Maternal separation alters maternal care, but has minor effects on behavior and brain opioid peptides in adult offspring

The aim of the study was to investigate the effect of repeated maternal separation (MS; 4 hr per day) during postnatal Days 1 to 15 on emotionality and voluntary ethanol intake in adult male and female Wistar rat offspring relative to controls exposed to a brief (5-min) daily handling procedure. Brain immunoreactive opioid peptide levels and plasma levels of corticosterone also were measured. There were mainly no alterations in any of the tested behaviors (i.e., fleeing and freezing responses, exploratory behavior spontaneous and amphetamine-induced locomotor activity and competitive behavior), ethanol intake, or immunoreactive opioid peptide levels in MS offspring, either in males or females, compared to their respective controls nor were there any differences in plasma corticosterone between groups. In addition, the dams' retrieval behavior of the pups also was studied, showing that MS dams spent more time in the nest with the pups after the 4-hr separation period compared to control dams. With respect to the used protocol of the MS procedure in the present study, our results do not provide support for the suggestion that this procedure is a relevant model for studying development of psychopathology and vulnerability to drug abuse. (C) 2004 Wiley Periodicals, Inc.