Effect of lithium-pilocarpine-induced status epilepticus on ultrasonic vocalizations in the infant rat pup

•SE was induced by lithium-pilocarpine in fourteen-day-old (P14) rat pups.•Maternal separation-induced USVs were monitored at P15, P16, and P21.•SE did decrease the latency to the first USV and the average duration of USVs.•The effect of SE on USVs was observed in male, but not in female, rat pups.

Evidence shows that febrile convulsions induced in rat pups increase ultrasonic vocalizations (USVs); however, the effect of status epilepticus (SE) induced in developing rats on USVs has not been fully investigated. The goal of this study was to analyze USVs following lithium-pilocarpine-induced SE in fourteen-day-old (P14) rat pups. The rat pups were given 3-mEq/kg lithium chloride i.p. on the day before the induction of SE, which was carried out at P14 by subcutaneous injection of 100-mg/kg pilocarpine hydrochloride; control animals were given an equal volume of lithium chloride and saline on P13 and P14, respectively. Ultrasonic vocalizations were monitored at P15, P16, and P21 with a Mini 3 Bat Detector Ultra Sound Advice (15 kHz-160 kHz) set at 40 ± 4 kHz and digitally recorded in WAV format using the Audacity 1.3 beta software. A clear box (60 × 40 × 30 cm) split down the middle with a holed wall was used; each pup was placed alone in one compartment, whereas its dam was placed on the other cage side at room temperature. Vocalizations were recorded over a 5-minute period, converted to sonograms and spectrograms, and analyzed using the Raven software. Parameters evaluated were as follows: USV frequency, latency to the first USV, and mean USV duration. There was a significant decrease in the latency (35.5 ± 6.9 s) and duration (50.8 ± 8.6 s) of USVs after SE compared with the control group (81.9 ± 10.8 s and 78.1 ± 9.9 s, respectively). Status epilepticus affected male and female rats differentially.