'Pharmacology of Fragrance: Odors and GPCRs' and 'Perception of odor mixtures'

Series Name Department of Engineering
Speaker Stuart Firestein and Terry Acree
Type Arts & Entertainment
Starts at Mar 14, 2014 01:00 PM
Ends at Mar 14, 2014 02:00 PM
Venue Maurice Shock First Floor SR 114A
Open To University staff and students
Ticket Price Free

There will be two short neuroscience talks on Friday 14 March between 1pm - 2pm. They will take place in Maurice Shock First Floor SR 114A (Medical Sciences).

All students and staff are welcome.

Title: Pharmacology of Fragrance: Odors and GPCRs

Stuart Firestein, Department of Biological Sciences, Columbia University, New York, NY 10027, USA

Odor receptors are the largest family of GPCR’s on the planet.  The identification of this large family of genes by Buck and Axel in 1991 showed that they have much in common with the other 450 or so GPCRs found in the mammalian genome. From this one might imagine that they can be profitably studied by using techniques developed for standard GPCR pharmacology – ligand screeing, structure activity relations, and a variety of modeling techniques.  We have utilized synthetic chemistry to examine the structure-function activity of an odor receptor by utilizing a variety of synthetically designed ligands that demonstrate mechanisms for agonism, antagonism, partial agonism and reverse agonism.   These analyses provide a theoretical picture of the requirements for a binding region within the receptor.  The existence of a range of ligands – from antagonists to high affinity agonists - for a given receptor must be taken into account when considering the type of upstream brain circuits that might be required to reduce the complex diversity of odor stimuli to the simpler categories of fragrance perception.  In addition to these common principles of pharmacology that can be applied profitably to odor receptors we suggest that the techniques and strategies of medicinal chemistry, normally targeted to a single specific receptor (e.g., dopamine, epinephrine, serotonin) can be modified for use in a large and varied receptor population. The med chem concept of bioisosterism, for example, may help to better define our thinking about broad and narrow tuning in receptors when applied to large numbers of receptors.

Title: Perception of odor mixtures.

Terry Acree, Food Science Program, Cornell University, Geneva, NY, USA.

Humans can recognize components in a mixture (“It contains ethyl isobutyrate”) as well as identify a mixture as a unique odor image (“it’s pineapple”). We tested the hypothesis, proposed by Le Berre in 2008, that a specific combination of three odorants is perceived as “pineapple” and not like the component odorants. Using a 3AFC oddity protocol with an olfactometer in an olfactorium subjects were tested for their use of the words for the components plus the word “pineapple” in response to various mixtures. After auditory and visual cues to inhale they experienced 10 ml puffs (in 75 msec.) of these mixtures repeated 30 times and then asked to choose one of the 4 words. The word “pineapple” was chosen less than 7 ±2% of the time (p =.01). This was significantly less than the component odors were chosen. These results indicate that after a brief odor stimulus trained subjects associate their experience most frequently with words for the components rather than identifying the olfactory perception as an odor image.  BUT humans mostly experience odor images so how do we measure this?