Low plasma tryptophan in carcinoid patients is associated with increased urinary cortisol excretion

Constitutive depletion of brain serotonin differentially affects rats' social and cognitive abilities

Central serotonin appears a promising transdiagnostic marker of psychiatric disorders and a modulator of some of their key behavioral symptoms. In adult male Tph2 -/- rats, constitutively lacking central serotonin, we tested individual's cognitive, social and non-social abilities and characterized group's social organization under classical and ethological testing conditions. Using unsupervised machine learning, we identified the functions most dependent on serotonin. Although serotonin depletion did not affect cognitive performances in classical testing, in the home-cage it induced compulsive aggression and sexual behavior, hyperactive and hypervigilant stereotyped behavior, reduced self-care and exacerbated corticosterone levels. This profile recalled symptoms of impulse control and anxiety disorders. Serotonin appeared essential for behavioral adaptation to dynamic social environments. Our animal model challenges the essential role of serotonin in decision-making, flexibility, impulsivity, and risk-taking. These findings highlight the importance of studying everyday life functions within the dynamic social living environment to model complexity in animal models.

Simultaneous determination of tryptophan, 5-hydroxytryptophan, tryptamine, serotonin, and 5-HIAA in small volumes of mouse serum using UHPLC-ED

In this paper we report a simple and efficient method for the concurrent analysis of tryptophan, 5-HTP, tryptamine, serotonin, and 5-HIAA in mouse serum using UHPLC-ED after protein precipitation and dilution. These compounds are neuroactive and are of interest in studies of mood and behavior; They are also biomarkers for the presence of neuroendocrine tumors and are used in the diagnosis of these cancers. After a brief series of validation experiments, this method was applied to serum from mouse behaviour experiments.•

A convenient UHPLC method with electrochemical detection for concomitant analysis of the serotonin pathway in serum, including, for the first time, tryptamine.

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The method met all performance criteria established for use in our lab and was applied in rodent experiments.

Updates in PTSD Animal Models Characterization

Post-traumatic stress disorder (PTSD) is a chronic, debilitating mental disorder afflicting more than 7% of the US population and 12% of military service members. Since the Afghanistan and Iraq wars, thousands of US service members have returned home with PTSD. Despite recent progress, the molecular mechanisms underlying the pathology of PTSD are poorly understood. To promote research on PTSD (especially its molecular mechanisms) and to set a molecular basis for discovering novel medications for this disorder, well-validated animal models are needed. However, to develop PTSD animal models is a challenging process, due to predisposing factors such as physiological, behavioral, emotional, and cognitive changes that emerge after trauma. Currently, there is no well-validated animal model of PTSD, although several stress paradigms mimic the behavioral symptoms and neurological alterations seen in PTSD. In this chapter, we will provide an overview of animal models of PTSD including learned helplessness, footshock, restraint stress, inescapable tail shock, single-prolonged stress, underwater trauma, social isolation, social defeat, early-life stress, and predator-based stress. We emphasize rodent models because they reproduce some of the behavioral and biotical phenotypes seen in PTSD. We will also present data showing that homologous biological measures are increasingly incorporated in studies to assess markers of risk and therapeutic response in these models. Therefore, PTSD animal models may be refined in hopes of capitalizing on the understanding of the molecular mechanisms and delivering tools in order to develop new and more efficacious treatments for PTSD.

Acute inflammatory bowel disease complicating chronic alcoholism and mimicking carcinoid syndrome

We report the case of a woman with a history of chronic alcohol abuse who was hospitalized with diarrhea, severe hypokalemia refractory to potassium infusion, nausea, vomiting, abdominal pain, alternations of high blood pressure with phases of hypotension, irritability and increased urinary 5-hydroxyindoleacetic acid and cortisol. Although carcinoid syndrome was hypothesized, abdominal computed tomography and colonoscopy showed non-specific inflammatory bowel disease with severe colic wall thickening, and multiple colic biopsies confirmed non-specific inflammation with no evidence of carcinoid cells. During the following days diarrhea slowly decreased and the patient's condition progressively improved. One year after stopping alcohol consumption, the patient was asymptomatic and serum potassium was normal. Chronic alcohol exposure is known to have several deleterious effects on the intestinal mucosa and can favor and sustain local inflammation. Chronic alcohol intake may also be associated with high blood pressure, behavior disorders, abnormalities in blood pressure regulation with episodes of hypotension during hospitalization due to impaired baroreflex sensitivity in the context of an alcohol withdrawal syndrome, increased urinary 5-hydroxyindoleacetic acid as a result of malabsorption syndrome, and increased urinary cortisol as a result of hypothalamic-pituitary-adrenal axis dysregulation. These considerations, together with the regression of symptoms and normalization of potassium levels after stopping alcohol consumption, suggest the intriguing possibility of a alcohol-related acute inflammatory bowel disease mimicking carcinoid syndrome.