Brain-wasting proteins called prions kill neurons by shortening the dendritic spines that the cells use to transmit signals to each other.
Prions are infectious and cause neurodegenerative diseases such as scrapie in animals and Creutzfeldt–Jakob disease in humans. To learn how they kill brain cells, David Harris at Boston University in Massachusetts and his co-workers exposed cultured mouse neurons to the prion that causes scrapie in mice. They found that the neurons' dendritic spines retracted within 24 hours, before the cells died. This occurred only in neurons that made the normal, non-infectious form of the prion protein, which suggests that the disease-associated prion might bind to the normal one to trigger dendritic loss.
This method could be used to test potential drugs against prion diseases, the authors say.