The effect of branched-chain amino acid-enriched parenteral nutrition on gut permeability

In situations of catabolic stress, the gut becomes atrophic and has a diminished barrier function as evidenced by an increased permeability to a variety of molecules. It is known that the parenteral administration of branched-chain amino acids (BCAA) reduce gut atrophy. The aim of this study was to examine the effect of BCAA-enriched solutions of parenteral nutrients on gut permeability. A secondary aim was to observe the association between gut permeability and variables that have been used to assess jejunal atrophy. Central venous lines were inserted into 30 rats before randomization to receive nutritional support with: (1) a conventional parenteral solution (CPN), (2) A 2.0% BCAA-enriched solution (BCAA), or (3) rat food ad lib (Rat Food). The rats were assessed after 7 d for nutritional status, gut morphology, and gut permeability ratio (ratio of the permeability to 14C raffinose and 3H mannitol). We found that rats in the Rat Food Group lost the least amount of weight, had the least amount of jejunal atrophy, and had better preservation of barrier function as determined by gut permeability. When compared with the CPN Group, the BCAA Group had better preservation of jejunal morphology and protein content (p < 0.05), but a similar gut permeability. A cross-correlation matrix demonstrated a significant negative correlation between permeability to mannitol and mucosal weight, mucosal protein content and mucosal DNA content. Branched-chain amino acid-enriched parenteral nutrition reduced gut atrophy but not the gut permeability associated with parenteral nutrition. In the parenterally nourished rat model, atrophy of the jejunum is associated with increased permeability to small molecules.