Posted December 3, 2014 by Michelle Petersen healthinnovations

Researchers obtain the holy grail of odorant receptor identification.

A group of researchers from the University of Kentucky, Duke University and Max Planck Research have identified the receptors activated by two odours using a new method that tracks responses to smells in live mice.

Using a fluorescent protein to mark nerve cells activated by odours the team identified receptors that allow mouse nerve cells to respond to two odours, eugenol, which is a component of several spices, most notably cloves; and muscone, known as musk.

This new method could help the medical community understand how these receptors allow mice, and eventually humans, to detect and discriminate odors, similar to the way in which the three receptors in the retinas of the eyes allow humans to discriminate colours. But unlike vision and hearing, the details of how the odour receptors discriminate odours, much like colour in vision or pitch in sound, are unknown.

The team state that before researchers have a medical application in mind, they must first create a roadmap for these receptors.

Scientists have been pursuing this holy grail of the sense of smell since Richard Axel and Linda Buck discovered these odorant receptors and their role in the organization of the olfactory system, winning them the Nobel Prize in Physiology or Medicine in 2004.

The challenge has been scientists’ ability to identify which receptors are activated by certain smells, particularly since humans have about 400 such receptors (mice have an astounding 1,100 receptors).

By using this new invention, called the Kentucky In Vivo Odorant-Ligand Receptor Assay, or in short, ‘the Kentucky Assay,’ scientists are now able to determine which receptors respond to certain odours in awake, freely behaving animals. There are many practical applications for this knowledge.

Knowing which receptors respond to a chemical would help us devise better flavors and fragrances. But perhaps more tantalizing is the idea that we could potentially design receptor blockers for offensive odours.

Source: University of Kentucky College of Medicine

OR Expression and Axonal Projections. Whole mount (parasagittal) view of a mouse genetically modified (schematic constructs) to express tau-lacZ and GFP from each allele of the P2 odorant receptor gene, subject to anti-b-gal and anti-GFP immunohistochemistry. Neurons express P2 monoallelically (green or red cells) in the olfactory epithelium (oe), and project their axons back into the olfactory bulb (ob) to the glomerulus (gl). Nuclei are counterstained by Toto-3 (blue, Shykind, 2005). Credit: Weill Cornell Medical College in Qatar.

Michelle Petersen View All

I am an award-winning science journalist and health industry veteran who has taught and worked in the field.

Featured by numerous prestigious brands and publishers, I specialize in clinical trial innovation–-expertise I gained while working in multiple positions within the private sector, the NHS, and Oxford University, where I taught undergraduates the spectrum of biological sciences integrating physics for over four years.

I recently secured tenure as a committee member for the Smart Works Charity, which helps women find employment in the UK.