CONICET | Buscador de Institutos y Recursos Humanos

The rate of ultrasonic vocalizations emitted by mouse pups can be modulated by a variety of conditions, including age, maternal separation and exposure to olfactory stimuli, and the degree of modulation varies depending on mouse strain. Here we addressed whether neonatal ultrasonic vocalizations were susceptible to maternal potentiation and to inhibition by the presentation of aversive olfactory stimuli in a transgenic mouse line that fluorescently reports glial cells (S100B-GFP mice), previously uncharacterized for these responses. We found that the rate of ultrasonic vocalizations during the first 5 minutes after nest separation peaked at the end of the first postnatal week. Nest separation of 1-week-old mouse pups during 5 minutes followed by re-exposure to the nest (mother plus littermates) for another 5 minutes produced potentiation of the rate of ultrasonic vocalizations, emitted in the 75-85 kHz frequency band, by 90 ± 31 %, from a basal value of 12 ± 8 vocalizations per minute. In addition, the aversive odorant citral diluted at 10 % produced an inhibition of 76 ± 10 % of the rate of vocalizations after maternal potentiation, while citral diluted at 1 % had no inhibitory effect. These data are consistent with published work characterizing other mouse strains and sets the starting point to explore the sensitivity of ultrasonic vocalization inhibition by aversive olfactory stimuli to evaluate differences in olfactory thresholds.