Date: Thursday, November 6th, 2003

Title: Linda Bartoshuk honorarium symposium.

Day Symposium
Speakers:
G.P. Smith Bourne Laboratory. "Sweet Taste and the Motivation to Eat."
Anthony Sclafani, Brooklyn College. "The Sixth Taste"
Valerie Duffy, Univ. of Connecticut. "Associations between oral sensation, dietary behaviors and health outcomes."
Gary Beauchamp, "Origin of Flavor Hedonics," Monell Chemical Senses

Evening Symposium
Linda Bartoshuk, Yale University
Topic: "Taste, Food Intake and Obesity"


Chairman: Harry R. Kissileff, Ph.D.
Rapporteur: Kathleen Keller, Ph.D.

Attendees and their Affiliation:

Day:
Solveig Haudorspottir, IHN-Columbia U
Soward M. Striker, U. Pittsburgh
Valerie Duffy, U. Connecticut
Audrey Chapo, Yale University
Gary Schwartz, WMC Cornell
Andras Hatnal, PSU-Hershey
Derek Snyder, Yale University
Tim Kowalski, Schering Plough
Charles Kearns, Schering Plough
Ralph Norgren, Penn State, Hershey
Anthony Azzara, Bourne Lab
Gerry Smith, Bourne Lab
Diane Klein, Columbia University
Tim Walsh, Columbia
Jennifer Nasser, Columbia
Beverly Tepper, Rutgers University
Lisa Belzer, Rutgers
Nori Geary, Weill Cornell
Allan Geliebter, St. Luke's Hospital
Carla Wolper, Obesity Research Center
Sami Heshan, Obesity Research Center
Maika Onishi, Barnard College
Zue Torsuhi, University of Maryland
Danielle Greenberg, Regeneron
Harry Kissileff, Columbia
Kathleen Keller, Columbia

Night: Kathleen Keller, Columbia
Katherine Halmi, Cornell
Douglas Mook, NYC
Margarita Lorence, Obesity Research Center
John Kral, Suny Downstate
Gerry Smith, Weill-Cornell
Herb Meiselman, Natick
Diane Johnson, Princeton
Khalid Touzani, Columbia
Cheryl Nussenbaum, Brooklyn College
Emma Ulin, Brooklyn College
Michael Lewis, Princeton
Janet Guss, Columbia
Karen Acroff, Brooklyn College
Tony Sclafani, Brooklyn College
Simon Thornton, University Henri
Ed Stricker, University of Pittsburg
Harry Kissileff, Columbia
Tim Kowalski, Schering Plough
Charles Kearns, Schering Plough
Ralph Norgren, Penn State, Hershey
Anthony Azzara, Bourne Lab
Gerry Smith, Bourne Lab
Jennifer Nasser, Columbia
Beverly Tepper, Rutgers University
Lisa Belzer, Rutgers
Danielle Greenberg, Regeneron

This symposium highlighted research from lead experts on the gustatory system. Special focus was given by each presenter to honor the contributions that Dr. Bartoshuk has made in the areas of psychophysics and taste genetics. This symposium was presented in honor of Dr. Bartoshuk's recent induction into the National Academy of Sciences.

Summary of Presentation 1: "Sweet taste and the Motivation to Eat" by G. P. Smith.

To investigate the hypothesis that central dopamine mediates the rewarding effect of orosensory stimulation by sucrose that increases eating, specific dopamine antagonists were administered prior to sham-feeding tests in which rats ingested various concentrations of sucrose. Sham feeding was used to preserve the orosensory stimulation of sucrose while it eliminated sucrose's postingestive effects. The antagonists decreased intake as a function of the concentration of sucrose. Microstructural analysis of licking demonstrated that the antagonists did not affect the motor performance of licking. Thus, the inhibitory effect of the antagonists on intake was due to a decrease in the rewarding effect of sucrose. Microdialysis experiments demonstrated that dopamine was released in the nucleus accumbens during sham feeding and that the synaptic action of dopamine in the accumbens was necessary for the normal rewarding effect of orosensory stimulation by sucrose.

Summary of Presentation 2: "The Sixth Taste" by Anthony Sclafani

Dr. Sclafani gave an intriguing overview of "the sixth taste," or the taste of polysaccharides derived from starch (eg. Polycose). Five taste qualities are recognized in humans: sweet, bitter, sour, salty, and umami. Rats and some other species may also have a sixth taste, the taste for “polycose.”. Rats are very attracted to the taste of polycose. Polycose contains small amounts of sugar (glucose, maltose) but consists primarily of glucose polymers of 3 or more glucose units. Dr. Sclafani reviewed several lines of evidence to suggest that rats can taste polycose. The results of conditioned taste aversion studies suggest that polycose and sucrose stimulate different taste qualities. Learned aversions to polycose and sucrose only weakly cross-generalize. Taste aversions to maltose generalized more to polycose than to sucrose indicating that maltose has more of a polycose-like taste than a sucrose-like taste (Nissenbaum & Sclafani, 1987). This is consistent with the findings that rats prefer both polycose and maltose to sucrose at low concentrations (Sclafani & Mann, 1987). Recent studies in mice indicate that sweet taste is mediated by a T1R2/T1R3 receptor complex. Knockout mice missing these receptor proteins fail to respond to sucrose and other sweeteners, but their response to polysaccharide solutions was not investigated in these studies. Thus, the hypothesized polysaccharide taste receptor(s) in rats, mice and other species remains to be identified. The degree to which polysaccharides and sucrose have different or similar taste features also requires further investigation.

Summary of Presentation 3: "Origin of Flavor Hedonics" by Gary Beauchamp.

Taste and smell are the primary senses involved in the perception of flavor and they are critical to an individual’s acceptance or rejection of foods and beverages. These senses are above all ones that involve affect or liking as would be expected for their critical role in determining what we take into our bodies. Linda Bartoshuk has made the rough generalization that the affect associated with olfaction is due mainly to learning whereas, in contrast, the affect for taste is largely inborn although it can be modified by bodily state. This presentation reviewed the evidence supporting and questioning this generalization. The critical issues were illustrated with recent data from our laboratories involving the role of dietary experience in modulating salt preferences in infants and the effects of early flavor learning in infants exposed to highly unpalatable (to older infants and adults) casein hydrolysate formulas. It was concluded that although Linda Bartoshuk’s generalization is generally true, affect for some taste stimuli is influenced by post-natal experience and it is likely that the affect associated with some volatile flavors (odorants) has an innate component.

Summary of Presentation 4: "Associations between Oral Sensation, Dietary Behaviors and Risk of Cardiovascular Disease (CVD)" by Valerie B. Duffy.

We hypothesize that variation in oral sensation influences chronic disease risk by impacting dietary behaviors. Bitterness of 6-n-propylthiouracil (PROP) and fungiform papilla (FP) number serve as genetic taste markers. Data support that nontasters (who taste PROP as least bitter or have lowest FP number) show dietary behaviors that increase CVD risk (eg, higher alcohol intake, greater preference for and intake of high-fat and sweet foods) and have greater measured CVD risk (eg, higher blood pressure, less favorable serum lipids). Taste genetics interacts with environmental factors (eg, taste-related pathologies) to affect oral sensation, dietary behaviors and disease risk. The generalizability of oral sensory and CVD risk relationships has begun to be tested on diverse samples.

Summary of Evening Presentation: "Psychophysics: A journey from the laboratory to the clinic" by Linda M. Bartoshuk.

Pfaffmann, famous for pioneering work in taste neurophysiology, was a great supporter of psychophysics. He wrote: “Indeed it can be said that without behavioral study, hand in hand with physiological and anatomical methods, one gets only a partial insight: telling where, and to some degree how, but not for what!” (Pfaffmann, 1974). The psychophysical studies he initially encouraged concerned mechanism (e.g., taste quality coding), but later methodological advances permitted valid comparisons of taste sensations across groups. This quantification of genetic as well as pathological variation permits the demonstration of links between oral sensory variation, food preferences, diet and health.

Q. Is there any relation between the artichoke and the ability to taste PROP?

A. No.

Q. What is the mechanism for the artichoke response?

A. Not known.

Q. Does it matter how concentrated tastes are when you mix tastes?

A. You start with similar concentrations of taste and diverge.

Q. How difficult was it for Pfaffman to let go of the idea of patterning?

A. He waffled because he didn't want to offend his students.

Q. How long did it take the idea that taste is analytic to show up in print?

A. I don't know.

Q. During that time, were there a lot of opponents to the idea that pushed labeling?

A. No.

Q. Is hearing different between tasters and nontasters.

A. I'll never know. We must assume that sound is the same for our methods to work.

Q. How did you actually do your pain experiments?

A. I asked people to rate a different number of pains on the same scale/normalized to the brightness of the sun.

Statement. There a racial and ethnic differences in pain response that might affect your results.

Q. Did they use the visual analogue scales (in pain experiments)?

A. (Not sure of answer?)

Q. Why would one be interested in perceived pain?

A. If perceived pain has not been measured correctly, medications may be prescribed incorrectly.

Q. What if the pain scale was normalized to brightness of the sun?

A. It would have worked correctly.

Q. Is pain like taste? Can they rate the intensity independent of how much it bothers them?

A. Yes.

Q. If a group is adapted to the taste of bitter, how does water taste after that?

A. Water tastes sweet after bitter.

Q. Is this why American children don't drink water?

A. Interesting response.

Q. What about fat.

A. Some think it has a taste. It has mouthfeel. Sensations may vary by taster status.

Q. What do you mean b y pathology for a super taster male?

A. Population of older male super tasters were obese.

Q. When I eat bitter cheeses and drink alcoholic beverages, the alcohol tastes sweeter. Why?

A. Nontasters taste alcohol as sweet, as well.

Q. What about temperature? Are super tasters more sensitive?

A. Temperature stimulation is difficult to do well. Barry Green does the best work.

Q. Is there an animal model of nontasters and super tasters?

A. In lower animals, SoA is a model. Higher apes don't show nontaster - super taster differences.

Q. Could you stimulate number of papillae in super tasters and nontasters to see how they react?

A. That is a great experiment to do.

Q. What is the association between PROP and alcohol?

Q. Duffy's work has addressed this question. However, most genetic work is on alcohol dehydrogenase.

Statement. We found difference in olfactory between nontasters and super tasters for diacetyl (butter flavor).

Q. Have experiments been done in other countries?

A. Haplotypes for tasters and nontasters differ greatly throughout the world.

Supported in part by Merck Research, Glaxosmithkline and The New York Obesity Research Center, St. Luke’s-Roosevelt Hospital.