Fig. 3.

Activated microglia exhibit a different distribution and morphology in ibogaine- versus 3-AP-treated animals. After ibogaine administration (100 mg/kg; 7 d survival), activated microglia form radial bands located primarily in the vermis (A); the most intensely activated microglia (C) are found at the depth of Purkinje cell bodies (which have degenerated, as observed in adjacent sections). After the 3-AP regimen (13 d survival), occasional activated microglia are observed far laterally in the hemispheres (B, arrowhead), primarily in the ansiform lobule, crus I, and less commonly in the vermis; these activated cells are found mainly in the molecular layer and tended not to be adjacent to Purkinje cell bodies (D). Enlarged, darkly immunoreactive cells are activated microglia. More delicate cellular profiles (C, D) with finer processes, smaller cell bodies, and less intense immunostaining are quiescent microglia. In ibogaine-treated animals, activated microglia (C) are larger and more darkly immunoreactive than those seen after the 3-AP regimen (D), suggesting that 3-AP may cause a smaller degree of neuronal insult. Coronal sections immunostained with antibody OX42 for complement receptor 3B. Scale bars: A, B, 500 μm; C, D, 50 μm. P, Purkinje cell layer.