MC192-saporin is an antibody conjugate comprising of the monoclonal antibody MC192 against rat p75^NTR, the nerve growth factor receptor, chemically conjugated via a reducible disulfide bridge to the ribosome-inactivating protein saporin, purified from saponaria officinalis. Unconjugated saporin is incapable of entering the cells due to the apparent lack of ligand. Upon specific binding via MC192 to the cells expressing p75^NTR, saporin transverses the cell membrane leading to lesion of neurochemically defined neuronal populations. The targets of MC192-Saporin are p75^NTR-expressing cells including cholinergic neurons of the basal forebrain, cerebellar Purkinje cells, medial septum, diagonal band of Broca, Nucleus basalis of Meynert and some tumour cells. MC192-saporin has been used in the study of learning and memory and its primary application is in vivo, MC192-saporin is specific for applications in rat. The antibody does not cross-react with human or mouse p75^NTR receptors.