What amphibians and fish can teach us about the brain

Vance Trudeau

“Applying the principles of comparative biology and evolution can provide ideas and solutions for human health problems. This requires important collaborative efforts between folks like me in biology and other researchers in medicine.”

– Vance Trudeau

What secrets might a healthier frog population help reveal about the human brain? Vance Trudeau and his colleagues are opening a door to the answer.

Known internationally for his groundbreaking work in the neurobiology of fish and frogs—and most recently for his “love potion” that led to frogs reproducing in captivity for the first time—the associate professor of biology at the University of Ottawa is determined to help clarify the connections between healthy environments and healthier brains.

“The part of the brain we study is very similarly organized in fish, frogs and mammals,” explains Trudeau. “The hormones that control reproduction in fish and frogs are virtually identical in humans.”

This striking likeness offers a scientific pathway toward healthier amphibians and humans.

“We want to help industries remediate effluents so that environmen­tal impacts can be lessened or eliminated,” notes Trudeau, “so we first have to find out potential effects in sensitive test organisms like frogs.”

“Bad news,” such as the recent B.C. Supreme Court findings on the complex causes of the drastic decline of sockeye salmon in the Fraser River, is a motivator for such research, says Trudeau, partly because of discordant opinions on what defines environmental health.

“Many understand that a clean environment means good health for animals and humans,” he says. “Others are still in denial and are stuck in the 19th- or early 20th-century mode of thinking, that is to say that water is limitless and can handle the pollution loads. The latter is clearly not true.”

Indeed, the evidence is overwhelming, including global declines in frog and other amphibian populations observed since the 1980s. These critical threats to global biodiversity remain poorly understood but Trudeau and his colleagues took a key counteractive step last year when they developed a “love potion”— a synthetic hormone mixture—to breed leopard frogs in captivity.

“The whole concept has changed my focus to helping zoos, researchers and conservation groups and encouraging them to start captive breeding,” says the biologist. “There is a global amphibian decline and we need to do something drastic to help.”

The breakthrough has since expanded and Trudeau now uses the method on other amphibian species, including salamanders.

“I am optimistic that we can assist anyone who wants to breed frogs for reintroductions,” he says. “The problem is always whether the animals we place back in nature have a clean habitat that won’t be ploughed under.”

Leveraging the amphibian-human neurological link, Trudeau and international collaborators are using frog models to study several issues affecting humans, including the role of estrogens in embryonic development, the impact of petroleum mining chemicals on hormone release, and how agricultural pesticides affect sexual development.

Some of Trudeau’s research involving fish, meanwhile, is helping to establish the role of a brain peptide called secretoneurin that he and his colleague Ajoy Basak think is a new vertebrate reproductive hormone. In a separate study, they are exploring the development of glial cells and neurons in fish because “fish have a great capacity for regeneration of cells in the brain,” Trudeau notes. “If we can understand why fish can regenerate brain cells after neurotoxic insult, we may discover why mammals are so poor at doing this.”

Although Trudeau’s work is indirectly linked to the human brain, he and his collaborators are keen to contribute to the University of Ottawa’s Brain and Mind Research Institute by drawing attention to the environmental factors affecting a healthy brain.

“The concept we have been developing based on our work with the brain is something called neuroendocrine disruption,” says Trudeau. “Discussions over the years with graduate students led us to the conclusion that pollutants upset key hormones that the brain produces— hormones that control sexual behaviour, reproduction and feeding in both vertebrates and invertebrates.”

“Applying the principles of comparative biology and evolution can provide ideas and solutions for human health problems,” he adds. “This requires important collaborative efforts between folks like me in biology and other researchers in medicine.”


by Tony Martins

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