Fig. 5.

BoNT/B prevents glutamate-mediated SIC in adjacent neurons. A, Left panel, Phase-contrast image of a microisland containing two astrocytes and two neurons (somas indicated by arrows). Right panel, Epifluorescence image of the same microisland after the microinjection of both astrocytes with fluoro-ruby. B, Representative whole-cell currents recorded from neurons in microislands in which the astrocytes were microinjected with either fluoro-ruby (left) or fluoro-ruby and BoNT/B (right). Although mechanically stimulated astrocytes injected with fluoro-ruby alone reliably evoked SIC in adjacent neurons, those injected with BoNT/B failed to evoke SIC. Mechanical stimulation of the astrocyte is indicated by the asterisk. Note the noise increase during the SIC, which is probably caused by the activation of NMDA receptors (Araque et al., 1998a). C, Proportion of mechanically stimulated astrocytes that evoked glutamate-dependent SIC in adjacent neurons. D, Current amplitude recorded in neurons after mechanical stimulation of adjacent astrocytes. Significant differences were established by the Student'st test at p < 0.01 (**).