Word: receptor
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...that's just what Tsien & Co. did, focusing not just on the NMDA receptor but on a particular component of it. Called NR2B, it's very active in young animals (which happen to be good at learning), less active in adults (who aren't), and is found mostly in the forebrain and hippocampus (where explicit, long-term memories are formed). The researchers spliced the gene that creates NR2B into the DNA of ordinary mouse embryos to create the strain they called Doogie. Then they ran the mice through a series of standardized tests--sort of a rodent...
...altered mice grow up looking and acting just like ordinary mice, with no evidence of seizures or convulsions, according to Tsien. That's critical. The NMDA receptor shows up throughout the brain, and though calcium is crucial to learning and memory, too much of it can lead to cell death. That's what happens during a stroke: when brain cells are deprived of oxygen, they release huge amounts of glutamate, which overstimulates nearby NMDA receptors and kills their host cells. Nature may have designed NR2B-based receptors to taper off in adult brains for a reason. Some scientists fear that...
Premature cell death isn't the only possible complication. Stanford's Robert Malenka has shown that the NMDA receptor is involved in sensitizing the brain to drugs like cocaine, heroin and amphetamines, and others are investigating its role in triggering chronic pain--two more indications that it may not be wise to try to fool Mother Nature...
...will be a while before such dangers arise, though, and--as cancer researchers have discovered all too often--it isn't even certain that what works in mice will work in people. Tsien and his colleagues believe it's not unreasonable to think it will. "The NMDA receptor in humans is nearly identical to the receptor in mice, rats, cats and other animals," he says. "We believe it's highly likely that it plays a similar role in humans...
...diners can season their own food. Add garnishes of high-flavor foods like bacon or ham bits, sun-dried tomatoes or orange slices. Think about what you're eating--people can often fill in the lost sensory information from memory. Chew thoroughly to enable more molecules to react with receptor sites in the mouth and nose. Switch from food to food, taking a bite of one, then another, to avoid becoming adapted, or inured, to a flavor...