By Nicole Garneau, PhD
Monday mornings I sort through the weekend's long trail of
emails. As part of this routine, I receive my weekly search results
on "chemoreception" from pubmed.gov-- an online database of
biomedical publications. Usually I scan the titles and chalk it up
to a "read later" file in my head- not today.
Today, there was one title that really caught my eye,
"Functional Bitter Taste Receptors are Expressed in Brain Cells." I
clicked on the link to read the abstract, crossing my fingers that
I had access to the full paper (sometimes publishers don't allow
open access for up to a year after publication).
It turns out, it's not the newest of news, as the study was
published in March, but it's new to me because my search filter
only pulled it up today, a good 2 months late for some reason. I
read on with interest and found that the study was done in rats,
and the scientists show evidence that yes in fact, at least in
rats, the animals have bitter receptors that in their brains that
when they bind bitter chemicals, it activates the cell.
What's interesting will be to see if there are taste cells in
the brain that are similar to taste cells in the tongue (within
taste buds, shown on the left) and to the taste cells that have
been found in the digestive system (shown on the right). Both of
these cell types are shown below with the signalling pathways that
occur once the cell is activated by a taste molecule. (This image
is from a paper published by David E. Cummings and Joost Overduin
in 2007.)
I don't have access to the full paper "Functional Bitter Taste
Receptors are Expressed in Brain Cells", but the authors indicate
that they discuss the physiological relevance of this in their
results section. I don't know much about the anatomy of rats, so I
can't guess what the authors discuss, but it is important to note
that although mice and rats are studied to understand mammalian
biology, and although there are many genes that are similar between
these groups, results in one species does not necessarily mean you
will find the same results in another species. This point that was
made clear in the recent AChemS (Association for Chemoreception
Sciences) meeting I attended in April, where even distinct
differences between mice and rats in terms of taste and smell were
discussed. So it is unclear at this point if mice or even humans
also have bitter receptors in their brains.
I want to also note that these authors were not at AChemS, and
so I don't have any insight from the meeting on the general feel
for this new discovery among other taste and smell scientists. I
did a quick to search on Bing to see if the story had been picke
dup elsewhere, but I couldn't find any other information. If I
learn more from my colleagues at the Rocky Mountain Taste and Smell
Center, I will put it up on the blog as a follow up post.
Until then, for those of you who are interested, you can read
the abstract HERE
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