Discovery of a brain protein in rats that appears to help regulatethe animal's response to amino acid-deficient diets may have implications for treatment of anorexia in humans. UC Davis neurophysiologist Dorothy W. Gietzen and colleagues recently found that the brain protein known as the NMDA (N-methyl-D-aspartate) receptor influences a chemical-sensing mechanism in the rat's brain and helps regulate the animal's response to amino acid-deficient diets. Sufficient amounts of amino acids are crucial for maintaining normal body functions, such as repair, maintenance, growth and reproduction. When given a drug blocking the NMDA receptor, rats continue eating a diet lacking in amino acids, rather than dramatically decreasing their consumption as is their normal response. "The NMDA receptor has been shown to have great potential for treating strokes, epilepsy and other seizure disorders, but this is the first evidence that it also modulates the animal's response to a dietary deficiency," says Gietzen, who reported the findings this winter at the annual meeting of the Society for Neuroscience.