Fig 2: Effect of LT‐102 treatment on BDNF expression and GluA1 phosphorylation. (A) Expression of BDNF, the ratio of pGluA1/GluA1, and total GluA1 following 24 h of LT‐102 incubation in the presence of 1 μM s‐AMPA (n = 6, one‐way ANOVA). (B) Expression of BDNF, the ratio of pGluA1/GluA1, and total GluA1 following 24 h of LT‐102 incubation in the absence of s‐AMPA (n = 6, one‐way ANOVA). (C) Expression of BDNF, the ratio of pGluA1/GluA1, and total GluA1 were significantly inhibited by NBQX (10 μM) (n = 6, Two‐way ANOVA). *p < 0.05, **p < 0.01, ***p < 0.001 vs Control (0); ### p < 0.001 vs LT‐102 (10 nM) + AMPA (1 μM); +++ p < 0.001 vs LT‐102 (30 nM) + AMPA (1 μM); ns means no significance.

Fig 3: Negative regulation of GLT-1 by astrocytes HDAC2 leads to dysfunction of glutamate reuptake in the synaptic cleft. In normal condition, the acetylation of histones in astrocytes facilitates the transcriptional regulation of GLT-1. Glutamate in the synaptic cleft is rapidly absorbed into astrocytes to maintain excitability of synapses. The increase of HDAC2 in astrocytes after SAH results in the deacetylation of histones and inhibits the transcription expression of GLT-1. The decrease of GLT-1 expression will lead to the impairment of glutamate reuptake in astrocytes and the long-term accumulation of glutamate in the synaptic space, resulting the dephosphorylation of ionized glutamate receptors GluN2B and GluA1 on the postsynaptic membrane. These eventually result in the long-term inhibition of synaptic excitability and DCI. DCI, delayed cognitive impairment.

Fig 4: The changes of interstitial glutamate concentration, astrocytic glutamate reuptake function, and the expression of GluN2B, GluA1 and glutamate transporters in hippocampus after SAH at 8 weeks. (A) The concentration of interstitial glutamate in the hippocampus of the mice was detected by HPLC-MS/MS. **, P<0.01, the SAH group vs. the sham group. N=8 mice per group. (B) Glutamate uptake assay on the hippocampal astrocytes sorted by immunomagnetic beads. **, P<0.01, the SAH group vs. the sham group. N=6 mice per group. (C,D) Western blot was performed to detect the expression of p-GluN2B/GluN2B, p-GluA1/GluA1, GLT-1, and GLAST protein in hippocampal tissue in the sham group and the SAH group at 1 week before and 8 weeks after SAH. **, P<0.01, vs. the indicated groups. N=5 animals in each group.

Fig 5: DHHC2 is required for GluA1 surface expression in response to LTP(A and B) Representative western blots (A) and statistical results (B) of co-immunoprecipitation between AKAP150 and PKA in the hippocampus after DHHC2 knockdown (n = 4 per group).(C) Representative western blots of GluA1, phosphorylated GluA1 at Ser831 and Ser845, and GluA1 surface expression after treating with HFS and LV-shDHHC2.(D–G) Statistical results of GluA1 expression (D), phosphorylation level of GluA1 at Ser831 (E) and Ser845 (F), and GluA1 surface expression (G) (n = 5 per group).(H) Time-course of LTP induced by HFS in hippocampal slices from the LV-eGFP/LV-shDHHC2-treated groups.(I) Statistical histogram showing LTP magnitude averaged from the last 15 min of recordings from the two groups (n = 4 per group).Two-way ANOVA for (A–G), and Student’s t test for (I). Data represented are means ± SEM. ∗p < 0.05, ∗∗p < 0.01 and ∗∗∗p < 0.001; #p < 0.05 and ##p < 0.01.