possibility that olfactory sensory neurogenesis may also serve an adaptive function has received relatively little consideration, largely due to the assumption that the generation of new OSNs is stochastic with respect to OSN subtype, as defined by the single odorant receptor gene that each neural precursor stochastically chooses for expression out of hundreds of possibilities. Accordingly, the relative birthrates of different OSN subtypes are predicted to be constant and impervious to olfactory experience. This assumption has been called into question, however, by evidence that the birthrates of specific OSN subtypes can be selectively altered by manipulating olfactory experience through olfactory deprivation, enrichment, and conditioning paradigms. Moreover, studies of recovery of the OSN population following injury provide further evidence that olfactory sensory neurogenesis may not be strictly stochastic with respect to subtype. Here we review this evidence and consider mechanistic and functional implications of the prospect that specific olfactory experiences can regulate olfactory sensory neurogenesis rates in a subtype-selective manner.
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Affiliation(s)
- Karlin E Rufenacht
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Alexa J Asson
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Kawsar Hossain
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Stephen W Santoro
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado, USA
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Hossain K, Smith M, Santoro SW. In mice, discrete odors can selectively promote the neurogenesis of sensory neuron subtypes that they stimulate. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.10.579748. [PMID: 38405728 PMCID: PMC10888860 DOI: 10.1101/2024.02.10.579748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
In mammals, olfactory sensory neurons (OSNs) are born throughout life, presumably solely to replace neurons lost via turnover or injury. This assumption follows from the hypothesis that olfactory neurogenesis is strictly stochastic with respect to neuron subtype, as defined by the single odorant receptor allele that each neural precursor stochastically chooses out of hundreds of possibilities. This hypothesis is challenged by recent findings that the birthrates of a fraction of subtypes are selectively diminished by olfactory deprivation. These findings raise questions about how, and why, olfactory stimuli are required to promote the neurogenesis of some OSN subtypes, including whether the stimuli are generic (e.g., broadly activating odors or mechanical stimuli) or specific (e.g., discrete odorants). Based on RNA-seq and scRNA-seq analyses, we hypothesized that the neurogenic stimuli are specific odorants that selectively activate the same OSN subtypes whose birthrates are accelerated. In support of this, we have found, using subtype-specific OSN birthdating, that exposure to male and musk odors can accelerate the birthrates of responsive OSNs. Collectively, our findings reveal that certain odor experiences can selectively "amplify" specific OSN subtypes, and that persistent OSN neurogenesis may serve, in part, an adaptive function.
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Affiliation(s)
- Kawsar Hossain
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Madeline Smith
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Stephen W Santoro
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
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3
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Coppola DM, Reisert J. The Role of the Stimulus in Olfactory Plasticity. Brain Sci 2023; 13:1553. [PMID: 38002512 PMCID: PMC10669894 DOI: 10.3390/brainsci13111553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 11/02/2023] [Accepted: 11/02/2023] [Indexed: 11/26/2023] Open
Abstract
Plasticity, the term we use to describe the ability of a nervous system to change with experience, is the evolutionary adaptation that freed animal behavior from the confines of genetic determinism. This capacity, which increases with brain complexity, is nowhere more evident than in vertebrates, especially mammals. Though the scientific study of brain plasticity dates back at least to the mid-19th century, the last several decades have seen unprecedented advances in the field afforded by new technologies. Olfaction is one system that has garnered particular attention in this realm because it is the only sensory modality with a lifelong supply of new neurons, from two niches no less! Here, we review some of the classical and contemporary literature dealing with the role of the stimulus or lack thereof in olfactory plasticity. We have restricted our comments to studies in mammals that have used dual tools of the field: stimulus deprivation and stimulus enrichment. The former manipulation has been implemented most frequently by unilateral naris occlusion and, thus, we have limited our comments to research using this technique. The work reviewed on deprivation provides substantial evidence of activity-dependent processes in both developing and adult mammals at multiple levels of the system from olfactory sensory neurons through to olfactory cortical areas. However, more recent evidence on the effects of deprivation also establishes several compensatory processes with mechanisms at every level of the system, whose function seems to be the restoration of information flow in the face of an impoverished signal. The results of sensory enrichment are more tentative, not least because of the actual manipulation: What odor or odors? At what concentrations? On what schedule? All of these have frequently not been sufficiently rationalized or characterized. Perhaps it is not surprising, then, that discrepant results are common in sensory enrichment studies. Despite this problem, evidence has accumulated that even passively encountered odors can "teach" olfactory cortical areas to better detect, discriminate, and more efficiently encode them for future encounters. We discuss these and other less-established roles for the stimulus in olfactory plasticity, culminating in our recommended "aspirations" for the field going forward.
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Affiliation(s)
- David M. Coppola
- Biology Department, Randolph-Macon College, Ashland, VA 23005, USA
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4
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Hossain K, Smith M, Santoro SW. A histological protocol for quantifying the birthrates of specific subtypes of olfactory sensory neurons in mice. STAR Protoc 2023; 4:102432. [PMID: 37436902 PMCID: PMC10511921 DOI: 10.1016/j.xpro.2023.102432] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/16/2023] [Accepted: 06/12/2023] [Indexed: 07/14/2023] Open
Abstract
Mammals typically have hundreds of distinct olfactory sensory neuron subtypes, each defined by expression of a specific odorant receptor gene, which undergo neurogenesis throughout life at rates that can depend on olfactory experience. Here, we present a protocol to quantify the birthrates of specific neuron subtypes via the simultaneous detection of corresponding receptor mRNAs and 5-ethynyl-2'-deoxyuridine. For preparation prior to beginning the protocol, we detail procedures for generating odorant receptor-specific riboprobes and experimental mouse olfactory epithelial tissue sections. For complete details on the use and execution of this protocol, please refer to van der Linden et al. (2020).1.
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Affiliation(s)
- Kawsar Hossain
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA; Molecular and Cellular Life Sciences Program, University of Wyoming, Laramie, WY 82071, USA
| | - Madeline Smith
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Stephen W Santoro
- Department of Pediatrics, Section of Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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5
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Olfactory Stimulation Regulates the Birth of Neurons That Express Specific Odorant Receptors. Cell Rep 2021; 33:108210. [PMID: 33027656 PMCID: PMC7569022 DOI: 10.1016/j.celrep.2020.108210] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 07/03/2020] [Accepted: 09/09/2020] [Indexed: 12/18/2022] Open
Abstract
In mammals, olfactory sensory neurons (OSNs) are born throughout life, ostensibly solely to replace damaged OSNs. During differentiation, each OSN precursor “chooses,” out of hundreds of possibilities, a single odorant receptor (OR) gene, which defines the identity of the mature OSN. The relative neurogenesis rates of the hundreds of distinct OSN “subtypes” are thought to be constant, as they are determined by a stochastic process in which each OR is chosen with a fixed probability. Here, using histological, single-cell, and targeted affinity purification approaches, we show that closing one nostril in mice selectively reduces the number of newly generated OSNs of specific subtypes. Moreover, these reductions depend on an animal’s age and/or environment. Stimulation-dependent changes in the number of new OSNs are not attributable to altered rates of cell survival but rather production. Our findings indicate that the relative birth rates of distinct OSN subtypes depend on olfactory experience. In mammals, the odorant receptor identities of newly generated olfactory sensory neurons are thought to be determined by each progenitor cell’s random choice of a single receptor. Here, van der Linden et al. show that, in mice, the birth rates of neurons expressing a subset of receptors depend on olfactory stimulation.
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Díaz D, Gómez C, Muñoz-Castañeda R, Baltanás F, Alonso JR, Weruaga E. The Olfactory System as a Puzzle: Playing With Its Pieces. Anat Rec (Hoboken) 2013; 296:1383-400. [DOI: 10.1002/ar.22748] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- D. Díaz
- Laboratory of Neuronal Plasticity and Neurorepair; Institute for Neuroscience of Castile and Leon (INCyL), Universidad de Salamanca; Salamanca Spain
- Area of Gene and Cell Therapy; Institute of Biomedical Research of Salamanca, IBSAL; Salamanca Spain
| | - C. Gómez
- Laboratory of Neuronal Plasticity and Neurorepair; Institute for Neuroscience of Castile and Leon (INCyL), Universidad de Salamanca; Salamanca Spain
- Institute for Molecular and Cell Biology of the Cancer, IBMCC, CSIC-Universidad de Salamanca; Salamanca Spain
| | - R. Muñoz-Castañeda
- Laboratory of Neuronal Plasticity and Neurorepair; Institute for Neuroscience of Castile and Leon (INCyL), Universidad de Salamanca; Salamanca Spain
- Area of Gene and Cell Therapy; Institute of Biomedical Research of Salamanca, IBSAL; Salamanca Spain
| | - F. Baltanás
- Laboratory of Neuronal Plasticity and Neurorepair; Institute for Neuroscience of Castile and Leon (INCyL), Universidad de Salamanca; Salamanca Spain
- Institute for Molecular and Cell Biology of the Cancer, IBMCC, CSIC-Universidad de Salamanca; Salamanca Spain
| | - J. R. Alonso
- Laboratory of Neuronal Plasticity and Neurorepair; Institute for Neuroscience of Castile and Leon (INCyL), Universidad de Salamanca; Salamanca Spain
- Area of Gene and Cell Therapy; Institute of Biomedical Research of Salamanca, IBSAL; Salamanca Spain
- Institute for High Research, Universidad de Tarapacá; Arica Chile
| | - E. Weruaga
- Laboratory of Neuronal Plasticity and Neurorepair; Institute for Neuroscience of Castile and Leon (INCyL), Universidad de Salamanca; Salamanca Spain
- Area of Gene and Cell Therapy; Institute of Biomedical Research of Salamanca, IBSAL; Salamanca Spain
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7
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Oshimoto A, Wakabayashi Y, Garske A, Lopez R, Rolen S, Flowers M, Arevalo N, Restrepo D. Potential role of transient receptor potential channel M5 in sensing putative pheromones in mouse olfactory sensory neurons. PLoS One 2013; 8:e61990. [PMID: 23613997 PMCID: PMC3628705 DOI: 10.1371/journal.pone.0061990] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 03/18/2013] [Indexed: 02/05/2023] Open
Abstract
Based on pharmacological studies of chemosensory transduction in transient receptor potential channel M5 (TRPM5) knockout mice it was hypothesized that this channel is involved in transduction for a subset of putative pheromones in mouse olfactory sensory neurons (OSNs). Yet, in the same study an electroolfactogram (EOG) in the mouse olfactory epithelium showed no significant difference in the responses to pheromones (and odors) between wild type and TRPM5 knockout mice. Here we show that the number of OSNs expressing TRPM5 is increased by unilateral naris occlusion. Importantly, EOG experiments show that mice lacking TRPM5 show a decreased response in the occluded epithelia to putative pheromones as opposed to wild type mice that show no change upon unilateral naris occlusion. This evidence indicates that under decreased olfactory sensory input TRPM5 plays a role in mediating putative pheromone transduction. Furthermore, we demonstrate that cyclic nucleotide gated channel A2 knockout (CNGA2-KO) mice that show substantially decreased or absent responses to odors and pheromones also have elevated levels of TRPM5 compared to wild type mice. Taken together, our evidence suggests that TRPM5 plays a role in mediating transduction for putative pheromones under conditions of reduced chemosensory input.
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Affiliation(s)
- Arisa Oshimoto
- Department of Cell and Developmental Biology, Neuroscience Program, and Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Yoshihiro Wakabayashi
- Laboratory of Neurobiology, National Institute of Agrobiological Sciences, Tsukuba, Japan
| | - Anna Garske
- Department of Cell and Developmental Biology, Neuroscience Program, and Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Roberto Lopez
- Department of Cell and Developmental Biology, Neuroscience Program, and Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Shane Rolen
- Department of Cell and Developmental Biology, Neuroscience Program, and Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Michael Flowers
- Department of Cell and Developmental Biology, Neuroscience Program, and Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Nicole Arevalo
- Department of Cell and Developmental Biology, Neuroscience Program, and Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Diego Restrepo
- Department of Cell and Developmental Biology, Neuroscience Program, and Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- * E-mail:
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8
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Studies of olfactory system neural plasticity: the contribution of the unilateral naris occlusion technique. Neural Plast 2012; 2012:351752. [PMID: 22690343 PMCID: PMC3368527 DOI: 10.1155/2012/351752] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Revised: 03/01/2012] [Accepted: 03/19/2012] [Indexed: 01/18/2023] Open
Abstract
Unilateral naris occlusion has long been the method of choice for effecting stimulus deprivation in studies of olfactory plasticity. A significant body of literature speaks to the myriad consequences of this manipulation on the ipsilateral olfactory pathway. Early experiments emphasized naris occlusion's deleterious and age-critical effects. More recent studies have focused on life-long vulnerability, particularly on neurogenesis, and compensatory responses to deprivation. Despite the abundance of empirical data, a theoretical framework in which to understand the many sequelae of naris occlusion on olfaction has been elusive. This paper focuses on recent data, new theories, and underappreciated caveats related to the use of this technique in studies of olfactory plasticity.
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9
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Gelhaye M, Padzys GS, Olry JC, Thornton SN, Martrette JM, Trabalon M. Mother-pup interactions during a short olfactory deprivation period in young rats. Dev Psychobiol 2011; 53:303-16. [PMID: 21271560 DOI: 10.1002/dev.20523] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 11/24/2010] [Indexed: 11/08/2022]
Abstract
The effects of short-term bilateral naris occlusion (inducing olfactory deprivation) on mother-pup interactions, suckling behavior and hormonal status during post-natal development in Wistar rats were studied. Bilateral naris occlusion was performed on 8-day-old rat pups and its effects were evaluated at Day 9 and at Day 15. The narins opened spontaneously between Day 12 and 14. Olfactory-deprived pups exhibited a greater level of corticosterone at both ages versus untreated or sham animals. Olfactory deprivation via naris occlusion, in young rats, alters mother-pup interactions with a decrease in the duration of mother-pup retrieving and an increase in pup licking. Olfactory-deprived pups showed also a lower mean duration of nursing and a decrease in nipple attachment, which appeared related to difficulties in finding the nipple. Olfactory-deprived pups had difficulty recognizing their nest. These behavioral alterations were accompanied by a diminution in milk ingested and growth retardation associated with a reduced level of thyroxin at both 9 and 15 days of age.
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Affiliation(s)
- Mathieu Gelhaye
- Université H. Poincaré, B.P.70239, 54506 Vandoeuvre-les-Nancy, France
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10
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Nasrallah HA, Hopkins T, Pixley SK. Differential effects of antipsychotic and antidepressant drugs on neurogenic regions in rats. Brain Res 2010; 1354:23-9. [PMID: 20682307 DOI: 10.1016/j.brainres.2010.07.075] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 07/13/2010] [Accepted: 07/21/2010] [Indexed: 11/30/2022]
Abstract
Increased neurogenesis in the hippocampus and subventricular zone (SVZ) of the brain of animals has been demonstrated following administration of several psychotropic medications. Such changes are thought to regenerate tissues and contribute to the beneficial effects of the medications. This study sought to determine if another neurogenic tissue, the peripheral olfactory epithelium (OE), might also exhibit changes after treatment with psychotropic medications. Young adult male rats were treated with risperidone and paliperidone, atypical antipsychotic medications; fluoxetine, a selective serotonin reuptake inhibitor (SSRI) antidepressant; and diluent control for 28days via drinking water. Bromodeoxyuridine (BrdU) was injected to label dividing cells and positive cells were quantified in the OE, cortical SVZ, and dentate gyrus (DG) of the hippocampus. In the first of two studies, paliperidone and risperidone treatment (at 1mg/kg/day) resulted in increased numbers over controls of BrdU positive cells in the OE. In the second study, examining OE, SVZ and DG in the same animal, paliperidone, but not risperidone or fluoxetine (0.6 mg/kg/day) resulted in increased cells in the OE and posterior SVZ. However, fluoxetine, but not paliperidone or risperidone treatment increased BrdU positive cells in the DG. These results show that psychotropic drug-induced cell proliferation occurs in the OE and parallels changes in the SVZ but not DG. Thus, the peripheral OE can serve as a proxy for certain psychotropic drug-induced actions on SVZ brain cell proliferation. This olfactory model can be employed in human research as a method to explore the neurogenesis effects of various pharmacologic treatments of neuropsychiatric disorders.
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Affiliation(s)
- Henry A Nasrallah
- Dept of Psychiatry, Univ of Cincinnati College of Medicine, Cincinnati, OH 45267-0521, USA
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Vedin V, Molander M, Bohm S, Berghard A. Regional differences in olfactory epithelial homeostasis in the adult mouse. J Comp Neurol 2009; 513:375-84. [PMID: 19177519 DOI: 10.1002/cne.21973] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The olfactory sensory neurons in the nasal cavity of the adult mouse are organized into a few regions that differ in their molecular properties, as several classes of genes show regional expression. Most renowned is the fact that expression of each of hundreds of different odorant receptor genes is limited to one such region, or zone, of the olfactory neuroepithelial sheet. Zone differences are in place at birth, as exemplified here by the expression of neuronal progenitor marker Foxg1. We herein describe that an adult pattern showing regional differences in neurogenesis develops during the first few weeks of postnatal life which, e.g., is reflected in the temporal and regional regulation of the neuronal progenitor marker Ascl1. The most dorsomedial zone shows significantly fewer cells in S-phase in the adult but not in newborn mice by two different measures. Moreover, we show that there are regional differences in the relative differentiation, cell survival, and thickness of the olfactory epithelium. These findings are compatible with the view that zones are inherently distinct and that such differences contribute to generate regional differences in cellular homeostasis that in turn may modulate the capacity of a region to adjust to extrinsic influence.
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Affiliation(s)
- Viktoria Vedin
- Department of Molecular Biology, Umeå University, Sweden
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Suh KS, Kim SY, Bae YC, Ronnett GV, Moon C. Effects of unilateral naris occlusion on the olfactory epithelium of adult mice. Neuroreport 2006; 17:1139-42. [PMID: 16837842 DOI: 10.1097/01.wnr.0000224762.54336.7d] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Sensory stimulation is an essential component of neuronal functions, including information processing, dendritic and axonal refinement, synaptic plasticity, and neuronal survival. We examined the roles of sensory stimulation in the maintenance of olfactory sensory neurons in the olfactory epithelium using the adult mouse olfactory system as the model system. Obstruction of sensory stimulation through unilateral naris occlusion caused downregulation of proliferation and upregulation of apoptosis of neurons in the olfactory epithelium. Sensory stimulation is therefore important in maintaining homeostasis in the adult olfactory epithelium. Our study contributes to further understanding the roles and mechanisms of sensory stimulation in the postnatal neuronal development as well as to the damage and potential treatments of patients who suffer recurrent nasal obstruction.
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Affiliation(s)
- Kyung Shik Suh
- Department of Neuroscience, The Johns Hopkins University, School of Medicine, Baltimore, Maryland, USA
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Mirich JM, Illig KR, Brunjes PC. Experience-dependent activation of extracellular signal-related kinase (ERK) in the olfactory bulb. J Comp Neurol 2004; 479:234-41. [PMID: 15452854 DOI: 10.1002/cne.20325] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Protein kinase-mediated signaling cascades play a fundamental role in translating extracellular signals into cellular responses in CNS neurons. The mitogen-activated protein kinase / extracellular signal-regulated kinase (MAPK/ERK) pathway participates in regulating diverse neuronal processes such as proliferation, differentiation, survival, synaptic efficacy, and long-term potentiation by inducing cAMP-response element (CRE)-mediated gene transcription. Central olfactory structures show plasticity throughout the lifespan, but the role of the MAPK/ERK pathway in odor-evoked activity has yet to be determined. Therefore, we examined the effect of odorant exposure and early postnatal deprivation on ERK activity. We found that odor stimulation induced ERK phosphorylation, that activation of the ERK pathway was decreased with early postnatal deprivation, and that ERK phosphorylation was subsequently increased by restoring stimulation. Further, locations of ERK activation in bulbar neurons after exposure to single odorants corresponded to odor-evoked activity patterns found with other measures of activity in the bulb. Finally, due to the cytoplasmic location of pERK, activated dendrites belonging to the primary excitatory output neurons of the bulb were observed following a single odor exposure. The results indicate that the MAPK/ERK pathway is activated by odorant stimulation and may play an important role in developmental sensory plasticity in the olfactory bulb.
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Affiliation(s)
- Jennifer M Mirich
- Department of Psychology, University of Virginia, Charlottesville, Virginia 22904, USA
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Brunjes P, Shurling DC. Cell death in the nasal septum of normal and naris-occluded rats. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2003; 146:25-8. [PMID: 14643008 DOI: 10.1016/j.devbrainres.2003.09.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Blocking airflow through an external naris of a newborn rat results in a thinning of the olfactory mucosa by postnatal day (P) 20, at least partially due to a reduction in mitotic rates. We employed the TUNEL method to examine patterns of cell death. By P20-30, significant differences in the numbers of labeled profiles were found in the middle 50% of the tissue, a region primarily containing olfactory sensory cells.
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Affiliation(s)
- Peter Brunjes
- Department of Psychology, University of Virginia, 102 Gilmer Hall Box 400400, Charlottesville, VA 22904-4400, USA.
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15
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Derby CD, Cate HS, Steullet P, Harrison PJH. Comparison of turnover in the olfactory organ of early juvenile stage and adult Caribbean spiny lobsters. ARTHROPOD STRUCTURE & DEVELOPMENT 2003; 31:297-311. [PMID: 18088988 DOI: 10.1016/s1467-8039(02)00050-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2002] [Accepted: 09/29/2002] [Indexed: 05/25/2023]
Abstract
Proliferation and turnover of neurons occurs in the olfactory systems of many animals. In this study, we examined developmental changes in turnover in the olfactory organ of the Caribbean spiny lobster Panulirus argus by examining two life-history stages-early juveniles and young adults. Turnover was compared using external morphology of the olfactory organ before and after molting to determine addition and loss of aesthetascs and other chemosensilla, and BrdU labeling to identify newly proliferated cells. The number of olfactory receptor neurons (ORNs) innervating each aesthetasc increased only slightly over development, but there was a net increase of olfactory sensory units (i.e. aesthetascs and their ORNs) at each molt. This increase was similar in early juveniles and young adults when expressed as absolute number of ORNs neurons but greater in early juveniles when expressed as a proportion of existing ORNs. The net increase in olfactory sensory units in early juveniles is due solely to addition, since virtually no aesthetascs are lost. In contrast, the net increase in olfactory sensory units in adults reflects addition of new units accompanied by considerable loss of old units. These developmental changes result in expansive enlargement of the olfactory organ without turnover in early juveniles, and a more modest growth combined with continuous turnover and replenishment of ORNs in adults.
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Affiliation(s)
- Charles D Derby
- Department of Biology, Center for Behavioral Neuroscience, Georgia State University, P.O. Box 4010, Atlanta, GA 30302-4010, USA
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