Figure 1.

Increased ZIP1 and ZIP3 expression during maturation of primary hippocampal neurons enhances Zn²⁺ uptake. A, ZIP1 (upper, magenta) and ZIP3 (lower, yellow) immunofluorescent labeling of DIV12 primary hippocampal neurons. Nuclei are stained with DAPI (blue). B, ZIP1 (upper, magenta) and ZIP3 (lower, yellow) co-immunolabeling with the axonal marker Tau (blue) of DIV21 primary hippocampal neurons. C, Analysis of mRNA expression levels of ZIP1 and ZIP3 in DIV17 hippocampal neurons compared with DIV10 (normalized to 1, shown as dotted line; n = 3 cultures per age group; *p ≤ 0.05, t test). D, Traces of FluoZin-3 fluorescence changes (left) in cultured hippocampal neurons perfused with 100 μm Zn²⁺ in Ringer's solution, added at the indicated time. Averaged initial slope of fluorescent signal rise (right), representing Zn²⁺ influx, in hippocampal neurons (DIV10: n = 34 coverslips in 5 independent experiments; DIV17: n = 23 coverslips in 4 independent experiments; ***p ≤ 0.001; using t test compared with DIV10). E, Representative images (10× magnification) of primary hippocampal neurons, before (50 s, marked in D) and after (250 s) exposure to 100 μm Zn²⁺-containing Ringer's solution, as used for D. Cultures of DIV10 neurons shown in left panels and DIV17 neurons shown in right panels. Scale bar for A, B: 10 µm.