Figure 9.

Deletion of Shh in DA neurons does not affect total Shh mRNA or protein levels in the SN

(A) The specificity of Shh and Gli1 qPCR primer/probe sets are validated in Shh global heterozygous KO mice. Using these validated primer/probe sets, we did not detect any changes in the levels of Shh or Gli1 mRNA levels in DATcre-shh cKO mice in the SN or STR, suggesting that Shh is not expressed in DAT + DA neurons (B). Consistent with these results, there is no difference in striatal mRNA expression levels of Gli1, Chat, Vchat, Gdnf, Drd1a or Drd2 between WT or DATcre-shh cKO mice (C). Similarly, to validate the specificity of the SHH ELISA kit, we measured SHH levels in brain lysate in WT or heterozygous global Shh KO mice. The results from this assay show a 50% decrease in SHH protein expression in brain lysates in Shh heterozygous knockout mice (D). However, using the same ELISA kit, we did not detect any changes in SHH levels in WT or DATcre-shh cKO mice in the STR, SN or SVZ regions (E), suggesting that Shh is not actively expressed in DA neurons under physiological conditions in the adult mouse brain. Each data point represents an individual mouse (3–6 month old). Mean + SEM. ∗<0.05, Student’s t test.