title: Quantitative and qualitative analysis of rat pup ultrasonic vocalization sounds induced by a hypothermic stimulus.
abstract: Ultrasonic vocalizations (USVs) are essential communicative sounds used between rodent pups and their mother. Rat pups emit USVs in stressful situations, such as when they are cold or separated from the nest. We verified the ontogenetic changes in USVs emitted by infant rats isolated from their mother during the pre-weaning period. The number of calls, and the median frequency and first peak of frequency of the calls were measured at 1, 3, 5, 7, 10, 12, and 14 days postnatal age in Wistar-Imamichi rats. Pups were placed in a cold glass beaker and USVs were recorded for 5 min. The number of calls increased to a peak on day 5 and then gradually decreased. The median frequency of calls decreased slowly during the first 12 days, and then increased slightly on day 14. Similarly, the first peak frequency of calls was the highest on day 1, and then decreased gradually by day 12. A small increase was observed on day 14. These changes in frequency were correlated with the physical development of the pups, whose body weights increased significantly with age except during postnatal days 7-10.
authors.affiliation: Behavioral Neuroscience Laboratory, Graduate School of Veterinary Medicine, Nippon Veterinary and Life Science University, Musashino, Tokyo, Japan. ; Department of Physiology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand.
authors.forename: Pudcharaporn
authors.initials: P
authors.lastname: Kromkhun
authors.forename: Masahiro
authors.initials: M
authors.lastname: Katou
authors.forename: Haruo
authors.initials: H
authors.lastname: Hashimoto
authors.forename: Misao
authors.initials: M
authors.lastname: Terada
authors.forename: Changjong
authors.initials: C
authors.lastname: Moon
authors.forename: Toru R
authors.initials: TR
authors.lastname: Saito
keywords: Development of infant rats; hypothermic stimulus; ultrasonic vocalization