Functional Change of Brain Serotonergic Activity and Free Tryptophan in the Plasma of Depressed Women

Abstract

The main objective was to show the decrement of serotoninergic brain activity in depressed women, through the analyses of the slope amplitude of N1/P2 components of the auditory-evoked potentials (AEP), and the measurement of the L-tryptophan free fraction in plasma (FFT). This cross-sectional study was carried out in 60 women, 30 depressed and 30 normal controls. Both groups were measured FFT, glucose, and neutral amino acids (NAA) levels; besides performing AEP to analyses the N1/P2 slope amplitude. It was found a lengthening in the slope amplitude of N1/P2 components of AEP in the group of depressed women, and despite that the level of FFT was low, there were no changes between bound fraction and the total L-Trp. The former suggests a decrease in serotonergic brain activity in the group of depressed women. Otherwise, since the auditory cortex response to sound is regulated by serotonergic innervation, it was expected a change in the behavior of AEP in the group of depressed patients. Thus, the slope amplitude of N1/P2 components of the AEP and the measurement of FFT have proved to be a good clinical indicators of the serotonergic neurotransmission state in the brain of depressed patients, and in another clinical conditions where brain serotonin is involved.

Update on the Relationship Between Depression and Neuroendocrine Metabolism

“…By analyzing the slope amplitude of N1/P2 components of auditory evoked potentials and the determination of Ltryptophan free fraction in plasma, it was found that the brain activity of serum neurosin and L-tryptophan free fraction decreased in women with depression (Vázquez-Estupiñan et al, 2019). After ovariectomy in female mice, it was found that FIGURE 2 | Mechanism underlying metabolism related depression.…”

“…By analyzing the slope amplitude of N1/P2 components of auditory evoked potentials and the determination of L -tryptophan free fraction in plasma, it was found that the brain activity of serum neurosin and L -tryptophan free fraction decreased in women with depression ( Vázquez-Estupiñan et al, 2019 ). After ovariectomy in female mice, it was found that while estrogen decreased, the expression of IL-1β and IL-18, NLRP3 and the level of inflammatory cytokines such as active caspase-1 in the hippocampus of female mice increased significantly.…”