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Cat got your tongue? New research says ‘no’
Cat taste receptors respond in a unique way to bitter compounds compared with human
receptors, according to research published in the open access journal BMC Neuroscience.
The study represents the first glimpse into how domestic cats perceive bitterness in food
at a molecular level, and could explain why cats are sometimes such picky eaters.
The ability to detect bitter chemicals is thought to have evolved because of its utility in
avoiding toxic compounds often found in plants. All cats, from pets to wild tigers, are
carnivores that consume little plant material. Domestic cats, however, may still
encounter bitter flavors in food and medicines.
Domestic cats have a reputation of being rather unpredictable in their dietary choices.
This could be explained by their perception of bitter, which differs from that of other
mammals due to variations in their repertoire of bitter receptors. It is the goal of many
pharmaceutical and food manufacturers to identify compounds that either block or alter
bitter perception, to create a more palatable product.
The teams at AFB International and Integral Molecular studied the behavior of two
different cat bitter taste receptors in cell-based experiments, investigating their
responsiveness to bitter compounds, and comparing these to the human versions of
these receptors.
TAS2R38 is a bitter taste receptor in humans of which some people have ‘supertaster’
variants that give them an extreme sensitivity to bitter compounds, explaining some
people’s strong aversions to broccoli and brussels sprouts.
Compared with the human TAS2R38 receptor, the cat version was 10-fold less sensitive
to a key bitter compound PTC and did not respond at all to another bitter compound
PROP.
Like its human counterpart, the cat bitter taste receptor Tas2r43 was activated by bitter
compounds aloin (found in the aloe plant) and denatonium (used to deter children and
pets from consuming chemicals such as antifreeze) but was less sensitive to both
compounds than the human receptor. It also differed from the human taste receptor by
being insensitive to saccharin, an artificial sweetener that tends to have a bitter
aftertaste in humans.
CORRECTION:
Like its human counterpart, the cat bitter taste receptor Tas2r43 was activated by bitter
compounds aloin (found in the aloe plant) and denatonium (used to deter children and
pets from consuming chemicals such as antifreeze) but responded differently to the
compounds. The cat receptor was less sensitive to aloin and more sensitive to
denatonium than the human receptor. It also differed from the human taste receptor
by being insensitive to saccharin, an artificial sweetener that tends to have a bitter
aftertaste in humans.
Co-author Nancy Rawson from AFB International, a pet food flavor company, said: “We
confront the challenge of ‘finicky cats’ every day. As such, it is exciting to find an
unexpected receptor response to bitter compounds that has never been described in the
literature to date for any other species. These insights and future discoveries will be
invaluable in formulating appealing food for cats, as well as enhancing the acceptability
of their medications.”
Co-author Joseph Rucker from Integral Molecular, a biotechnology company, said:
“Feline bitter taste has not been well studied. We applied our experience in studying
membrane proteins, such as taste receptors, to enable this first glimpse into how
domestic cats perceive bitterness in food at a molecular level. We were surprised to see
that one of the cat taste receptors responded to a more limited range of bitter
compounds compared to humans, suggesting that cats may be detecting a narrower, or
at least a different, repertoire of bitter-tasting compounds.”
The team also found that probenecid, a known inhibitor of human bitter taste receptors,
also worked on both cat taste receptors, preventing stimulation when in the presence of
PTC, aloin and denatonium.
The team says that these insights and further study could be instrumental in formulating
appetizing food for household cats as well as designing masking agents to enhance the
acceptability of medications.
The authors are employees of Integral Molecular and AFB International. Joseph Rucker is
a shareholder of Integral Molecular. These data are part of a patent application filed by
AFB International.
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BioMed Central
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Notes to editor:
1.
Research article
Michelle M Sandau, Jason R Goodman, Anu Thomas, Joseph B Rucker and Nancy E
Rawson
A functional comparison of the domestic cat bitter receptors Tas2r38 and Tas2r43 with
their human orthologs
BMC Neuroscience 2015
doi: 10.1186/s128628-015-0170-6
After embargo, article available at journal website here:
http://dx.doi.org/10.1186/s128628-015-0170-6
Please name the journal in any story you write. If you are writing for the web, please
link to the article. All articles are available free of charge, according to BioMed Central's
open access policy.
2.
BMC Neuroscience is an open access, peer-reviewed journal that considers articles
on all aspects of the nervous system, including molecular, cellular, developmental and
animal model studies, as well as cognitive and behavioral research, and computational
modeling.
BMC Neuroscience is part of the BMC series which publishes subject-specific journals
focused on the needs of individual research communities across all areas of biology and
medicine. We offer an efficient, fair and friendly peer review service, and are committed
to publishing all sound science, provided that there is some advance in knowledge
presented by the work.
3.
BioMed Central is an STM (Science, Technology and Medicine) publisher which has
pioneered the open access publishing model. All peer-reviewed research articles
published by BioMed Central are made immediately and freely accessible online, and are
licensed to allow redistribution and reuse. BioMed Central is part of Springer
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