Effect of ethylcholine mustard aziridinium (AF64A) and of the monoamine oxidase-B-inhibitor L-deprenyl on the morphology of the rat hippocampus.

The effect of intracerebroventricular (ICV) administration of ethylcholine mustard aziridinium (AF64A) and of the monoamine oxidase (MAO)-B inhibitor L-deprenyl on MAO-A and MAO-B activities and on the morphology of the rat neostriatum and hippocampus were studied. The ICV administration of AF64A was without effect on MAO-A and MAO-B in the neostriatum and caused an increase of MAO-B but not of MAO-A in the hippocampus. No changes in neostriatal micro-anatomy were noticeable in AF64A-injected rats, whereas the neurotoxin caused an impairment in hippocampal micro-anatomy consisting in the loss of nerve cells and of silver-gold impregnated fibres in the CA-1--CA-3 fields. The treatment of AF64A-injected animals with doses of L-deprenyl from 11.17 microM/kg/day significantly reduced MAO-B activity in the hippocampus and improved the morphology of the hippocampus formation. L-deprenyl was without effect on MAO-A activity both in the neostriatum and in the hippocampus, as well as on neostriatal MAO-B activity and morphology. The possibility that MAO-B inhibition may represent a principle for the treatment of age-related physiological and pathological changes characterized by increased MAO-B activity is discussed.