CINCINNATI--A cell-signaling pathway in the brain that is linked to the development of cancer and diabetes is also a key part of networks that regulate food intake, say University of Cincinnati (UC) researchers.
The finding might one day lead to new ways of helping obese people lose weight, either with new drugs or by carefully designing diets that can activate this pathway.
Scientists from UC's Genome Research Institute demonstrated that the signaling pathway mTOR--activated by nutrient and hormonal signals--plays a role in the brain's ability to sense how much energy the body has available.
As more biochemical pathways by which appetite gets regulated become identified and understood in greater detail they become obvious targets for appetite suppressing drug development.
This finding, the researchers say, suggests that very specific micronutrients may drive these pathways in the brain and could lead to a more scientific approach to diet design to help regulate body weight.
The study, led by Randy Seeley, PhD, professor in UC's psychiatry department, appears in the May 12, 2006 issue of the journal Science.
One caveat: These researchers used rats, not humans.
Another caveat: The method of leucine delivery was injection, not diet. They injected it into a specific area of the brain no less. So that's a big caveat. Will it produce the same effect when consumed?
The mTOR pathway is very sensitive to "branched-chain" amino acids, particularly leucine, Dr. Seeley explains. In laboratory studies, he and his team found that when they administered leucine directly to the hypothalamus, a brain region that controls a number of metabolic processes, animals ate less.
Other, similar amino acids did not give the same results.
This animal study, says Dr. Seeley, could eventually have implications for human obesity.
"Rather than basing our diets only on macronutrients like fat or carbohydrates, we might one day be designing diets based on micronutrients like amino acids," he says.
To see whether the mTOR pathway in the hypothalamus responds to amino acids, Seeley injected 1 microgram of leucine directly into the brains of rodents, near the hypothalamus. Over the next day, the rats that received the injection consumed 25 grams of food on average while the control rats consumed 30 g of food.
A reduction in calories consumed by a sixth per day would prevent weight gain in most people. It would also allow for a slow weight loss.
They saw an even larger reduction in calories consumed when leucine was delivered after a 24 hour fast. But to do 24 hour fasts would probably require a far more effective appetite suppressant. If we had such a powerful appetite suppressant we wouldn't need leucine.
You can buy L-Leucine as a powder or capsule. The powder form would be cheaper. I'm not encouraging anyone to try this. Also, if you do try it I would suggest you do so in moderation. Amino acids compete with each other for absorption in a few transport mechanisms that bring amino acids into cells. You don't want to starve your cells of other amino acids by saturating one of those transport mechanisms. Though I'm not sure that's a real problem.
New Haven, Conn. - Nearly half of the people responding to an online survey about obesity said they would give up a year of their life rather than be fat, according to a study by the Rudd Center for Food Policy and Obesity at Yale.
The 4,000 respondents in varying numbers between 15% and 30% also said they would rather walk away from their marriage, give up the possibility of having children, be depressed, or become alcoholic rather than be obese. Five percent and four percent, respectively, said they would rather lose a limb or be blind than be overweight.
"We were surprised by the sheer number of people who reported they would be willing to make major sacrifices to avoid being obese. It drives home the message that weight bias is powerful and pervasive," said Marlene Schwartz, associate director of the Rudd Center and lead author of the study in Obesity, which was issued this month.
15 percent said they would trim a decade off their lives for a thinner waistline.
Whatever company comes up with a really powerful yet safe appetite suppressant is going to make billions of dollars in profits. Mind you, such a treatment has to test as safe chiefly for the benefit of regulatory agencies. Many of the potential customers are willing to run bigger risks.
|Share |||Randall Parker, 2006 May 17 10:01 PM Brain Appetite|