Abstract
Maternal deprivation for 24 h produces an immediate increase in basal and stress-induced corticosterone (CORT) secretion. Given the impact of elevated CORT levels on brain development, the goal of the present study was to characterize the effects of maternal deprivation at postnatal days 3 (DEP3) or 11 (DEP11) on emotional behavior and neuropeptide Y immunoreactivity (NPY-ir) in the basolateral amygdala (BLA) and dorsal hippocampus (dHPC) of male and female rats. Litters were distributed in control non-deprived (CTL), DEP3, or DEP11 groups. In Experiment 1, within each litter, one male and one female were submitted to one of the following tests: novelty suppressed feeding (NSF), sucrose negative contrast test (SNCT), and forced swimming test (FST), between postnatal days 52 and 60. In Experiment 2, two males and two females per litter were exposed to the elevated plus maze and 1 h later, perfused for investigation of NPY-ir, on PND 52. The results showed that DEP3 rats displayed greater anxiety-like behavior in the NSF and EPM, compared to CTL and DEP11 counterparts. In the SNCT, DEP3 and DEP11 males showed less suppression of the lower sucrose concentration intake, whereas all females suppressed less than males. Both manipulated groups displayed more immobility in the FST, although this effect was greater in DEP3 than in DEP11 rats. NPY-ir was reduced in DEP3 and DEP11 males and females in the BLA, whereas in the dHPC, DEP3 males showed less NPY-ir than DEP11, which, in turn, presented less NPY-ir than CTL rats. Females showed less NPY-ir than males in both structures. Because the deprivation effects were more intense in DEP3 than in DEP11, in Experiment 3, the frequency of nursing posture, licking-grooming, and interaction with pups was assessed upon litter reunion with mothers. Mothers of DEP11 litters engaged more in anogenital licking than mothers of DEP3 litters. The present results indicate that maternal deprivation changed affective behavior with greater impact in the earlier age and reduced the expression of NPY in emotion-related brain areas. The age-dependent differential effects of deprivation on maternal behavior could, at least in part, explain the outcomes in young adult rats.
Highlights
Affective disorders are highly prevalent with profound impact on society (Baxter et al, 2013)
Novelty Suppressed Feeding (Figure 1) Two-way ANOVA detected main effect of group for the latency to eat the pellet [F(2,54) = 5.925; p < 0.005]; both deprivation on PND 3 (DEP3) males and females took longer to eat than CTL and DEP11 (p < 0.05)
Impairment of body weight gain replicated previous findings (Wertheimer et al, 2016), and in the present study, we found that females, regardless of their infancy history, showed heavier adrenals than their male counterparts; in addition, maternal deprivation on postnatal day (PND) 3 resulted in the heaviest adrenal weights both in males and females, suggesting that DEP3 adolescents may be under chronic stress (Jankord et al, 2011)
Summary
Affective disorders are highly prevalent with profound impact on society (Baxter et al, 2013). Depression, for instance, has been recognized by the World Health Organization as the leading cause of disability worldwide, and it is estimated that 300 million people of all ages suffer from depression (WHO, 2018). These disorders result from the interaction between genetic background and environmental adversity during critical periods of development, such as infancy and adolescence (Plotsky et al, 1998; Caspi et al, 2003). In a large longitudinal study with Canadian children, loss of a parent, either by death, divorce, or separation, between 4 and 8 years of age is a strong predictor of depression at 16– 20 years of age, for girls but not boys (Bellamy and Hardy, 2015), indicating a sex-dependent impact of early parental loss
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
