Figure 9.

The neuroprotective effect of carbamazepine against rotenone is mediated by GABA_A but not GABA_B receptors and occludes the action of l-sulpiride. A, A low concentration of the GABA_A receptor antagonist bicuculline (bic) blocked the neuroprotective effect of CBZ. B, The histogram summarizes cumulative data recorded 30 min after the onset of 1 μm rotenone, showing that the neuroprotective action of CBZ was antagonized by bicuculline and picrotoxin (PTX) but not by the GABA_B receptor antagonist CGP46381. Note that bicuculline, picrotoxin, and CGP46381, when applied alone, did not significantly affect the rotenone-induced effect. C, The histogram shows that coadministration of 30 μm CBZ plus 10 μm l-sulpiride did not produce an additive neuroprotective action compared with the effect achieved when a single drug was given in isolation, suggesting that CBZ and l-sulpiride share a common mechanism of action. Cumulative data from the different experimental condition were obtained 20 min after the onset of the application of 1 μm rotenone.