RESUMEN
Across vertebrate species, the olfactory epithelium (OE) exhibits the uncommon feature of lifelong neuronal turnover. Epithelial stem cells give rise to new neurons that can adequately replace dying olfactory receptor neurons (ORNs) during developmental and adult phases and after lesions. To relay olfactory information from the environment to the brain, the axons of the renewed ORNs must reconnect with the olfactory bulb (OB). In Xenopus laevis larvae, we have previously shown that this process occurs between 3 and 7 weeks after olfactory nerve (ON) transection. In the present study, we show that after 7 weeks of recovery from ON transection, two functionally and spatially distinct glomerular clusters are reformed in the OB, akin to those found in non-transected larvae. We also show that the same odourant response tuning profiles observed in the OB of non-transected larvae are again present after 7 weeks of recovery. Next, we show that characteristic odour-guided behaviour disappears after ON transection but recovers after 7-9 weeks of recovery. Together, our findings demonstrate that the olfactory system of larval X. laevis regenerates with high accuracy after ON transection, leading to the recovery of odour-guided behaviour.
Asunto(s)
Larva , Bulbo Olfatorio , Xenopus laevis , Animales , Bulbo Olfatorio/fisiología , Regeneración Nerviosa/fisiología , Odorantes , Traumatismos del Nervio Olfatorio , Nervio Olfatorio/fisiología , Mucosa Olfatoria/citología , Mucosa Olfatoria/fisiología , Olfato/fisiología , Neuronas Receptoras Olfatorias/fisiologíaRESUMEN
Osteoglossiformes (bonytongue fishes) possess many morphological specializations associated with functions such as airbreathing, feeding, and electroreception. The olfactory organ also varies among species, notably in the family Osteoglossidae. Herein, we describe the olfactory organ of an osteoglossid, Heterotis niloticus, to compare it with the olfactory organs of other osteoglossiforms. We demonstrate the presence of an olfactory rosette within the olfactory chamber. This structure consists of a short median raphe surrounded by olfactory lamellae, which possess dorsal lamellar processes. On the surface of the olfactory lamellae, there are secondary lamellae formed by the olfactory epithelium. Within the olfactory epithelium, two zones can be distinguished: parallel brands of sensory cells located in the cavities between the secondary lamellae and a nonsensory area covering the remaining part of the olfactory lamellae. The olfactory epithelium is formed by ciliated and microvillus olfactory sensory neurons, supporting cells, goblet cells, basal cells and ciliated nonsensory cells. Additionally, rodlet cells were observed. The results confirm large variability in terms of the olfactory organ of Osteoglossiformes, particularly of Osteoglossidae, and support the secondary lamellae evolution hypothesis within this family.
Asunto(s)
Peces , Mucosa Olfatoria , Animales , Peces/anatomía & histología , Mucosa Olfatoria/anatomía & histología , Mucosa Olfatoria/fisiología , Olfato/fisiología , Células CaliciformesRESUMEN
INTRODUCTION: Olfactory dysfunction (OD) is a typical symptom of chronic rhinosinusitis (CRS), which adversely affects the patient's quality of life and results in mood depression. Studies investigating the impairment of olfactory epithelium (OE) have indicated that inflammation-induced cell damage and dysfunction in OE plays a vital role in the development of OD. Consequently, glucocorticoids and biologics are beneficial in the management of OD in CRS patients. However, the mechanisms underlying OE impairment in CRS patients have not been fully elucidated. AREAS COVERED: This review focuses on mechanisms underlying inflammation-induced cell impairment in OE of CRS patients. Additionally, the methods used for detection of olfaction and both currently available and potentially new clinical treatments for OD are reviewed. EXPERT OPINION: Chronic inflammation in OE impairs not only olfactory sensory neurons but also non-neuronal cells that are responsible for regeneration and support for neurons. The current treatment for OD in CRS is mainly aimed at attenuating and preventing inflammation. Strategies for use of combinations of these therapies may achieve greater efficacy in restoration of the damaged OE and consequently better management of OD.
Asunto(s)
Trastornos del Olfato , Rinitis , Sinusitis , Humanos , Olfato/fisiología , Calidad de Vida , Mucosa Olfatoria/fisiología , Inflamación/terapia , Sinusitis/terapia , Trastornos del Olfato/etiología , Trastornos del Olfato/terapia , Enfermedad Crónica , Rinitis/terapiaRESUMEN
In this study, we present a detailed flow analysis using an anatomically accurate rat nasal cavity model, in which the anatomy and physiology of the nasal airway was thoroughly examined. Special efforts were given to the swirling flow structures in the nasal vestibule (anterior section of the nose, lined by squamous epithelium), fractional flow patterns in the olfactory (posterior superior section of the rat nose, lined by olfactory epithelium), and a designated method to precisely quantify flow apportionment in the olfactory region was developed. Results revealed distinct inspiratory flow patterns in the anterior vestibule region, where the accelerated airflow undergoes two sharp turns as traveling through the tortuous airway, making a route in a shape of 8. Besides this, exceptionally large flow apportionment was observed at the interface of the olfactory recess, which can be as much as 15 times greater than that in the human nose. The thorough understanding of the airflow dynamics in the rat nasal cavity is necessary to avoid potential misinterpretation of rat-derived inhalation toxicity results. Research findings are expected to play a fundamental role in developing unbiased rat to human interspecies data extrapolation schemes.
Asunto(s)
Cavidad Nasal , Mucosa Olfatoria , Administración por Inhalación , Animales , Cavidad Nasal/fisiología , Nariz/fisiología , Mucosa Olfatoria/fisiología , Ratas , Olfato/fisiologíaRESUMEN
PURPOSE: Olfactory adaptation is a peripheral (at the epithelium level) or a central (at the brain level) mechanism resulting from repeated or prolonged odorous exposure that can induce a perceptual decrease. The aim of this study was to assess whether a peripheral adaptation occurs when an odor is repeated ten times. Moreover, the specificity of the peripheral adaptation to the nature of the odorant was investigated. METHODS: Four odorants (eugenol, manzanate, ISO E Super and phenylethanol) were presented using precisely controlled air-dilution olfactometry. They differed in terms of their physicochemical properties. Electrophysiological recordings were made at the level of the olfactory mucosa, the so-called electro-olfactogram (EOG). Thirty-five right-handed participants were recruited. RESULTS: Sixty-nine percent of the participants presented at least one EOG, whatever the odor condition. The EOG amplitude did not significantly decrease over 10 repeated exposures to any odorant. The intensity ratings tended to decrease over stimulations for manzanate, PEA, and eugenol. No correlation was found between the mean EOG amplitudes and the mean intensity ratings. However, the presence of EOG amplitude decreases over stimulations for few subjects suggests that peripheral adaptation might exist. CONCLUSION: Overall, our results did not establish a clear peripheral adaptation measured with EOG but indicate the eventuality of such an effect.
Asunto(s)
Eugenol , Olfato , Humanos , Odorantes , Mucosa Olfatoria/fisiología , Olfato/fisiologíaRESUMEN
The Delta Smelt (Hypomesus transpacificus) is a small, semi-anadromous fish native to the San Francisco Bay-Delta Estuary and has been declared as critically endangered. Their olfactory biology, in particular, is poorly understood and a basic description of their sensory anatomy is needed to advance our understanding of the sensory ecology of species to inform conservation efforts to manage and protect them. We provide a description of the gross morphology, histological, immunohistochemical, and ultrastructural features of the olfactory rosette in this fish and discuss some of the functional implications in relation to olfactory ability. We show that Delta Smelt have a multilamellar olfactory rosette with allometric growth. Calretinin immunohistochemistry revealed a diffuse distribution of olfactory receptor neurons within the epithelium. Ciliated, microvillous and crypt neurons were clearly identified using morphological and immunohistochemical features. The olfactory neurons were supported by robust ciliated and secretory sustentacular cells. Although the sense of smell has been overlooked in Delta Smelt, we conclude that the olfactory epithelium has many characteristics of macrosmatic fish. With this study, we provide a foundation for future research into the sensory ecology of this imperiled fish.
Asunto(s)
Conducta Animal/fisiología , Especies en Peligro de Extinción , Mucosa Olfatoria/anatomía & histología , Osmeriformes/anatomía & histología , Olfato/fisiología , Estimulación Acústica , Animales , Calbindina 2/metabolismo , Estuarios , Femenino , Inmunohistoquímica , Masculino , Mucosa Olfatoria/fisiología , Mucosa Olfatoria/ultraestructura , Vías Olfatorias/anatomía & histología , Vías Olfatorias/fisiología , Vías Olfatorias/ultraestructura , Neuronas Receptoras Olfatorias/fisiología , Neuronas Receptoras Olfatorias/ultraestructura , Osmeriformes/fisiologíaRESUMEN
The adult olfactory epithelium (OE) regenerates sensory neurons and nonsensory supporting cells from resident stem cells after injury. How supporting cells contribute to OE regeneration remains largely unknown. In this study, we elucidated a novel role of Ym2 (also known as Chil4 or Chi3l4), a chitinase-like protein expressed in supporting cells, in regulating regeneration of the injured OE in vivo in both male and female mice and cell proliferation/differentiation in OE colonies in vitro We found that Ym2 expression was enhanced in supporting cells after OE injury. Genetic knockdown of Ym2 in supporting cells attenuated recovery of the injured OE, while Ym2 overexpression by lentiviral infection accelerated OE regeneration. Similarly, Ym2 bidirectionally regulated cell proliferation and differentiation in OE colonies. Furthermore, anti-inflammatory treatment reduced Ym2 expression and delayed OE regeneration in vivo and cell proliferation/differentiation in vitro, which were counteracted by Ym2 overexpression. Collectively, this study revealed a novel role of Ym2 in OE regeneration and cell proliferation/differentiation of OE colonies via interaction with inflammatory responses, providing new clues to the function of supporting cells in these processes.SIGNIFICANCE STATEMENT The mammalian olfactory epithelium (OE) is a unique neural tissue that regenerates sensory neurons and nonsensory supporting cells throughout life and postinjury. How supporting cells contribute to this process is not entirely understood. Here we report that OE injury causes upregulation of a chitinase-like protein, Ym2, in supporting cells, which facilitates OE regeneration. Moreover, anti-inflammatory treatment reduces Ym2 expression and delays OE regeneration, which are counteracted by Ym2 overexpression. This study reveals an important role of supporting cells in OE regeneration and provides a critical link between Ym2 and inflammation in this process.
Asunto(s)
Quitinasas/metabolismo , Inflamación/metabolismo , Mucosa Olfatoria/fisiología , Regeneración/fisiología , Animales , Femenino , Masculino , Ratones , Ratones TransgénicosRESUMEN
Spinal cord injury (SCI) can cause chronic paralysis and incontinence and remains a major worldwide healthcare burden, with no regenerative treatment clinically available. Intraspinal transplantation of olfactory ensheathing cells (OECs) and injection of chondroitinase ABC (chABC) are both promising therapies but limited and unpredictable responses are seen, particularly in canine clinical trials. Sustained delivery of chABC presents a challenge due to its thermal instability; we hypothesised that transplantation of canine olfactory mucosal OECs genetically modified ex vivo by lentiviral transduction to express chABC (cOEC-chABC) would provide novel delivery of chABC and synergistic therapy. Rats were randomly divided into cOEC-chABC, cOEC, or vehicle transplanted groups and received transplant immediately after dorsal column crush corticospinal tract (CST) injury. Rehabilitation for forepaw reaching and blinded behavioural testing was conducted for 8 weeks. We show that cOEC-chABC transplanted animals recover greater forepaw reaching accuracy on Whishaw testing and more normal gait than cOEC transplanted or vehicle control rats. Increased CST axon sprouting cranial to the injury and serotonergic fibres caudal to the injury suggest a mechanism for recovery. We therefore demonstrate that cOECs can deliver sufficient chABC to drive modest functional improvement, and that this genetically engineered cellular and molecular approach is a feasible combination therapy for SCI.
Asunto(s)
Condroitinasas y Condroitín Liasas/administración & dosificación , Mucosa Olfatoria/fisiología , Mucosa Olfatoria/trasplante , Recuperación de la Función/fisiología , Traumatismos de la Médula Espinal/enzimología , Traumatismos de la Médula Espinal/rehabilitación , Animales , Células Cultivadas , Condroitinasas y Condroitín Liasas/biosíntesis , Perros , Masculino , Mucosa Olfatoria/citología , Ratas , Ratas Wistar , Traumatismos de la Médula Espinal/patologíaRESUMEN
Olfactory dysfunction is one of the most frequent and specific symptoms of coronavirus disease 2019 (COVID-19). Information on the damage and repair of the neuroepithelium and its impact on olfactory function after COVID-19 is still incomplete. While severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causes the ongoing worldwide outbreak of COVID-19, little is known about the changes triggered by SARS-CoV-2 in the olfactory epithelium (OE) at the cellular level. Here, we report profiles of the OE after SARS-CoV-2 infection in golden Syrian hamsters, which is a reliable animal model of COVID-19. We observed severe damage in the OE as early as 3 days postinoculation and regionally specific damage and regeneration of the OE within the nasal cavity; the nasal septal region demonstrated the fastest recovery compared to other regions in the nasal turbinates. These findings suggest that anosmia related to SARS-CoV-2 infection may be fully reversible.
Asunto(s)
Anosmia/fisiopatología , COVID-19/patología , Mucosa Olfatoria/patología , Neuronas Receptoras Olfatorias/patología , Regeneración , SARS-CoV-2 , Animales , Anosmia/etiología , COVID-19/complicaciones , COVID-19/fisiopatología , Modelos Animales de Enfermedad , Mesocricetus , Cavidad Nasal , Tabique Nasal , Mucosa Olfatoria/fisiología , Neuronas Receptoras Olfatorias/fisiología , Tamaño de los Órganos , Cornetes NasalesRESUMEN
In the mouse, 129 functional class I odorant receptor (OR) genes reside in a ~ 3 megabase huge gene cluster on chromosome 7. The J element, a long-range cis-regulatory element governs the singular expression of class I OR genes by exerting its effect over the whole cluster. To elucidate the molecular mechanisms underlying class I-specific enhancer activity of the J element, we analyzed the J element sequence to determine the functional region and essential motif. The 430-bp core J element, that is highly conserved in mammalian species from the platypus to humans, contains a class I-specific conserved motif of AAACTTTTC, multiple homeodomain sites, and a neighboring O/E-like site, as in class II OR-enhancers. A series of transgenic reporter assays demonstrated that the class I-specific motif is not essential, but the 330-bp core J-H/O containing the homeodomain and O/E-like sites is necessary and sufficient for class I-specific enhancer activity. Further motif analysis revealed that one of homeodomain sequence is the Greek Islands composite motif of the adjacent homeodomain and O/E-like sequences, and mutations in the composite motif abolished or severely reduced class I-enhancer activity. Our results demonstrate that class I and class II enhancers share a functional motif for their enhancer activity.
Asunto(s)
Secuencias de Aminoácidos/genética , Elementos de Facilitación Genéticos/genética , Receptores Odorantes/genética , Animales , Cromosomas Humanos Par 7/genética , Expresión Génica/genética , Proteínas de Homeodominio/genética , Humanos , Ratones , Mutación , Mucosa Olfatoria/metabolismo , Mucosa Olfatoria/fisiología , Receptores Odorantes/clasificaciónAsunto(s)
Vías Olfatorias/anatomía & histología , Vías Olfatorias/fisiología , Percepción Olfatoria/fisiología , Olfato/fisiología , Animales , Humanos , Odorantes , Bulbo Olfatorio/anatomía & histología , Bulbo Olfatorio/fisiología , Corteza Olfatoria/anatomía & histología , Corteza Olfatoria/fisiología , Mucosa Olfatoria/anatomía & histología , Mucosa Olfatoria/fisiología , Receptores Odorantes/fisiologíaRESUMEN
In experiments on rats, co-transplantation of olfactory ensheathing cells of the human olfactory mucosa and neural stem/progenitor cells from the same source into post-traumatic cysts of the spinal cord led to improvement of the motor activity of the hind limbs and reduced the size of the cysts in some animals by 4-12%. The transplantation of a combination of the olfactory mucosa cells is effective and can be used in preclinical trials for the treatment of spinal cord injuries.
Asunto(s)
Quistes/terapia , Células Epiteliales/trasplante , Células-Madre Neurales/trasplante , Recuperación de la Función/fisiología , Esferoides Celulares/trasplante , Traumatismos de la Médula Espinal/terapia , Animales , Tratamiento Basado en Trasplante de Células y Tejidos/métodos , Quistes/patología , Quistes/fisiopatología , Células Epiteliales/citología , Células Epiteliales/fisiología , Femenino , Humanos , Actividad Motora/fisiología , Células-Madre Neurales/citología , Células-Madre Neurales/fisiología , Mucosa Olfatoria/citología , Mucosa Olfatoria/fisiología , Cultivo Primario de Células , Ratas , Ratas Wistar , Esferoides Celulares/citología , Esferoides Celulares/fisiología , Médula Espinal/patología , Médula Espinal/fisiopatología , Traumatismos de la Médula Espinal/patología , Traumatismos de la Médula Espinal/fisiopatología , Trasplante Heterólogo , Resultado del TratamientoRESUMEN
Microglial cells are the first line immune cells that initiate inflammatory responses following cerebral ischemia/reperfusion(I/R) injury. Microglial cells are also associated with a novel subtype of pro-inflammatory programmed cell death known as pyroptosis. Research has been directed at developing treatments that modulate inflammatory responses and protect against cell death caused by cerebral I/R. Key among such treatments include mesenchymal stem cell (MSC) therapy. A unique type of MSC termed olfactory mucosa mesenchymal stem cell (OM-MSC) confers neuroprotection by promoting the secretion of paracrine factors, and neuroprotection. This study investigated whether hypoxic OM-MSCs could inhibit microglial cell death upon I/R insult in vitro. A traditional oxygen-glucose deprivation/reperfusion (OGD/R) model, analogous to I/R, was established. Results showed that OGD/R induced apoptosis and pyroptosis in microglial cells while hypoxia in OM-MSCs significantly attenuated these effects. Moreover, the effects of OM-MSCs were mediated by Hypoxia-inducible factor 1-alpha (HIF-1α). Taken together, these findings reveal that hypoxia-preconditioned OM-MSC inhibits pyroptotic and apoptotic death of microglial cell in response to cerebral ischemia/reperfusion insult by activating HIF-1α in vitro.
Asunto(s)
Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Células Madre Mesenquimatosas/metabolismo , Microglía/metabolismo , Mucosa Olfatoria/fisiología , Isquemia Encefálica/metabolismo , Diferenciación Celular , Hipoxia de la Célula , Supervivencia Celular , Células Cultivadas , Humanos , Células Madre Mesenquimatosas/citología , Piroptosis , ReperfusiónRESUMEN
Olfactory receptor neurons (ORNs) use odour-induced intracellular cAMP surge to gate cyclic nucleotide-gated nonselective cation (CNG) channels in cilia. Prolonged exposure to cAMP causes calmodulin-dependent feedback-adaptation of CNG channels and attenuates neural responses. On the other hand, the odour-source searching behaviour requires ORNs to be sensitive to odours when approaching targets. How ORNs accommodate these conflicting aspects of cAMP responses remains unknown. Here, we discover that olfactory marker protein (OMP) is a major cAMP buffer that maintains the sensitivity of ORNs. Upon the application of sensory stimuli, OMP directly captured and swiftly reduced freely available cAMP, which transiently uncoupled downstream CNG channel activity and prevented persistent depolarization. Under repetitive stimulation, OMP-/- ORNs were immediately silenced after burst firing due to sustained depolarization and inactivated firing machinery. Consequently, OMP-/- mice showed serious impairment in odour-source searching tasks. Therefore, cAMP buffering by OMP maintains the resilient firing of ORNs.
Asunto(s)
AMP Cíclico/metabolismo , Canales Catiónicos Regulados por Nucleótidos Cíclicos/metabolismo , Proteína Marcadora Olfativa/metabolismo , Neuronas Receptoras Olfatorias/metabolismo , Animales , Butorfanol/farmacología , Cilios/metabolismo , Células HEK293 , Humanos , Masculino , Medetomidina/farmacología , Potenciales de la Membrana/efectos de los fármacos , Ratones Endogámicos C57BL , Ratones Noqueados , Midazolam/farmacología , Odorantes , Proteína Marcadora Olfativa/genética , Mucosa Olfatoria/citología , Mucosa Olfatoria/efectos de los fármacos , Mucosa Olfatoria/fisiología , Neuronas Receptoras Olfatorias/citología , Neuronas Receptoras Olfatorias/fisiología , Técnicas de Placa-ClampRESUMEN
We have previously provided the first evidence that the microbiota modulates the physiology of the olfactory epithelium using germfree mice. The extent to which changes to the olfactory system depend on the microbiota is still unknown. In the present work, we explored if different microbiota would differentially impact olfaction. We therefore studied the olfactory function of three groups of mice of the same genetic background, whose parents had been conventionalized before mating with microbiota from three different mouse strains. Caecal short chain fatty acids profiles and 16S rRNA gene sequencing ascertained that gut microbiota differed between the three groups. We then used a behavioural test to measure the attractiveness of various odorants and observed that the three groups of mice differed in their attraction towards odorants. Their olfactory epithelium properties, including electrophysiological responses recorded by electro-olfactograms and expression of genes related to the olfactory transduction pathway, also showed several differences. Overall, our data demonstrate that differences in gut microbiota profiles are associated with differences in olfactory preferences and in olfactory epithelium functioning.
Asunto(s)
Conducta Animal , Ácidos Grasos Volátiles/metabolismo , Microbioma Gastrointestinal/fisiología , Mucosa Olfatoria/fisiología , Olfato/fisiología , Animales , Bacteroidetes , Ciego , Electrodiagnóstico , Firmicutes , Contenido Digestivo/química , Microbioma Gastrointestinal/genética , Perfilación de la Expresión Génica , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C3H , Odorantes , ARN Ribosómico 16S/genéticaRESUMEN
Spinal cord injury (SCI) remains one of the biggest challenges in the development of neuroregenerative therapeutics. Cell transplantation is one of numerous experimental strategies that have been identified and tested for efficacy at both preclinical and clinical levels in recent years. In this Review, we briefly discuss the state of human olfactory cell transplantation as a therapy, considering both its current clinical status and its limitations. Furthermore, we introduce a mesenchymal stromal cell derived from human olfactory tissue, which has the potential to induce multifaceted reparative effects in the environment within and surrounding the lesion. We argue that no single therapy will be sufficient to treat SCI effectively and that a combination of cell-based, rehabilitation and pharmaceutical interventions is the most promising approach to aid repair. For this reason, we also introduce a novel pharmaceutical strategy based on modifying the activity of heparan sulfate, an important regulator of a wide range of biological cell functions. The multi-target approach that is exemplified by these types of strategies will probably be necessary to optimize SCI treatment.
Asunto(s)
Heparitina Sulfato/uso terapéutico , Trasplante de Células Madre Mesenquimatosas/métodos , Mucosa Olfatoria/citología , Traumatismos de la Médula Espinal/terapia , Regeneración de la Medula Espinal , Trasplante de Células/métodos , Proteoglicanos Tipo Condroitín Sulfato/metabolismo , Proteoglicanos de Heparán Sulfato/metabolismo , Heparina/uso terapéutico , Heparitina Sulfato/análogos & derivados , Humanos , Células Madre Mesenquimatosas/citología , Regeneración Nerviosa , Neuroglía , Mucosa Olfatoria/fisiología , Neuronas Receptoras OlfatoriasRESUMEN
The presence of active neurogenic niches in adult humans is controversial. We focused attention to the human olfactory neuroepithelium, an extracranial site supplying input to the olfactory bulbs of the brain. Using single-cell RNA sequencing analyzing 28,726 cells, we identified neural stem cell and neural progenitor cell pools and neurons. Additionally, we detailed the expression of 140 olfactory receptors. These data from the olfactory neuroepithelium niche provide evidence that neuron production may continue for decades in humans.
Asunto(s)
Neurogénesis/fisiología , Mucosa Olfatoria/inervación , Mucosa Olfatoria/fisiología , Análisis de la Célula Individual , Adulto , Envejecimiento/fisiología , Humanos , Células-Madre Neurales/fisiología , Neuronas Receptoras Olfatorias/fisiología , Análisis de Secuencia de ARN , OlfatoRESUMEN
In the mouse olfactory bulb (OB), odor input from the olfactory epithelium innervates topographically to form odorant maps, which are mirror-image arrangements of glomerular clusters with domain organization. However, the functional role of the mirror-image representation in the OB remains unknown. Predator odors induce stress responses, and the dorsal domain of the dorsolateral wall of the olfactory bulb (dlOB) is known to be involved in this process. However, it remains unclear whether the activities in the medial wall of the OB (mOB), the other mirror half, are also involved in stress responses. Therefore, in this study, we investigated whether the mOB and dlOB are required for the induction of stress responses using lesioning or electrical stimulation. Although there were no significant differences in the number of activated neurons in the bed nucleus of the stria terminalis, posterior piriform cortex or amygdalo-piriform transition area, fewer activated neurons were observed in the anterior piriform cortex (APC) following lesion of both the mOB and dlOB combined. No changes were observed in the density of activated cells in any examined brain region following stimulation of either the mOB or dlOB alone. However, activated neurons in the APC were significantly more numerous following simultaneous stimulation of the mOB and dlOB. Collectively, our results suggest that simultaneous activation in both the mOB and dlOB is needed to induce APC neural activities that produce stress-like behavior. These findings provide insight into olfactory information processing, and may also help in the development of therapies for odor-induced stress behaviors.
Asunto(s)
Neuronas/fisiología , Bulbo Olfatorio/fisiología , Vías Olfatorias/fisiología , Olfato/fisiología , Animales , Masculino , Ratones , Odorantes , Mucosa Olfatoria/fisiología , Proteínas Proto-Oncogénicas c-fos/metabolismoRESUMEN
The colonial naked mole rat Heterocephalus glaber is a subterranean, eusocial rodent. The H. glaber vomeronasal organ neuroepithelium (VNE) displays little postnatal growth. However, the VNE remains neuronal in contrast to some mammals that possess nonfunctional vomeronasal organ remnants, for example, catarrhine primates and some bats. Here, we describe the vomeronasal organ (VNO) microanatomy in the naked mole rat and we make preliminary observations to determine if H. glaber shares its minimal postnatal VNE growth with other African mole rats. We also determine the immunoreactivity to the mitotic marker Ki67, growth-associated protein 43 (GAP43), and olfactory marker protein (OMP) in six adult and three subadult H. glaber individuals. VNE volume measurements on a small sample of Cryptomys hottentotus and Fukomys damarensis indicate that the VNE of those African mole rat species are also likely to be growth-deficient. Ki67(+) cells show that the sensory epithelium is mitotically active. GAP43 labelling indicates neurogenesis and OMP(+) cells are present though less numerous compared to GAP43(+) cells. In this respect, the VNO of H. glaber does not appear vestigial. The African mole rat VNE may be unusually variable, perhaps reflecting reduced selection pressure on the vomeronasal system. If so, African mole rats may provide a useful genetic model for understanding the morphological variability observed in the mammalian VNO. Anat Rec, 2019. © 2019 Wiley Periodicals, Inc. Anat Rec, 303:318-329, 2020. © 2019 American Association for Anatomy.