Maternal Deprivation Influences Pup Ultrasonic Vocalizations of C57BL/6J Mice.

Xiaowen Yin,Zhaoxin Wang,Xudong Zhao,Yan Yang,Ling Chen,Jiabei Yuan,Haojie Wang,Qunkang Cheng,Yong Xia,Jianshu Dong,Yuqiang Ding

doi:10.1371/journal.pone.0160409

Abstract

Maternal deprivation (MD) is frequently used as an early life stress model in rodents to investigate behavioral and neurological responses under stressful conditions. However, the effect of MD on the early postnatal development of rodents, which is when multiple neural systems become established, is rarely investigated due to methodological limitations. Ultrasonic vocalizations (USVs) are one of the few responses produced by neonatal rodents that can be quantitatively analyzed, and the quantification of USVs is regarded as a novel approach to investigate possible alterations in the neurobehavioral and emotional development of infant rodents under stress. To investigate the effect of MD on pup mice, we subjected C57BL/6J mice to MD and recorded the USVs of pups on postnatal days 1, 3, 7, 8, and 14. To determine whether the effect of MD on USVs was acute or cumulative, pre- and post-separation USV groups were included; sex differences in pup USV emission were also investigated. Our results suggest that (i) USV activity was high on postnatal days 3–8; (ii) the MD effect on USVs was acute, and a cumulative effect was not found; (iii) the MD mice vocalized more and longer than the controls at a lower frequency, and the effect was closely related to age; and (iv) female pups were more susceptible than males to the effect of MD on USV number and duration between postnatal days 3–8.

Highlights

Adversity, such as parental loss, neglect or abuse, can increase the risk of mental disorders later in life [1,2], as demonstrated by previous animal studies of non-human primates and rodents
Ultrasonic vocalizations (USVs) of Animal facility-reared (AFR) mice were used to investigate the developmental profile of USVs in C57BL/6J pups without maternal deprivation
Statistical analysis showed a significant effect of age on USV number (F = 3.02, P = 0.0173), with post hoc tests revealing an increase at P7 and P8 compared to the corresponding values at P1 and P14; in contrast, no difference was found between P3, P7 and P8 (Table 1A) (Fig 2A)

Summary

Introduction

Adversity, such as parental loss, neglect or abuse, can increase the risk of mental disorders later in life [1,2], as demonstrated by previous animal studies of non-human primates and rodents. Acute Effect of Maternal Deprivation on USV Emission time (e.g.,1-24h) over a number of postnatal days (e.g., P1-14) [10,11], is a stressful procedure for rodents that can be used to investigate behavioral and neurobiological responses to early adversity [4,12]. Adult rats that experienced repeated MD in early life showed enhanced vulnerability to stress, as demonstrated by an increase in depressive behaviors, such as a lower sucrose preference in a sucrose preference test and a longer immobility time in a forced swimming test [13]. The effect of MD in early life, the neonatal days during which multiple neural systems are established [15,16], has rarely been investigated, which may be partially due to the lack of parameters that can be quantitatively analyzed in very young rodents

Methods

Results

Discussion

Conclusion