Scientists identify stomach’s timekeepers of hunger
August 14, 2009(PhysOrg.com) -- New York collaborators at Columbia and Rockefeller Universities have identified cells in the stomach that time the release of a hormone that makes animals anticipate food and eat even when they are not hungry. The finding, which has implications for the treatment of obesity, marks a landmark in the decades-long search for the timekeepers of hunger. The work reveals what the stomach “tells” the brain.
Rae Silver, head of the Laboratory of Neurobiology and Behavior at Columbia University and Helene L. and Mark N. Kaplan Professor at Barnard College, Joseph LeSauter, senior research scientist at Barnard, and their colleague Donald W. Pfaff, at Rockefeller University, are the first to show that these cells, which release a hormone called ghrelin, are controlled by a circadian clock that is set by mealtime patterns. They also show that the hormone’s release whets the appetite of mice, spurring them to actively search for and consume food, even when they are not hungry.
“Circadian clocks allow animals to anticipate daily events rather than just react to them,” notes LeSauter, first author of the paper. “The cells that produce ghrelin have circadian clocks that presumably synchronize the anticipation of food with metabolic cycles.”
The scientists show that the stomach cells release ghrelin into the general circulation before mealtime. The hormone triggers a flurry of food-seeking behavior such as digging in the bedding around the food hopper, and it also stimulates eating. These behaviors are part of the subjective experience of hunger.
LeSauter, who spearheaded the project, studied genetically engineered mice that lack the receptor that recognizes ghrelin and compared them with normal mice on identical feeding schedules. He found that the mice that lack the ghrelin receptor had normal overall activity throughout the day but began to forage for food much later and to a lesser extent than their normal counterparts. However, when foraging and other anticipatory behaviors actually began, foraging increased in a remarkably predictable manner in both sets of mice.
Pfaff believes that ghrelin, which is released from stomach cells and travels through the bloodstream to the brain, influences a decision-making process in brain cells. These brain cells are constantly deciding whether or not to eat and, as mealtime draws near, the presence of ghrelin increases the proportion of “yes” decisions. “We applied mathematics to precise behavioral data and then interpreted them in the context of neurobiology,” says Pfaff. “And that’s very, very rare.”
Previous studies have shown that people given ghrelin injections feel voraciously hungry and eat more at a buffet than they otherwise would. The new research suggests that the stomach tells the brain when to eat, and establishing a regular meal schedule will regulate the stomach’s release of ghrelin. “If you eat all the time, ghrelin secretion will not be well controlled,” says Silver. “It’s a good thing to eat meals at a regularly scheduled time of day.”
The research also suggests that ghrelin, the only known natural appetite stimulant made outside the brain, is a promising target for drug developers. Unlike drugs that focus on satiety, those that target ghrelin could help curb appetite before dieters take that first bite.
More information: PNAS 106(32): 13582-13587 (August 11, 2009); Stomach ghrelin-secreting cells as food-entrainable circadian clocks; Joseph LeSauter, Nawshin Hoque, Michael Weintraub, Donald W. Pfaff and Rae Silver
-
Hunger hormone: Makes food more attractive
May 06, 2008 |
not rated yet |
0
-
Gut hormone makes food look even yummier
May 06, 2008 |
not rated yet |
0
-
Fatty foods fire up hunger hormone
Jun 06, 2009 |
not rated yet |
0
-
Hormone that controls hunger and appetite also linked to reduced fertility
Mar 31, 2008 |
not rated yet |
0
-
When eating and dieting, follow your gut
Jul 29, 2009 |
not rated yet |
0
-
Engineers build first sub-10-nm carbon nanotube transistor
Feb 01, 2012 |
4.9 / 5 (31) |
30
-
Something old, something new: Evolution and the structural divergence of duplicate genes
Jan 31, 2012 |
4.6 / 5 (7) |
1
-
The hidden nanoworld of ice crystals: Revealing the dynamic behavior of quasi-liquid layers
Jan 30, 2012 |
5 / 5 (3) |
1
-
Stock market network reveals investor clustering
Jan 27, 2012 |
3.9 / 5 (23) |
8
-
Of microchemistry and molecules: Electronic microfluidic device synthesizes biocompatible probes
Jan 26, 2012 |
5 / 5 (1) |
0
-
Is Everyday Technology Killing Us?
Feb 08, 2012
-
Exercise and weight loss
Feb 08, 2012
-
Why do we have head aches? Our brains can't feel anything.
Feb 07, 2012
-
"The end of diseases" by David Agus, interview from Daily Show with Jon Stewart
Feb 04, 2012
-
Oncolytic adenovirus
Feb 04, 2012
-
Nutrition label stuffs and diets
Feb 02, 2012
- More from Physics Forums - Medical Sciences
More news stories
Complex wiring of the nervous system may rely on a just a handful of genes and proteins
Researchers at the Salk Institute have discovered a startling feature of early brain development that helps to explain how complex neuron wiring patterns are programmed using just a handful of critical genes. ...
7 hours ago |
4.9 / 5 (9) |
0
|
Both maternal and paternal age linked to autism
Older maternal and paternal age are jointly associated with having a child with autism, according to a recently published study led by researchers at The University of Texas Health Science Center at Houston (UTHealth).
Medicine & Health / Psychology & Psychiatry
12 hours ago |
4.3 / 5 (3) |
0
|
New understanding of DNA repair could eventually lead to cancer therapy
A research group in the Faculty of Medicine & Dentistry at the University of Alberta is hoping its latest discovery could one day be used to develop new therapies that target certain types of cancers.
11 hours ago |
4.8 / 5 (5) |
0
|
Curry spice component may help slow prostate tumor growth
Curcumin, an active component of the Indian curry spice turmeric, may help slow down tumor growth in castration-resistant prostate cancer patients on androgen deprivation therapy (ADT), a study from researchers ...
13 hours ago |
4.4 / 5 (8) |
0
|
Team isolates nerve cells involved in storing long term memory and gene proteins associated with them
(Medical Xpress) -- A research team in Taiwan has succeeded in isolating two nerve cells in fruit fly brains that are believed to be the major players in allowing for the formation of long term memories. Furthermore, ...
Anonymous knocks CIA website offline (Update)
The website of the Central Intelligence Agency was inaccessible on Friday after the hacker group Anonymous claimed to have knocked it offline.
Google users warned of threat to smartphone wallets
Users of Google smartphone wallets were being warned on Friday that there is a way to crack pass codes intended to thwart thieves from going on illicit shopping sprees.
New error-correcting codes guarantee the fastest possible rate of data transmission
Error-correcting codes are one of the triumphs of the digital age. Theyre a way of encoding information so that it can be transmitted across a communication channel such as an optical fiber o ...
Humans may have helped the decline of African rainforests 3000 years ago
(PhysOrg.com) -- Large areas of rainforests in Central Africa mysteriously disappeared over three thousand years ago, to be replaced by savannas. The prevailing theory has been that the cause was a change ...
The power of estrogen -- male snakes attract other males
A new study has shown that boosting the estrogen levels of male garter snakes causes them to secrete the same pheromones that females use to attract suitors, and turned the males into just about the sexiest ...
New power source discovered
(PhysOrg.com) -- Researchers at the Massachusetts Institute of Technology (MIT) and RMIT University have made a breakthrough in energy storage and power generation.