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

Abstract

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.

Gestational Dexamethasone Treatment Elicits Sex-Dependent Alterations in Locomotor Activity, Reward-Based Memory and Hippocampal Cholinergic Function in Adolescent and Adult Rats

“…As found in earlier studies (Levin et al, 2001(Levin et al, , 2002Marmendal et al, 2004;Moraes et al, 2004), control rats showed marked sex differences in activity ( Figure 1a) and habituation (Figure 1b) in the figure-8 apparatus. Males Figure 1 Effects of dexamethasone on activity (a) and habituation (b) in the figure-8 apparatus.…”

Individual Differences and Social Influences on the Neurobehavioral Pharmacology of Abused Drugs

“…A number of studies failed to observe significant effects of maternal separation on alcohol intake in rodents (Marmendal et al, 2004;Roman et al, 2004Gustafsson et al, 2005Gustafsson et al, , 2007Gustafsson and Nylander, 2006;Marmendal et al, 2006;Advani et al, 2007;Oreland et al, 2011). Although the reason for the discrepancy is not clear, because of the myriad of procedural differences across studies, several tentative conclusions may be drawn.…”

“…Most studies show an increase (Zimmerberg and Shartrand, 1992;Kehoe et al, 1996Kehoe et al, , 1998Pryce et al, 2001;Brake et al, 2004;Marin and Planeta, 2004;Kikusui et al, 2005) or no effect (Lehmann et al, 1998;Li et al, 2003;Marmendal et al, 2004;Kosten et al, 2005a,c;Hensleigh et al, 2011) compared with stimulant effects in controls, whereas others show a decrease (Matthews et al, 1996a;Moffett et al, 2006). Factors that likely account for these differences are drug history before acute stimulant administration, doses of stimulant tested, and sex.…”

“…One explanation for the less-than-optimal protection in AFR and NH groups is that having the dam and pups in the same vicinity continuously may be stressful because dams in a natural setting typically leave the nest completely for brief periods (Moffett et al, 2007). Another explanation is that brief (AFR or NH groups) and longer (MS15 group) separations differentially alter maternal behaviors toward the pups once they are returned (Marmendal et al, 2004;Francis and Kuhar, 2008;Der-Avakian and Markou, 2010).…”

Effect of Complete Maternal and Littermate Deprivation on Morphine-Induced Fos-Immunoreactivity in the Adult Male Rat Brain

“…6). On the other hand, the maternal separation (MS) paradigm, which involves the removal of pups from dams for an extended period of time (1-24 h), either during a single separation episode or for multiple days after birth until weaning, has been associated with effects that may be considered deleterious (7,8). Some, but not all, researchers have found that as adults MS rats generally exhibit enhanced anxiety and fearfulness, exaggerated hypothalamic-pituitary-adrenal (HPA) axis activity and behavioral responses to stressors (9), as well as elevated locomotor activity in novel environments (10 -12).…”