Next the researchers repeated the low-oxygen, normal-oxygen experiment with a different twist: They blocked IGF signaling in the fish embryos, using either genetic methods or pharmacological inhibitors.

"We found that if you block IGF signaling, the animal cannot catch up," Duan said. "From this we learned that the IGF signal is not only changing, but that the change is really necessary for the animal to catch up."

Duan's group went on to investigate the specific biochemical pathways involved. They found that one, called the MAP kinase pathway, is critical for catch-up growth. However, it may not be the only pathway that figures in, and the specific pathway used may depend on circumstances.

"You can think of it like your route to work. Maybe you normally take I-94, but if it's blocked, you use other routes that you normally don't use," Duan said.

In future research, Duan's group wants to explore the long-term effects of changes in the IGF-MAP kinase pathway that are related to catch-up growth.

"If we find lasting changes, we may be able to figure out ways of intervening to reduce the risk of associated health problems that develop later in life," Duan said.

Source: University of Michigan