Glial cells, which make up 90 percent of the human brain but are widely believed to play a lesser role than nerve cells, actually prevent the latter from getting overexcited, Chinese scientists have found.

In addition to supporting nerve cells -- a media that transmits and processes signals in the human brain, glial cells are believed to prevent excessive activities of nerve cells, whose overexcitement can lead to brain damage including epilepsy and stroke.

The recent issue of Neuron, a leading international magazine on neuroscience, carries a thesis on the subject that is the result of studies by scientists with the Institute of Neuroscience of the Shanghai Institute for Biological Sciences, under the Chinese Academy of Sciences.

The research team, headed by Duan Shumin, found that when nerve cells get overexcited, nearby glial cells release ATP, a nucleotide that supplies large amounts of energy to cells for various biochemical processes -- including muscle contraction and sugar metabolism -- to protect the nerve cells.

Their discovery can help doctors further study the neural system and causes for various diseases, experts say.

In a separate essay published in the Proceedings of the US National Academy of Sciences, Duan and his colleagues say glial cells can also help improve a person's memory by releasing D-serine, a common component of many proteins, which can enhance the learning and memorizing capacity of the human brain.

(Xinhua News Agency December 11, 2003)