Primary midbrain cultures from E17 rat embryos were treated with IQ, MeIQ, MeIQx, 4,8-DiMeIQx and PhIP for 24 h at concentrations of 100 nM – 5 µM. Cells were stained for tyrosine hydroxylase, TH (green) to identify dopamine neurons and microtubule-associated protein 2, MAP2 (red) to identify all neurons. Quantification was performed at all doses, while representative images are shown here from a 1 µM treatment, where the majority of tested HCAs exhibited selective dopamine toxicity. Images were obtained used an automated Cytation 3 cell imaging reader with a 4× objective. Scale bar represents 100 µm.