Angiotensin II protects DA neurons in vitro from MPP+ toxicity only in the presence of the AT1 receptor antagonist losartan. (a) Microscopic view of TH+ (DA) neurons in VM cultures in the presence of media or MPP+ (10 μM) alone, MPP+ with Ang II (100 nM), and MPP+ with either losartan (1 μM) or PD123319 (1 μM). Scale bar equal to 50 μm. (b) Quantification of TH+ neuron counts in VM cultures treated with increasing concentrations of MPP+ (1–100 μM) in the presence or absence of Ang II (100 nM) and AT receptor antagonists, losartan (1 μM) (AT1R) and/or PD123319 (1 μM) (AT2R). Results are mean ± SEM. (n = 4–6). (*) Represents a significant difference (p ≤ 0.05, One-way ANOVA followed by Newman-Keuls post-hoc test) from MPP+.