Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Calorie restriction leads to some brain benefits but not others in mice

25.10.2004


Severe calorie restriction prevents certain aging-related changes in the brain, including the accumulation of free radicals and impairments in coordination and strength, according to a mouse study at Washington University School of Medicine in St. Louis. However, the dietary changes did not seem to prevent mice from developing some cognitive deficits associated with age, such as declines in memory. The study will be presented at 3 p.m. PT on Sunday, Oct. 24 at Neuroscience 2004, the Society for Neuroscience’s 34th Annual Meeting in San Diego.



"Our findings help us understand the processes underlying both normal aging and calorie restriction benefits," says principal investigator Laura L. Dugan, M.D., associate professor of neurology, of medicine and of anatomy and neurobiology. "If some aspects of aging are influenced by free radical damage, we may be able to prevent or reverse these impairments."

Though numerous studies have shown severe calorie restriction helps animals live longer and resist some effects of aging, scientists still do not know why. One theory suggests a restrictive diet decreases the effect of free radical damage. Free radicals are chemically reactive molecules produced either as byproducts of the body’s natural processes or as a result of stress from the environment, like smog or sunlight. It’s normal to have some free radicals, but scientists think accumulating too many may cause cell damage and contribute to a variety of diseases ranging from stroke to cancer. Antioxidants like vitamins C and E help prevent free radicals from wreaking too much havoc.


Since there is evidence that both antioxidants and calorie restriction increase lifespan and reduce aging-related diseases, Dugan and her colleagues hypothesized that calorie restriction, like antioxidants, helps protect the brain against free radical damage. To test their theory, the team compared young and old mice fed normal diets with old mice fed 35 percent fewer calories starting at about one year old. One year for mice is roughly the physiological equivalent of 40 years in humans.

The animals were injected with a fluorescent dye that changes color when it interacts with a free radical called superoxide. The researchers studied brain slices from the three groups to measure levels of superoxide in specific areas of the brain. Old mice fed normal diets had significantly more superoxide in several regions of the brain than their young counterparts, particularly in one region implicated in Parkinson’s disease, called the substantia nigra. But calorie-restricted old mice did not. "For the last 20 years there have been studies that suggest free radicals, particularly superoxide, are involved in cumulative damage with aging and that the nervous system may be one of the most vulnerable targets," Dugan says. "Most of that evidence has been indirect, though. By using sensitive, state-of-the-art methods, we were actually able to see which cells are producing excess levels of free radicals."

Dugan and her colleagues then evaluated animals that retained low levels of superoxide to see if they maintained their ability to do a range of behavioral tasks. They found that old, calorie-restricted animals were just as good as young animals at tests of grip strength, coordination and flexibility, like quickly climbing down a pole and hanging upside down from a screen. Old animals fed normal diets were significantly worse at these tasks.

But calorie restriction had almost no effect on several drills used to measure pure cognitive performance. In one test of spatial learning and memory called the Morris water maze, mice are placed in a pool of opaque water and have to learn to find a submerged platform in order to climb out of the pool. Old mice, regardless of their diet, performed much worse than young mice on this task when they were required to learn different consecutive platform locations.

Calorie restriction also did not result in improved performance on a fear-conditioning task. When a tone is matched with an electric shock, young mice eventually learn to "freeze" when they hear the tone. Old mice, regardless of diet, were much worse at this. In fact, the researchers noticed a trend that suggests mice on calorie restriction diets were even worse than old mice on normal diets. The researchers are not sure, though, whether this poor performance is a sign of learning deficits or of hearing problems that often develop in older mice. "It’s interesting to me that calorie restriction does not seem to reverse age-related cognitive impairments," says David Wozniak, Ph.D., research associate professor of psychiatry, who supervised the behavioral studies. "We need to do bigger, more extensive studies to fully understand these findings, but the bottom line is that you don’t get uniformly positive results from calorie restriction. I don’t think anyone has really stressed this point before, particularly with regard to the lack of effects on cognition."

In addition to validating these findings in larger groups of mice, the team also is exploring the possibility that adjusting other dietary factors may enhance and add to the calorie restriction diet’s benefits. The researchers also have begun testing the protective effects of potent antioxidants on aging mice fed normal diets to see whether they too can prevent or reverse some of the effects of aging.

"We believe sensitive signaling pathways that are particularly important in the brain are disrupted by high levels of free radicals and that these disruptions may explain why, under normal circumstances, brain function declines over time," Dugan says. "Fortunately, it would be much easier to reverse a misregulation in signaling than it would to reverse cell damage."

Gila Z. Reckess | EurekAlert!
Further information:
http://www.wustl.edu

More articles from Health and Medicine:

nachricht Opioids: no effect without side effect
21.01.2019 | Universitätsklinikum Jena

nachricht The cytoskeleton of neurons has been found to be involved in Alzheimer's disease
18.01.2019 | University of the Basque Country

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Ten-year anniversary of the Neumayer Station III

The scientific and political community alike stress the importance of German Antarctic research

Joint Press Release from the BMBF and AWI

The Antarctic is a frigid continent south of the Antarctic Circle, where researchers are the only inhabitants. Despite the hostile conditions, here the Alfred...

Im Focus: Ultra ultrasound to transform new tech

World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles

The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.

Im Focus: Flying Optical Cats for Quantum Communication

Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.

In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...

Im Focus: Nanocellulose for novel implants: Ears from the 3D-printer

Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.

It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:

Im Focus: Elucidating the Atomic Mechanism of Superlubricity

The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.

One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Our digital society in 2040

16.01.2019 | Event News

11th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Aachen, 3-4 April 2019

14.01.2019 | Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

 
Latest News

Scientists discover new 'architecture' in corn

21.01.2019 | Life Sciences

Broadband achromatic metalens focuses light regardless of polarization

21.01.2019 | Physics and Astronomy

Nuclear actin filaments determine T helper cell function

21.01.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>