TIME-COURSE OF CHOLINERGIC AND MONOAMINERGIC CHANGES IN RAT-BRAIN AFTER IMMUNOLESIONING WITH 192-IGG-SAPORIN

192 IgG-saporin, an immunotoxin targeted at the low affinity NGF recep tor, was infused into the lateral ventricle of rat brain. Three days a nd one week post lesion, choline acetyltransferase activity was marked ly decreased in cortex, hippocampus, olfactory bulbs, and septum (brai n regions innervated by the cholinergic neurons of the basal forebrain ) with no change in cerebellum, striatum or pons. Measurement of monoa mine levels revealed increases in HVA, DOPAC and dopamine, primarily i n the olfactory bulbs at the 28-day time point only, suggesting a comp ensation for cholinergic inactivity. High levels of basal forebrain ch olinergic lesioning can be obtained with this immunotoxin with minimal or no effects on monoaminergic or other cholinergic systems.