Fig. 2: H3K27me3 mediates the spatial memory deficits induced by Pb exposure.

a Schematic illustration of experimental design and construction of lentivectors. Pb-exposed rats were injected with repackaged lentivirus at PND10. Animals were trained for 5 days (four trials per day) to find the hidden platform, and followed by the probe trial 24 h later, in which the platform is not present. Spine examinations were conducted at PND21 and PND60, respectively. b Representative images of hippocampus following the injection of pReceiver-EZH2-containing virus (n = 8, scale bar: 100 μm). c Immunoblots and quantification of protein levels of H3K27me3 upon the overexpression of EZH2 at PND21 (n = 6, Mann–Whitney U test; column 1 vs. column 2; independent two-sample t test, two-tailed; column 2 vs. column 3 **P = 0.0088; column 3 vs. column 4 *P = 0.0025). d–f The Morris water maze (MWM) tests assessing the capacities to be trained to find the hidden platform (n = 8, independent two-sample t test, two-tailed; column 1 vs. column 2 *P = 0.0182; column 2 vs. column 4 *P = 0.0162; column 3 vs. column 4 *P = 0.0460). The latency d was recorded and analyzed (two-way ANOVA) during the training days. For assessment, based on their respective moving tracks (e), the number of times crossing the platform (f) were counted at PND60. g–l Morphological analysis of dendritic spines of hippocampal neurons (~150 dendritic spines per experimental condition). g Representative images of neuronal dendritic arborization in the region of CA1. Representative images (h) and quantification of spine densities were shown in the region of CA1 (i, independent two-sample t test, two-tailed for column 2 vs. column 4, column 7 vs. column 8; Mann–Whitney U test for other comparisons). j Representative images of neuronal dendritic arborization in the region of DG. Representative images (k) and quantification of spine densities were shown in the region DG (l, independent two-sample t test, two-tailed for column 1 vs. column 2, column 7 vs. column 8 *P = 0.0122; Mann–Whitney U test for other comparisons). Vec and EZH2-OE refer to the rats infected with lentivirus harboring the empty and pReceiver-EZH2 vector, respectively. The data are represented as mean ± SEM; ***P < 0.001, **P < 0.01, and *P < 0.05. Symbols show individual samples. The different types of symbols represent the different groups. In c, the solid circle, solid square, solid triangle, and inverted solid triangle represent control, Pb, Pb+EZH2-OE, and Pb+Vec, respectively. In f, the solid circle, solid square, solid triangle, and inverted solid triangle represent control, Pb, Pb+Vec, and Pb+EZH2-OE, respectively