Abstracts

Rationale: Early-life status epilepticus (SE) is known to cause long-term deficits in learning, memory, social behavior, and communication. In order to better understand the acute effects of SE, our laboratory has used ultrasonic vocalizations (USV) to investigate early communication deficits in mice. We have previously found that male mice that had experienced SE on postnatal day (PD) 10 present a decreased number of 50KHz USVs on PD12. In the current study, we aimed to investigate the effects of SE on communication at an earlier timepoint in development that has not previously been investigated. Also, we assessed if there were any dimorphic effects of SE in communication.

Methods: Male and female C57BL/6 mice were housed and monitored at Baylor University for this experiment. We induced SE using an intraperitoneal injection of 0.5% KA (2.5mg/kg) on PD7. Age-matched control male and female pups were administered 0.9% physiological saline. After the injection, the mice were placed into an individual container with clean bedding and monitored through the duration of SE, which is characterized by continuous tonic-clonic seizures lasting 1-2 h. Control pups were also monitored during this time. On PD8 mice were placed individually into containers where they were separated from the dam and sire. Their vocalizations were recorded for a total of two minutes through the Avisoft software. The files were analyzed in Matlab DeepSqueak where the calls were quantified and characterized.  Vocalizations were then individually characterized based on established categories. A measure of total number of calls; total number of complex, two-component, upward, downward, chevron, short, composite, frequency steps, and flat calls; total duration of calls; Percentage of complex, two-component, upward, downward, chevron, short, composite, frequency steps, and flat calls; total duration of call; Average call duration; Average Median Frequency of calls; Average Amplitude of calls; and first call latency. 

Results: Analysis of USVs showed that total number of calls did not differ between the groups.  Two-way ANOVA revealed an interaction between treatment and sex in the total number of flat calls (p < 0.05).  But a Tukey post hoc analysis showed no significant difference between the groups indicating a female sex effect. An interaction between treatment and sex was also identified for call duration and peak frequency. Post hoc analysis revealed that SE females pups presented lower call duration and increased peak frequency compared to female controls (P < 0.05). A significant main effect was found with a two-way ANOVA with females having a significantly higher average amplitude.