Odorant Receptors in the Formation of the Olfactory Bulb Circuitry

Physiology ◽  
2012 ◽  
Vol 27 (4) ◽  
pp. 200-212 ◽  
Author(s):  
Claudia Lodovichi ◽  
Leonardo Belluscio
Keyword(s):  
Olfactory Bulb ◽  
Axon Guidance ◽  
Sensory Neurons ◽  
Odorant Receptors ◽  
Olfactory Sensory Neurons ◽  
Neural Connectivity ◽  
Axon Terminals ◽  
Primary Function

In mammals, smell is mediated by odorant receptors expressed by sensory neurons in the nose. These specialized receptors are found both on olfactory sensory neurons' cilia and axon terminals. Although the primary function of ciliary odorant receptors is to detect odorants, their axonal role remains unclear but is thought to involve axon guidance. This review discusses findings that show axonal odorant receptors are indeed functional and capable of modulating neural connectivity.

scholarly journals Immature olfactory sensory neurons provide behaviorally useful sensory input to the olfactory bulb

2021 ◽  
Author(s):  
Jane S Huang ◽  
Tenzin Kunkhyen ◽  
Beichen Liu ◽  
Ryan J Muggleton ◽  
Jonathan T Avon ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
Sensory Neurons ◽  
Sensory Input ◽  
Odorant Receptors ◽  
Projection Neurons ◽  
Olfactory Sensory Neurons ◽  
Odor Processing ◽  
Newborn Neurons ◽  
Behavioral Assays

Postnatal neurogenesis provides an opportunity to understand how newborn neurons functionally integrate into circuits to restore lost function. Newborn olfactory sensory neurons (OSNs) wire into highly organized olfactory bulb (OB) circuits throughout life, enabling lifelong plasticity and regeneration. Immature OSNs can form functional synapses capable of evoking firing in OB projection neurons. However, what contribution, if any, immature OSNs make to odor processing is unknown. Indeed, because immature OSNs can express multiple odorant receptors, any input that they do provide could degrade the odorant selectivity of input to OB glomeruli. Here, we used a combination of in vivo 2-photon calcium imaging, optogenetics, electrophysiology and behavioral assays to show that immature OSNs provide odor input to the OB, where they form monosynaptic connections with excitatory neurons. Importantly, immature OSNs responded as selectively to odorants as mature OSNs. Furthermore, mice successfully performed odor detection tasks using sensory input from immature OSNs alone. Immature OSNs responded more strongly to low odorant concentrations but their responses were less concentration dependent than those of mature OSNs, suggesting that immature and mature OSNs provide distinct odor input streams to each glomerulus. Together, our findings suggest that sensory input mediated by immature OSNs plays a previously unappreciated role in olfactory-guided behavior.

scholarly journals Axon Guidance of Mouse Olfactory Sensory Neurons by Odorant Receptors and the β2 Adrenergic Receptor

Cell ◽  
2004 ◽  
Vol 117 (6) ◽  
pp. 833-846 ◽  
Author(s):  
Paul Feinstein ◽  
Thomas Bozza ◽  
Ivan Rodriguez ◽  
Anne Vassalli ◽  
Peter Mombaerts
Keyword(s):  
Axon Guidance ◽  
Sensory Neurons ◽  
Adrenergic Receptor ◽  
Odorant Receptors ◽  
Olfactory Sensory Neurons ◽  
Β2 Adrenergic Receptor

scholarly journals Region-specific amyloid-β accumulation in the olfactory system influences olfactory sensory neuronal dysfunction in 5xFAD mice

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Gowoon Son ◽  
Seung-Jun Yoo ◽  
Shinwoo Kang ◽  
Ameer Rasheed ◽  
Da Hae Jung ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
Sensory Neurons ◽  
Olfactory System ◽  
Amyloid Β ◽  
Olfactory Sensory Neurons ◽  
Basal Cells ◽  
Irreversible Damage ◽  
5Xfad Mouse ◽  
Peripheral Areas ◽  
5Xfad Mice

Abstract Background Hyposmia in Alzheimer’s disease (AD) is a typical early symptom according to numerous previous clinical studies. Although amyloid-β (Aβ), which is one of the toxic factors upregulated early in AD, has been identified in many studies, even in the peripheral areas of the olfactory system, the pathology involving olfactory sensory neurons (OSNs) remains poorly understood. Methods Here, we focused on peripheral olfactory sensory neurons (OSNs) and delved deeper into the direct relationship between pathophysiological and behavioral results using odorants. We also confirmed histologically the pathological changes in 3-month-old 5xFAD mouse models, which recapitulates AD pathology. We introduced a numeric scale histologically to compare physiological phenomenon and local tissue lesions regardless of the anatomical plane. Results We observed the odorant group that the 5xFAD mice showed reduced responses to odorants. These also did not physiologically activate OSNs that propagate their axons to the ventral olfactory bulb. Interestingly, the amount of accumulated amyloid-β (Aβ) was high in the OSNs located in the olfactory epithelial ectoturbinate and the ventral olfactory bulb glomeruli. We also observed irreversible damage to the ectoturbinate of the olfactory epithelium by measuring the impaired neuronal turnover ratio from the basal cells to the matured OSNs. Conclusions Our results showed that partial and asymmetrical accumulation of Aβ coincided with physiologically and structurally damaged areas in the peripheral olfactory system, which evoked hyporeactivity to some odorants. Taken together, partial olfactory dysfunction closely associated with peripheral OSN’s loss could be a leading cause of AD-related hyposmia, a characteristic of early AD.

scholarly journals G protein-coupled odorant receptors underlie mechanosensitivity in mammalian olfactory sensory neurons

2014 ◽  
Vol 112 (2) ◽  
pp. 590-595 ◽  
Author(s):  
Timothy Connelly ◽  
Yiqun Yu ◽  
Xavier Grosmaitre ◽  
Jue Wang ◽  
Lindsey C. Santarelli ◽  
...  
Keyword(s):  
G Protein ◽  
Sensory Neurons ◽  
Ectopic Expression ◽  
Host Cells ◽  
Odorant Receptors ◽  
Olfactory Sensory Neurons ◽  
Mechanical Stimuli ◽  
Genetic Ablation ◽  
Mechanical Responses ◽  
G Protein Coupled

Mechanosensitive cells are essential for organisms to sense the external and internal environments, and a variety of molecules have been implicated as mechanical sensors. Here we report that odorant receptors (ORs), a large family of G protein-coupled receptors, underlie the responses to both chemical and mechanical stimuli in mouse olfactory sensory neurons (OSNs). Genetic ablation of key signaling proteins in odor transduction or disruption of OR–G protein coupling eliminates mechanical responses. Curiously, OSNs expressing different OR types display significantly different responses to mechanical stimuli. Genetic swap of putatively mechanosensitive ORs abolishes or reduces mechanical responses of OSNs. Furthermore, ectopic expression of an OR restores mechanosensitivity in loss-of-function OSNs. Lastly, heterologous expression of an OR confers mechanosensitivity to its host cells. These results indicate that certain ORs are both necessary and sufficient to cause mechanical responses, revealing a previously unidentified mechanism for mechanotransduction.

scholarly journals Widespread inhibition, antagonism, and synergy in mouse olfactory sensory neurons in vivo

2019 ◽  
Author(s):  
Shigenori Inagaki ◽  
Ryo Iwata ◽  
Masakazu Iwamoto ◽  
Takeshi Imai
Keyword(s):  
Sensory Neurons ◽  
Calcium Imaging ◽  
Odorant Receptor ◽  
Sensory Information ◽  
Olfactory Sensory Neurons ◽  
Axon Terminals ◽  
Two Photon ◽  
Odor Mixtures ◽  
The Brain

SUMMARYSensory information is selectively or non-selectively inhibited and enhanced in the brain, but it remains unclear whether this occurs commonly at the peripheral stage. Here, we performed two-photon calcium imaging of mouse olfactory sensory neurons (OSNs) in vivo and found that odors produce not only excitatory but also inhibitory responses at their axon terminals. The inhibitory responses remained in mutant mice, in which all possible sources of presynaptic lateral inhibition were eliminated. Direct imaging of the olfactory epithelium revealed widespread inhibitory responses at OSN somata. The inhibition was in part due to inverse agonism toward the odorant receptor. We also found that responses to odor mixtures are often suppressed or enhanced in OSNs: Antagonism was dominant at higher odor concentrations, whereas synergy was more prominent at lower odor concentrations. Thus, odor responses are extensively tuned by inhibition, antagonism, and synergy, at the early peripheral stage, contributing to robust odor representations.

scholarly journals Expression Patterns of Odorant Receptors and Response Properties of Olfactory Sensory Neurons in Aged Mice

2009 ◽  
Vol 34 (8) ◽  
pp. 695-703 ◽  
Author(s):  
Anderson C. Lee ◽  
Huikai Tian ◽  
Xavier Grosmaitre ◽  
Minghong Ma
Keyword(s):  
Sensory Neurons ◽  
Expression Patterns ◽  
Odorant Receptors ◽  
Olfactory Sensory Neurons ◽  
Response Properties ◽  
Aged Mice
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