Neuron-glia interactions: indirect effect of GABA on cultured glial cells.

A study was made of the action of GABA on the membrane potentail and resistance of satellite glial (SG) cells in cultures of rat dorsal root ganglia. GABA (10(-4) M) depolarized all SG cells tested without producing significant changes in membrane resistance. Similar results were obtained from astrocytes of cultured rat spinal cord and brain stem, although only half of the cells tested were depolarized by GABA. Bicuculline (10(-5) and 10(-6) M) which blocked the GABA-depolarization on cultured dorsal root ganglion (DRG) neurons, also markedly reduced or blocked the action of GABA on SG cells. When GABA was tested in sodium-free bathing solution, the amino acid caused a depolarization of similar shape and amplitude as in normal (137 mM Na+) bathing fluid, indicating that uptake processes are probably not involved in producing the depolarization by GABA. It is suggested that the depolarizing action of GABA on glial cells is an indirect effect due to the release of potassium from adjacent neurons during the action of the amino acid.