These results contribute to a better understanding of how early-acquired dietary habits determine the attenuation or prevention of obesity development in later life and can provide some benefit for optimizing the future dietary strategies in young and adult obese individuals.

The aim of the study was to assess the impact of preweaning overnutrition upon the ontogeny of intestinal microbiota, alkaline phosphatase activity (AP) and parameters of growth and obesity in male Sprague-Dawley rats. We tested whether intestinal characteristics acquired in suckling pups could programme the development of enhanced fat deposition during normalized nutrition beyond weaning. Postnatal nutrition was manipulated by adjusting the number of pups in the nest to 4 (small litters - SL) and 10 (normal litters - NL). In the postweaning period both groups were fed with a standard diet. The jejunal and colonic Lactobacillus/Enterococcus (LAB) and the Bacteroides/Prevotella (BAC) were determined using the FISH technique, and the jejunal AP activity was assayed histochemically. At 15 and 20 days of age the SL pups became heavier, displayed increased adiposity accompanied by significantly higher LAB and lower numbers of BAC and with higher AP activity in comparison with rats nursed in NL nests. These differences persisted to day 40 and withdrawal of the previous causal dietary influence did not prevent the post-weaning fat accretion. These results reveal the significance of early nutritional imprint upon the gut microbial/functional development and allow better understanding of their involvement in the control of obesity.

The influence was evaluated of post-weaning normal nutrition and over-nutrition upon the development of the intestinal microbiota, the alkaline phosphatase activity (AP) and occurrence of obesity in male Sprague-Dawley rats (from days 21 to 40 the control rats were submitted to ad libitum intake of a standard laboratory diet whereas overfed rats received the same diet supplemented with milk-based high fat liquid diet). The jejunal numbers of two dominant divisions of bacteria, i.e. Firmicutes (Lactobacillus/ Enterococcus--LAB) and the Bacteroidetes (Bacteroides/Prevotella--BAC), were determined using the fluorescent in situ hybridization (FISH) method, and the jejunal AP activity was assayed histochemically. On day 40, the overfed rats in comparison with control animals displayed increased adiposity accompanied by enhanced AP activity, abundance of LAB, lower amounts of BAC and, thereafter, higher LAB/BAC ratio (L/B). The numbers of LAB and L/B index positively correlated with body fat, energy intake and AP activity, whereas numbers of BAC showed an opposite tendency. These results revealed the significance of nutritional imprint upon the post-weaning development of intestinal microbial and functional axis and contribute to better understanding of their involvement in energy-balance control and in adverse and/or positive regulation of adiposity.