Maternal deprivation alters growth, food intake, and neuropeptide Y in the hypothalamus of adolescent male and female rats

Abstract

Maternal deprivation (MD) for 24 hr during the neonatal period impairs body weight gain in adolescent and adult rats. It has been previously shown that maternally deprived rats consume less standard and carbohydrate-rich diets. Because neuropeptide Y (NPY) is implicated in feeding behavior, we assessed, prospectively, the effects of maternal deprivation, imposed on postnatal days (PND) 3 (DEP3) or 11 (DEP11), on physical development (snout-anal length and body weight gain, measured once a week) and food intake (assessed daily, during the rest and active phases, from PND 23 to PND 51); NPY-immunoreactivity (NPY-ir) in the arcuate nucleus of the hypothalamus was evaluated in male (at PND 52) and female rats in estrous (at PND 53-60). DEP3 and DEP11 male and female adolescents were smaller, lighter, and ate less during the active phase, than their CTL counterparts. This change in food intake was accompanied by reduced NPY-ir in the arcuate nucleus of the hypothalamus. The present results indicate that maternal deprivation had a negative impact on the physical development and feeding behavior of adolescent rats that may be explained by reduced hypothalamic NPY production.

Maternal Deprivation Increases Anxiety- and Depressive-Like Behaviors in an Age-Dependent Fashion and Reduces Neuropeptide Y Expression in the Amygdala and Hippocampus of Male and Female Young Adult Rats

“…In the present study, we tested the impact of maternal deprivation imposed in two moments of the neonatal development, immediately before (DEP3) and in the midst of the SHRP (DEP11), on physiological variables, such as body weight gain and relative adrenal weight, and on emotional behavior and NPY-ir in the BLA, vHPC, and dHPC of male and female rats. Impairment of body weight gain replicated previous findings ( Wertheimer et al, 2016 ), and in the present study, we also found that females, regardless of their infancy history, showed heavier adrenals than their male counterparts; in addition, maternal deprivation on 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 ). There was a clear distinctive age-dependent effect of maternal deprivation on emotional behavior, inasmuch as DEP3 adolescents of both sexes displayed the highest anxiety index and the greatest frequency of immobility in the FST; DEP11 adolescents, in turn, displayed more immobility than their CTL counterparts.…”

“…Twenty-eight litters were distributed in CTL (nine litters), DEP3 (10 litters), and DEP11 (nine litters). In each litter, two males and two females were tested in the elevated plus maze, whereas the remainder of the litter was not tested and provided baseline values of parameters published previously ( Wertheimer et al, 2016 ) and NPY-ir.…”

“…Disruption of the mother-infant relationship by means of 3 or 6 h of maternal separation leads to increased anxiety- and depressive-like behaviors ( Huot et al, 2001 ) and reduces NPY-immunoreactivity (ir; Husum and Mathé, 2002 ) and hippocampal levels ( Jiménez-Vasquez et al, 2001 ). Data on the effects of maternal deprivation on NPY are scarce, but the evidence indicates an overall reduction: DEP9 animals exhibit lower NPY levels in the hippocampus and occipital cortex than control rats ( Husum et al, 2002 ), while DEP3 and DEP11 male and female adolescents display reduced food intake during the rats’ active period and lower NPY-ir in the arcuate nucleus of the hypothalamus than controls ( Wertheimer et al, 2016 ). Therefore, it appears as though neonatal stress leads to reduction of NPY in several brain areas involved with motivated and emotional behaviors, and this effect could represent a neurobiological underpinning of vulnerability to later psychopathology.…”

Maternal regulation of the infant's hypothalamic‐pituitary‐adrenal axis stress response: Seymour ‘Gig’ Levine's legacy to neuroendocrinology

“…The effects of MD on prepulse inhibition were replicated by Husum and Mathé, who also showed that DEP9 male rats exhibited lower levels of neuropeptide Y (NPY) in the occipital cortex and hippocampus; whether or not the changes in prepulse inhibition and NPY are related still needs clarification, although this could be a possibility because dopamine negatively regulates NPY levels. NPY levels were also shown to be reduced in the hypothalamus, as well as in the amygdala and hippocampus (unpublished data, A. S. Miragaia, G. S. Wertheimer, A. C. Consoli, R. Cabbia, B. M. Longo, C. E. Girardi, D. Suchecki) of male and female DEP3 and DEP11 rats. Therefore, the NPY system may be a particularly interesting endpoint worthy of investigation, giving its involvement with mood and anxiety disorders …”

Sex Differences in the Neuropeptide Y System and Implications for Stress Related Disorders

“…In the amygdala, early-life stress increased NPY mRNA levels at 30 days postnatally in females, only [ 126 ]. When examined as adolescents, early-life stress decreased NPY neuron density in the arcuate nucleus equally in both sexes, as compared to unstressed controls [ 127 ]. However, when animals exposed to early-life stress were examined in adolescence, females tended to exhibit lower NPY expression in specific brain regions.…”