Fig. 3

The effect of SiPCL-NP-exposure on tyrosine hydroxylase-immunoreactive (TH-ir) cell numbers was studied in SH-SY5Y cells undifferentiated (Undiff) or differentiated with retinoic acid (RA) or staurosporine (ST). SiPCL-NPs were incubated for 24 h at day in vitro (DIV) 1 (A), DIV4 (B) or DIV6 (C) at a concentration of (2.6 × 10¹⁰ NPs/ml). The dopaminergic phenotype was analyzed at DIV7. The data represent TH-ir cells and are given as mean percentage (%) of TH-ir cells of the total number of cells. Error bars correspond to SEM. Significant differences between control- and NP-exposed-groups are labeled with asterisks (*p ≤ 0.001; **p ≤ 0.0001). Representative immunofluorescence microscopy images of TH-ir cells (red) are depicted in D–F (D = Undiff NP DIV4, E = RA NP DIV4, F = ST NP DIV4). NPs are shown in red and cell nuclei in blue. Magnification ×630, scale bar = 10 μm