These conditions mimic ischemic stroke, where a clot stops blood flow to a region of the brain, cutting off the supply of these essential substances. But more cultured cells died when a neurotrophin was present, the researchers found. A day after the deprivation, less than 20 percent of the control cells were dead, but about 50 percent of the cells exposed to a neurotrophin had disintegrated. Oxygen-deprived neurons suffer a swift, swollen death called necrosis. But the beneficial effects of growth factors have been observed most conclusively in cells at risk for a lingering suicide known as apoptosis.
Clinicians hope to use growth factors to treat neurodegenerative disorders and stroke.
So unmasking a potentially deleterious side of these molecules might allow us to interfere with that side and make that net effect better. Discovering how the factors sabotage cells will be an essential first step. It already is known that the neurotransmitter glutamate is a key weapon in oxygen-glucose deprivation. When cells run short of chemical energy, glutamate floods out of the neurons in which it is stored and overactivates receptors on nearby cells. Because these receptors are ion channels, they let in deadly amounts of sodium and calcium.