June 29, 2009

Super-Sleeper Frogs Could Be Model For Reversing Obesity

A team of researchers has discovered that animals that sleep longer store energy for a long duration of time, something scientists believe could be useful the treatment of obesity and other disorders.

In an effort to conserve energy when resources are scarce, some species of animals, like the burrowing frog (Cyclorana alboguttata), go through a period of torpor.

These frogs can survive for several years buried in the mud without any food or water.

They are able to survive such extended periods of sleep because the metabolism of their cells changes radically during the dormancy period, allowing them to maximize the use of their limited energy resources without ever running out.

Researchers at the University of Queensland, Australia, said this discovery could prove to have important medical applications in the long term.

Scientist Sara Kayes believes it could potentially be useful in the treatment of energy-related disorders such as obesity.

The team noted that when the operation efficiency of the mitochondria (the tiny "power plants" of the cell) was measured during the dormancy period, it was significantly higher compared to that observed in active animals.

This lead to the question: If this is such an efficient way to use energy resources during dormancy, how come that it is not more widespread in the animal kingdom?

This mitochondrial coupling allows these frogs to be extremely efficient in the use of the limited energy stores they have by increasing the total amount of energy obtained per unit consumed. Therefore, the frogs can easily outperform other species whose energy production efficiency remains essentially the same even when they happen to be inactive for extended periods.

However, a potential drawback of this ability may be the increased production of reactive oxygen species, which may in turn lead to oxidative stress, researchers said.

These small molecules are believed to cause most of the damage during periods of re-awakening, so increasing mitochondrial coupling may be harmful for animals that tend to exhibit short periods of spontaneous arousal during the dormancy period.

But the burrowing frogs likely remain deeply asleep during the entire period of dormancy. And since they're cold-blooded, they don't have the need to maintain a basal level of heat production, minimizing their energy needs.


Image Caption: This is the burrowing frog (Cyclorana alboguttata) used as model organism in the study. Credit: Sara M. Kayes


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