Neonatal Overfeeding Induced by Reducing the Litter Size Leads to an Obese Phenotype and Increases Preference for Sweet Food in Adult Male Rats

Abstract

Aim: the aim of this study was to induce obesity in rats using the neonatal overfeeding protocol and evaluate in adult male animals standard chow intake, sweet food intake, the preference between sweet food and standard chow, locomotor activity and anxiety-like behavior. Methodology: The neonatal overfeeding protocol consisted of reducing the litter size to 4 animals (small litters = SL) compared to 8 animals in normal litters (NL). In these experiments we used 55 offspring from 18 litters. Results: obesity was successfully induced as observed by increased body weight and depots of abdominal fat in SL animals compared to NL; [F(1, 53)=15.018; P<.001] for body weight and [t(48.06)=2.186 P=.03] for abdominal fat.No difference between groups was found in standard chow [t (16)=1.843 P=.08] and sweet food intake [t(53)=0.453 P=.65], however in the test that evaluated the preference between both foods SL animals consumed more sweet food than NL [t(48) =2.481 P=.02]. Additionally, there was no difference between groups regarding locomotor activity [t(52)=0.073 P=.94] but SL animals showed reduced anxiety-like behavior compared to NL [t(39.36)=2.205 P=.03]. Conclusion: this study supports the use of neonatal overfeeding protocol as a model of early obesity and showed for the first time the increased preference for sweet food in adult neonatal overfed animals.