AF64A affects septal choline acetyltransferase but not parvalbumin immunoreactive cells.

Rats received bilateral intracerebroventricular (ICV) infusions of either AF64A (1.5 nmol/ventricle; n = 9) or vehicle (3.0 microliters/ventricle; n = 7). Four weeks later, the animals were anesthetized and their brains processed to visualize and quantify choline acetyltransferase (ChAT) immunoreactive (IR) and parvalbumin-IR GABAergic neurons in the septal complex by immunocytochemistry (PAP method). AF64A significantly reduced the number of ChAT-IR perikarya in the medial septum (28%), ventral limb of the diagonal band of Broca (30%), and horizontal limb of the diagonal band of Broca (20%), but did not affect the number of parvalbumin-containing GABAergic neurons in any of the septal subdivisions. These results provide further evidence that AF64A is a selective cholinotoxin.