Brain cells that appear to control appetite have been identified by scientists from the University of Warwick. Professor Nicholas Dale in the School of Life Sciences says that tanycytes, cells found in part of the brain that controls energy levels, detect nutrients in food and signal satiety to the brain.
According to the new research published in Molecular Metabolism, tanycytes respond to amino acids found in foods, via the same receptors that sense the flavor of amino acids (umami taste).
Two amino acids that react most with tanycytes, and therefore are likely to make you feel fuller, are arginine and lysine. These amino acids are found in high concentration in foods such as pork shoulder, beef sirloin steak, chicken, mackerel, plums, apricots, avocadoes, lentils, and almonds.
The researchers made their discovery by adding concentrated amounts of arginine and lysine into brain cells, which were made fluorescent so that any microscopic reactions would be visible. They observed that within 30 seconds, the tanycytes detected and responded to the amino acids, releasing information to the part of the brain that controls appetite and body weight.
They found that signals from amino acids are directly detected by the umami taste receptors by removing or blocking these receptors and observing that the amino acids no longer reacted with tanycytes.
"Amino acid levels in blood and brain following a meal are a very important signal that imparts the sensation of feeling full. Finding that tanycytes, located at the centre of the brain region that controls body weight, directly sense amino acids has very significant implications for coming up with new ways to help people to control their body weight within healthy bounds," explains Nicholas Dale, who is Ted Pridgeon Professor of Neuroscience at the University of Warwick.
Image: Tanycyte cells reacting to a puff of the amino acid arginine. Image courtesy of Professor Nicholas Dale/Ms. Greta Lazutkaite.