Intergenerational effects of complete maternal deprivation and replacementstimulation on maternal behavior and emotionality in female rats

The present study investigated the effects of early rearing experiences on the development of maternal behavior in Sprague-Dawley female rats. Pups fr om individual litters were assigned to four different groups on Day 3 of li fe. From days 4 to 20 of life, these were reared artificially without mothe r and receiving minimal "licking-like" tactile stimulation (AR-MIN), or max imal stimulation (AR-MAX) or were reared with their mothers (MR-CONTROL and MR-SHAM). At 70-100 days all AR and MR animals were mated and then observe d with their own offspring, culled to eight pups. After maternal testing op en-field tests were conducted. The female offspring in these litters (all r aised by their MR and AR mothers) were reared to adulthood and then observe d interacting with their offspring. Results show that in adulthood AR mothers engaged in significantly fewer pu p-retrievals and less pup-licking (genital and body), and crouching, but si gnificantly more non-maternal tail-chasing, digging, and hanging/climbing. As well, they were more active in the open field. Comparisons between the t wo AR groups and the MR groups, showed that most of the differences were be tween the AR-MIN and MR groups, with the AR-MAX animals showing levels of b ehavior between the two, and differing from neither Analyses of covariance indicated that early experience and adult emotional behavior both influence adult maternal behavior but their effects are independent of one another. A cross-generational effect of artificial rearing was also found. Daughters of AR and MR mothers that were observed after the birth of their own litte rs in adulthood showed a pattern of behavior that mimicked the pattern show n by their mothers. These results are discussed in terms of the variety of possible behavioral, endocrine, and neurochemical mechanisms that mediate the effects of early experiences on adult maternal behavior (C) 2001 John Wiley & Sons, Inc.