CDNF and Parkinson disease: By contrast, Ren et al. reported that AAV2-mediated expression of CDNF in the striatum efficiently protected the TH+ cells and surprisingly improved the drug-induced rotational behavior of PD rats and raised the level of TH+ neurons in the SNpc to 77.0% of the control side, when AAV2-CDNF was administered 6 weeks post lesion with 6-OHDA [27].