[yeahright]

Food Restriction Increases Dopamine Receptor Levels in Obese Rats; Evidence for Interplay of Brain's 'Reward' Chemical With Availability of Food in Obesity

AScribe Newswire

10-26-07

UPTON, N.Y., Oct. 25 (AScribe Newswire) -- A brain-imaging study of genetically obese rats conducted at the U.S. Department of Energy's Brookhaven National Laboratory provides more evidence that dopamine - a brain chemical associated with reward, pleasure, movement, and motivation - plays a role in obesity. The scientists found that genetically obese rats had lower levels of dopamine D2 receptors than lean rats. They also demonstrated that restricting food intake can increase the number of D2 receptors, partially attenuating a normal decline associated with aging.

"This research corroborates brain-imaging studies conducted at Brookhaven that found decreased levels of dopamine D2 receptors in obese people compared with normal-weight people," said Brookhaven neuroscientist Panayotis (Peter) Thanos, lead author of the current study, which will be published in the journal Synapse and is now available online.

It's not clear whether reduced receptor levels are a cause or consequence of obesity: Overeating may chronically reduce receptor levels, which, over the long term, could eventually contribute to obesity. But having genetically low receptor levels may also lead to obesity by predisposing the individual to overeating in an attempt to stimulate a "blunted" reward system. Either way, revving up receptor levels by restricting food intake could enhance the impact of this common strategy for combating obesity.

"Consuming fewer calories is obviously important for people trying to lose weight, plus improving the brain's ability to respond to rewards other than food may help prevent overeating," Thanos said. Because food intake can have such a dramatic effect on dopamine receptor levels, "this study also provides further evidence for the interplay of genetic factors with the environment in the development of obesity in our society," he said.

The finding that food restriction can attenuate the effects of aging on the brain's ability to respond to dopamine may also help explain why food restriction slows down other changes associated with aging, such as declines in locomotor activity and sensitivity to reward.

Study methods and main findings

The researchers measured dopamine D2 receptor levels in adolescent and young adult genetically obese Zucker rats and lean rats. Between measures, half of the rats in each group were given free access to food while the other half were given 70 percent of the daily average amount of food eaten by the unrestricted group.

The scientists measured D2 receptor levels using two different techniques: micro-positron emission tomography (microPET) in living animals, which uses a radioactively tagged molecule that competes with the brain's natural dopamine for D2 receptor binding sites, and autoradiography, which uses a tracer that binds more strongly than natural dopamine but can only be used in tissue samples rather than in living animals. Together these two methods indicate the absolute number of D2 receptors found in the brain and how many are available or free during day-to-day function, which might be relevant to further elucidating the role of dopamine in obesity.

One main finding was that the overall number of D2 receptors was lower in obese than in lean rats. Also D2 receptor levels decreased with age, but this decline was significantly blunted in food-restricted rats compared with those given free access to food. This attenuation was most apparent in the obese rats.

Another main finding was that D2 receptor availability - that is, the number of receptors available for binding dopamine - was greater at adulthood in the obese rats compared to the lean rats. This suggests that perhaps the release of dopamine had significantly decreased with age in the obese unrestricted animals more than in the restricted ones or the lean rats. The possibility of lower release of dopamine in obese subjects is presently being examined, the researchers say.

This research was funded by the Office of Biological and Environmental Research within the U.S. Department of Energy's Office of Science and by the Intramural Research Program of the National Institute on Alcohol Abuse and Alcoholism, which is part of the National Institutes of Health.

For more information about Peter Thanos's research, see Brookhaven Medical Department.

One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation of State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

[EasyEJL]

wow thats interesting

[yeahright]

Originally Posted by EasyEJL

wow thats interesting

Obese rats....but yeah. It makes sense that the body would try and compensate as body composition changes....I'm constantly amazed the all the latest studies showing how resilient the body really is. It wasn't that long ago that the accepted model was that the body essentially stopped growing after adolescence and that it was just a long slow degeneration after that.

[EasyEJL]

well but this is more like reverse feedback loop in its own way, if overeating makes you feel less satisfied so you eat more...

[Force of Green]

Eat colorful foods, get a wide variety of anti-oxidants, drink lots of fresh water (not always filtered or distilled), get your 8 hours or whatever your magic number of sleep is, and learn to manage your stress... You'll be surprised at how much you can slow (maybe even reverse some aspects) of aging.

Some supps to consider for longevity:

1. Curcumin
2. Green tea, white tea, oolong tea
3. Schizandra
4. Goji berry
5. Ashwaganda
6. Resveratrol
7. Grapeseed extract
8. L-Carnitine (ALCAR and PLCAR)

Plenty more...

The caloric restriction subpart of this thread reminded me of articles about 'caloric restriction increases lifespan' and I am wondering if the two can be correlated.

Logically one can induce:

Caloric restricted lifestyle increases lifespan
Caloric restriction increases quantity of dopamine receptors

Induction: Increased quantity of dopamine receptors increases lifespan.

Interesting.

Another main finding was that D2 receptor availability - that is, the number of receptors available for binding dopamine - was greater at adulthood in the obese rats compared to the lean rats. This suggests that perhaps the release of dopamine had significantly decreased with age in the obese unrestricted animals more than in the restricted ones or the lean rats. The possibility of lower release of dopamine in obese subjects is presently being examined, the researchers say.

When there are more receptors available for any given hormone to bind to, the body can compensate by releasing less of the hormone. When receptors are being occupied or blocked, the body can compensate by releasing more of that given hormone that has affinity to that receptor. Hmmm... and both work in retrospect.

I'm wondering if a dopamine balance is the key to anti-aging via caloric restriction. If one could find a product to increase dopamine receptors to in turn decrease the need for more dopamine release, then maybe it's possible to reap the benefits of a caloric restricted diet without reducing calories below baseline.

I remember reading about how ashwaganda (a staple of mine now) has the ability to increase dopamine levels in the brain, while at the same time having a suppressive effect on dopamine receptors. To my knowledge, this would cause the need to increase D2 receptors due to the increased dopamine concentration that is a result of ashwaganda administration.

I have not found an article online that concurs with what I'm saying here, but maybe I'm onto something? Who knows. Just figured I'd use this thread to think out loud.

Personally I think everyone should be taking Sensoril (patented ashwaganda extract). It calms you in times of stress and energizes you in times of fatigue. Is that a miracle right there or what?

[strategicmove]

Originally Posted by yeahright;

Obese rats....but yeah. It makes sense that the body would try and compensate as body composition changes....I'm constantly amazed the all the latest studies showing how resilient the body really is. It wasn't that long ago that the accepted model was that the body essentially stopped growing after adolescence and that it was just a long slow degeneration after that.

Agree. Applied correctly, some model of calorie restriction produces profound anti-aging benefits. The Life Extension Foundation and some other sources have a dense collection of highly informative related information.