Neuroscience Researchers Identify Function of Brain Receptor Subunit Linked to Memory, Stroke, Dementia Researchers at Brigham and Women's Hospital and Harvard Medical School have characterized the function of a subunit of the NMDA receptor, a specialized molecule on nerve cells that admits calcium when activated by the neurotransmitter glutamate. The subunit, dubbed NR3A, appears to regulate the activity of the NMDA receptor in ways that may protect nerve cells from damage. Their findings are published in the May 28 Nature.
NMDA receptors are important in nerve cell migration and synapse formation during development.
Paradoxically, NMDA receptors are also responsible for nerve cell injury in a variety of neurologic diseases, including stroke, head and spinal cord trauma, and various forms of dementia, including AIDS dementia. Mice that do not have the NR3A subunit appear to be normal. When Lipton and his colleagues conducted electrophysiological tests, however, they found heightened NMDA receptor activity in the nerve cells. Ionic current was 2.8-fold higher than in neurons containing the NR3A subunit, increasing the amount of calcium entering the cells. These findings suggest that the NR3A subunit may play a protective role, inhibiting the ionic current that passes through the NMDA receptor and reducing the amount of calcium entering the nerve cell.