The effects of early rearing environments on maternal behavior in adult female rats

Publisher Website
Google Scholar
Abstract
The purpose of this study was to determine the effect of presence of siblings and exposure to colony cues during early life on the onset of maternal behavior at 20 and 75 days of life, and on subsequent emotional behavior in juvenile and adult female rats. Different groups of animals were reared either (1) with a large number or a small number of siblings (sibling factor), or (2) in the colony room or in a room apart from other mothers with pups (colony factor). Animals were tested for latency (in days) to show maternal behavior at either 20 or 75 days of age, and for emotional behavior (using the open field apparatus) at either 20–40 or 80–100 days of age. Exposure to colony sensory cues significantly reduced latencies for pup retrieval and nestbuilding in adults, but not in juveniles. Exposure to a large number of siblings reduced the latencies, in both adults and juveniles, to nest build; in juveniles, to lie over 75% of the litter; and in adults, to adopt a nursing posture. Consistent with prior research, juveniles had longer latencies than adults for a number of pup‐directed behaviors including: latency to become maternal, latency to retrieve pups, latency to adopt a lactating posture, latency to lick/genital lick, and latency to nest‐build. In the emotionality tests, the young animals scored as less emotional than the adults, an effect which was further exaggerated by early colony exposure. Overall results indicated that manipulation of early rearing environments does have a significant positive effect on later responses to young pups by both juvenile and adult female rats.