Glioblastoma cells express crucial enzymes involved in androgen synthesis: 3β-hydroxysteroid dehydrogenase, 17-20α-hydroxylase, 17β-hydroxysteroid dehydrogenase and 5α-reductase.

Glioblastoma (GB) is the most common and aggressive primary brain tumour in adult humans. Therapeutic resistance and tumour recurrence after surgical removal contribute to poor prognosis for glioblastoma patients. Men are known to be more likely than women to develop an aggressive form of GB, and differences in sex steroids have emerged as a leading explanation for this finding.

Another abnormal trait in the serotonin metabolism path in intrauterine growth-restricted infants.

Background: The present study was aimed to obtain information on the interaction kinetics of L-tryptophan (L-Trp) with plasma albumin from normal, intrauterine growth-restricted (IUGR) and nutritionally recovered (NR) newborn infants.

Methods: A case study cohort was planned in 37 newborns during the first 3 months of life. At birth two groups were formed.

A functional disturbance in the auditory cortex related to a low serotonergic neurotransmission in women with type 2 diabetes.

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.

N1/P2 component of auditory evoked potential reflect changes of the brain serotonin biosynthesis in rats.

It is known that L-tryptophan stimulates serotonin synthesis in the brain and serotonergic neuronal activity. Also, the N1/P2 component of auditory evoked potential (AEP) is a good indicator of this activity in the auditory cortex. In the present work, we examined the effect of the L-tryptophan administration on electric activity of the auditory cortex recorded as the N1/P2 component of the AEP in adult male rats.

A low brain serotonergic neurotransmission in children with type 1 diabetes detected through the intensity dependence of auditory-evoked potentials.

Objective: To determine in children with type 1 diabetes the plasma free fraction of L-tryptophan (FFT) and the intensity-dependent auditory-evoked potentials (IDAEPs) as indicators of possible changes in brain serotonergic neurotransmission.

Research Design And Methods: A prospective and comparative study was performed in children with type 1 diabetes and normal control subjects. We measured FFT, bound and total plasma L-tryptophan, neutral amino acids (NAAs), albumin, free fatty acids (FFAs), glucose, and HbA1c(A1C) and recorded IDAEPs with four intensities (40, 60, 90, and 103 dB).

Inhibition and kinetic changes of brain tryptophan-5-hydroxylase during insulin-dependent diabetes mellitus in the rat.

In the present study we report results on the possible mechanism of inhibition of tryptophan-5-hydroxylase activity induced by insulin-dependent diabetes mellitus (IDDM). Kinetic experiments were done with different L-tryptophan (L-Trp) concentrations in the rat brain at different days of evolution of the disease. Additionally, different activation conditions of the enzyme were evaluated, to gain information on the mechanism of the activity changes.

Serotonergic receptors in the brain of in utero undernourished rats.

In this study, we report that 5-HT(1A) receptors are already present in fractions of axonal growth cones, from the normal rat fetal brain (E-17). Also, in utero undernourished (UN) rat pups at birth show a noteworthy enhancement in the B(max) of [3H]5-hydroxytryptamine (5-HT) and [3H]8-hydroxy-(2-N,N-dipropilamin)-tetralin (([3H])8-OH-DPAT), in the brainstem and cerebral cortex up to the second week after birth. Afterwards, there is a significant decrease in the binding of these ligands.

Serotonin-related tryptophan in children with insulin-dependent diabetes.

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.

Developmental impairment of auditory evoked N1/P2 component in rats undernourished in utero: its relation to brain serotonin activity.

In utero undernourishment produces an elevation of L-tryptophan and serotonin in the brain, including the auditory cortex (A1), such changes seem to be related to an increase in the free fraction (FFT) of plasma L-tryptophan that is transported into the brain through the blood-brain barrier, where it is taken up by serotonergic neurons for serotonin synthesis. Our observations support that FFT has a positive correlation with L-tryptophan (L-Trp) and serotonin levels in the auditory cortex (r=0.95 and 0.