THE EFFECTS OF PRE-WEANING SOCIAL ISOLATION AND MOTHER’S PRESENCE ON THE OBJECT EXPLORATION BEHAVIOR OF INFANT <i>OCTODON DEGUS</i>

Abstract

The unique social behavior of degus (Octodon degus) makes them a suitable animal model for social and emotional studies. Using degu pups, we examined the effects of repetitive short-term isolation on novel object exploratory behavior at 3, 4, 5, 6, and 7 weeks of age. Isolated pups were separated from their family 14 times for 30 min a day from 6-23 days post-birth. Non-isolated pups were reared with their families. A two-condition (with-mother or without-mother) object exploration test showed an isolation effect at 3 weeks. Compared with non-isolated pups, isolated pups showed longer start latency under the without-mother condition than under the with-mother condition, and less frequent contact with a novel object even when their mother was present. Non-isolated pups showed more frequent contact with the novel object under the with-mother condition than the without-mother condition. Repetitive maternal separation in early life negatively affected degu novel object exploratory behavior.

Influence of Pre-Weaning Social Isolation on Post-Weaning Emotion Tendency and Mother–Infant Interactions in Infant Octodon Degus

“…Our findings that early isolation affected behavior at the initial stage of weaning, especially at 3 weeks, were consistent with our previous study [17] despite the different time points at which isolation began and regardless of how many times isolation was performed. Thus, it seems that the third week of life is a critical stage for observing the effects of early isolation on exploration behavior.…”

“…In a previous study, we compared object exploration behavior between isolated and nonisolated pups [17]. The isolated pups took longer to come out from their nest, and even with their mother present in the test environment, they explored novel objects less frequently than nonisolated pups.…”

“…There were two males and three females in the isolated group and three males and two females in the nonisolated group. The separation procedure was the same as that described by Uekita and Kawakami (2016) [17], except for the start time and the number of repetitions of separation. Degus in the isolated group were separated from their family once per day from P8 until P15 (seven times in total).…”

“…Uekita and Kawakami (2016) investigated how the isolation experienced before weaning influenced exploratory behavior after weaning [17]. They isolated pups from their family for 30 min a day, 14 times from P6 to P23.…”