ELEVATION OF AMINO-ACIDS IN THE INTERSTITIAL SPACE OF THE RAT-BRAIN FOLLOWING INFUSION OF LARGE NEUTRAL AMINO AND KETO ACIDS BY MICRODIALYSIS - LEUCINE INFUSION

A microenvironment similar to that found in maple syrup urine disease was created in the brain of free-moving, awake rats by the infusion of leucine into the brain using microdialysis. To determine the effects on amino acid homeostasis the eluate of the probe was analyzed. Perfus ion with leucine elevated the interstitial levels of large neutral ami no acids suggesting hetero exchange of large neutral amino acids from neuronal cells into the interstitial space. The data also demonstrated the inter relationship of leucine and glutamine, both of which may be nitrogen sinks in the brain. Elevation of large neutral amino acids i n the interstitial space suggests a decreased concentration in neurons which might have an effect on the synthesis of serotonin and catechol amines and suggests a mechanism by which elevated leucine may affect n euronal function in maple syrup urine disease.