Loss of DARPP-32 induced by Htt171-82Q is more severe in old rats.

<p>Young (3 week) and old (15 month) rats received a stereotaxic injection of a mixture of lentiviral vectors (4 µl, 200 ng/µl of p24) encoding either Htt171-82Q and β-Gal or Htt171-18Q and β-Gal. Histological evaluation was carried out 12 weeks after infection using DARPP-32 immunohistochemistry. <i>A</i>, representative photomicrograph showing the loss of DARPP-32 in the striatum of a young rat. <i>B</i>, loss of DARPP-32 in the striatum of an old rat. Black arrowheads indicate the area with loss of staining. <i>C</i>, quantification of the volume of DARPP-32-depleted striatum. The loss measured after infection with lenti-Htt171-18Q corresponds to the mechanical damage caused by the injection needle. Note that lesions produced by Htt171-82Q are (+40%) larger in old rats. Results are expressed as mean+/−SEM. *p<0.05, Htt171-82Q vs. Htt171-18Q; #, p<0.01, young vs. old, ANOVA and Bonferroni's <i>post hoc</i> test.