We investigated the impact of a high-fat (HF) diet during pre- and post-weaning periods on the intestinal microbiota and alkaline phosphatase (AP) activity in male rats. Nutrition from birth was influenced by feeding rat dams with either a standard or HF diet. After weaning male pups nursed by control dams continued on a standard diet (CC) or HF diet (C-HF), while offspring nursed by HF dams continued on HF diet (HF) or standard diet (HF-C). The numbers of Bacteroides/Prevotella (BAC) and Lactobacillus/Enterococcus (LAB) in the gut were determined by FISH technique. HF pups displayed enhanced adiposity and increased AP activity (19 %), as well as higher LAB (P<0.001) and lower numbers of BAC (P<0.001) in the jejunum and colon than controls. In HF-C rats, post-weaning lower fat intake resulted in decreased fat deposition accompanied by reduced AP activity (20 %) compared to HF rats. Composition of the intestinal microbiota in these rats was not influenced. In contrast, in comparison with controls, C-HF rats displayed higher LAB (P<0.001) and lower BAC (P<0.001) together with increased adiposity and AP activity (14 %). These results indicate that consumption of diet with different fat content could modulate gut microbial/functional conditions depending on the period when the nutritional manipulation occurs., Z. Šefčíková, D. Bujňáková., and Obsahuje bibliografii