Fig 1.
A1-B1. Input/output (I/O) curves obtained in CA1 area following Schaffer collateral stimulation in hippocampal slices from the three experimental groups of FSL rats (A1) and SD rats (B2). In all groups, the I/O curves were fitted to a sigmoid curve and the fitting resulting curve compared statistically according to the F test (see Material and Methods). According to this analysis, in FSL rats the sigmoid curve from the social isolation group (SI) differs significantly from the rest of the groups (GH and SI+R; ***P<0.0001), indicating an increase in synaptic transmission after social isolation. In SD rats (B1), each experimental group has its own sigmoidal function but they are not significantly different from each other. (N = 7 slices; 7 animals per group). A2-B2. LTP of Shaffer collateral (SC)-CA1 pyramidal cells synapses from FSL (A2) and SD (B2) hippocampal slices. Potentiation was measured as the slope of the fEPSP normalized to the average slope before high frequency stimulation (HFS). Time 0 indicates the onset of 3 HFS. (N = 7 slices, 7 animals per group). Top traces in A2 represent averaged fEPSPs from 5–0 minutes before stimulation (1) or 35–40 minutes after stimulation from representative slices taken from FSL:SI and FSL:SI+R groups. A3. Paired-pulse facilitation (PPF) obtained in CA1 area following collateral stimulation in hippocampal slices from the three experimental groups of FSL rats. PPF ratio: second fEPSP slope/first fEPSP slope. (N = 7 slices; 7 animals per group). C. Summary of the experiments shown in A2-B2. At 45–55 min after post-induction, potentiation in the FSL_SI group is decreased compared to FSL_GH group (*P<0.05). Running counteracts this effect (* P<0.05). SD rats show a higher level of potentiation compared to FSL rats (*** P<0.001 FSL_GH vs. SD_GH) no affected by social isolation or running. Bar-graph data in C represent means ± s.e.m. GH:group-housed, SI: social-isolated, SI +R: social-isolated with access to a running wheel.
Fig 2.
Quantification of the D-serine content in the hippocampal homogenates by enantioselective chromatography (N = 7–8 animals per group).
Bar-graph represent means ± s.e.m. GH:group-housed, SI: social-isolated, SI +R: social-isolated with access to a running wheel.
Fig 3.
A-C. Representative western blots with their corresponding molecular weights (kDa) (A) and densitometry analysis for the different tested proteins: AMPA-R subunits: GluA1-2 (B), the astrocytic marker GFAP (C) and glial glutamate transporters: GLAST and GLT-1 (D) presented as percentage (%) of GH (control group) after normalization to β-actin or vinculin (loading control). Bar-graph data represent means ± s.e.m. (N = 6–8 animals per group). GH: group-housed, SI: social-isolated, SI +R: social-isolated with access to a running wheel. ***, * vs. GH; # vs. SI+R; one-way ANOVA followed by Bonferroni’s multiple comparisons test. GH:group-housed, SI: social-isolated, SI +R: social-isolated with access to a running wheel.