I believe tyrosime hydroxylase is located in several places in brain see Ref https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4023077/ and TH is rate limiting in the synthesis of dopamine (as well as epinephrine and norepinephrine).Perhaps dual staining with a more specific FOXA2 antibody which is a transcriptional activator that regulates specification and differentiation of dopaminergic neurons.