Aim Metabolic sources switch from carbohydrates in utero, to fatty acids after birth and then a mix once adults. O‐GlcNAcylation (O‐GlcNAc) is a post‐translational modification considered as a nutrient sensor. The purpose of this work was to assess changes in protein O‐GlcNAc levels, regulatory enzymes and metabolites during the first periods of life and decipher the impact of O‐GlcNAcylation on cardiac proteins. Methods Heart, brain and liver were harvested from rats before and after birth (D‐1 and D0), in suckling animals (D12), after weaning with a standard (D28) or a low‐carbohydrate diet (D28F), and adults (D84). O‐GlcNAc levels and regulatory enzymes were evaluated by western blots. Mass spectrometry (MS) approaches were performed to quantify levels of metabolites regulating O‐GlcNAc and identify putative cardiac O‐GlcNAcylated proteins. Results Protein O‐GlcNAc levels decrease drastically and progressively from D‐1 to D84 (13‐fold, P < .05) in the heart, whereas the changes were opposite in liver and brain. O‐GlcNAc levels were unaffected by weaning diet in any tissues. Changes in expression of enzymes and levels of metabolites regulating O‐GlcNAc were tissue‐dependent. MS analyses identified changes in putative cardiac O‐GlcNAcylated proteins, namely those involved in the stress response and energy metabolism, such as ACAT1, which is only O‐GlcNAcylated at D0. Conclusion Our results demonstrate that protein O‐GlcNAc levels are not linked to dietary intake and regulated in a time and tissue‐specific manner during postnatal development. We have identified by untargeted MS putative proteins with a particular O‐GlcNAc signature across the development process suggesting specific role of these proteins.

Sepsis in the young population, which is particularly at risk, is rarely studied. O-GlcNAcylation is a post-translational modification involved in cell survival, stress response and metabolic regulation. O-GlcNAc stimulation is beneficial in adult septic rats. This modification is physiologically higher in the young rat, potentially limiting the therapeutic potential of O-GlcNAc stimulation in young septic rats. The aim is to evaluate whether O-GlcNAc stimulation can improve sepsis outcome in young rats. Endotoxemic challenge was induced in 28-day-old rats by lipopolysaccharide injection (E. Coli O111:B4, 20 mg·kg−1) and compared to control rats (NaCl 0.9%). One hour after lipopolysaccharide injection, rats were randomly assigned to no therapy, fluidotherapy (NaCl 0.9%, 10 mL·kg−1) ± NButGT (10 mg·kg−1) to increase O-GlcNAcylation levels. Physiological parameters and plasmatic markers were evaluated 2h later. Finally, untargeted mass spectrometry was performed to map cardiac O-GlcNAcylated proteins. Lipopolysaccharide injection induced shock with a decrease in mean arterial pressure and alteration of biological parameters (p < 0.05). NButGT, contrary to fluidotherapy, was associated with an improvement of arterial pressure (p < 0.05). ATP citrate lyase was identified among the O-GlcNAcylated proteins. In conclusion, O-GlcNAc stimulation improves outcomes in young septic rats. Interestingly, identified O-GlcNAcylated proteins are mainly involved in cellular metabolism.