MICHIGAN STATE (US)—A stress hormone identified in the 500-million-year-old sea lamprey may be used to help scientists understand the evolution of the endocrine system.

Corticosteroid hormones control stress response in animals with backbones, including humans.

While scientists have learned quite a bit about these so-called stress hormones in most modern animals, little is known about the hormones’ earliest forms in prehistoric creatures such as the lamprey.

“By identifying 11-deoxycortisol as a stress hormone in lamprey, it allows us to better understand how the endocrine system in vertebrates evolved into the complex systems we see in humans today,” says Weiming Li, professor of fisheries and wildlife at Michigan State University.

The hormone is the only one the researchers have found so far in the lamprey, and Li says the researchers are hypothesizing that it may be the only corticosteroid hormone in the lamprey.

In contrast, humans have more than 30 corticosteroid hormones.

The research  appears in the Proceedings of the National Academy of Sciences.

Native to the Atlantic Ocean, sea lampreys are an invasive species in the Great Lakes. They stay alive by attaching themselves to other fish, such as salmon and trout, and then suck out the fish’s body fluids. One sea lamprey can kill 40 or more pounds of fish.

The U.S. and Canadian governments spend about $10 million to $15 million per year on lamprey control.

The research identifies the pheromone male lampreys use to attract females to their nests to mate. Li is testing the effectiveness of a synthetic version of the pheromone as a control for the destructive parasites.

While the identification of 11-deoxycortisol likely won’t directly help his lamprey control work, Li says this new discovery will bolster understanding on how the fish has successfully adapted since the Paleozoic Era.

“Most jawless animals similar to the lamprey didn’t survive into the modern era, so they’re not available for us to use as we strive to learn more about how human systems developed,” Li explains. “The sea lamprey, a survivor, gives us a snapshot of what happened as vertebrates evolved into the animals we know today.”

Researchers from the University of British Columbia; Kunsan National University in Korea; and the U.S. Geological Survey Conte Anadromous Fish Research Center contributed to the research, which is supported by the National Science Foundation, the Confederated Tribes of the Umatilla Indian Reservation, the Bonneville Power Administration, the Great Lakes Fishery Commission, the MSU College of Agriculture and Natural Resources, and the National Institute of Mental Health.

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