Olfactory neurons adapt to their environment

The UNIGE team shed light on the very large variability and persistent adaptation of olfactory neurons.


Section of the nasal cavity of the rat (wide view). Within a dense cluster of olfactory neurons (in blue), olfactory neurons expressing a specific type of receptor (Olfr151) are highlighted in light green.
© Madeleina Boylat

Olfactory receptors, present in space (Surface generally refers to the surface layer of an object. The term A…) Sensory neurons in the nasal cavity recognize the odor molecules and transmit this information to brain (The brain is the main organ of the central nervous system of animals. Brain processes…). How do these neurons detect a wide variety of signals and adapt to different levels of Energizing (A stimulus is a physical or chemical event that activates one or more…)? A joint team from the College of Science and the College of medicine (Medicine (from the Latin medix, “that heals”) is science and …) From’University of Geneva (University of Geneva (UNIGE) is the public university of the Canton of Geneva in…) (UNIGE) investigated the gene expression profile of these neurons, in the presence or absence of odorant stimulation. The scientists discovered unexpected variation in these features depending on the olfactory receptor expressed and previous exposures to odors. These findings, due to be read in Nature Communications, highlight a wide range of olfactory neuron identities and their adaptations to the surrounding environment.

In mammals, the perception of odors is ensured by millions of olfactory neurons located at the . level Mucosa (Mucous membranes (from the Latin mucus) are thin layers of tissue of ectodermal origin …) from the nasal cavity. These neurons have receptors on their surface that are able to bind specifically to a compound (A molecule is an electrically neutral chemical group of at least two atoms, which…) Smells good. Each olfactory neuron expresses only one embarrassed (A gene is the sequence of deoxyribonucleic acid (DNA) that determines…) Encoding an olfactory receptor, selected from a repertoire of about 450 in humans and 1,200 in the mouse (The term mouse is an obscure generic name that could be assigned to French speakers before…).

When the volatile molecule is recognized by the receptor, the latter is activated and generates a Signal (General terminology A signal is a simplified message and is generally encrypted. There is…) refer to a lamp (The bulb is an underground vertical shoot with modified leaves used…) The brain’s sense of smell, a signal that is then converted into smell. The olfactory system responds to highly changing environments and must be able to adapt very quickly. For example, during continuous stimulation by molecules of a specific smell, the perceived intensity gradually decreases and sometimes disappears.

Professor Ivan Rodriguez’s group from the Department of hereditary (Genetics (from the Greek genno γεννώ = birth) is…) And the development of the College of Science in cooperation with Professor Alan Carleton from the Department of Neurology (Neurosciences correspond to the range of all biological disciplines and …) In medical school, he is interested in the adaptive mechanisms of neurons, particularly olfactory neurons in mice. In a previous study, scientists found that after a receptor was stimulated by an odor molecule for less than a hour (The hour is the unit of time. The word denotes the amount…)the gene expression that encodes this receptor decreased in nervous cells (A neuron, or neuron, is an passive cell that forms the functional unit…)indicating a very fast adaptation mechanism.

Neurons with a specific profile

Biologists took this approach and explored the possibility that this adaptation to the olfactory experience affects not only the genetic coding of the receptor, but other genes as well. To do this, the profile of genes expressed before and after olfactory stimulation in thousands of olfactory neurons was determined by sequencing messenger RNAs (the molecules that subsequently allow the production of proteins).

“To our great surprise, we found that he is at rest, i.e. at environment (Environment is everything that surrounds us. It is all natural elements and…) Without stimulation, the RNA profiles of the olfactory sensory neuron populations do indeed differ from each other, and are specific to the olfactory receptors they express,” Louis Flores-Horge reports, PhD student (PhD student is a committed junior researcher under the direction of a director…) in the Department of Genetics and Evolution and co-first author of the study. Thus, neurons expressing the same receptor not only share this receptor, but also differ in the expression of hundreds of other genes. Genes whose expression level appears to be directed by the expressed olfactory receptor, which will therefore play a dual role.

A single molecule alters the expression of hundreds of genes

The biologists then analyzed the expression of the genes in these neurons after stimulation by odor molecules. They note that these induce massive changes in gene expression in the activated neurons. “Whereas it was believed that the bonding of the odor molecule would only lead toactivation (Activation may refer to:) From the corresponding receptor, we discover that olfactory neurons drastically change their identity by modulating the expression of hundreds of genes after activation. And this new identity depends again on the future expressed. We are faced with an unexpected coping mechanism, particle (The word massive can be used as 🙂fast and reversible,” says Evan Rodriguez, the study’s latest co-author.

Thus this work reveals that olfactory neurons should not be considered sensors that simply transition from a resting state to a stimulated state, but that their identity is in constant evolution, not only according to the expressed receptor but also according to previous experiences. This discovery adds another level to complication (Complexity is a concept used in philosophy and epistemology (for …) and flexibility of the olfactory system. A better understanding of how to define this identity will be the next challenge for the Geneva team.

the post:
this is Research (Scientific research identifies in the first place all actions taken with a view to …) Published in Nature Communications – DOI: 10.1038/s41467-022-30511-4

Contacts:
– Evan Rodriguez – Full Professor. Department of Genetics and Evolution. Faculty of Science – Ivan.Rodriguez at unige.ch
– Alan Carlton – Full Professor. Department of Basic Neurosciences. Faculty of Medicine – Alan.Carleton at unige.ch

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