03 May 2001

Two reports in tomorrow's Science add to a growing body of evidence that glial cells play more than a "housekeeping" role and are essential for neuronal signalling (see also 26 January news). M. Iino and colleagues report that Bergmann glial cells, a type of astrocyte in the cerebellum, appear to regulate dendritic growth. The Bergmann glial cells wrap around the dendrites of cerebellar neurons and may play a role in stabilizing the dendrites. These glial cells have AMPA receptors that are missing a subunit, and thereby become permeable to calcium ions. When the researchers introduced the missing subunit into the cells via a viral vector (in rats) , the cells pulled back, exposing the dendrites and premitting the growth of new neuronal connections.

In the same issue, SHR Oliet and colleagues in France show that astrocytes mop up the excitatory neurotransmitter glutamate from the synaptic cleft. The team studied lactating rats, which have markedly reduced astrocyte sheaths around synapses. The reduction in astrocyte sheathing resulted in less efficient removal of glutamate and and an attendant reduction in release of the neurotransmitter. This emerging view of a more complex interaction of glia and neurons suggests that "defining signal processing in the CNS as a purely neuronal phenomenon may be an oversimplification, " write Vittorio Gallo and Ramesh Chittajallu in a related Perspective.—June Kinoshita

Email address for S. Ozawa: ozawas@med.gunma-u.ac.jp

Email address for Stéphane H. R. Oliet: stephane.oliet@bordeaux.inserm.fr