Ground squirrels like this one produce anabolic steroids in order to bulk up for winter hibernation, but a new study show that they’ve evolved mechanisms to avoid the negative side effects associated with anabolic steroids. (Photo credit: Tim Karels)
A new study shows that Arctic ground squirrels use anabolic steroids to beef up for winter hibernation, but that they have evolved systems to avoid the negative side effects.
Most hibernating animals burn fat during the winter, Arctic ground squirrels hibernate at such low temperatures that they need to burn muscle as well. A previous study showed that their levels of testosterone and other anabolic steroids spike in late summer to help them bulk up, but that they didn’t exhibit the negative side effects (e.g. highly aggressive behaviour, lowered immune response) commonly associated with anabolic steroids.
The new study shows that the squirrels have evolved to have more steroid receptors where they are needed (i.e. in muscle cells) but fewer receptors in other types of cells (e.g. immune cells) that could be negatively affected by the steroids. In this way, they get the benefit of the steroids without the risk.
Original research paper published in the Proceedings of the Royal Society B: Biological Sciences on November 4, 2014.
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