Developmental overfeeding alters hypothalamic neuropeptide mRNA levels and response to a high-fat diet in adult mice

It has been suggested that nutritional manipulations during the first weeks of life can alter the development of the hypothalamic circuits involved in energy homeostasis. We studied the expression of a large number of the hypothalamic neuropeptide mRNAs that control body weight in mice that were overfed during breastfeeding (mice grown in a small litter, SL) and/or during adolescence (adolescent mice fed a high-fat diet, AHF). We also investigated possible alterations in mRNA levels after 50 days of a high-fat diet (high-fat challenge, CHF) at 19 weeks of age. Both SL and AHF conditions caused overweight during the period of developmental overfeeding. During adulthood, all of the mouse groups fed a CHF significantly gained weight in comparison with mice fed a low-fat diet, but the mice that had undergone both breast and adolescent overfeeding (SL-AHF-CHF mice) gained significantly more weight than the control CHF mice. Of the ten neuropeptide mRNAs studied, only neuropeptide Y (NPY) expression was decreased in all of the groups of developmentally overfed adult mice, but CHF during adulthood by itself induced a decrease in NPY, agouti-related protein (AgRP) and orexin (Orx) mRNA levels. Moreover, in the developmentally overfed CHF mice NPY, AgRP, galanin (GAL) and galanin-like peptide (GalP) mRNA levels significantly decreased in comparison with the control CHF mice. These results show that, during adulthood, hypothalamic neuropeptide systems are altered (NPY) and/or abnormally respond to a high-fat diet (NPY, AgRP, GAL and GalP) in mice overfed during critical developmental periods.