Lab Anim Res.  2013 Jun;29(2):77-83. 10.5625/lar.2013.29.2.77.

Quantitative and qualitative analysis of rat pup ultrasonic vocalization sounds induced by a hypothermic stimulus

Affiliations
  • 1Behavioral Neuroscience Laboratory, Graduate School of Veterinary Medicine, Nippon Veterinary and Life Science University, Musashino, Tokyo, Japan. trsaito@nvlu.ac.jp
  • 2Central Institute for Experimental Animals, Kawasaki, Kanagawa, Japan.
  • 3Department of Laboratory Animal science, Dokkyo University School of Medicine, Mibu, Tochigi, Japan.
  • 4Department of Veterinary Anatomy, College of Veterinary Medicine, Chonnam National University, Gwangju, Korea.
  • 5Department of Physiology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand.

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.

Keyword

Development of infant rats; hypothermic stimulus; ultrasonic vocalization

MeSH Terms

Animals
Body Weight
Cold Temperature
Enzyme Multiplied Immunoassay Technique
Glass
Humans
Infant
Mothers
Rats
Rodentia
Ultrasonics

Figure

  • Figure 1 Methods for measuring and recording USVs in hypothermic rat pups.

  • Figure 2 USV spectrograms of rat pups and method for analyzing USV. A: USV spectrogram in rats aged 3 days. B: Methods for analyzing USV and the identification of first peak frequency and median frequency.

  • Figure 3 Body weights of rat pup postnatal days 1, 3, 5, 7, 10, 12 and 14. Data are represented as means±SEM. *P<0.05.

  • Figure 4 Number of USV of rat pups postnatal days 1, 3, 5, 7, 10, 12 and 14. A: Mean number of USV calling of each sex and number of USV in each rat pups, B: Mean±SEM of number of USV in combined sex.

  • Figure 5 First peak frequency of USV of rat pups postnatal days 1, 3, 5, 7, 10, 12 and 14. A: Mean±SEM of first peak frequency of USV in male, female and combined sex. B: Mean±SEM of first peak frequency of USV in combined sex. *P<0.05.

  • Figure 6 Median frequency of USV of rat pups postnatal days 1, 3, 5, 7, 10, 12 and 14. A: Mean±SEM of median frequency of USV in male, female and combined sex. B: Mean±SEM of median frequency of USV in combined sex. *P<0.05.


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