Fig. 4

Identification of miR-142-5p as a molecule responsible for SC-EV-induced memory impairment and dendritic spine damage. We designed and constructed an AAV carrying a specific Schwann cell promoter that modulates (upregulates or encloses) miR-142-5p expression in Schwann cells after sciatic nerve injection. (A) Flowchart for establishing the CCI model, injecting AAV, and evaluating memory-related behaviors. (B) The AAV-miRNA-142-5p sponge enhanced the spontaneous alternation behavior of CCI rats compared with that of rats in the CCI + AAV-NC group; however, AAV-miR-142-5p aggravated this behavior. n = 9–10 rats. two-way ANOVA followed by Tukey’s multiple comparisons test was used. (C) The AAV-miRNA-142-5p sponge increased the recognition index of CCI rats in the ORM, OLM and TOM tests compared with that of rats in the CCI + AAV-NC group; however, AAV-miR-142-5p aggravated this index. n = 8–10 rats. ordinary one-way followed by Tukey’s multiple comparisons test was used for OLM and TOM; mixed-effect analysis followed by Holm-Šídák’s multiple comparisons test was used for ORM; (D, E) After Golgi staining, Sholl analysis and ImageJ analysis showed that, compared with those in neurons in the rat hippocampus of the CCI + AAV-NC group, the AAV-miRNA-142-5p sponge rescued the dendritic complexity, dendritic length, density, and spine head size in hippocampal neurons of CCI rats, but AAV-miR-142-5p exacerbated these parameters. n = 5–6 stained sections from 3 animals in each group. ordinary one-way followed by Tukey’s multiple comparisons test was used for spine head size and dendritic length; two-way ANOVA followed by Tukey’s multiple comparisons test was used for dendritic complexity; mixed-effects analysis followed by Tukey’s multiple comparisons test was used for dendritic density; (F) DIL staining showed that the miR-142-5p antagomir effectively counteracted the reduction in dendritic spine density observed in primary hippocampal neurons following exposure to plasma_EV^CCI. n = 6 images from three wells per group. ordinary one-way followed by Tukey’s multiple comparisons test was used. (G) The AAV-miRNA-142-5p sponge increased PSD95, SYN and BDNF protein levels in the hippocampus of CCI rats, but AAV-miR-142-5p decreased PSD95, SYN and BDNF protein levels. Ordinary one-way followed by Tukey’s multiple comparisons test was used. The data are shown as the means ± SDs. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001