Maple syrup urine disease (MSUD) is a rare metabolic disorder associated with acute and chronic brain dysfunction. This condition has been shown to lead to macroscopic cerebral alterations that are visible on imaging studies. Cerebral oedema is widely considered to be detrimental for MSUD patients; however, the mechanisms involved are still poorly understood. Therefore, we investigated whether acute administration of
branched-chain amino acids (BCAA) causes cerebral oedema, modifies the Na(+),K(+)-
ATPase activity, affects the permeability of the blood-brain barrier (BBB) and alters the levels of
cytokines in the hippocampus and cerebral cortex of 10-day-old rats. Additionally, we investigated the influence of concomitant administration of
dexamethasone on the alterations caused by BCAA. Our results showed that the animals submitted to the model of MSUD exhibited an increase in the brain water content, both in the cerebral cortex and in the hippocampus. By investigating the mechanism of cerebral oedema, we discovered an association between H-BCAA and the Na(+),K(+)-
ATPase activity and the permeability of the BBB to small molecules. Moreover, the H-BCAA administration increases Il-1β,
IL-6 and TNF-α levels in the hippocampus and cerebral cortex, whereas
IL-10 levels were decreased in the hippocampus. Interestingly, we showed that the administration of
dexamethasone successfully reduced cerebral oedema, preventing the inhibition of Na(+),K(+)-
ATPase activity, BBB breakdown and the increase in the
cytokines levels. In conclusion, these findings suggest that
dexamethasone can improve the acute cerebral oedema and
brain injury associated with high levels of BCAA, either through a direct effect on brain capillary Na(+),K(+)-
ATPase or through a generalized effect on the permeability of the BBB to all compounds.