OBJECTIVE: Central 5-HT1A receptor is involved in the modulation of sensorimotor gating function. However, its precise role is not clearly defined in developmentally social deprived (isolation rearing, IR) rats featured with impaired sensorimotor gating ability. We therefore aimed to examine the effects of 5HT1A activation on acoustic startle response (ASR) and prepulse inhibition (PPI) in IR rats in a condition of compromised presynaptic 5-HT functions. METHODS: Social control (SOC) and IR rats received an intracerebraoventricular (ICV) injection of 5-HT depletor, 5,7-DHT. Seven days later rats entered a protocol of 8-OH-DPAT, a 5-HT1A agonist, in which locomotor activity, ASR and PPI and their tissue levels of 5-HT were measured. RESULTS: Our results found that both IR and 5,7-DHT decreased the tissue concentration of 5-HT. IR-induced hyperactivity and gating impairment were unaffected by 5-HT depletion. 8-OH-DPAT strengthened the ASR in IR but not SOC rats and the drug-reduced PPI could be adjusted by 5,7-DHT pretreatment. 8-OH-DPAT at 100 μg/kg enhanced PPI in 5-HT-depleted SOC rats. However for IR rats, 8-OH-DPAT strengthened PPI in sham rats but downgraded it in depletion condition. CONCLUSION: The integrity of central 5-HT system is important to 5-HT1A-modulated sensorimotor gating in isolation-reared rats.
8-Hydroxy-2-(di-n-propylamino)tetralin ; Acoustics ; Animals ; Motor Activity ; Prepulse Inhibition ; Rats ; Receptor, Serotonin, 5-HT1A ; Reflex, Startle ; Sensory Gating ; Serotonin ; Serotonin 5-HT1 Receptor Agonists ; Social Control, Formal

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

OBJECTIVE: Post weanling isolation-reared (IR) rats are featured with depressive phenotype, yet its mechanism is not clearly defined particularly in terms of the involvement of central 5-HT1A receptors. The present study aims to examine the effects of 5HT1A activation on forced swim test (FST) in IR rats following 5-HT depletion. METHODS: Social control (SOC) and IR rats received an intracerebraoventricular (ICV) injection of 5-HT depletion agent, 5,7-DHT. 14 days after the surgery, rats were assessed their performance in FST with or without the challenge with a 5-HT1A agonist, 8-OH-DPAT. Rats were then sacrificed for analyzing their 5-HT tissue levels and the expressions of their 5-HA1A receptors in prefrontal cortex (PFC), hippocampus (HPX), and amygdala (AMY). RESULTS: 5,7-DHT decreased the tissue concentration of 5-HT in both IR and SOC rats. IR rats were more immobile and less sensitive to the lesion-induced immobility, however this effect was reversed by acute challenge of 8-OH-DPAT. 5,7-DHT lesion increased the expression of PFC 5-HT1A receptors. CONCLUSION: The integrity of central 5-HT system is developmentally crucial for the 5-HT1A-relevant depression profile in rats of social isolation.
8-Hydroxy-2-(di-n-propylamino)tetralin ; Amygdala ; Animals ; Depression* ; Hippocampus ; Phenotype ; Prefrontal Cortex ; Rats* ; Receptor, Serotonin, 5-HT1A ; Serotonin 5-HT1 Receptor Agonists ; Serotonin* ; Social Control, Formal ; Social Isolation

Irritable bowel syndrome is a group of symptoms that includes abdominal pain and changes in the form and frequency of stool. Since its symptoms are usually long-lasting, the disease significantly degrades quality of life. Several pharmacological therapies have been suggested according to the type of symptoms (e.g., abdominal pain, constipation, or diarrhea). In order to control abdominal pain, smooth muscle antispasmodics, antidepressants including tricyclic antidepressants and selective serotonin reuptake inhibitors, or 5-HT3 antagonists can be used. To improve constipation, dietary fiber or laxatives, 5-HT4 agonists, and chloride channel activators are available. Opioid agonists, mixed opioid agonists/antagonists such as eluxadoline, and bile salt sequestrants can be considered for diarrhea. In addition, probiotics and non-absorbable oral antibiotics can be used for the normalization of the gut microbiome and the treatment of small intestinal bacterial overgrowth, respectively. It is necessary to understand the characteristics of each drug and their combinations, because any single regimen cannot improve all symptoms in patients with irritable bowel syndrome. In this review, the mechanisms of action, efficacy, and adverse events associated with drugs used for irritable bowel syndrome are summarized.
Abdominal Pain ; Anti-Bacterial Agents ; Antidepressive Agents ; Antidepressive Agents, Tricyclic ; Bile ; Chloride Channel Agonists ; Constipation ; Diarrhea ; Dietary Fiber ; Drug Therapy* ; Gastrointestinal Microbiome ; Humans ; Irritable Bowel Syndrome* ; Laxatives ; Muscle, Smooth ; Parasympatholytics ; Probiotics ; Quality of Life ; Serotonin 5-HT3 Receptor Antagonists ; Serotonin 5-HT4 Receptor Agonists ; Serotonin Uptake Inhibitors

Irritable bowel syndrome is a group of symptoms that includes abdominal pain and changes in the form and frequency of stool. Since its symptoms are usually long-lasting, the disease significantly degrades quality of life. Several pharmacological therapies have been suggested according to the type of symptoms (e.g., abdominal pain, constipation, or diarrhea). In order to control abdominal pain, smooth muscle antispasmodics, antidepressants including tricyclic antidepressants and selective serotonin reuptake inhibitors, or 5-HT3 antagonists can be used. To improve constipation, dietary fiber or laxatives, 5-HT4 agonists, and chloride channel activators are available. Opioid agonists, mixed opioid agonists/antagonists such as eluxadoline, and bile salt sequestrants can be considered for diarrhea. In addition, probiotics and non-absorbable oral antibiotics can be used for the normalization of the gut microbiome and the treatment of small intestinal bacterial overgrowth, respectively. It is necessary to understand the characteristics of each drug and their combinations, because any single regimen cannot improve all symptoms in patients with irritable bowel syndrome. In this review, the mechanisms of action, efficacy, and adverse events associated with drugs used for irritable bowel syndrome are summarized.
Abdominal Pain ; Anti-Bacterial Agents ; Antidepressive Agents ; Antidepressive Agents, Tricyclic ; Bile ; Chloride Channel Agonists ; Constipation ; Diarrhea ; Dietary Fiber ; Drug Therapy* ; Gastrointestinal Microbiome ; Humans ; Irritable Bowel Syndrome* ; Laxatives ; Muscle, Smooth ; Parasympatholytics ; Probiotics ; Quality of Life ; Serotonin 5-HT3 Receptor Antagonists ; Serotonin 5-HT4 Receptor Agonists ; Serotonin Uptake Inhibitors

5-Hydroxytryptamine 2C (5-HT) receptor is one of the major targets of anti-obesity agents, due to its role in regulation of appetite. In the present study, the 70% EtOH extract of the roots of Bupleurum chinense was revealed to have agonistic activity on 5-HT receptor, and the subsequent bioassay-guided isolation led to identification of several saikosaponins as the active constituents with 5-HT receptor agonistic activity in vitro and anti-obesity activity in vivo. The new compound, 22-oxosaikosaponin d (1), was determined by extensive spectroscopic analyses (HR-ESI-MS, IR, and 1D and 2D NMR). The primary structure-activity relationship study suggested that the intramolecular ether bond between C-13 and C-28 and the number of sugars at C-3 position were closely related to the 5-HT receptor agonistic activity. Saikosaponin a (3), the main saponin in B. chinense, showed obviously agonistic activity on 5-HT receptor with an EC value of 21.08 ± 0.33 μmol·Lin vitro and could reduce food intake by 39.1% and 69.2%, and weight gain by 13.6% and 16.4%, respectively, at 3.0 and 6.0 mg·kgin vivo. This investigation provided valuable information for the potential use of B. chinense as anti-obesity agent.
Animals ; Anti-Obesity Agents ; chemistry ; isolation & purification ; pharmacology ; Biological Assay ; Bupleurum ; chemistry ; Male ; Oleanolic Acid ; analogs & derivatives ; chemistry ; isolation & purification ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Saponins ; chemistry ; isolation & purification ; pharmacology ; Serotonin 5-HT2 Receptor Agonists ; chemistry ; isolation & purification ; pharmacology ; Structure-Activity Relationship

OBJECTIVETo investigate the activity of pyramidal neurons in the medial prefrontal cortex (mPFC) of normal and 6-OHDA-lesioned rats and the responses of the neurons to 5-hydroxytryptamine-7 (5-HT(7)) receptor stimulation.

METHODSThe changes in spontaneous firing of the pyramidal neurons in the mPFC in response to 5-HT(7) receptor stimulation were observed by extracellular recording in normal and 6-OHDA-lesioned rats.

RESULTSBoth systemic and local administration of 5-HT(7) receptor agonist AS 19 resulted in 3 response patterns (excitation, inhibition and no change) of the pyramidal neurons in the mPFC of normal and 6-OHDA-lesioned rats. In normal rats, the predominant response of the pyramidal neurons to AS 19 stimulation was excitatory, and the inhibitory effect of systemically administered AS 19 was reversed by GABAA receptor antagonist picrotoxinin. In the lesioned rats, systemic administration of AS 19 also increased the mean firing rate of the pyramidal neurons, but the cumulative dose for producing excitation was higher than that in normal rats. Systemic administration of AS 19 produced an inhibitory effect in the lesioned rats, which was partially reversed by picrotoxinin. Local administration of AS 19 at the same dose did not change the ?ring rate of the neurons in the lesioned rats.

CONCLUSIONThe activity of mPFC pyramidal neurons is directly or indirectly regulated by 5-HT7 receptor, and degeneration of the nigrostriatal pathway leads to decreased response of these neurons to AS 19.

Action Potentials ; Animals ; Oxidopamine ; Parkinson Disease ; metabolism ; Prefrontal Cortex ; cytology ; Pyramidal Cells ; drug effects ; Rats ; Receptors, Serotonin ; metabolism ; Serotonin Receptor Agonists ; pharmacology

Migraine is one of the common and frequently encountered diseases. The study proves that 5-hydroxytryptamine (5-HT) receptor, plays an important role in the occurrence of migraine. Rat striatum was used for preparation of the cell membrane stationary phase (CMSP) in our experiments. The cell membrane chromatography (CMC)-offline-HPLC system was applied to specifically recognize the components from the drug pair of Chuanxiong Rhizoma and Angelicae Dahuricae Radix, which interact with the receptors on CMSP. The dissociation equilibrium constant (KD) was measured in a rat striatum/CMC system, performed by continuously pumping sumatriptan, a 5-HT1D agonist, ranging from 2.42 x 10(-8) to 4.84 x 10(-7) mol · L(-1) through a CMC column, and the capacity factors (k') were recorded. The KD value obtained from the model was (4.59 ± 0.33) x 10(-6) mol · L(-1) for imperatorin, and the rat model of migraine induced by nitroglycerin was applied to validate the pharmacological effects of the drug pair. The results indicated that the CMC method could be a quick and efficient way for characterizing the drug-receptor interactions in vitro.
Angelica ; chemistry ; Animals ; Cell Membrane ; chemistry ; Chromatography, High Pressure Liquid ; methods ; Drug Evaluation, Preclinical ; methods ; Drugs, Chinese Herbal ; chemistry ; Male ; Migraine Disorders ; drug therapy ; Rats ; Rats, Sprague-Dawley ; Receptor, Serotonin, 5-HT1D ; chemistry ; Serotonin Receptor Agonists ; analysis

A significant proportion of chronic constipation patients are dissatisfied with their treatment. Recently, a number of new medications have been introduced for patients refractory to conventional laxatives, such as prucalopride, lubiprostone, linaclotide, and elobixibat. Prucalopride is a novel gastrointestinal prokinetic agent that acts as a 5-hydroxytryptamine type 4 (5-HT4) agonist. Compared with older nonselective 5-HT4 agonists, the higher selectivity of prucalopride for 5-HT4 receptors can reduce the risk of significant adverse cardiovascular events. Prucalopride improves stool frequency and consistency, and reduces the need for rescue medications. Lubiprostone, a chloride channel activator, increases the secretion of intestinal fluid, improves the stool frequency and consistency, and reduces straining. Linaclotide, a guanylate cyclase-C agonist, is effective in treating patients with chronic constipation and its effect on visceral sensitivity, as shown mainly in animal studies, provides an attractive pharmaceutical option for patients with irritable bowel syndrome with constipation. Elobixibat is an ileal sodium-dependent bile acid transporter inhibitor that blocks the enterohepatic circulation of bile acids, increasing the bile acid concentration in the intestine, which accelerates colonic transit and softens the stool. A phase III trial of the treatment of chronic constipation and irritable bowel syndrome with constipation is underway. The clinical application of new-generation laxatives will contribute to the management of chronic constipation refractory to conventional laxatives.
Animals ; Bile ; Bile Acids and Salts ; Chloride Channels ; Colon ; Constipation ; Enterohepatic Circulation ; Humans ; Intestines ; Irritable Bowel Syndrome ; Laxatives* ; Receptors, Serotonin, 5-HT4 ; Serotonin ; Serotonin 5-HT4 Receptor Agonists ; Lubiprostone

OBJECTIVETo investigate the effects of serotonin (5-HTIA) receptors in the hippocampal dentate gyrus (DG) on active avoidance learning in rats.

METHODSTotally 36 SD rats were randomly divided into control group, antagonist group and agonist group(n = 12). Active avoidance learning ability of rats was assessed by the shuttle box. The extracellular concentrations of 5-HT in the DG during active avoidance conditioned reflex were measured by microdialysis and high performance liquid chromatography (HPLC) techniques. Then the antagonist (WAY-100635) or agonist (8-OH-DPAT) of the 5-HT1A receptors were microinjected into the DG region, and the active avoidance learning was measured.

RESULTS(1) During the active avoidance learning, the concentration of 5-HT in the hippocampal DG was significantly increased in the extinction but not establishment in the conditioned reflex, which reached 164.90% ± 26.07% (P <0.05) of basal level. (2) The microinjection of WAY-100635 (an antagonist of 5-HT1A receptor) into the DG did not significantly affect the active avoidance learning. (3) The microinjection of 8-OH-DPAT(an agonist of 5-HT1A receptor) into the DG significantly facilitated the establishment process and inhibited the extinction process during active avoidance conditioned reflex.

CONCLUSIONThe data suggest that activation of 5-HT1A receptors in hipocampal DG may facilitate active avoidance learning and memory in rats.

8-Hydroxy-2-(di-n-propylamino)tetralin ; pharmacology ; Animals ; Avoidance Learning ; Dentate Gyrus ; physiology ; Piperazines ; pharmacology ; Pyridines ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptor, Serotonin, 5-HT1A ; physiology ; Serotonin ; physiology ; Serotonin Receptor Agonists ; pharmacology