Neurons without NGF die off (top) unless cycloheximide is added (bottom).
JOHNSON
Take away their supply of nerve growth factor (NGF), and neurons lose the will to live. In 1988, the conventional wisdom held that the cells wasted away because NGF helped keep metabolism churning. After all, NGF is a trophic factor, meaning that it literally “nourishes” the cell. But neuroscientist Eugene Johnson (Washington University, St. Louis) and colleagues suspected that the molecule instead prevented neurons from committing suicide—a controversial assertion that they confirmed with some simple experiments. The issue was important, Johnson says, because droves of surplus neurons perish during development, and uncovering the requirements for cell survival might clarify how this attrition helps wire the nervous system. The knowledge might also reveal measures for sparing neurons jeopardized by stroke and neurodegenerative diseases.
Johnson and colleagues reasoned that if NGF were essential for metabolism,...
