In the present study, we used a rat model of HD [11]–[15] in which striatal degeneration is induced by lentiviral vectors encoding the 171 N-terminal amino acids of human Htt with an 82 CAG-repeat pathological expansion (Htt-171-82Q), in order to directly compare the neurotoxicity of mutant Htt in young and old animals. Here, HTT is linked to Huntington disease.