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Scientists are now one step closer to resolving a head-scratcher of why poison frogs don't poison themselves, according to a new study released on Thursday that has potential implications for developing new treatments for pain and addiction.
The new research, led by scientists at The University of Texas (UT) at Austin and published in the US journal Science, studied a subgroup of poison frogs that produce a toxin called epibatidine to protect them from predation.
The toxin is known to bind to receptor – proteins on the outside of cells – in an animal's nervous system and can cause hypertension, seizures, and even death.
Being toxic gives animals an edge over predators.
The researchers discovered that a small genetic mutation in the frogs – a change in just three of the 2,500 amino acids that make up the receptor – prevents the toxin from acting on the frogs' own receptors, making them resistant to its lethal effects.
Not only that, but precisely the same change appeared independently three times in the evolution of these frogs.
"Being toxic can be good for your survival – it gives you an edge over predators," said Rebecca Tarvin, a postdoctoral researcher at UT Austin and one of the authors on the paper.
"So why aren't more animals toxic? Our work is showing that a big constraint is whether organisms can evolve resistance to their own toxins. We found evolution has hit upon this same exact change in three different groups of frogs, and that, to me, is quite beautiful."
There are hundreds of species of poisonous frogs, each of which uses dozens of different neurotoxins.
There are hundreds of species of poisonous frogs, each of which uses dozens of different neurotoxins.
For decades, medical researchers have known that one of the toxins, epibatidine, also can act as a powerful nonaddictive painkiller.
Hundreds of compounds have been developed from this toxin, including one that advanced in the drug-development process to human trials before being ruled out due to other side effects.
The researchers said their work offers new information about epibatidine that could eventually prove helpful in designing drugs such as new pain relievers or drugs to fight nicotine addiction.
(ASIA PACIFIC DAILY)
