Fucose as a Cleavage Product of 2'Fucosyllactose Does Not Cross the Blood-Brain Barrier in Mice.

Scope: To further examine the role of the human milk oligosaccharide 2'fucosyllactose (2´FL) and fucose (Fuc) in cognition. Using C-labeled 2'FL,thestudy previously showed in mice that C-enrichment of the brain is not caused by C -2´FL itself, but rather by microbial metabolites. Here, the study applies C -Fuc in the same mouse model to investigate its uptake into the brain.

Methods And Results: Mice received C -Fuc via oral gavage (2 mmol C -Fuc/kg body weight) or intravenously (0.4 mmol/kg body weight). C-enrichment is measured in organs, including various brain regions, biological fluids and excrements. By EA-IRMS, the study observes an early rise of C-enrichment in plasma, 30 min after oral dosing. However, C-enrichment in the brain does not occur until 3-5 h post-dosing, when the C-Fuc bolus has already reached the lower gut. Therefore, the researcher assume that C-Fuc is absorbed in the upper small intestine but cannot cross the blood-brain barrier which is also observed after intravenous application of C -Fuc.

Conclusions: Late C-enrichment in the rodent brain may be derived from C -Fuc metabolites derived from bacterial fermentation. The precise role that Fuc or 2´FL metabolites might play in gut-brain communication needs to be investigated in further studies.