Abstracts

Rationale:
One of the most common comorbid disorders diagnosed in children with epilepsy is Autism spectrum disorder. While previous studies have provided evidence for how early-life seizures can impact behavioral outcomes in adulthood, few studies have examined the mechanism in which seizures effect autistic-like behaviors in an acute time period. Heightened neuroinflammation and altered signaling via the mammalian target of rapamycin (mTOR) pathway are two potential processes that could underlie epileptogenesis, and in addition are known to interact to influence disease states.
Method:
The present study examined the role of PI3K/Akt/mTOR pathway activity and neuroinflammatory signaling in the development of autistic-like behavior following seizures in the neonatal period. Male and female C57Bl/6 mice were administered 3 flurothyl seizures on postnatal (PD) 10, followed by administration of minocycline, the mTOR inhibitor rapamycin, or a combined treatment of both therapeutics. On PD12, isolation-induced ultrasonic vocalizations (USVs) of mice were examined to determine the impact of seizures and treatment on communicative behaviors, a component of the autistic-like phenotype. Hippocampal tissue was collected on PD12 to examine cytokine expression with qRT-PCR, along with western blotting to examine mTOR protein expression and glial reactivity in both sexes.
Results:
Three flurothyl seizures on PD10 increased the quantity of USVs emitted by female mice compared to control mice on PD12 (p < 0.05), however, no difference in USV quantity was detected in male mice. Rapamycin treatment significantly altered USV properties in both sexes. Rapamycin-treated male and female mice emitted significantly fewer USVs and USVs of reduced duration compared to several other treatment groups (p < 0.05). The types of calls emitted were significantly different between seizure and control pups, with male seizure mice emitting a significantly reduced proportion of complex call types (p < 0.05). Seizures did not result in enhanced hippocampal pro-inflammatory cytokine expression (IL-1β, IL-6, or TNFα) on PD12 in either sex. Seizures significantly increased p70S6K expression in male mice, however, no other changes in mTOR activity were observed in either sex. Mice that received rapamycin treatment had significantly reduced hippocampal expression of % total pS6(235,236) and % total pS6(240,244). Flurothyl seizures resulted in increased astrocyte reactivity (GFAP) in male mice (p < 0.05), however, females had no change in GFAP expression in the hippocampus.
Conclusion:
These findings emphasize the importance of differences that may exist across preclinical seizure models, as three flurothyl seizures did not induce as drastic of changes in mTOR activity or inflammation as observed in other models. Early-life seizures can have a profound impact on the developing brain, and thus it is critical to continue investigating potential therapeutics that target the underlying pathology of seizures and could prevent the development of cognitive and behavioral comorbidities.
Funding:
:National Institutes of Health (NIH) [Grant Number: NS088776]