Fig. 5.

Ablation of the inferior olive with the 3-AP regimen profoundly attenuates subsequent microglial activation induced by ibogaine. Left column (A, C, E), Treatment with ibogaine alone produces radial bands of darkly stained, activated microglia, primarily in the molecular and Purkinje cell layers of the cerebellar vermis. In most cases, the radial bands of microglia are coextensive with bands of degenerating Purkinje cells (Fig. 1). Right column (B, D, F), Animals that received the 3-AP regimen followed by ibogaine 6 d later demonstrate few signs of microglial activation. After the 3-AP regimen, ibogaine no longer produces more than an occasional radial stripe of activated microglia. The great majority of cells seen are resting microglia that are faintly stained and have delicate processes. Activated microglia are infrequent in the rats that received the 3-AP regimen plus ibogaine. Photomicrographs of coronal sections show microglial cells immunostained with antiserum OX42 for complement receptor 3B. Drug doses: A, C, E, ibogaine (100 mg/kg);B, D, F, 3-AP regimen given 6 d before ibogaine (100 mg/kg). In all cases, survival was 7 d after ibogaine administration. Scale bars: A, B, 500 μm; C, D, 100 μm; E, F, 50 μm.