Ghrelin is produced in taste cells and ghrelin receptor null mice show reduced taste responsivity to salty (NaCl) and sour (citric acid) tastants.
BACKGROUND
The gustatory system plays a critical role in determining food preferences, food intake and energy balance. The exact mechanisms that fine tune taste sensitivity are currently poorly defined, but it is clear that numerous factors such as efferent input and specific signal transduction cascades are involved.


RESULTS
Using immunohistochemical analyses, we show that ghrelin, a hormone classically considered to be an appetite-regulating hormone, is present within the taste buds of the tongue. Prepro-ghrelin, prohormone convertase 1/3 (PC 1/3), ghrelin, its cognate receptor (GHSR), and ghrelin-O-acyltransferase (GOAT , the enzyme that activates ghrelin) are expressed in Type I, II, III and IV taste cells of mouse taste buds. In addition, ghrelin and GHSR co-localize in the same taste cells, suggesting that ghrelin works in an autocrine manner in taste cells. To determine a role for ghrelin in modifying taste perception, we performed taste behavioral tests using GHSR null mice. GHSR null mice exhibited significantly reduced taste responsivity to sour (citric acid) and salty (sodium chloride) tastants.


CONCLUSIONS
These findings suggest that ghrelin plays a local modulatory role in determining taste bud signaling and function and could be a novel mechanism for the modulation of salty and sour taste responsivity.
Shin
Yu-Kyong
YK
National Institute on Aging/National Institutes of Health, Baltimore, Maryland, United States of America.
Martin
Bronwen
B
Kim
Wook
W
White
Caitlin M
CM
Ji
Sunggoan
S
Sun
Yuxiang
Y
Smith
Roy G
RG
Sévigny
Jean
J
Tschöp
Matthias H
MH
Maudsley
Stuart
S
Egan
Josephine M
JM
D000818:Animals; D002478:Cells, Cultured; D019343:Citric Acid / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism*; D054439:Ghrelin / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D045664:Proprotein Convertase 1 / Q000378:metabolism; D054440:Receptors, Ghrelin / Q000172:deficiency* / Q000235:genetics; D015398:Signal Transduction; D012965:Sodium Chloride / Q000378:metabolism*; D013650:Taste Buds / Q000166:cytology / Q000378:metabolism*; D055697:Taste Perception
D054439:Ghrelin; D054440:Receptors, Ghrelin; D019343:Citric Acid; D012965:Sodium Chloride; D045664:Proprotein Convertase 1