Current Topics in Medicinal Chemistry - Volume 18, Issue 19, 2018

Generalized Anxiety Disorder (GAD) commonly co-occurs with mood disorders, especially Major Depressive Disorder (MDD) and bipolar disorder (BD), which are accompanied by activated neuro-immune and neuro-oxidative pathways. The aim of this narrative review is to review the phenomenological similarities and dissimilarities and the shared pathways between GAD and mood disorders. We searched PubMed, Scopus, and Google Scholar for articles published in English from 1980 to present. GAD and mood disorders, either MDD or BD, show some phenomenological overlaps and a high degree of comorbidity, especially between GAD and MDD. Both GAD and mood disorders are also frequently comorbid with other anxiety disorders, substance use disorders and medical conditions, including cardio- vascular disorder (CVD). Mood disorders have a worse prognosis when GAD is present. GAD and mood disorders are associated with female sex and may partly share genetic variants of risk. Moreover, both GAD and mood disorders frequently share similar environmental risks factors including Early Life Time Trauma (ELT) and Psychological Stressors in Adulthood (PSA). Increased nitro-oxidative stress and lipid peroxidation coupled to lowered lipid-associated antioxidant defenses are evident in GAD, MDD and type I bipolar patients. Patients with comorbid GAD and MDD show significantly higher nitro- oxidative biomarkers as compared with patients presenting with either GAD or MDD as well as patients with BD with or without co-occurring GAD. Activated immune-inflammatory processes characterized by increased levels of CRP and pro-inflammatory cytokines are other shared pathways that underpin GAD and mood disorders. Moreover, these pathways may explain comorbidities with medical disorders including CVD. Aberrations in HPA-axis, GABA and glutamate neurotransmission, NMDA and mu opioid-receptors and neuroimaging fields have yielded more inconsistent findings. In conclusion, here we propose a new model explaining GAD and the comorbidity between GAD and mood disorders. Common triggers such as ELT/PSA may underpin GAD and its comorbidity with mood disorders via activated neuro-oxidative, neuro-nitrosative and neuro-immune pathways.

Background: Increased intestinal permeability with heightened translocation of Gramnegative bacteria, also known as “leaky gut”, is associated with the pathophysiology of neuroimmune disorders, such as Major Depressive Disorder (MDD), Chronic Fatigue Syndrome (CSF) and (deficit) schizophrenia, as well as with general medical disorders, including irritable bowel syndrome. This review aims to summarize clinical biochemistry and molecular immunology tests that may aid in the recognition of leaky gut in clinical practice. Methods: We searched online libraries, including PubMed/MEDLINE, Google Scholar and Scopus, with the key words “diagnosis” or “biomarkers” and “leaky gut”, “bacterial translocation”, and “intestinal permeability” and focused on papers describing tests that may aid in the clinical recognition of leaky gut. Results: To evaluate tight junction barrier integrity, serum IgG/IgA/IgM responses to occludin and zonulin and IgA responses to actomyosin should be evaluated. The presence of cytotoxic bacterial products in serum can be evaluated using IgA/IgM responses to sonicated samples of common Gram-negative gut commensal bacteria and assays of serum lipopolysaccharides (LPSs) and other bacterial toxins, including cytolethal distenting toxin, subunit B. Major factors associated with increased gut permeability, including gut dysbiosis and yeast overgrowth, use of NSAIDs and alcohol, food hypersensitivities (IgE-mediated), food intolerances (IgG-mediated), small bacterial overgrowth (SIBO), systemic inflammation, psychosocial stressors, some infections (e.g., HIV) and dietary patterns, should be assessed. Stool samples can be used to assay gut dysbiosis, gut inflammation and decreased mucosal defenses using assays of fecal growth of bacteria, yeast and fungi and stool assays of calprotectin, secretory IgA, β-defensin, α- antitrypsin, lysozyme and lactoferrin. Blood and breath tests should be used to exclude common causes of increased gut permeability, namely, food hypersensitivities and intolerances, SIBO, lactose intolerance and fructose malabsorption. Discussion: Here, we propose strategies to recognize “leaky gut” in a clinical setting using the most adequate clinical chemistry and molecular immunology assays.

The identification of anxious symptoms is crucial to diagnose anxiety disorders, as well as to monitor their treatment in clinical practice and research. The aim of this review is to discuss the different ways of assessing anxiety in clinical research, including clinical trials, and the different kinds of animal behavioral tests used to study anxiety and test the efficacy of anxiolytics in pre-clinical studies. In clinical practice, a categorical classification (such as the Diagnostic and Statistical Manual of Mental Disorders and the International Statistical Classification of Diseases and Related Health Problems) distinguishes the cases of the disease versus non-disease. Some structured and semi-structured interviews can be used to arrive at these diagnoses. On the other hand, anxiety can also be assessed using a dimensional approach, through self-report or hetero-evaluation questionnaires. Regarding the assessment of anxiety in animals, several behavioral tests are described and evaluated, namely the Social Interaction Test, Elevated Plus Maze and Open Field Test. Under a critical view, these two approaches are presented and discussed, in order to improve the outcome of research in this field.

Depression is deeply rooted in human behavior. The development of new antidepressants demands the creation of animal models to investigate new drugs, which potentially could work as antidepressants. The aim of this review is to discuss the different ways of assessing depression in clinical research, including clinical trials, and the different animal behavioral tests used to study depression and test the efficacy of antidepressants in pre-clinical studies. In clinical practice, a categorical classification, such as the Diagnostic and Statistical Manual of Mental Disorders (DSM) and the International Statistical Classification of Diseases and Related Health Problems (ICD) can be used for diagnosis, through the use of structured and semi-structured interviews. On the other hand, depression can also be assessed using a dimensional approach, through self- or clinicianrated questionnaires. Regarding the assessment of the efficacy of antidepressants in animal models, several tests are routinely used, namely the Forced Swim Test, the Modified Forced Swim Test, the Tail Suspension Test and the Sucrose Preference Test. These tests are informative, providing that the following rules are taken into account: 1) more than one test is used, with coherent results; 2) secondary drug effects, the most frequent being putative changes in motor activity, are taken into account and properly controlled with specific tests run concomitantly; 3) each test and specific protocol is validated with data from at least a gold standard antidepressant drug. We herein briefly discuss the potential and limitations of each of those tests.

Introduction: Anxiety disorders manifest in women more than in men by almost twofold. This narrative review aims to summarize the sex-related biological factors, which underpin anxiety, focusing on the interactions of sex and tryptophan/serotonin with anxiety. Methods: A literature search was conducted using Google Scholar, PubMed/MEDLINE, Scopus, and EMBASE databases from inception until December 31, 2017. Results: This review shows that sex may interact with many serotonin functions thereby modulating anxiety, including 5-HT1A and 5-HT2C receptors, 5-HT transporter and central 5-HT concentrations and metabolism. Sex-steroids modulate the expression of serotonin transporter genes, creating a difference in serotonin availability. Sex and estrous cycle phases lead to varying anxiety responses to tryptophan depletion. Testosterone, progesterone and estrogen are important factors in mediating sex differences in serotonin responses to anxiety-generating behavioral tests. At prenatal levels, there are sexrelated differences in the reciprocal relationships between serotonin and the HPA-axis, which modulate anxiety-like behaviors. Activated immune-inflammatory pathways induce indoleamine-2,3-dioxynease (IDO) and the tryptophan catabolite (TRYCAT) pathway thereby increasing tryptophan degradation and increasing the production of TRYCATs including kynurenine and quinolinic acid, which may create an overall anxiogenic effect. The effects of immune activation on IDO are significantly more pronounced in women than men, and therefore, females may show increased levels of anxiogenic TRYCAT following immune challenge. Aberrations in the IDO-activated TRYCAT pathway are found in pregnant females and parturients and are associated with increased anxiety levels in the postnatal period. Conclusion: The results of this review underscore the necessity of studying the associations between serotonin and anxiety in both sexes taking into account the effects of immune activation on IDO and production of anxiogenic TRYCATs. Future anxiety research should focus on the interactions between serotonin/tryptophan and sex, sex hormones, the menstrual cycle, pregnancy, the HPA axis and the immune system through the production of anxiogenic TRYCATs.