A lowly weed uses one of the same communications systems as does the human brain, scientists have found.

In the November 12 issue of the journal Nature, Dr. Gloria Coruzzi and co-workers at New York University report that they turned up the sequence for proteins called glutamate receptors in a gene hunt through the DNA of Arabidopsis, a plant that is frequently used in laboratory research.

In the human brain, the amino acid glutamate acts as a chemical messenger and carries out a host of important functions, playing a role in everything from acquiring and storing memories to possibly contributing to certain mental health ailments. Past research has detected signs of glutamate overload in the post-mortem brains of people with schizophrenia, and faulty glutamate signaling has also been linked to Alzheimer's disease.

Glutamate and other neurotransmitters are squirted out by nerve cells and exert their effects through protein molecules called receptors that are nestled within the outer layers of adjacent nerve cells. These receptors serve as sentries that permit the passage of only certain molecules.

"This opens up a new connection between plants and animals," said Coruzzi, whose research on plant glutamate receptors was funded by NIH's National Institute of General Medical Sciences.

Glutamate is not the only substance produced by plants that functions in the brain. Other plant-derived molecules that act in the brain include caffeine and cocaine. Until now, it was widely believed that the receptors for these molecules--which are essential for transmitting messages into the cell--were found only in animals. But Coruzzi's previous research with Arabidopsis led her to believe otherwise.

Several years ago, while studying the weed's metabolism, Coruzzi noted that the incorporation of nitrogen from the environment into glutamate and other related molecules was regulated by light. A
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Contact: Alison Davis
davisa@nigms.nih.gov
301-496-7301
NIH/National Institute of General Medical Sciences
12-Nov-1998