9cRA treatment increased survival of TH cells in lesioned nigra. TH (+) cell number (A) in SN and (B) in VTA were counted using unbiased stereology in 11 rats. (A) Injection of 6-OHDA reduced cell number of dopamine neurons in lesioned side (L) SN (p<0.001). Treatment with 9cRA significantly increased dopamine cell number in the lesioned side (L) SN (p=0.026). No change was found in the contralateral (non-lesioned, R) side SN (p=0.432). (B) TH cell number in A10. There is no significant difference after lesioning or after 9cRA treatment in VTA (p=0.734).