Fig. 4. ASD astrocyte chimeric mice exhibit impaired fear memory and hippocampal LTP along with repetitive behavior.

a–d ASD astrocyte chimeric mice displayed deficits in fear memory but not in fear learning. a Schematic summarizing classical fear-conditioning paradigm. On day 1, mice were trained to associate an audible tone (30 s duration, 70 dB) with a co-terminating foot shock (1-s duration, 0.7 mA). Testing days 2 and 3 measured freezing behavior in response to exposure to the training context or an audible cue in a novel context, respectively. Freezing behavior in the testing trials provided a quantifiable measure of fear memory (see also “Methods”). b There was no significant difference in the rate of acquisition learning between CTRL and ASD mice (ANOVA with Bonferroni posthoc test p value >0.05). c ASD chimeric mice showed reduced freezing behavior when exposed to the fear context (unpaired t-test = 0.009). d No differences were found in the freezing behavior between CTRL or ASD chimeric mice during cue presentation in a novel context (unpaired t-test = 0.10). e, f LTP was tested as a synaptic correlate of learning and memory in hippocampal brain slices (400 µm) of 4–6-month old transplanted mice. ASD astrocyte chimeric brain slices showed reduced potentiation in the early phase of LTP compared to control (30–60 min). ASD astrocyte chimeric brain slices displayed the greatest differences in the fEPSP slope within the first 60 min of recording (f). g, h To test ASD chimeric mice for repetitive behavior, we employed the marble burying test as well as monitored circling and backflipping. Marbles were scored as buried if at least 60% of the marble was covered (30-min period) (g). ASD astrocyte chimeric mice buried significantly more marbles when compared to CTRL astrocyte chimeric mice (unpaired t-test = 0.009) but exhibited no circling or backflipping (h). Taken together, these results indicate that ASD astrocytes induce ASD-related perseverative behavior, memory dysfunction, and hippocampal LTP deficits. Data are represented as mean ± SEM. Fear testing: CTRL n = 21 male and female mice/4 distinct lines, ASD n = 22 male and female mice/3 distinct lines; LTP: CTRL n = 10 slices, 4 mice/2 distinct lines; ASD n = 10 slices, 5 mice/2 distinct lines). Marble burying behavior: CTRL n = 16 mice/5 distinct lines, ASD n = 13 mice/5 distinct lines.