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The discovery that the drug amiloride, a potassium-sparing diuretic, can reduce the degeneration of nerve tissue offers fresh hope for MS sufferers.

The researchers hypothesised that the acid-sensing ion channel (ASIC1) plays a role in the development of MS.

ASIC1 works by gauging acid levels around the cell and fluxes sodium and calcium molecules into and out of cells accordingly. This function is an important part of the process of sensing pain and touch.

Using mice with a condition that mimics some aspects of the human form of MS, the researchers found that the ASIC1 channel contributes to degeneration of the nerve axon.

The next step was to identify drugs that could target the ASIC1 channel.

The heart failure drug amiloride is a known ASIC1 antagonist. MS mice were injected daily with amiloride for a number of weeks.

Those injected with the drug showed reduced axonal degeneration compared with mice that had not been injected.

Lead researcher Professor Lars Fugger, of the Medical Research Council human immunology unit at the University of Oxford, said: 'When sodium and calcium levels accumulate in excessive proportions within nerve cells the axon becomes damaged. We found this damage was reduced in mice given amiloride. The drug works by blocking the action of the channel that lets sodium and calcium molecules into the cell.'

Using established drugs in new ways is cheaper than starting the discovery process from scratch, added Professor Fugger.

The research team is planning a clinical trial that will aim to find out if amiloride is beneficial in treating MS in humans.

sanjay.tanday@haymarket.com

Nature Medicine Online 2007

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