The Role of Serotonin in Ventricular Repolarization in Pregnant Mice

Shanyu Cui,박혜원,박혜림,문다솜,이승현,김효은,윤누리,김하일,Michael Kim,박희남,이문형,정보영 연세대학교의과대학 2018 Yonsei medical journal Vol.59 No.2

Purpose: The mechanisms underlying repolarization abnormalities during pregnancy are not fully understood. Although maternalserotonin (5-hydroxytryptamine, 5-HT) production is an important determinant for normal fetal development in mice, its role in mothers remains unclear. We evaluated the role of serotonin in ventricular repolarization in mice hearts via 5Htr3 receptor (Htr3a) and investigated the mechanism of QT-prolongation during pregnancy. Materials and Methods: We measured current amplitudes and the expression levels of voltage-gated K+ (Kv) channels in freshly-isolated left ventricular myocytes from wild-type non-pregnant (WT-NP), late-pregnant (WT-LP), and non-pregnant Htr3a homozygousknockout mice (Htr3a-/--NP). Results: During pregnancy, serotonin and tryptophan hydroxylase 1, a rate-limiting enzyme for the synthesis of serotonin, were markedly increased in hearts and serum. Serotonin increased Kv current densities concomitant with the shortening of the QT intervalin WT-NP mice, but not in WT-LP and Htr3a-/--NP mice. Ondansetron, an Htr3 antagonist, decreased Kv currents in WT-LP mice, but not in WT-NP mice. Kv4.3 directly interacted with Htr3a, and this binding was facilitated by serotonin. Serotonin increasedthe trafficking of Kv4.3 channels to the cellular membrane in WT-NP. Conclusion: Serotonin increases repolarizing currents by augmenting Kv currents. Elevated serotonin levels during pregnancy counterbalance pregnancy-related QT prolongation by facilitating Htr3-mediated Kv currents.

Ondansetron Inhibits Voltage-Gated K+ Current of Ventricular Myocytes from Pregnant Mouse

Shanyu Cui,박혜원,박혜림,문다솜,김효은,윤누리,정보영 대한부정맥학회 2017 International Journal of Arrhythmia Vol.18 No.2

Background: The Htr3a antagonist, ondansetron, has been reported to prolong the QT interval and induce Torsades de pointes in the treatment of postoperative nausea and vomiting. To explore the mechanisms underlying these findings, we examined the effects of ondansetron on the mouse cardiac voltage-gated K+ (Kv) channel. Methods and Results: Ondansetron increased QT intervals in late pregnant (LP) mice. We measured the Kv channels in freshly isolated left ventricular (LV) myocytes from non-pregnant (NP) and late pregnant (LP) mice, using patch-clamp electrophysiology. Ondansetron blocked Kv current at a dose of 50 μM, and reduced the amplitude of peak current densities in a dose-dependent manner (0, 1, 5, 50 μM), in LP but not in NP mice. In contrast, serotonin and the Htr3 agonist, m-CPBG, increased Kv current densities in NP, but not in LP mice. Interestingly, during pregnancy, serum serotonin levels were markedly increased, suggesting the saturation of the effect of serotonin. Immunostaning data showed that Kv4.3 protein and Htr3a co-localize at the membrane and t-tubule of cardiomyocytes. Moreover, Kv4.3 membrane trafficking was enhanced in response to Htr3a-mediated serotonin stimulation in NP, but not in LP mice. Membrane analysis showed that serotonin enhances Kv4.3 membrane trafficking in NP, but not LP mice. Conclusion: Ondansetron reduced Kv current densities, and reduced the Kv4.3 membrane trafficking in LP mouse ventricular cardiomyocytes. This data suggests that QT prolongation by ondansetron is mediated by the reduction of Kv current densities and Kv4.3 membrane trafficking.

The Anoctamin Family Channel Subdued Mediates Thermal Nociception in <i>Drosophila</i>

Jang, Wijeong,Kim, Ji Young,Cui, Shanyu,Jo, Juyeon,Lee, Byoung-Cheol,Lee, Yeonwoo,Kwon, Ki-Sun,Park, Chul-Seung,Kim, Changsoo American Society for Biochemistry and Molecular Bi 2015 The Journal of biological chemistry Vol.290 No.4

<P>Calcium-permeable and thermosensitive transient receptor potential (TRP) channels mediate the nociceptive transduction of noxious temperature in <I>Drosophila</I> nociceptors. However, the underlying molecular mechanisms are not completely understood. Here we find that Subdued, a calcium-activated chloride channel of the <I>Drosophila</I> anoctamin family, functions in conjunction with the thermo-TRPs in thermal nociception. Genetic analysis with deletion and the RNAi-mediated reduction of <I>subdued</I> show that <I>subdued</I> is required for thermal nociception in nociceptors. Further genetic analysis of <I>subdued</I> mutant and thermo-TRP mutants show that they interact functionally in thermal nociception. We find that Subdued expressed in heterologous cells mediates a strong chloride conductance in the presence of both heat and calcium ions. Therefore, our analysis suggests that Subdued channels may amplify the nociceptive neuronal firing that is initiated by thermo-TRP channels in response to thermal stimuli.</P>

Extracellular Vesicles Derived from Hypoxic Human Mesenchymal Stem Cells Attenuate GSK3β Expression via miRNA-26a in an Ischemia-Reperfusion Injury Model

박혜원,박혜림,문다솜,강지영,강지영,Michael Kim,Shanyu Cui,이승현,정보영 연세대학교의과대학 2018 Yonsei medical journal Vol.59 No.6

Purpose: Bioactive molecules critical to intracellular signaling are contained in extracellular vesicles (EVs) and have cardioprotectiveeffects in ischemia/reperfusion (IR) injured hearts. This study investigated the mechanism of the cardioprotective effectsof EVs derived from hypoxia-preconditioned human mesenchymal stem cells (MSCs). Materials and Methods: EV solutions (0.4 μg/μL) derived from normoxia-preconditioned MSCs (EVNM) and hypoxia-preconditionedMSCs (EVHM) were delivered in a rat IR injury model. Successful EV delivery was confirmed by the detection of PKH26staining in hearts from EV-treated rats. Results: EVHM significantly reduced infarct size (24±2% vs. 8±1%, p<0.001), and diminished arrhythmias by recovering electricalconduction, INa current, and Cx43 expression. EVHM also reversed reductions in Wnt1 and β-catenin levels and increases in GSK3βinduced after IR injury. miRNA-26a was significantly increased in EVHM, compared with EVNM, in real-time PCR. Finally, in in vitroexperiments, hypoxia-induced increases in GSK3β expression were significantly reduced by the overexpression of miRNA-26a. Conclusion: EVHM reduced IR injury by suppressing GSK3β expression via miRNA-26a and increased Cx43 expression. Thesefindings suggest that the beneficial effect of EVHM is related with Wnt signaling pathway.

Deletion of the Serotonin Receptor Type 3A in Mice Leads to Sudden Cardiac Death During Pregnancy.

Park, Hyewon,Oh, Chang-Myung,Park, Junbeom,Park, Hyelim,Cui, Shanyu,Kim, Hyung Suk,Namkung, Jun,Park, Sang-Kyu,Pak, Hui-Nam,Lee, Moon-Hyoung,Kim, Hail,Joung, Boyoung Japanese Circulation Society 2015 CIRCULATION JOURNAL Vol.79 No.8

<P>The serotonin receptor type 3 (Htr3) blocker is associated with QT prolongation and torsades de pointes. However, little is known about effects of Htr3 on the heart arrhythmia.Methods?and?Results:An electrophysiological study Involving knock-out (KO) female mice lacking functional Htr3a (Htr3a(-/-)) and their wild-type littermates during non-pregancy (NP) and late pregnancy (LP) was performed. Htr3a mRNA was present in the wild-type, but not in theHtr3a(-/-)mouse hearts. Serotonin and tryptophan hydroxylase 1 (Tph1), a rate-limiting enzyme of serotonin synthesis in hearts, is increased during pregnancy. The heart weight and size were increased in the pregnant mice regardless of a mutation. The QTc intervals were prolonged after pregnancy in both the wild (NP: 171.216.8 vs. LP: 247.714.3 ms; P<0.001) andHtr3a(-/-)mice (NP: 187.918.7 vs. LP: 275.611.0 ms, P<0.001). Compared with wild-type LP mice,Htr3a(-/-)LP mice had increased spontaneous ventricle tarchycardia (VT; 56% vs. 0%, P=0.002), VT inducibility (66% vs. 25%, P=0.002) and mortality (56% vs. 0%, P=0.002). Pharmacologic administration of serotonin and Htr3 agonists (m-CPBG) decreased the QT interval in wild mice, but not inHtr3a(-/-)mice.</P>

Long-Term Isolation Elicits Depression and Anxiety-Related Behaviors by Reducing Oxytocin-Induced GABAergic Transmission in Central Amygdala

Han, Rafael T.,Kim, Young-Beom,Park, Eui-Ho,Kim, Jin Yong,Ryu, Changhyeon,Kim, Hye Y.,Lee, JaeHee,Pahk, Kisoo,Shanyu, Cui,Kim, Hyun,Back, Seung K.,Kim, Hee J.,Kim, Yang In,Na, Heung S. Frontiers Media S.A. 2018 Frontiers in molecular neuroscience Vol.11 No.-

<P>Isolation stress is a major risk factor for neuropsychiatric disorders such as depressive and anxiety disorders. However, the molecular mechanisms underlying isolation-induced neuropsychiatric disorders remain elusive. In the present study, we investigated the subcellular mechanisms by which long-term isolation elicits depression and anxiety-related behaviors in mice. First, we found that long-term isolation induced depression-related behaviors in the forced swimming test (FST) and the sucrose preference test, as well as anxiety-related behaviors in the elevated zero maze test (EZMT) and the open field test. Next, we showed that intracentral amygdala (CeA) injection of oxytocin (OXT), but not intracerebroventricular injection, attenuated isolation-induced depression and anxiety-related behaviors via oxytocin receptor (OXTR), not vasopressin-1a receptor (V1aR), in the FST and EZMT, respectively. Quantitative real-time polymerase chain reaction analysis revealed that after 5 weeks of isolation, mRNA transcription of OXTR in the CeA, but not that of V1aR, significantly decreased, whereas OXT and vasopressin mRNA transcription in the paraventricular nucleus of hypothalamus did not change significantly. Whole-cell patch clamping of acute brain slices demonstrated that the frequency of miniature inhibitory postsynaptic currents (mIPSCs) in CeA neurons, but not their amplitude, was lower in isolated mice than in group-housed mice. Notably, OXT treatment increased the mIPSC frequency in the CeA neurons, but to a lesser extent in the case of isolated mice than in that of group-housed mice via OXTR. Taken together, our findings suggest that long-term isolation down-regulates OXTR mRNA transcription and diminishes OXT-induced inhibitory synaptic transmission in the CeA and may contribute to the development of depression and anxiety-related behaviors in isolated mice through the enhancement of CeA activity.</P>