Yusuke Murata

Chronic treatment with tandospirone, a serotonin 1A receptor partial agonist, inhibits psychosocial stress-induced changes in hippocampal neurogenesis and behavior

BACKGROUND The 5-hydroxytryptamine (5-HT) 1A receptors are considered a potential target for the treatment of mental and neuropsychiatric disorders. Several studies have indicated that 5-HT1A receptor agonists increase hippocampal neurogenesis, which is implicated in the action mechanism of antidepressants. However, these agents have not been applied to humans due to intolerable side effects. We recently showed that chronic administration of tandospirone, a clinically available 5-HT1A receptor partial agonist, increased hippocampal neurogenesis dose-dependently. The present study was done to determine if chronic tandospirone treatment has antidepressant potential from the standpoint of hippocampal neurogenesis and behavior. METHODS Male Sprague-Dawley rats were intraperitoneally administered a vehicle or tandospirone (10mg/kg) once daily for 28 days. Two weeks after starting the injections, animals were exposed to intermittent social defeat (four times over two weeks). The effects of stress and tandospirone on the rodents׳ behavior were evaluated by the Novelty-Suppressed Feeding (NSF) test. The quantification of hippocampal neurogenesis was estimated using immunostaining with Ki-67 and doublecortin (DCX). RESULTS Chronic tandospirone treatment reversed the psychosocial stress-induced increase in the latency in the NSF test and decrease in the density of DCX-positive cells in the dentate gyrus of the dorsal and ventral hippocampus. However, no difference in the density of Ki-67-positive cells was observed between the vehicle- and tandospirone-administered groups. LIMITATIONS To clarify the antidepressant potential of TDS, the other behavioral tests for depression will be required. CONCLUSIONS Our findings suggest that tandospirone has antidepressant potential through an inhibiting effect on stress-induced changes in hippocampal neurogenesis.

Effects of the serotonin 1A, 2A, 2C, 3A, and 3B and serotonin transporter gene polymorphisms on the occurrence of paroxetine discontinuation syndrome.

Paroxetine discontinuation symptoms can at times be severe enough to reduce the quality of life. However, it is currently not possible to predict the occurrence of discontinuation syndrome before the initiation or discontinuation of paroxetine treatment. In this study, we investigated the effects of genetic polymorphisms in the serotonin 1A, 2A, 2C, 3A, and 3B receptor, the serotonin transporter, and the cytochrome P450 2D6 (CYP2D6) genes on the occurrence of paroxetine discontinuation syndrome. A consecutive series of 56 Japanese patients who had a diagnosis of major depressive or anxiety disorder according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, were treated with paroxetine. Paroxetine discontinuation syndrome was found in 35.7% of the patients by direct interview. Patients who stopped taking paroxetine abruptly experienced paroxetine discontinuation syndrome significantly more often than patients who had a tapering off of the dosage of medication. Patients who had the -1019C allele experienced paroxetine discontinuation syndrome more frequently than patients who had the -1019G homozygote (nominal P = 0.0423) of the serotonin 1A receptor gene. However, this result did not remain significant after the Bonferroni correction for multiple comparisons. The findings suggest that the abrupt stoppage of medication is a major risk factor for the occurrence of paroxetine discontinuation syndrome and that C(-1019)G polymorphism of the serotonin 1A receptor gene may be related to the occurrence of the syndrome.

Estimated urinary salt excretion by a self-monitoring device is applicable to education of salt restriction.

The objective was to investigate the validity of a self-monitoring device that estimates 24-h urinary salt excretion from overnight urine samples as a tool for education regarding salt restriction. Twenty healthy volunteers consumed test meals for 14 days, with salt content as follows: 10 g (days 1–5); 5 g (days 6–8, 12 and 14); and 13 g (days 9–11 and 13). On days 2–15, urinary salt excretion was estimated from overnight urine samples by a self-monitoring device. Twenty-four-hour urine samples were collected on days 5 and 8 to measure salt excretion directly. Blood pressure was measured in the morning and during sleep on days 1–15. Estimated urinary salt excretion measured by the device showed a correlation with salt intake, and the ratio of estimated urinary salt excretion to salt intake was 0.84±0.10 (days 2–6), 1.27±0.28 (days 7–9), 0.70±0.11 (days 10–12), 1.37±0.22 (day 13), 0.68±0.13 (day 14) and 1.33±0.19 (day 15). The correlation between estimated urinary salt excretion measured by a device and directly measured 24-h urinary salt excretion was significant (r=0.65, P<0.05) during the period of 10 g salt intake, but not during 5 g salt intake. Blood pressure in the morning was not influenced by the change in salt intake, but systolic pressure during sleep showed a significant increase or decrease according to the levels of salt intake. In conclusion, a self-monitoring device, which can estimate 24-h urinary salt excretion from overnight urine samples, is considered to be a practical tool for education regarding salt restriction, although a similar future investigation is needed in older and/or hypertensive subjects.

Self-management of salt intake: clinical significance of urinary salt excretion estimated using a self-monitoring device

Self-measured salt excretion from overnight urine samples shows significant correlation with 24-h-urinary salt excretion, but it is not known whether a self-measuring method can monitor daily fluctuations in individual salt consumption. In this study, we measured salt excretion from 24-h urine samples (24-h salt) in 50 volunteers over 3 test days (2 weekdays and 1 holiday), and examined to what extent the values correlated with estimates of 24-h salt excretion from overnight urine samples obtained using a self-monitoring device (ON salt). Urine collection was considered successful when the difference between the predicted and actual 24-h-urinary creatinine excretion was within 30%. Thirty-three (M/F=7/26; 39.6±16.7 years) out of 50 participants completed their urine collections successfully and their samples were used in the analysis. Twenty-four-hour salt and ON salt did not significantly differ between test days and between the weekdays and the holiday. Moreover, there was a significant positive correlation between 24-h salt and ON salt for each test day. The coefficients of variation (CVs) for 24-h salt among test days and among subjects were 24.7% and 21.3%, respectively. The CVs for ON salt were lower than those for 24-h salt (13.3% and 17.7%, respectively). In conclusion, self-measurement of salt excretion from overnight urine samples allows estimation of daily salt intake; thus, the use of a self-monitoring device may be a useful motivational tool for personal salt restriction.

Hepcidin/ferroportin expression levels involve efficacy of pegylated-interferon plus ribavirin in hepatitis C virus-infected liver

AIM To investigate the relationship between the iron-metabolism-related gene expression profiles and efficacy of antiviral therapy in chronic hepatitis C patients. METHODS The hepatic expression profile of iron-metabolism-related genes was analyzed and its association with virological response to pegylated-interferon plus ribavirin combination therapy was evaluated. A hundred patients with chronic hepatitis C (genotype1b, n = 50; genotype 2, n = 50) were enrolled and retrospectively analyzed. Liver biopsy samples were subjected to quantitative polymerase chain reaction for iron-metabolism-related genes and protein expression (Western blotting analysis) for ferroportin. As a control, normal liver tissue was obtained from 18 living donors of liver transplantation. Serum hepcidin level was measured by sensitive liquid chromatography/electrospray ionization tandem mass spectrometry. RESULTS Iron overload is associated with liver damage by increasing oxidative stress and hepatitis C virus (HCV) is reported to induce iron accumulation in hepatocytes in vivo. Conversely, iron administration suppresses HCV replication in vitro. Therefore, the association between HCV infection and iron metabolism remains unclear. Compared with controls, patients had significantly higher gene expression for transferrin, iron-regulatory proteins 1 and 2, divalent metal transporter 1, and ferroportin, but similar for transferrin receptors 1 and 2, and hepcidin. When the expression profiles were compared between sustained virological response (SVR) and non-SVR patients, the former showed significantly lower transcription and protein expression of hepcidin and ferroportin. Expression of hepcidin-regulating genes, BMPR1, BMPR2, and hemojuvelin, was significantly increased, whereas BMP2 was decreased in HCV-infected liver. BMPR2 and hemojuvelin expression was significantly lower in the SVR than non-SVR group. HCV infection affects the expression of iron-metabolism-related genes, leading to iron accumulation in hepatocytes. CONCLUSION Decreased expression of hepcidin and ferroportin in SVR patients indicates the importance of hepatocytic iron retention for viral response during pegylated-interferon plus ribavirin treatment.

Intracellular mechanisms underlying lipid accumulation (white opaque substance) in gastric epithelial neoplasms: A pilot study of expression profiles of lipid‐metabolism‐associated genes

White opaque substance (WOS) is a novel endoscopic finding in gastric neoplasms, indicating the intracellular accumulation of lipid droplets (LDs). However, gastric lipid metabolism has not been extensively investigated, even in normal mucosa. We investigated the expression profiles of lipid‐metabolism‐associated genes in gastric neoplasms.

HMGA1a induces alternative splicing of estrogen receptor alpha in MCF-7 human breast cancer cells

The high-mobility group A protein 1a (HMGA1a) protein is known as an oncogene whose expression level in cancer tissue correlates with the malignant potential, and known as a component of senescence-related structures connecting it to tumor suppressor networks in fibroblasts. HMGA1 protein binds to DNA, but recent studies have shown it exerts novel functions through RNA-binding. Our previous studies have shown that sequence-specific RNA-binding of HMGA1a induces exon-skipping of Presenilin-2 exon 5 in sporadic Alzheimer disease. Here we show that HMGA1a induced exon-skipping of the estrogen receptor alpha (ERα) gene and increased ERα46 mRNA expression in MCF-7 breast cancer cells. An RNA-decoy of HMGA1a efficiently blocked this event and reduced ERα46 protein expression. Blockage of HMGA1a RNA-binding property consequently induced cell growth through reduced ERα46 expression in MCF-7 cells and increased sensitivity to tamoxifen in the tamoxifen-resistant cell line, MCF-7/TAMR1. Stable expression of an HMGA1a RNA-decoy in MCF-7 cells exhibited decreased ERα46 protein expression and increased estrogen-dependent tumor growth when these cells were implanted in nude mice. These results show HMGA1a is involved in alternative splicing of the ERα gene and related to estrogen-related growth as well as tamoxifen sensitivity in MCF-7 breast cancer cells.

Comparison of a salt check sheet with 24-h urinary salt excretion measurement in local residents.

The salt check sheet developed by Tsuchihashi et al. is widely used in general practice to assess salt intake and the associated diets. However, its appropriateness for the general population has not been assessed alongside 24-h urinary salt excretion monitoring. Therefore, in local residents, we analyzed the correlation between check-sheet scores and 24-h urinary salt excretion levels to determine the appropriateness of the check sheet. We asked 176 local residents to complete the salt check sheet and provide urinary samples; the latter were obtained using a proportional sampling method over a 24-h period. One hundred and forty subjects completed the study (men/women: 23/117, mean±s.d. age: 52.7±19.6 years, blood pressure: 122.3±18.0/74.3±11.1 mm Hg), of whom 51 (36.4%) had hypertension. The total salt check-sheet scores were widely distributed (mean±s.d.: 11.1±4.2 points, range: 0–22 points), and the subjects were divided into the following groups on the basis of salt levels: 29.3% were ‘low’ (0–8 points), 42.8% were ‘medium’ (9–13 points), 23.6% were ‘high’ (14–19 points) and 4.3% were ‘very high’ (>20 points). The mean 24-h urinary salt excretion level was 8.5±3.3 g. The subjects with higher salt-intake levels tended to have increased 24-h urinary salt excretion levels, with significant differences between the three groups (‘low’ vs. ‘medium’ vs. ‘high to very high’ salt levels: 7.6±2.9 g vs. 8.4±2.8 g vs. 9.6±4.2 g, respectively; P=0.03). The total salt check-sheet scores significantly correlated with the 24-h urinary salt excretion levels (r=0.27; P<0.01). Thus, the salt check sheet is applicable for the general population.

Pathophysiological analysis of primary biliary cirrhosis focusing on choline/phospholipid metabolism

Injury to biliary epithelial cells caused by disorders in bile composition may be the initial step in the pathogenesis of primary biliary cirrhosis (PBC). We therefore examined choline/phospholipid metabolism in livers of patients with PBC.

Reduction of Group II Metabotropic Glutamate Receptors during Development of Benzodiazepine Dependence

Prolonged use of benzodiazepines often leads to dependence and withdrawal syndrome. However, the cellular mechanisms underlying benzodiazepine dependence have not been fully clarified. Several investigators have shown an involvement of metabotropic glutamate receptors (mGluRs) in the pathophysiology of dependence or withdrawal. This study was performed to elucidate the role of mGluRs in benzodiazepine dependence. Withdrawal signs were precipitated in mice by flumazenil injection (25 mg/kg) after continuous subcutaneous infusion of benzodiazepines for 7 days, and the effects of several Gi-coupled receptor ligands on forskolin-stimulated cyclic AMP accumulation were examined in the cerebral cortex of mice. The mRNA expression for mGluRs was determined by RT-PCR. A single injection of flumazenil precipitated typical withdrawal signs such as tail elevation and tremor in mice treated with diazepam or alprazolam, but not quazepam. The inhibitory effect of nonselective mGluR ligands on adenylate cyclase activity was diminished in mice that showed signs of benzodiazepine withdrawal. The mRNA expression levels of mGluR2 and mGluR3 were lowered in the cerebral cortex of mice pretreated with diazepam or alprazolam. Our findings suggest that the reduction in the expression of group II mGluRs subunits may be involved in the development of benzodiazepine dependence.