Evidence for reduced homovanillic acid (HVA) in the cerebrospinal fluid of patients with depression

Metabolic profiles of saliva in male mouse models of chronic sleep disorders induced by psychophysiological stress

Disordered sleep is a global social problem and an established significant risk factor for psychological and metabolic diseases. We profiled non-targeted metabolites in saliva from mouse models of chronic sleep disorder (CSD). We identified 288 and 55 metabolites using CE-FTMS and LC-TOFMS, respectively, among which concentrations of 58 (CE-FTMS) and three (LC-TOFMS) were significantly changed by CSD. Pathway analysis revealed that CSD significantly suppressed glycine, serine and threonine metabolism. Arginine and proline metabolic pathways were among those that were both upregulated and downregulated. Pathways of alanine, aspartate and glutamate metabolism, genetic information processing, and the TCA cycle tended to be downregulated, whereas histidine metabolism tended to be upregulated in mice with CSD. Pyruvate, lactate, malate, succinate and the glycemic amino acids alanine, glycine, methionine, proline, and threonine were significantly decreased, whereas 3-hydroxybutyric and 2-hydroxybutyric acids associated with ketosis were significantly increased, suggesting abnormal glucose metabolism in mice with CSD. Increases in the metabolites histamine and kynurenic acid that are associated with the central nervous system- and decreased glycine, might be associated with sleep dysregulation and impaired cognitive dysfunction in mice with CSD. Our findings suggested that profiling salivary metabolites could be a useful strategy for diagnosing CSD.

The comorbidity of depression and neurocognitive disorder in persons with HIV infection: call for investigation and treatment

Depression and neurocognitive disorder continue to be the major neuropsychiatric disorders affecting persons with HIV (PWH). The prevalence of major depressive disorder is two to fourfold higher among PWH than the general population (∼6.7%). Prevalence estimates of neurocognitive disorder among PWH range from 25 to over 47% - depending upon the definition used (which is currently evolving), the size of the test battery employed, and the demographic and HIV disease characteristics of the participants included, such as age range and sex distribution. Both major depressive disorder and neurocognitive disorder also result in substantial morbidity and premature mortality. However, though anticipated to be relatively common, the comorbidity of these two disorders in PWH has not been formally studied. This is partly due to the clinical overlap of the neurocognitive symptoms of these two disorders. Both also share neurobehavioral aspects - particularly apathy - as well as an increased risk for non-adherence to antiretroviral therapy. Shared pathophysiological mechanisms potentially explain these intersecting phenotypes, including neuroinflammatory, vascular, and microbiomic, as well as neuroendocrine/neurotransmitter dynamic mechanisms. Treatment of either disorder affects the other with respect to symptom reduction as well as medication toxicity. We present a unified model for the comorbidity based upon deficits in dopaminergic transmission that occur in both major depressive disorder and HIV-associated neurocognitive disorder. Specific treatments for the comorbidity that decrease neuroinflammation and/or restore associated deficits in dopaminergic transmission may be indicated and merit study.

The comparison of sex differences in depression-like behaviors and neuroinflammatory changes in a rat model of depression induced by chronic stress

Background

Clinical prevalence of major depression is higher in women than men, while the psychoneuroimmunological mechanisms underlying the differences between the two sexes are not fully understood.

Methods

The present study explored sex differences in the behaviors and depressive pathological mechanisms induced by chronic unpredictable mild stress (CUMS). Depression- and anxiety-like behaviors were assessed by the sucrose preference test (SPT), force swimming test (FST), open field test (OFT), and elevated plus-maze (EPM). The enzyme-linked immunosorbent assay (ELISA) was used to measure cytokine concentrations, high-performance liquid chromatography (HPLC) was used to measure monoamine neurotransmitters and metabolite contents, and real-time quantitative PCR (qPCR) and western blotting (WB) were used to measure glial parameters in the hippocampus.

Results

Under control conditions, female rats exhibited shorter immobility times in the FST, lower interferon (IFN)-γ, and interleukin (IL)-4 levels in the hippocampus, lower norepinephrine (NE) and homovanillic acid (HVA), and higher p75 and glial-derived neurotrophic factor (GDNF) expression than male rats. CUMS markedly reduced rat body weight gain, sucrose preference, locomotor activity, number of entries into the central zone and rearing in the OFT, as well as the number of entries into and time spent in open arms of the EPM; however, CUMS increased the immobility times of the rats of both sexes in the FST. Interestingly, more pronounced changes in sucrose preference and locomotor activity were observed in female rats than in males. Consistently, CUMS-increased glucocorticoid concentration, M1 microglial marker CD11b, and peripheral IL-1β and IL-4, while decreased hippocampal IL-10, serotonin (5-HT), dopamine metabolite 3,4-dihydroxyphenylacetic acid (DOPAC), and norepinephrine metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) were more significant in females than in males.

Conclusion

These data revealed possible mechanisms by which females suffer more depression than males at least in a stressful environment.

Gut Microbiota and Pathophysiology of Depressive Disorder

BACKGROUND

Accumulating evidence has suggested that the bi-directional communication pathway, the microbiota-gut-brain axis, plays an important role in the pathophysiology of many neuropsychiatric diseases including major depressive disorder (MDD). This review outlines current evidence and promising findings related to the pathophysiology and treatment of MDD.

SUMMARY

There are at least 4 key biological molecules/systems underlying the pathophysiology of MDD: central dopamine, stress responses by the hypothalamic-pituitary-adrenal axis and autonomic nervous system, inflammation, and brain-derived neurotrophic factor. Animal experiments in several depression models have clearly indicated that gut microbiota is closely related to these molecules/systems and administration of probiotics and prebitotics may have beneficial effects on them. Although the results of microbiota profile of MDD patients varied from a study to another, multiple studies reported that bacteria which produce short-chain fatty acids such as butyrate and those protective against metabolic diseases (e.g., Bacteroidetes) were reduced. Clinical trials of probiotics have emerged, and the majority of the studies have reported beneficial effects on depression symptoms and related biological markers. Key Messages: The accumulating evidence suggests that research on the microbiota-gut-brain axis in major depressive disorder (MDD) is promising to elucidate the pathophysiology and to develop novel treatment of MDD, although there is still a long distance yet to reach the goals.

Influence of prenatal transportation stress-induced differential DNA methylation on the physiological control of behavior and stress response in suckling Brahman bull calves

The objective of this experiment was to examine potential differential methylation of DNA as a mechanism for altered behavioral and stress responses in prenatally stressed (PNS) compared with nonprenatally stressed (Control) young bull calves. Mature Brahman cows (n = 48) were transported for 2-h periods at 60 ± 5, 80 ± 5, 100 ± 5, 120 ± 5, and 140 ± 5 d of gestation (Transported group) or maintained as nontransported Controls (n = 48). From the offspring born to Transported and Control cows, a subset of 28-d-old intact bulls (n = 7 PNS; n = 7 Control) were evaluated for methylation of DNA of behavior and stress response-associated genes. Methylation of DNA from white blood cells was assessed via reduced representation bisulfite sequencing methods. Because increased methylation of DNA within gene promoter regions has been associated with decreased transcriptional activity of the corresponding gene, differentially methylated (P ≤ 0.05) CG sites (cytosine followed by a guanine nucleotide) located within promoter regions (n = 1,205) were used to predict (using Ingenuity Pathway Analysis software) alterations to canonical pathways in PNS compared with Control bull calves. Among differentially methylated genes (P ≤ 0.05) related to behavior and the stress response were OPRK1, OPRM1, PENK, POMC, NR3C2, TH, DRD1, DRD5, COMT, HTR6, HTR5A, GABRA4, GABRQ, and GAD2. Among altered (P < 0.05) signaling pathways related to behavior and the stress response were Opioid Signaling, Corticotropin-Releasing Hormone Signaling, Dopamine Receptor Signaling, Dopamine-DARPP32 Feedback in cAMP Signaling, Serotonin Receptor Signaling, and GABA Receptor Signaling. Alterations to behavior and stress response-related genes and canonical pathways supported previously observed elevations in temperament score and serum cortisol through weaning in the larger population of PNS calves from which bulls in this study were derived. Differential methylation of DNA and predicted alterations to behavior and stress response-related pathways in PNS compared with Control bull calves suggest epigenetic programming of behavior and the stress response in utero.