New Zealand
November 24, 2008
Two
AgResearch scientists’
groundbreaking research into ryegrass staggers is featuring in
the December issue of
The Journal of Pharmacology and Experimental Therapeutics –
an American publication that focuses on novel discoveries in
pharmacology.
The research done by Forage Scientists, Dr Julie Dalziel and Dr
Sarah Finch and their teams, in collaboration with a group of US
researchers, looks at how toxins cause ryegrass staggers.
Through this research, which was funded by a grant from the
Marsden Fund (Royal Society of New Zealand) to Drs Dalziel and
Finch, scientists finally know the mechanism that causes this
condition.
Ryegrass staggers is characterised by muscle tremors and poor
muscle coordination. The disease was first reported in the 1880s
and is thought to cost New Zealand agriculture $100 million
annually in lost animal production.
Building on previous research by various scientists within
AgResearch, Drs Dalziel and Finch have now discovered the
biological receptor that the toxin acts on to cause this
neurological disorder. “We knew the cause, but we didn’t know
how the tremor-causing compounds were having their effect,” says
Dr Finch.
Drs Finch and Dalziel focussed on an ion channel called the BK
Channel. Ion channels are responsible for the electrical
signalling that underlies movement, sensation and thought. An
ion channel that has a specialized role in regulating this
electrical signalling is the BK channel (large conductance
calcium-activated potassium channel).
Dr Finch says through using mice that did not have BK channels
(bred by their collaborators at Stanford University) they have
discovered that without a BK channel the toxins didn’t have an
effect on animals. She explains that the experiments involved
giving mice lolitrem B (the toxin produced by the endophytic
fungus). “Ordinary mice gave a tremor response similar to
ryegrass staggers while mice without BK channels gave no
response,” she says. “This discovery is of great significance
and over a century after the first report of ryegrass staggers,
the mechanism of tremor production is finally known. This means
we can now start looking at ways to treat ryegrass staggers by
reversing the effect or preventing it from happening
altogether.”
Dr Dalziel says their findings also provide valuable insight
into human disorders of motor function. “These findings could be
useful from a pharmaceutical viewpoint, as they suggest new
therapies for human neural dysfunction of tremor and impaired
motor coordination and balance,” she says. |
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