Bee venom toxin leads to new treatment for dementia
12 July 2010
A toxin extracted from the venom of the honey bee has
potential for developing new treatments for neural conditions such as
muscular dystrophy, depression and dementia.
Apamin, a natural peptide toxin found in bee venom, is known for
its ability to block a type of ion channel that enables a high-speed
and selective flow of potassium ions out of nerves.
The blocking of these channels in the brain causes nerves
to become hyperexcitable, producing improved learning that has
implications for the treatment of dementia and depression. In
addition, injection of apamin improves the symptoms experienced by
sufferers of myotonic muscular dystrophy (MD).
Until now, the exact mechanism by which apamin acts was poorly
understood. In a study published in the Journal of Biological
Chemistry , two teams from the University of Bristol and the
University of Liege in Belgium describe the results of their joint
work on these KCa2 potassium ion channels, also called SK channels.
Using computer models and a genetic approach, the researchers
were able to pinpoint exactly where apamin binds to block the
channel. To block ion channels, most molecules act as a plug at
their external mouth. Perhaps surprisingly, the researchers have
discovered that apamin binds away from the channel pore, and causes
the shape of the channel to change through an ‘allosteric’
mechanism, resulting in the block.
This discovery could accelerate research into the design of new
SK channel blockers which could imitate the action of apamin, to
target SK channels in neural and muscular conditions such as
dementia, depression or MD.
Professor Neil Marrion, from the University of Bristol’s
Physiology & Pharmacology department, said: “Drug design depends on
knowing the target. Our findings have provided a new approach to
designing a therapeutic agent that could help with the treatment of
a number of conditions.”
Professor Vincent Seutin, from the GIGA Neurosciences at the
University of Liège, commented on the study: “I am very enthusiastic
about the results of our study and I believe that, with the help of
this piece of information, the targeting of these channels for the
development of future drugs has been made easier.”
1. Cedric Lamy, Samuel J Goodchild, Kate L Weatherall,
David E Jane, Jean-Francois Liegeois, Vincent Seutin and Neil V
Marrion. Allosteric block of KCa2 channels by apamin". The
Journal of Biological Chemistry. doi 10.1074/jbc.M110.110072.