AgResearch scientists overcome first hurdle in finding treatment for ryegrass staggers
24 November 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 NZ) 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.