Sustained hyperphagia in adolescent rats that experienced neonatal maternal separation

Area of Science:

• Neurobiology
• Animal Models
• Eating Disorders

Background:

• Binge eating disorders have complex neurobiological underpinnings.
• Understanding these mechanisms is crucial for developing effective treatments.
• Animal models offer a controlled system to investigate these pathways.

Purpose of the Study:

• To investigate the neurobiological basis of bingeing-related eating disorders.
• To utilize an animal model to explore the effects of early life stress on feeding behaviors.
• To examine the neuroendocrine responses to fasting and refeeding cycles in adolescence.

Main Methods:

• Sprague-Dawley rat pups underwent daily maternal separation (MS) or were non-handled (NH) during the first two weeks of life.
• Pups were subjected to repeated cycles of 24-hour food deprivation followed by 24-hour refeeding (RF) from postnatal day 28-40.
• Body weight, food intake, arcuate nucleus neuropeptide Y (NPY) mRNA expression, and plasma corticosterone levels were measured.

Main Results:

• Maternal separation pups exhibited a smaller decrease in weight gain during fasting/refeeding cycles compared to non-handled controls.
• Compensatory hyperphagia persisted in MS pups throughout the experimental period, unlike in NH pups.
• Early life stress (MS) blunted NPY mRNA response but exaggerated corticosterone response to initial fasting, while later chronic fasting/refeeding increased both NPY and corticosterone in MS/RF pups.

Conclusions:

• Neonatal maternal separation may predispose individuals to exaggerated feeding responses to challenges like repeated fasting.
• This heightened feeding response might be linked to increased hypothalamic-pituitary-adrenal (HPA) axis responsiveness.
• The study suggests that increased hypothalamic NPY action may not be essential for compensatory hyperphagia following food deprivation.