Factors affecting emotional eating and eating palatable food in adults

Highly Palatable Food during Adolescence Improves Anxiety-Like Behaviors and Hypothalamic-Pituitary-Adrenal Axis Dysfunction in Rats that Experienced Neonatal Maternal Separation

BACKGROUND: This study was conducted to examine the effects of ad libitum consumption of highly palatable food (HPF) during adolescence on the adverse behavioral outcome of neonatal maternal separation. METHODS: Male Sprague-Dawley pups were separated from dam for 3 hours daily during the first 2 weeks of birth (maternal separation, MS) or left undisturbed (nonhandled, NH). Half of MS pups received free access to chocolate cookies in addition to ad libitum chow from postnatal day 28 (MS+HPF). Pups were subjected to behavioral tests during young adulthood. The plasma corticosterone response to stress challenge was analyzed by radioimmunoassay. RESULTS: Daily caloric intake and body weight gain did not differ among the experimental groups. Ambulatory activities were decreased defecation activity and rostral grooming were increased in MS controls (fed with chow only) compared with NH rats. MS controls spent less time in open arms, and more time in closed arms during the elevated plus maze test, than NH rats. Immobility duration during the forced swim test was increased in MS controls compared with NH rats. Cookie access normalized the behavioral scores of ambulatory and defecation activities and grooming, but not the scores during the elevated plus maze and swim tests in MS rats. Stress-induced corticosterone increase was blunted in MS rats fed with chow only, and cookie access normalized it. CONCLUSION: Prolonged access to HPF during adolescence and youth partly improves anxiety-related, but not depressive, symptoms in rats that experienced neonatal maternal separation, possibly in relation with improved function of the hypothalamic-pituitary-adrenal (HPA) axis.

Experience of Neonatal Maternal Separation May Lead to a Long-term Modulation in the Neuronal Activity of Nucleus Accumbens in the Offspring

Dysfunction of the nucleus accumbens (NAcb) is implicated in the development of anhedonia, a core symptom of major depressive disorder. In order to define the neural basis of depression-like behaviors induced by experience of neonatal maternal separation (MS), both basal and stress-induced neuronal activations in the NAcb of adolescent rats with MS experience were examined parallel with palatable food intake. Rat pups were separated from dam daily for 180 min during the first two weeks of age (MS), and non-handled control (NH) pups were left undisturbed. After weaning on postnatal day (PND) 22, a half of NH or MS pups were subjected to 1 h of restraint stress every even day during PND 28~40 (NH/R or MS/R), and then had free choices of chow and chocolate cookie for 1 h immediately after returned to home cage. The rest half of NH and MS pups (NH/C or MS/C) received free choices of chow and cookie in the same time schedule with stress group, just omitting restraint stress. Cookie intake was significantly decreased in MS/C, whereas c-Fos expression in the NAcb and plasma corticosterone increased, compared to NH/C. Restraint stress suppressed cookie intake and increased the NAcb c-Fos expression in NH/R, but not in MS/R. The plasma corticosterone of NH/R, but not of MS/R, increased following repeated restraint stress. These results suggest that the increased neuronal activation in the NAcb of MS/C may be implicated in the development of anhedonia by MS experience, perhaps, in relation with a blunted responsivity of the hypothalamic-pituitary- adrenal axis to stress.