Researchers begin big push in ‘crucial’ research of extranasal olfactory receptors.

It is known that olfactory receptors (ORs) are expressed in the olfactory epithelium of the nose and detect common odorants in the environment, they have also been mapped outside of the olfactory system in other human tissues, including the testis, lung, intestine, skin, heart, and blood.  However, the function of the majority of ORs in non-olfactory tissues remains unclear, leaving much to be uncovered in regards to these neuron-like cells scattered throughout the body, and manual body regulation.  Now, a literature review from researchers at Ruhr-Universität Bochum provides the most up-to-date overview of receptors detected so far and their functions within the human body.  The team state that understanding the molecular and cellular mechanisms of action of extranasal ORs will ultimately lead to their clinical utility.  The opensource study is published in the journal Physiological Reviews.  

Previous studies show that ORs fulfil important functions in tissues outside of the nose; subsequently, researchers successfully described the role of olfactory receptors in more than 20 different types of human tissue.  Using up to date DNA sequencing it was shown  that 5 to 80 different types of olfactory receptors can be found per tissue.  Olfactory receptors outside the nose act as chemoreceptors being activated by a specific molecule which in turn can stimulate the cells to multiply, move, or release specific chemical transmitters. Cell death is also affected by olfactory receptors. with cell-biological effects  many and varied as ORs have the ability to switch on different signalling pathways in cells.

The current lit review elaborates potential clinical applications, such as cancer diagnosis and therapy, and discusses the steps researchers could take to ensure ORs’ full potential.  The team state that cancer cells often contain specific ORs in large amounts, often different ones to those found in healthy cells.  They go on to hypothesize that ORs could be used as specific markers in cancer diagnosis, and have potential for cancer therapy, especially in intestinal or bladder cancer whose cells are easily accessible for odorants.

It was found that applications in the field of wellness and healthcare are also viable, with skin regeneration, intestinal digestion, and hair growth regulated via olfactory receptors; this therapeutic method is already being applied for tissue repair and for promoting digestion.  The lab state that in order to exploit the ORs’ potential in the areas outlined ongoing in-depth research is crucial, and stress that the activating odorants of only about 50 of the 350 human olfactory receptors have been identified to date.

The team surmise that they have provided an up-to-date review of the occurrence of human ORs outside of the nose with a focus on their effects on various human tissues.  For the future, the researchers state it is essential to decode additional olfactory receptors, to find the relevant signalling pathways, and to shed light on the function of receptors in the human body.

Source: Ruhr-Universität Bochum



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