Original Article
International Journal of Obesity (2008) 32, 1355–1362; doi:10.1038/ijo.2008.108; published online 22 July 2008
Sustained hyperphagia in adolescent rats that experienced neonatal maternal separation
V Ryu1, J-H Lee1, S B Yoo1, X F Gu1, Y W Moon2 and J W Jahng1
- 1Department of Oral and Maxillofacial Surgery, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
- 2Department of Biology, Catholic University of Korea College of Medicine, Seoul, Republic of Korea
Correspondence: Professor Dr JW Jahng, Department of Oral & Maxillofacial Surgery, Dental Research Institute, Seoul National University School of Dentistry, Seoul 110-768, Korea. E-mails: jwjahng@snu.ac.kr; J-H Lee, leejongh@snu.ac.kr
Received 14 March 2008; Revised 10 June 2008; Accepted 18 June 2008; Published online 22 July 2008.
Abstract
Objective:
To examine the neurobiological basis of bingeing-related eating disorders using an animal model system.
Design:
Sprague–Dawley pups were separated from dam for 3 h daily during the first two weeks of birth (maternal separation (MS)), or left undisturbed (non-handled (NH)). Pups were subjected to repeated fasting/refeeding (RF) cycles; that is, 24 h food deprivation and 24 h RF (NH/RF or MS/RF), or had free access to food and water (NH/fed control (FC) or MS/FC) from postnatal day (PND) 28–40.
Measurements:
Body weight gain and food intake were recorded. The arcuate expression of neuropeptide Y (NPY) and plasma corticosterone levels were analyzed on PND 29 and 40.
Results:
Decrease in weight gain by repeated fasting/RF cycles was smaller in MS pups than in NH. Interestingly, weight changes responding to fasting or RF increased in MS/RF compared with NH/RF. Compensatory hyperphagia was diminished in NH/RF after the third fasting trial, but persisted in MS/RF throughout the experimental period. The arcuate expression of NPY mRNA responding to food deprivation was blunted, but elevation of plasma corticosterone exaggerated, in the MS group, compared to the NH group, on PND 29 after the first fasting session. However, both the arcuate NPY mRNA and plasma corticosterone levels were increased in MS/RF, but not in NH/RF, on PND 40 after the six sets of fasting/RF cycles, compared to the free FC groups.
Conclusion:
Experience of neonatal MS may lead to an exaggerated feeding response to repeated fasting/RF challenges at adolescence, perhaps, due to increased responsiveness of the hypothalamic–pituitary–adrenal gland axis. Additionally, the results suggested that an increased action of the hypothalamic NPY may not be necessary to induce compensatory hyperphagia following food deprivation.
Keywords:
body weight, early life stress, food deprivation, hyperphagia, hypothalamic–pituitary–adrenal axis, neuropeptide Y
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