Vacuum-cleaner noise and acute stress responses in female C57BL/6 mice (Mus musculus)

Abstract

Audiogenic stress is a well-documented phenomenon in laboratory rodents. Despite the recommendation in the Guide for the Care and Use of Laboratory Animals to consider noise a concern in the animal facility, only a small body of literature empirically addresses the effects of facility noise on laboratory rodents, particularly mice. The objective of this study was to determine whether facility noise generated by a vacuum cleaner induces an acute stress response in a commonly used strain of laboratory mouse under common housing conditions. In each of 2 experiments, 10 young adult, female C57BL/6Cr mice were exposed for 1 h to noise produced by a vacuum cleaner, and 10 control mice were not. In the first experiment, fecal samples were collected to measure concentrations of fecal corticosterone metabolites just before and 2, 4, 6, 8, 10, 14, 24, and 32 h after noise exposure. In the second experiment, stress-sensitive behavioral tests were performed 2 d before, immediately after, and 24 h after noise exposure. Physiologic and behavioral measurements indicated that vacuum cleaner noise did not cause an acute stress response in the noise-exposed mice but may have affected the diurnal variation of their corticosterone levels. These findings could contribute to the development of best practices in noise-control protocols for animal facilities.

Figure 1.

Mean fecal corticosterone metabolite concentrations in mice during the ACTH stimulation test and in control mice injected with saline. Significant (P < 0.001) differences between groups are marked with asterisks. Error bars represent standard error. Significant sources of variation include time (P < 0.0001), treatment (P < 0.0001), and treatment × time (P < 0.0001).

Figure 2.

Mean fecal corticosterone metabolite concentrations in mice exposed to vacuum-cleaner noise and in control mice. Significant (P < 0.01) differences between groups are marked with asterisks. Error bars represent standard error. Significant sources of variation include time (P < 0.0001) and noise exposure × time (P = 0.0114).

Figure 3.

Light–dark box test scores in mice before, immediately after, and 24 h after exposure to vacuum-cleaner noise. Comparisons between noise-exposed and control mice included: (A) latency to exit dark box in light–dark box apparatus, and (B) time spent in exposed side of light–dark box apparatus. Error bars represent standard error.

Figure 4.

Open-field test scores in mice before, immediately after, and 24 h after vacuum noise exposure. The control group spent significantly (*, P = 0.024) less time in the inner zone of the apparatus during subsequent trials. Error bars represent standard error.