Endocrine Reviews 20 (6): 805-875
Copyright © 1999 by The Endocrine Society

Current and Potential Drugs for Treatment of Obesity
George A. Bray and Frank L. Greenway

c. Amino acids. Administration of 5-hydroxy tryptophan to obese and diabetic subjects (152, 318) will decrease food intake probably by enhancing brain tryptophan, which is converted to serotonin, a neurotransmitter known to reduce food intake. Tryptophan is transported across the blood brain barrier by a transporter that also transports other large neutral amino acids. When these other amino acids are increased, tryptophan entry is reduced by competition for the transporter.