Michelle S. Carvalho

Background: Schizophrenia (SCZ) is a severe mental disorder of multifactorial origin in which the role of amino acids is relatively unknown. Based on the hypothesis that there is an imbalance in amino acid levels in individuals with SCZ compared with healthy controls (HCs), the aim of this study was to identify the 20 proteinogenic amino acids involved in protein synthesis.Methods: This study included 43 sex‐ and age‐matched individuals: 20 HCs and 23 with SCZ diagnosed using the Diagnostic and Statistical Manual of Mental Disorders criteria. Using proton nuclear magnetic resonance, we identified the serum levels of the 20 amino acids proteinogenic. We perform multivariate statistical exploratory analyzes to identify compounds, quantify, and identify the main biomarkers of SCZ.Results: We identified the serum levels of 19 of the 20 amino acids. Cysteine, the main precursor of glutathione, was not detected. Multivariate exploratory analysis identified lysine, Tryptophan (TRP), and glutamate as possible biomarkers of SCZ. Both lysine and TRP levels were lower and glutamate levels were higher in individuals with SCZ than in HCs. The observed reduction in plasma TRP levels in SCZ was attributed to the activation of the kynurenine pathway and has implications for serotonin synthesis. A strong positive correlation was observed between lysine and TRP, and a weak negative correlation between lysine and glutamate. This result is consistent with the lysine catalysis process because lysine degradation generates glutamate and favors an increase in dopamine.Conclusions: The results are consistent with the lysine catalysis process because lysine degradation generates glutamate and favors an increase in dopamine. We were unable to identify any studies suggesting a relationship between lysine catabolism and SCZ pathophysiology, but we recognize this association as innovative.

Approximately 255 million people consume illicit drugs every year, among which 18 million use cocaine. A portion of this drug is represented by crack, but it is difficult to estimate the number of users since most are marginalized. However, there are no recognized efficacious pharmacotherapies for crack-cocaine dependence. Inflammation and infection in cocaine users may be due to behavior adopted in conjunction with drug-related changes in the brain. To understand the metabolic changes associated with the drug abuse disorder and identify biomarkers, we performed a ¹H NMR-based metabonomic analysis of 44 crack users’ and 44 healthy volunteers’ blood serum. The LDA model achieved 98% of accuracy. From the water suppressed ¹H NMR spectra analyses, it was observed that the relative concentration of lactate was higher in the crack group, while long chain fatty acid acylated carnitines were decreased, which was associated with their nutritional behavior. Analyses of the aromatic region of CPMG ¹H NMR spectra demonstrated histidine and tyrosine levels increased in the blood serum of crack users. The reduction of carnitine and acylcarnitines and the accumulation of histidine in the serum of the crack users suggest that histamine biosynthesis is compromised. The tyrosine level points to altered dopamine concentration.

The use of ketamine as an option in the treatment of depressive disorder is growing rapidly, supported by numerous clinical trials attesting its efficacy and safety. Esketamine, the S (+) enantiomer of ketamine, is the most widely used form in the anesthetic environment in some countries, and new studies have shown that it may also be effective in depression and with better tolerability. However, no study so far has directly compared esketamine with racemic ketamine. Here we propose a protocol of a clinical trial to evaluate esketamine as a noninferior medication when compared to ketamine in the treatment of patients with treatment-resistant depression. This study protocol is for a randomized, controlled, double-blind noninferiority clinical trial. Subjects will be 18 years or older, with major depression characterized as treatment-resistant. Participants will receive a single infusion of either esketamine (0.25 mg/kg) or ketamine (0.5 mg/kg) over 40 minutes. The primary outcome will be the difference in remission rates between the 2 treatment arms at 24 and 72 hours after drug infusion. Secondary outcomes will include other timepoints, measurements of cognition, dissociation, and blood biomarkers. A head-to-head study is the best way to evaluate whether the esketamine is in fact comparable to the racemic ketamine in terms of both efficacy and safety, and, if positive, it would be an initial step to increase the access to that type of treatment worldwide. The study was approved by the local Institutional Review Board (University Hospital Professor Edgard Santos—Federal University of Bahia—Number: 46657415.0.0000.0049). Subjects will only participate after voluntarily agreeing and signing the Informed Consent Form. The study findings will be published in peer-reviewed journals and presented at national and international conferences. This trial has been registered in the Japan Primary Registries Network (JPRN): UMIN000032355, which is affiliated with the World Health Organization.

O triptofano (TRP) é um aminoácido essencial, encontrado no plasma principalmente ligado à albumina, e com apenas uma pequena fração encontrada na forma livre. Ao atravessar a barreia hematoencefálica, seus metabólitos exercem diferentes ações no sistema nervoso central. Importantes metabólitos neuroativos resultantes do metabolismo do TRP (como a serotonina, melatonina, 3-hidroxiquinurenina, ácido quinolínico e quinurênico, dentre outros) têm sido associados a doenças neurodegenerativas como o Mal de Alzheimer, a doença de Huntington, o transtorno bipolar (TB) e a esquizofrenia (SCZ). Além disto, há também relatos sobre a sua relação com a depressão, as doenças inflamatórias, diversas alergias e com doenças infecciosas. O objetivo deste trabalho foi reunir informações recentes e atualizadas sobre o que se sabe sobre papel do TRP e as seus metabólitos, enfatizando a relação desse aminoácido e seus metabólitos na fisiopatologia da SCZ, com enfoque na via das quinureninas e sobretudo suas eventuais associações com as doenças mentais.