Serotonin-related tryptophan in children with insulin-dependent diabetes

Herrera, Rocı́o; Manjarrez, Gabriel; Nishimura, Elisa; Hernandez, Jorge

doi:10.1016/S0887-8994(02)00462-9

« Previous Next »Pediatric Neurology
Volume 28, Issue 1 , Pages 20-23, January 2003

Serotonin-related tryptophan in children with insulin-dependent diabetes

Rocı́o Herrera, MD
- Laboratory of Neurochemistry, XXI Century, National Medical Center, Mexican Institute of Social Security, Mexico City, Mexico
Gabriel Manjarrez, PhD
- Laboratory of Neurochemistry, XXI Century, National Medical Center, Mexican Institute of Social Security, Mexico City, Mexico
- Communications should be addressed to: Dr. Manjarrez; Laboratory of Neurochemistry; Specialties Hospital; XXI Century; National Medical Center; Mexican Institute of Social Security; Av. Cuauhtémoc 330; Col. Doctores; CP 06720, Mexico City, Mexico.
Elisa Nishimura, MD
- Service of Endocrinology, Pediatric Hospital; XXI Century, National Medical Center, Mexican Institute of Social Security, Mexico City, Mexico
Jorge Hernandez, PhD
- Laboratory of Neurontogeny, Department of Physiology, Biophysics and Neurosciences, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, México; and the Facultad de Medicina, Universidad Autónoma de Querétaro, Queretaro City, Queretaro, México, Mexico.

Received 11 October 2001; accepted 12 June 2002.

Abstract

In the course of the present research in school children with insulin-dependent diabetes mellitus, we observed that the free fraction of l-tryptophan, the free fraction of l-tryptophan/total l-tryptophan, and the free fraction of l-tryptophan/neutral amino acids ratios, are significantly reduced. The decrease of free fraction of l-tryptophan in plasma with a concomitant decrease of the free fraction of l-tryptophan/neutral amino acids ratio suggest a decrease in the transport of the precursor amino acid to the brain and in the serotonin synthesis rate, similar to that observed in diabetic animals. This finding may be of relevance in the pathophysiology and in the clinical picture, which could be related to an alteration of serotonin metabolism and neurotransmission in the brain and may be possibly related to neuropsychiatric disorders in diabetic school children. Thus we propose that the free fraction of l-tryptophan and the free fraction of l-tryptophan/neutral amino acids ratios may be clinically useful as indicators of brain serotonergic activity in these patients. In our laboratory, we are currently obtaining additional data on the functional role of the brain serotonergic system in humans to further support the relevance of our results.