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Updated: Jun 26, 2026
Eliciting and Analyzing Male Mouse Ultrasonic Vocalization (USV) Songs
Published on: May 9, 2017
Freezing urine reduces its efficacy for eliciting ultrasonic vocalizations from male mice
Frauke Hoffmann1, Kerstin Musolf, Dustin J Penn
1Konrad Lorenz Institute for Ethology, Austrian Academy of Sciences, Savoyenstr. 1a, Vienna A-1160, Austria.
Abstract:
Studies on chemosensory communication generally rely on using samples of emanations that have been frozen for convenience, and assume that freezing has no detrimental effects. Female urine triggers courtship ultrasonic vocalizations (USVs) in male mice, and in this study, we examined whether freezing urine affects males' USV responses. We used wild-derived house mice (Mus musculus musculus), and recorded males' USVs after being presented samples of fresh versus frozen urine. We found that males emitted significantly fewer USVs when presented with frozen versus fresh urine, and furthermore, males were no longer able to discriminate the scent of familiar versus unfamiliar females after samples were frozen. Our findings indicate that freezing alters the bioactivity of urinary compounds both by reducing its potential to elicit behavioral responses from receivers (male courtship USVs) and eliminating important information about senders (familiarity). Freezing may denature the major urinary proteins (MUPs) released in rodent urine that play an important role in chemical communication. Our results raise concerns about the negative results of studies utilizing frozen samples for studying chemical signals.
Insights
Freezing mouse urine samples significantly reduces male courtship ultrasonic vocalizations (USVs) and eliminates scent-based familiarity cues. This suggests freezing alters crucial chemical signals in animal communication studies.
Area of Science:
- Animal Behavior
- Chemical Ecology
- Mammalian Communication
Background:
- Chemosensory communication studies often use frozen samples, assuming no negative impact on chemical signals.
- Female urine is known to elicit courtship ultrasonic vocalizations (USVs) in male mice.
Purpose of the Study:
- To investigate the effect of freezing on the bioactivity of mouse urine.
- To determine if freezing alters male mice's ultrasonic vocalization (USV) responses to female urine.
- To assess if freezing impacts the ability of male mice to discriminate familiar from unfamiliar female scents.
Main Methods:
- Recorded USVs from male wild-derived house mice (Mus musculus musculus).
- Presented males with samples of fresh versus frozen female urine.
- Analyzed differences in USV emission and scent discrimination between fresh and frozen urine samples.
Main Results:
- Males emitted significantly fewer USVs in response to frozen urine compared to fresh urine.
- Freezing eliminated male mice's ability to discriminate between familiar and unfamiliar female urine scents.
- Findings suggest freezing denatures key urinary proteins (MUPs) crucial for chemical communication.
Conclusions:
- Freezing significantly alters the bioactivity of mouse urinary signals.
- Frozen samples reduce behavioral responses and eliminate sender-specific information like familiarity.
- Results question the validity of studies using frozen samples for chemical signal research.
