Scientists unravel mystery of snake venom

Scientists have unraveled the mystery of how the Costa Rican coral snake's venom causes seizures in its victims, a finding that could boost research into schizophrenia, epilepsy and chronic pain, researchers said Monday.
The recipe involves a pair of proteins called micrurotoxins (MmTX) that bind to pores on nerve cells in the brain and spinal cord known as GABA(A) receptors, resulting in potentially deadly seizures, according to the study in the Proceedings of the National Academy of Sciences, a peer-reviewed US journal.
"What we found are the first known animal toxins, and by far the most potent compounds, to target GABA(A) receptors," said Frank Bosmans, assistant professor of physiology and neuroscience at the Johns Hopkins University School of Medicine.
"Once they bind to the receptors, they don't let go."
MmTX was found to bind to GABA(A) receptors more tightly than any other compound known, and also attached to a unique site on the GABA(A) receptor protein.
When that happened, the receptor's pore opened permanently and the nerve cell was never able to reset, causing it to misfire.
Researchers hope their findings will help advance study of epilepsy, schizophrenia and chronic pain, which are caused by errors in the GABA(A) receptors.
"Anti-anxiety medications like diazepam and alprazolam bind to GABA(A) receptors too, but they cause relaxation instead of seizures because they bind much more loosely," said Bosmans.
The study was funded by France's Centre National de la Recherche Scientifique.
Experts on the research team came from Aix Marseille University in France, University Medical Center Hamburg-Eppendorf in Germany, Johns Hopkins University in Baltimore, Maryland, the Universidad de Costa Rica and the Universitat des Saarlandes in Germany.