A Functional Disturbance in the Auditory Cortex Related to a Low Serotonergic Neurotransmission in Women with Type 2 Diabetes

Vol. 86, No. 4, 2007

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Clinical Neuroendocrinology

A Functional Disturbance in the Auditory Cortex Related to a Low Serotonergic Neurotransmission in Women with Type 2 Diabetes
Gabriel Manjarrez^a, Felipe Vazquez^a, Margarita Delgado^b, Rocio Herrera^a, Jorge Hernandez^c

^aLaboratory of Developmental Neurochemistry and
^bService of Audiology, Specialties Hospital, XXI Century National Medical Center (CMN SXXI), Mexican Institute of Social Security (IMSS) and
^cLaboratory of Neurontogeny, Department of Physiology, Biophysics and Neurosciences, Center of Research and Advanced Studies (CINVESTAV) IPN, Mexico City, Mexico

Address of Corresponding Author

Neuroendocrinology 2007;86:289-294 (DOI: 10.1159/000109375)

Key Words

Auditory evoked potential (N1/P2) component
Serotonin
L-Tryptophan
Type 2 diabetes

Abstract

Background/Aims: To determine if the slope of the amplitude/stimulus intensity function (ASF) of the N1/P2 component of the auditory evoked potential was increased in women with type 2 diabetes reflecting a low brain serotonergic activity in the auditory cortex. Methods: In a comparative study in women with type 2 diabetes and controls, we measured free, bound and total plasma L-tryptophan (L-Trp), neutral amino acids (NAA) and free fatty acids (FFA) and recorded the N1/P2 component of the auditory evoked potential. Results: The diabetic patients were overweight and FFA and NAA in plasma were significantly elevated. The free, bound to albumin and total L-Trp were decreased. The values of free/total L-Trp and free/NAA ratios were significantly lower. The latencies of N1 and P2 at all intensities and the slope ASF of the N1/P2 component significantly increased. Conclusion: The decrease of the free fraction of L-Trp in plasma and the increase of the ASF slope of the N1/P2 component reflect a functional relationship between the brain serotonergic activity and the N1/P2 changes in the auditory cortex, suggesting a cortical impaired activity associated with anomalies of brain serotonergic neurotransmission in women with type 2 diabetes. We proposed the ASF slope together with measurement of the plasma FFT as noninvasive clinical indicators of serotonergic neurotransmission in the brain in these as well as in other types of patients.

Author Contacts

Gabriel Manjarrez
Laboratory of Developmental Neurochemistry
Specialties Hospital, CMN SXXI, IMSS, Av. Cuauhtémoc 330, Col. Doctores
Mexico City, CP 06720 (Mexico)
Tel. +52 55 5578 0240, Fax +52 55 5761 0952, E-Mail willisga@df1.telmex.net.mx

Article Information

Received: March 21, 2007
Accepted after revision: August 21, 2007
Published online: October 2, 2007
Number of Print Pages : 6
Number of Figures : 2, Number of Tables : 2, Number of References : 46

Medline Abstract (ID 17911977)

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