Memory disruption in rats with nigral lesions induced by MPTP: a model forearly Parkinson's disease amnesia

Intra-nigral administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyrindin e (MPTP) caused a lesion in the substantia nigra, compact part (SNc) and a specific loss of dopamine and its metabolites in the striatum of rats, The animals were then tested in the two-way active avoidance task. MPTP-treated animals presented lower learning scores in the training and test sessions, an effect that was not caused by motor impairment or by a decreased sensit ivity to footshock since their reaction time to the footshock (unconditione d stimulus - UCS) was not reduced. These lower scores were also not attribu table to lower acoustic sensitivity or to a slowing in the association of t he sound cue (conditioned stimulus - CS) with the UCS since the reaction ti me to the CS in the active avoidance response did not differ between MPTP-t reated and control groups, Therefore, these results are more properly attri butable to an impairment of the memory acquisition and retention processes, In addition, this study is presented as a model of early Parkinson's Disea se amnesia and is discussed in terms of the importance of the nigrostriatal pathway to memory acquisition and storage processes, (C) 2001 Elsevier Sci ence B.V. All rights reserved.