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. 2021 Jan 11;13(2):e12632. doi: 10.15252/emmm.202012632

Figure 6. Slc6a20a‐mutant mice show abnormal increases in extracellular glycine levels and NMDAR function.

Figure 6

  1. Schematic diagram showing the generation of Slc6a20a‐mutant mice. The SLC6A20 antibody is denoted by “Y” above exon (Ex) 6.
  2. Decreased levels of Slc6a20a, but not Slc6a20b, mRNAs in the brain of Slc6a20a +/− (HT) and Slc6a20a −/− (KO) mice (P21–28), as shown by qRT–PCR analysis. (n = 4, 3, 3 mice for WT, HT, and KO; *P < 0.05, **P < 0.01, ns, not significant, one‐way ANOVA with Bonferroni's test). The error bars represent SEM.
  3. Reduced expression of SLC6A20 proteins in the brains of Slc6a20a +/− and Slc6a20a −/− mice (P21 for HT and P24–28 for WT and KO), as indicated by immunoblot analysis of total brain lysates. β‐actin and α‐tubulin were used as loading controls. (n = 3 mice for WT, HT, and KO, *P < 0.05, Student's t‐test). The error bars represent SEM.
  4. Increased extracellular levels of glycine and proline in the brain of Slc6a20a +/− and Slc6a20a −/− mice, as shown by microdialysis analyses. Note that glycine levels are increased in both Slc6a20a +/− and Slc6a20a −/− mice, whereas proline levels are increased only in Slc6a20a −/− mice. (glycine, n = 19 mice for WT, 11 for HT, 8 for KO, **P < 0.01, Mann–Whitney U‐test; proline, n = 15 mice for WT, 11 for HT, 14 for KO, ***P < 0.001, ns, not significant, Mann–Whitney U‐test). The error bars represent SEM.
  5. Increased NMDA/AMPA ratio at hippocampal SC‐CA1 synapses in Slc6a20a +/− mice (P17–20), as indicated by the ratio of NMDAR EPSCs to AMPAR EPSCs. (n = 9 neurons from three mice for WT and 11 (4) for Slc6a20a HT mice, **P < 0.01, Mann–Whitney U‐test). The error bars represent SEM.
  6. Normal frequency and amplitude of mEPSCs in hippocampal CA1 pyramidal cells in Slc6a20a +/− mice (P17–20). (mEPSC, n = 14 neurons from three mice for WT and 16 (3) for HT; ns, not significant, Student's t‐test). The error bars represent SEM.

Source data are available online for this figure.