No abstract available.

Monoamine oxidase B (MAOB) is a key enzyme for GABA production in astrocytes in several brain regions. To date, the role of astrocytic MAOB has been studied in MAOB null knockout (KO) mice, although MAOB is expressed throughout the body. Therefore, there has been a need for genetically engineered mice in which only astrocytic MAOB is targeted. Here, we generated an astrocyte-specific MAOB conditional KO (cKO) mouse line and characterized it in the cerebellar and striatal regions of the brain. Using the CRISPR-Cas9 gene-editing technique, we generated Maob floxed mice (B6-Maob em1Cjl /Ibs) which have floxed exons 2 and 3 of Maob with two loxP sites. By crossing these mice with hGFAP-CreER T2 , we obtained Maob floxed::hGFAP-CreER T2 mice which have a property of tamoxifen-inducible ablation of Maob under the human GFAP (hGFAP) promoter. When we treated Maob floxed::hGFAP-CreER T2 mice with tamoxifen for 5 consecutive days, MAOB and GABA immunoreactivity were significantly reduced in striatal astrocytes as well as in Bergmann glia and lamellar astrocytes in the cerebellum, compared to sunflower oil-injected control mice. Moreover, astrocyte-specific MAOB cKO led to a 74.6% reduction in tonic GABA currents from granule cells and a 76.8% reduction from medium spiny neurons. Our results validate that astrocytic MAOB is a critical enzyme for the synthesis of GABA in astrocytes. We propose that this new mouse line could be widely used in studies of various brain diseases to elucidate the pathological role of astrocytic MAOB in the future.

The principal inhibitory transmitter, γ-aminobutyric acid (GABA), is critical for maintaining hypothalamic homeostasis and released from neurons phasically, as well as from astrocytes tonically. Although astrocytes in the arcuate nucleus (ARC) of the hypothalamus are shown to transform into reactive astrocytes, the tonic inhibition by astrocytic GABA has not been adequately investigated in diet-induced obesity (DIO). Here, we investigated the expression of monoamine oxidase- B (MAOB), a GABA-synthesizing enzyme, in reactive astrocytes in obese mice. We observed that a chronic high-fat diet (HFD) significantly increased astrocytic MAOB and cellular GABA content, along with enhanced hypertrophy of astrocytes in the ARC. Unexpectedly, we found that the level of tonic GABA was unaltered in chronic HFD mice using whole-cell patch-clamp recordings in the ARC. Furthermore, the GABA-induced current was increased with elevated GABA A receptor α5 (GABRA5) expression. Surprisingly, we found that a nonselective GABA transporter (GAT) inhibitor, nipecotic acid (NPA)-induced current was significantly increased in chronic HFD mice. We observed that GAT1 inhibitor, NO711-induced current was significantly increased, whereas GAT3 inhibitor, SNAP5114-induced current was not altered. The unexpected unaltered tonic inhibition was due to an increase of GABA clearance in the ARC by neuronal GAT1 rather than astrocytic GAT3. These results imply that increased astrocytic GABA synthesis and neuronal GABA A receptor were compensated by GABA clearance, resulting in unaltered tonic GABA inhibition in the ARC of the hypothalamus in obese mice. Taken together, GABA-related molecular pathways in the ARC dynamically regulate the tonic inhibition to maintain hypothalamic homeostasis against the HFD challenge.

INTRODUCTION: Psychiatric comorbidity is common in patients with functional dyspepsia (FD) but a good screening tool for psychiatric disorders in gastrointestinal clinical practice is lacking. Aims: 1) Evaluate the performance and optimal cut-off of 12-item General Health Questionnaire (GHQ-12) as a screening tool for psychiatric disorders in FD patients; 2) Compare health-related quality of life (HRQoL) in FD patients with and without psychiatric comorbidities. METHODS: Consecutive patients fulfilling Rome III criteria for FD without medical co-morbidities and gastroesophageal reflux disease were recruited in a gastroenterology clinic. The followings were conducted at 4 weeks after index oesophagogastroduodenoscopy: self-administrated questionnaires on socio-demographics, dyspeptic symptom severity (4-point Likert scale), GHQ-12, and 36-item short-form health survey (SF-36). Psychiatric disorders were diagnosed with Structured Clinical Interview for DSM-IV Axis I Disorders (SCID) by a trained psychiatrist, which served as reference standard. RESULTS: 55 patients underwent psychiatrist-conducted interview and questionnaire assessment. 27 (49.1%) had current psychiatric disorders as determined by SCID (anxiety disorders: 38.2%, depressive disorders: 16.4%). Receiver operating characteristic curve analysis of GHQ-12 revealed an area under curve of 0.825 (95%CI: 0.698-0.914). Cut-off of GHQ-12 at > or =3 gave a sensitivity of 63.0% (95%CI = 42.4-80.6%) and specificity of 92.9% (95%CI = 76.5%-98.9%). Subjects with co-existing psychiatric disorders scored significantly lower in multiple domains of SF-36 (mental component summary, general health, vitality and mental health). By multivariate linear regression analysis, current psychiatric morbidities (Beta = -0.396, p = 0.002) and family history of psychiatric illness (Beta = -0.299, p = 0.015) were independent risk factors for poorer mental component summary in SF-36, while dyspepsia severity was the only independent risk factor for poorer physical component summary (Beta = -0.332, p = 0.027). CONCLUSIONS: Concomitant psychiatric disorders adversely affect HRQoL in FD patients. The use of GHQ-12 as a reliable screening tool for psychiatric disorders allows early intervention and may improve clinical outcomes of these patients.
Area Under Curve ; Axis, Cervical Vertebra ; Comorbidity ; Diagnostic and Statistical Manual of Mental Disorders ; Dyspepsia ; Early Intervention (Education) ; Gastroenterology ; Gastroesophageal Reflux ; Health Surveys ; Humans ; Linear Models ; Mass Screening ; Mental Disorders ; Psychiatry ; Quality of Life ; Surveys and Questionnaires ; Risk Factors ; ROC Curve ; Rome ; Sensitivity and Specificity

Although gastroesophageal reflux disease is not as common in Asia as in western countries, the prevalence has increased substantially during the past decade. Gastroesophageal reflux disease is associated with considerable reductions in subjective well-being and work productivity, as well as increased healthcare use. Proton pump inhibitors (PPIs) are currently the most effective treatment for gastroesophageal reflux disease. However, there are limitations associated with these drugs in terms of partial and non-response. Dexlansoprazole is the first PPI with a dual delayed release formulation designed to provide 2 separate releases of medication to extend the duration of effective plasma drug concentration. Dexlansoprazole has been shown to be effective for healing of erosive esophagitis, and to improve subjective well-being by controlling 24-hour symptoms. Dexlansoprazole has also been shown to achieve good plasma concentration regardless of administration with food, providing flexible dosing. Studies in healthy volunteers showed no clinically important effects on exposure to the active metabolite of clopidogrel or clopidogrel-induced platelet inhibition, with no dose adjustment of clopidogrel necessary when coprescribed. This review discusses the role of the new generation PPI, dexlansoprazole, in the treatment of gastroesophageal reflux disease in Asia.
Asia* ; Blood Platelets ; Delayed-Action Preparations ; Delivery of Health Care ; Dexlansoprazole* ; Efficiency ; Esophagitis ; Gastroesophageal Reflux* ; Healthy Volunteers ; Plasma ; Prevalence ; Proton Pump Inhibitors ; Proton Pumps* ; Protons*