Cortical GABAergic inhibitory neurons are composed of three major classes, each expressing parvalbumin (PV), somatostatin (SOM) and 5-hydroxytryptamine receptor 3A (Htr3a), respectively. Htr3a
Animals ; Interneurons/metabolism* ; Mice ; Neurons/metabolism* ; Parvalbumins/metabolism* ; Receptors, Serotonin, 5-HT3/genetics* ; Serotonin ; Somatostatin/metabolism*

PURPOSE: The mechanisms underlying repolarization abnormalities during pregnancy are not fully understood. Although maternal serotonin (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 homozygous knockout 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 interval in 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 increased the 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.
*Action Potentials/drug effects ; Animals ; Cell Membrane/drug effects/metabolism ; Disease Models, Animal ; Electrocardiography ; Female ; HSC70 Heat-Shock Proteins/metabolism ; HSP90 Heat-Shock Proteins/metabolism ; Heart Ventricles/drug effects/*metabolism ; Mice, Inbred C57BL ; Mice, Knockout ; Myocytes, Cardiac/drug effects/metabolism ; Potassium Channels/metabolism ; Pregnancy ; Rabbits ; Rats, Sprague-Dawley ; Receptors, Serotonin, 5-HT3/metabolism ; Serotonin/*metabolism ; Serotonin 5-HT3 Receptor Agonists/pharmacology

BACKGROUND: Intravenous palonosetron-HCl, a second-generation antagonist of selective serotonin type 3 (5-HT3) receptors, can prevent chemotherapy-induced nausea and vomiting (CINV) and postoperative nausea and vomiting (PONV). 5-HT3 receptors are abundant in the lower brainstem and the substantia gelatinosa of the spinal cord, which provides a theoretical rationale for neuraxial administration of 5-HT3 receptor antagonists for CINV, PONV, and opioid-induced nausea and vomiting. However, there are no reports of neuraxial administration of palonosetron-HCl. Before neuraxial administration of a drug is accepted for clinical use, its safety must be proven. This study was conducted to determine whether neuraxial administration of palonosetron-HCl produces neurologic injury. METHODS: Male Sprague-Dawley rats under general anesthesia were catheterized intrathecally and the catheter tip was advanced caudally to the L1 vertebra. After 7 days, 20 µl of normal saline (N group, n = 6) or 20 µl (1 µg) of palonosetron-HCl (P group, n = 6) were injected intrathecally once per day for 2 weeks. Neurotoxic changes were evaluated by light microscopy (LM) and electron microscopy (EM) of the spinal cord. Behavioral changes were also evaluated in both groups. RESULTS: One of the N group rats and three of the P group rats demonstrated abnormal behavior during intrathecal drug injection, but otherwise their behavior was normal. The spinal cords of the N group did not have any abnormal findings by LM or EM. The spinal cords of the P group had multiple vacuoles in the white matter by LM, especially in the dorsal funiculus, and EM revealed myelin, axonal, and mitochondrial swelling. CONCLUSIONS: Results suggest that chronic intrathecal administration of palonosetron-HCl produced microscopic morphologic changes in the spinal cords of rats.
Anesthesia, General ; Animals ; Axons ; Brain Stem ; Catheters ; Humans ; Injections, Spinal ; Male ; Microscopy ; Microscopy, Electron ; Mitochondrial Swelling ; Myelin Sheath ; Nausea ; Postoperative Nausea and Vomiting ; Rats* ; Rats, Sprague-Dawley ; Receptors, Serotonin, 5-HT3 ; Serotonin ; Spinal Cord* ; Spine ; Substantia Gelatinosa ; Vacuoles ; Vomiting ; White Matter

Lamotrigine is an antiepileptic drug widely used to treat epileptic seizures. Using whole-cell voltage clamp recordings in combination with a fast drug application approach, we investigated the effects of lamotrigine on 5-hydroxytryptamine (5-HT)₃ receptors in NCB-20 neuroblastoma cells. Co-application of lamotrigine (1~300 µM) resulted in a concentration-dependent reduction in peak amplitude of currents induced by 3 µM of 5-HT for an IC₅₀ value of 28.2±3.6 µM with a Hill coefficient of 1.2±0.1. These peak amplitude decreases were accompanied by the rise slope reduction. In addition, 5-HT₃-mediated currents evoked by 1 mM dopamine, a partial 5-HT₃ receptor agonist, were inhibited by lamotrigine co-application. The EC₅₀ of 5-HT for 5-HT₃ receptor currents were shifted to the right by co-application of lamotrigine without a significant change of maximal effect. Currents activated by 5-HT and lamotrigine co-application in the presence of 1 min pretreatment of lamotrigine were similar to those activated by 5-HT and lamotrigine co-application alone. Moreover, subsequent application of lamotrigine in the presence of 5-HT and 5-hydroxyindole, known to attenuate 5-HT₃ receptor desensitization, inhibited 5-HT₃ receptor currents in a concentration-dependent manner. The deactivation of 5-HT₃ receptor was delayed by washing with an external solution containing lamotrigine. Lamotrigine accelerated the desensitization process of 5-HT₃ receptors. There was no voltage-dependency in the inhibitory effects of lamotrigine on the 5-HT3 receptor currents. These results indicate that lamotrigine inhibits 5-HT₃-activated currents in a competitive manner by binding to the open state of the channels and blocking channel activation or accelerating receptor desensitization.
Dopamine ; Epilepsy ; Neuroblastoma* ; Receptors, Serotonin, 5-HT3 ; Serotonin

BACKGROUND: Postoperative nausea and vomiting (PONV) is a major concern during the post-surgical period. 5-hydroxy-tryptamine (5-HT3) receptor antagonists may be useful for the prevention of PONV. The recently developed 5-HT3 receptor antagonists, ramosetron and palonosetron, have a greater receptor affinity and a longer elimination half-life. This study was designed to assess the efficacy of palonosetron and ramosetron for prevention of PONV in patients receiving intravenous patient-controlled analgesia (IV-PCA) with opioids after gynecological oncology surgery. METHODS: In this prospective trial, 290 female patients scheduled for elective gynecologic oncology surgery with IV-PCA with opioids were randomized to receive either 0.3 mg ramosetron or 0.075 mg palonosetron intravenously. The occurrence of nausea and vomiting and the use of rescue antiemetics were recorded immediately after the end of surgery, and 0-3 h, 3-24 h, and 24-48 h postoperatively. RESULTS: The total incidence of PONV was similar between the two groups 0-48 h after surgery, but the incidence of nausea was significantly lower in the ramosetron group 24-48 h postoperatively (11.5% vs. 22.0%, P = 0.036). The incidence of vomiting and the use of rescue antiemetics were not significantly different between the two groups during any of the time intervals. Pain intensity scores and total fentanyl consumption were significantly lower in the ramosetron group 24-48 h postoperatively compared to the palonosetron group (P = 0.021, P = 0.041, respectively). CONCLUSIONS: The prophylactic effects of ramosetron and palonosetron on PONV incidence in the postoperative 48 h were similar in patients undergoing gynecologic oncology surgery and those receiving opioid-based IV-PCA.
Analgesia, Patient-Controlled ; Analgesics, Opioid ; Antiemetics ; Female ; Fentanyl ; Half-Life ; Humans ; Incidence ; Nausea ; Postoperative Nausea and Vomiting* ; Prospective Studies ; Receptors, Serotonin, 5-HT3 ; Vomiting

PURPOSE: This study reported patient outcomes of chemotherapy-induced nausea and vomiting (CINV) prophylaxis for highly emetogenic chemotherapy (HEC) and moderately emetogenic chemotherapy (MEC) regimens and evaluated its adherence to acute-phase CINV prophylaxis in the Korean population subset of the Pan Australasian Chemotherapy Induced Emesis burden of illness (PrACTICE) study. MATERIALS AND METHODS: This subgroup analysis evaluated 158 Korean patients receiving HEC or MEC and compared the data (wherever possible) with that of 648 patients from the Asia-Pacific (AP) region. Study endpoints included evaluation of primary CINV prophylaxis and adherence to acute-phase CINV prophylaxis in cycle 1 (American Society of Clinical Oncology [ASCO] Quality Oncology Practice Initiative [QOPI]). RESULTS: In South Korea and the AP, a 5-hydroxytryptamine-3 receptor antagonist (5HT₃-RA) prophylaxis for the acute phase was administered to 79/80 patients (98.8%) for HEC and 70/71 patients (98.6%) for MEC regimens (QOPI-1). Triple regimen (corticosteroid–5HT₃-RA–neurokinin 1-RA) was initiated in 46/80 patients (57.5%) for prophylaxis of acute CINV in cycle 1 of HEC (QOPI-3). Double regimen (corticosteroid–5HT₃-RA, with or within NK₁-RA) was initiated in 61/71 patients (83.1%) for control of acute CINV in cycle 1 of MEC a(QOPI-2). CONCLUSION: Active management of CINV is necessary in cycle 1 of HEC in South Korea, despite higher rates than the AP region. Adherence to the international guidelines for CINV prophylaxis requires attention in the acute phase in cycle 1 of the HEC regimen.
Antiemetics ; Cost of Illness* ; Drug Therapy* ; Humans ; Korea* ; Medical Oncology ; Nausea* ; Receptors, Serotonin, 5-HT3 ; Vomiting*

OBJECTIVETo compare the effects of electroacupuncture (EA) and moxibustion therapies on patients with diarrhea-predominant irritable bowel syndrome (D-IBS).

METHODSA total of 60 D-IBS patients were randomly allocated to the EA group (30 cases) and moxibustion group (30 cases). Before and after treatment, the gastrointestinal symptoms and psychological symptoms were scored by Visual Analogue Scale, Bristol Stool Form Scale, Hamilton Anxiety Rating Scale (HAMA), and Hamilton Depression Rating Scale (HAMD); the expressions of 5-hydroxytryptamine (5-HT), 5-HT3 receptor (5-HT3R), and 5-HT4 receptor (5-HT4R) in the sigmoid mucosal tissue were measured by immunohistochemical staining. Additionally, the effects on the functional brain areas of the anterior cingulate cortex (ACC), insular cortex (IC) and prefrontal cortex (PFC) were observed by functional magnetic resonance imaging.

RESULTSCompared with before treatment, both EA and moxibustion groups reported significant improvements in abdominal pain and abdominal bloating after treatment (P<0.01 or P<0.05). The moxibustion group reported greater improvements in defecation emergency, defecation frequency, and stool feature than the EA group (P<0.01). Both HAMA and HAMD scores were significantly decreased in the moxibustion group than in the EA group (P<0.01). Both groups demonstrated significantly reduced expressions of 5-HT, 5-HT3R and 5-HT4R in the colonic mucosa after treatment (P<0.01), with a greater reduction of 5-HT in the moxibustion group (P<0.05). Finally, decreased activated voxel values were observed in the left IC, right IC and PFC brain regions of patients in the moxibustion group under stimulation with 150 mL colorectal distension after treatment (P<0.05 or P<0.01), while in the EA group only PFC area demonstrated a reduction (P<0.05).

CONCLUSIONMoxibustion can significantly improve the symptoms of D-IBS, suggesting that moxibustion may be a more effective therapy than EA for D-IBS patients.

Adult ; Anxiety ; Brain ; physiology ; Cerebral Cortex ; physiopathology ; Colon, Sigmoid ; chemistry ; Depression ; Diarrhea ; physiopathology ; Electroacupuncture ; Gastrointestinal Tract ; physiology ; Gyrus Cinguli ; physiopathology ; Humans ; Immunohistochemistry ; Intestinal Mucosa ; chemistry ; Irritable Bowel Syndrome ; physiopathology ; psychology ; therapy ; Magnetic Resonance Imaging ; Moxibustion ; Pain Measurement ; Prefrontal Cortex ; physiopathology ; Receptors, Serotonin, 5-HT3 ; analysis ; Serotonin ; analysis

BACKGROUND/AIMS: Several disorders of the gastrointestinal tract are associated with abnormal serotonin (5-HT) signaling or metabolism where the 5-HT3 and 5-HT4 receptors are clinically relevant. The aim was to examine the distribution of 5-HT3, 5-HT4, and 5-HT7 receptors in the normal human colon and how this is associated with receptor interacting chaperone 3, G protein coupled receptor kinases, and protein LIN-7 homologs to extend previous observations limited to the sigmoid colon or the upper intestine. METHODS: Samples from ascending, transverse, descending, and sigmoid human colon were dissected into 3 separate layers (mucosa, longitudinal, and circular muscles) and ileum samples were dissected into mucosa and muscle layers (n = 20). Complementary DNA was synthesized by reverse transcription from extracted RNA and expression was determined by quantitative or end point polymerase chain reaction. RESULTS: The 5-HT3 receptor subunits were found in all tissues throughout the colon and ileum. The A subunit was detected in all samples and the C subunit was expressed at similar levels while the B subunit was expressed at lower levels and less frequently. The 5-HT3 receptor E subunit was mainly found in the mucosa layers. All splice variants of the 5-HT4 and 5-HT7 receptors were expressed throughout the colon although the 5-HT4 receptor d, g, and i variants were expressed less often. CONCLUSIONS: The major differences in 5-HT receptor distribution within the human colon are in relation to the mucosa and muscular tissue layers where the 5-HT3 receptor E subunit is predominantly found in the mucosal layer which may be of therapeutic relevance.
Colon* ; Colon, Sigmoid ; DNA, Complementary ; G-Protein-Coupled Receptor Kinases ; Gastrointestinal Tract ; Humans ; Ileum ; Intestines ; Metabolism ; Mucous Membrane ; Polymerase Chain Reaction ; Receptors, Serotonin ; Receptors, Serotonin, 5-HT3 ; Receptors, Serotonin, 5-HT4 ; Reverse Transcription ; RNA ; Serotonin

Subcutaneous injection of BmK I could be adopted to well establish a novel pain model. Moreover, 5-hydroxytryptamine (serotonin, 5-HT) receptor is involved in regulating animal pain-related behaviors. However, the underlying mechanism of 5-HT3R on BmK I-induced pain remains unclear. Animal behavioral testing, RT-PCR and Western blotting were used to yield the following results: first, intraplantar (i.pl.) injection of BmK I (10 μg) induced elevated mRNA and protein levels of 5-HT3AR in bilateral L4-L5 spinal cord; Second, intrathecal (i.t.) injection of ondansetron (a specific antagonist of 5-HT3AR) reduced spontaneous pain responses, attenuated unilateral thermal and bilateral mechanical hypersensitivity elicited by BmK I; Microglia could be activated by BmK I (i.pl.) in both sides of L4-L5 spinal cord, and this effect was reversed by intrathecal pre-treatment with 5-HT3AR antagonist. Meanwhile, the 5-HT3AR in L4-L5 spinal cord was almost co-localized with NeuN (a marker of nerve cell), but not co-expressed with Iba-1 (a marker of microglia). Finally, the expression level of CX3CL1 and CX3CR1 was reduced by intrathecal pre-treatment with ondansetron. Our results indicate that both 5-HT3AR signaling pathway and microglia are activated in the process of induction and maintenance of BmK I-induced pain nociception. Meanwhile, our results suggest that the neuronal 5-HT3AR may communicate with microglia indirectly via CX3CL1 which is involved in regulating the BmK I-induced hyperalgesia and sensitization.
Animals ; Behavior, Animal ; Chemokine CX3CL1 ; metabolism ; Hyperalgesia ; chemically induced ; Inflammation ; physiopathology ; Injections, Spinal ; Microglia ; drug effects ; Rats ; Rats, Sprague-Dawley ; Receptors, Serotonin, 5-HT3 ; metabolism ; Scorpion Venoms ; adverse effects ; Spinal Cord ; metabolism ; physiopathology

Chronic diarrhea is usually associated with a number of non-infectious causes. When definitive treatment is unavailable, symptomatic drug therapy is indicated. Pharmacologic agents for chronic diarrhea include loperamide, 5-hydroxytryptamine type 3 (5-HT3) receptor antagonists, diosmectite, cholestyramine, probiotics, antispasmodics, rifaximin, and anti-inflammatory agents. Loperamide, a synthetic opiate agonist, decreases peristaltic activity and inhibits secretion, resulting in the reduction of fluid and electrolyte loss and an increase in stool consistency. Cholestyramine is a bile acid sequestrant that is generally considered as the first-line treatment for bile acid diarrhea. 5-HT3 receptor antagonists have significant benefits in patients with irritable bowel syndrome (IBS) with diarrhea. Ramosetron improves stool consistency as well as global IBS symptoms. Probiotics may have a role in the prevention of antibiotic-associated diarrhea. However, data on the role of probiotics in the treatment of chronic diarrhea are lacking. Diosmectite, an absorbent, can be used for the treatment of chronic functional diarrhea, radiation-induced diarrhea, and chemotherapy-induced diarrhea. Antispasmodics including alverine citrate, mebeverine, otilonium bromide, and pinaverium bromide are used for relieving diarrheal symptoms and abdominal pain. Rifaximin can be effective for chronic diarrhea associated with IBS and small intestinal bacterial overgrowth. Budesonide is effective in both lymphocytic colitis and collagenous colitis. The efficacy of mesalazine in microscopic colitis is weak or remains uncertain. Considering their mechanisms of action, these agents should be prescribed properly.
Abdominal Pain ; Anti-Inflammatory Agents ; Bile ; Budesonide ; Cholestyramine Resin ; Citric Acid ; Colitis, Collagenous ; Colitis, Lymphocytic ; Colitis, Microscopic ; Diarrhea* ; Drug Therapy ; Humans ; Irritable Bowel Syndrome ; Loperamide ; Mesalamine ; Parasympatholytics ; Probiotics ; Receptors, Serotonin, 5-HT3 ; Serotonin