ABSTRACT
Renal vasculature, which is highly innervated by sympathetic fibers, contributes to cardiovascular homeostasis. This renal sympathetic outflow is inhibited by 5-HT in normoglycaemic rats. Considering that diabetes induces cardiovascular complications, we aimed to determine whether diabetic state modifies noradrenergic input at renal level and its serotonergic modulation in rats. Alloxan diabetic rats were anaesthetized (pentobarbital; 60 mg/kg i.p.) and prepared for in situ autoperfusion of the left kidney to continuously measure systemic blood pressure (SBP), heart rate (HR), and renal perfusion pressure (RPP). Electrical stimulation of renal sympathetic outflow induces frequency-dependent increases (Δ) in RPP (23.9 ± 2.1, 59.5 ± 1.9, and 80.5 ± 3.5 mm Hg at 2, 4, and 6 Hz, respectively), which were higher than in normoglycaemic rats, without modifying HR or SBP. Intraarterial bolus of 5-HT and 5-CT (5-HT1/5/7 agonist) reduced electrically induced ΔRPP. Only L-694,247 (5-HT1D agonist) reproduced 5-CT inhibition on sympathetic-induced vasoconstrictions, whereas it did not modify exogenous noradrenaline-induced ΔRPP. 5-CT inhibition was exclusively abolished by i.v. bolus of LY310762 (5-HT1D antagonist). An inhibitor of guanylyl cyclase, ODQ (i.v.), completely reversed the L-694,247 inhibitory effect. In conclusion, diabetes induces an enhancement in sympathetic-induced vasopressor responses at the renal level. Prejunctional 5-HT1D receptors, via the nitric oxide pathway, inhibit noradrenergic-induced vasoconstrictions in diabetic rats.
Subject(s)
Diabetes Mellitus, Experimental , Serotonin , Rats , Animals , Serotonin/metabolism , Rats, Wistar , Receptor, Serotonin, 5-HT1D/metabolism , Diabetes Mellitus, Experimental/metabolism , Kidney , Norepinephrine/pharmacology , Norepinephrine/metabolism , Sympathetic Nervous System/metabolism , Electric Stimulation , Blood PressureABSTRACT
Competing endogenous RNAs (ceRNAs) are a newly discovered class of molecular regulators involved in many diseases, especially tumors. Therefore, exploration of the potential ceRNA regulatory network regarding the occurrence and development of pancreatic cancer will provide a new theoretical basis for its diagnosis and treatment. Based on the above background, we applied a bioinformatics approach to mine the public database The Cancer Genome Atlas (TCGA) and performed a series of subsequent molecular biology assays to confirm the hypothesis that HOXA10-AS/ miR-340-3p/HTR1D axis could modulate the malignant progression of pancreatic cancer. Here, our present study demonstrated that the expression level of HTR1D, positively correlated with the level of lncRNA HOXA10-AS and negatively associated with the level of miR-340-3p, was significantly increased in pancreatic cancer cell lines (PCs) compared with that in normal HPDE6-C7 cells. Knocking down HTR1D obviously inhibited the proliferation and migration of PCs and promoted apoptosis by upregulating p-AKT. Elevated miR-340-3p blocked the progression of pancreatic cancer by downregulating HTR1D. Lessened level of lncRNA HOXA10-AS reduced the sponging of miR-340-3p, resulting in an increase of miR-340-3p and a subsequent decrease of HTR1D to ultimately suppress the malignant biological behaviors of cancer. These data illustrated that the HOXA10-AS/miR-340-3p/HTR1D ceRNA axis acted a crucial part in the malignant biological behavior of pancreatic cancer in an AKT-dependent manner.
Subject(s)
MicroRNAs , Pancreatic Neoplasms , RNA, Long Noncoding , Receptor, Serotonin, 5-HT1D/metabolism , Cell Line, Tumor , Cell Proliferation , Gene Expression Regulation, Neoplastic , Homeobox A10 Proteins , Humans , MicroRNAs/genetics , MicroRNAs/metabolism , Pancreatic Neoplasms/genetics , Pancreatic Neoplasms/pathology , Phosphatidylinositol 3-Kinases/genetics , Phosphatidylinositol 3-Kinases/metabolism , Proto-Oncogene Proteins c-akt/genetics , Proto-Oncogene Proteins c-akt/metabolism , RNA, Long Noncoding/genetics , RNA, Long Noncoding/metabolism , Signal Transduction , Pancreatic NeoplasmsABSTRACT
Serotonin (5-hydroxytryptamine, 5-HT) and its receptors play important roles in the development and progression of malignant tumors. The effect of the 5-HT receptor 1D (HTR1D), a member of the serotonin receptor family, on gastric cancer (GC) is not clear. Analysis of clinical data has shown that high expression of HTR1D was associated with poor prognosis in patients with GC and was an independent risk factor for reduced overall survival (OS) and disease-free survival (DFS). The present study assessed the effects of HTR1D knockdown and the HTR1D inhibitor GR127935 on the biological behavior of GC cells, which both impaired the proliferation and migration of GC cells. RNA sequencing showed that GR127935 inhibited tumor progression by limiting DNA replication and the cell cycle, inducing ferroptosis, and affecting tumor metabolism. Taken together, these findings showed that HTR1D has a potent oncogenic effect on GC and may provide a novel therapeutic target.
Subject(s)
Receptor, Serotonin, 5-HT1D/metabolism , Serotonin , Stomach Neoplasms , Cell Line, Tumor , Cell Movement , Cell Proliferation , Gene Expression Regulation, Neoplastic , Humans , Receptor, Serotonin, 5-HT1D/genetics , Receptors, Serotonin/genetics , Receptors, Serotonin/metabolism , Serotonin 5-HT1 Receptor Antagonists , Stomach Neoplasms/pathologyABSTRACT
BACKGROUND: 5-Hydroxytryptamine (5-HT) receptors 1B, 1D and 1F have key roles in migraine pharmacotherapy. Selective agonists targeting these receptors, such as triptans and ditans, are effective in aborting acute migraine attacks and inhibit the in vivo release of calcitonin gene-related peptide (CGRP) in human and animal models. The study aimed to examine the localization, genetic expression and functional aspects of 5- HT1B/1D/1F receptors in the trigeminal system in order to further understand the molecular sites of action of triptans (5-HT1B/1D) and ditans (5-HT1F). METHODS: Utilizing immunohistochemistry, the localization of 5-HT and of 5-HT1B/1D/1F receptors was examined in rat trigeminal ganglion (TG) and combined with quantitative polymerase chain reaction to quantify the level of expression for 5-HT1B/1D/1F receptors in the TG. The functional role of these receptors was examined ex vivo with a capsaicin/potassium induced 5-HT and CGRP release. RESULTS: 5-HT immunoreactivity (ir) was observed in a minority of CGRP negative C-fibres, most neuron somas and faintly in A-fibres and Schwann cell neurolemma. 5-HT1B/1D receptors were expressed in the TG, while the 5-HT1F receptor displayed a weak ir. The 5-HT1D receptor co-localized with receptor activity-modifying protein 1 (RAMP1) in Aδ-fibres in the TG, while 5-HT1B-ir was weakly expressed and 5-HT1F-ir was not detected in these fibres. None of the 5-HT1 receptors co-localized with CGRP-ir in C-fibres. 5-HT1D receptor mRNA was the most prominently expressed, followed by the 5-HT1B receptor and lastly the 5-HT1F receptor. The 5-HT1B and 5-HT1D receptor antagonist, GR127935, could reverse the inhibitory effect of Lasmiditan (a selective 5-HT1F receptor agonist) on CGRP release in the soma-rich TG but not in soma-poor TG or dura mater. 5-HT release in the soma-rich TG, and 5-HT content in the baseline samples, negatively correlated with CGRP levels, showing for the first time a physiological role for 5-HT induced inhibition. CONCLUSION: This study reveals the presence of a subgroup of C-fibres that store 5-HT. The data shows high expression of 5-HT1B/1D receptors and suggests that the 5-HT1F receptor is a relatively unlikely target in the rat TG. Furthermore, Lasmiditan works as a partial agonist on 5-HT1B/1D receptors in clinically relevant dose regiments.
Subject(s)
Serotonin , Tryptamines , Animals , Benzamides , Calcitonin Gene-Related Peptide/metabolism , Piperidines/pharmacology , Pyridines , Rats , Receptor, Serotonin, 5-HT1B/genetics , Receptor, Serotonin, 5-HT1B/metabolism , Receptor, Serotonin, 5-HT1D/metabolism , Serotonin/metabolism , Trigeminal Ganglion/metabolism , Tryptamines/pharmacologyABSTRACT
Over the past decades, great attention has been given to the nervous system modulating effects on the immune response in inflammation-associated injuries, such as acute intestinal ischemia-reperfusion (IR). Recently, we proved the anti-inflammatory and antioxidant effects of 5-hydroxytryptamine (5-HT)1B/1D receptors in intestinal IR injury in rats. Also, the alpha7 nicotinic acetylcholine (α7-nACh) receptor has anti-inflammatory effects in different inflammation-associated injuries. Starting from these premises, we aimed to examine the function of the α7-nACh receptors and the functional interactions between the anti-inflammatory and antioxidant effects of α7-nACh and 5-HT1B/1D receptors in acute intestinal IR injury. To confirm the expression and localization of α7-nACh receptors on the ileum nerves, an immunofluorescence-based method was applied. Then, intestinal IR injury was induced by 30-min occlusion of superior mesenteric artery and reperfusion for 2 h in rats. Acute systemic administration of α7-nACh receptor agonist PNU-282987 and antagonist methyllycaconitine, and 5-HT1B/1D receptors agonist (sumatriptan) and antagonist (GR127, 935) were used in the model of intestinal IR injury. Finally, biochemical and histological parameters were assessed. Α7-nACh receptors were expressed by 9% on the ileum nerves. Likewise, activation of the α7-nACh receptor showed anti-inflammatory and antioxidant effects in intestinal IR injury but not as well as 5-HT1B/1D receptors. Interestingly, 5-HT1B/1D receptors via attenuation of glutamate (Glu) release indirectly activated the α7-nACh receptor and its protective effects against inflammation and oxidative stress. The protective effect of the α7-nACh receptor on intestinal IR injury was activated indirectly through the 5-HT1B/1D receptors' modulatory impact on Glu release.
Subject(s)
Receptor, Serotonin, 5-HT1B/metabolism , Receptor, Serotonin, 5-HT1D/metabolism , Reperfusion Injury , alpha7 Nicotinic Acetylcholine Receptor/metabolism , Animals , Rats , Reperfusion Injury/drug therapy , Reperfusion Injury/prevention & control , Serotonin 5-HT1 Receptor Agonists , SumatriptanABSTRACT
Serotonin (5-HT) acts as a neurotransmitter in the central nervous system (CNS) and as a mediator released by enterochromaffin cells to regulate intestinal motility. However, this amine also plays an important role as an inflammatory mediator and induces phenotypic changes of nociceptors. Despite the wide knowledge of the role of 5-HT in nociception, most studies have focused on its role in the CNS, while a clear information about its role in peripheral tissues is still lacking. In the present study, we investigated the role of peripheral 5-HT receptors in the nociceptive response induced by 5-HT or carrageenan in mice by using antagonists that target different 5-HT receptors. Mechanical nociceptive threshold was measured with an analgesimeter and evaluated after intraplantar (i.pl.) injection of 5-HT or carrageenan. 5-HT antagonists were injected via the i.pl. route. 5-HT (10, 20, 40 or 80 µg/paw) or carrageenan (100 µg/paw) induced mechanical allodynia. Pretreatment with isamoltane (5 µg; 5-HT1B antagonist) or ketanserine (1 µg; 5-HT2A antagonist) did not affect the mechanical allodynia induced by 5-HT. This response was inhibited by BRL 15572 (10 µg; 5-HT1D antagonist) or SB 269970 (25 µg; 5-HT7 antagonist). On the other hand, mechanical allodynia induced by 5-HT or carrageenan was exacerbated by ondansetron (10, 20 or 40 µg; 5-HT3 antagonist). The results indicate that activation of 5-HT1D and 5-HT7 receptors plays a role in the mechanical allodynia induced by 5-HT in mice. This study also demonstrates the inhibitory role of peripheral 5-HT3 receptors in the nociceptive response induced by 5-HT or carrageenan.
Subject(s)
Hyperalgesia/metabolism , Receptor, Serotonin, 5-HT1D/metabolism , Receptors, Serotonin, 5-HT3/metabolism , Receptors, Serotonin/metabolism , Animals , Carrageenan , Disease Models, Animal , Hyperalgesia/chemically induced , Hyperalgesia/physiopathology , Male , Mice , Nociception , Ondansetron/pharmacology , Pain Threshold , Serotonin , Serotonin Antagonists/pharmacology , Signal TransductionABSTRACT
BACKGROUND: Hepatocellular Carcinoma (HCC) is a primary liver cancer with high mortality. Paeoniflorin is a pinane monoterpene picroside with anti-tumor effect isolated from Chinese peony root and white peony root. OBJECTIVE: The study was conducted to investigate the underlying mechanism of Paeoniflorin (PF) regulating Hepatocellular Carcinoma (HCC) progression via 5-hydroxytryptamine receptor 1D (5-HT1D). METHODS: HepG2 and SMMC-7721 hepatoma cells were treated with different concentrations of PF (0, 5, 10, 20 µM). Cell proliferation, apoptosis, migration, and invasion were examined by CCK-8 and colony formation assays, flow cytometry, wound healing assay, and transwell assay, respectively. RTqPCR assay was used to detect the expression level of 5-HT1D, and Western blot assay was used to detect the expressions of 5-HT1D and Wnt/ß-catenin pathway-related proteins. RESULTS: With the increase in PF concentration, the mRNA levels of 5-HT1D in HepG2 and SMMC- 7721 hepatoma cells were decreased in a dose-dependent manner, and the proliferation, colony formation, migration and invasion ability of cells were gradually weakened, while the apoptosis rate was gradually increased. Overexpression of 5-HT1D significantly promoted the proliferation, colony formation, migration and invasion of HepG2 and SMMC-7721 cells, and increased the expression of Wnt/ß-catenin pathway-related proteins, ß -actenin, survivin, C-myc, and Cyclin D1. Furthermore, 5-HT1D overexpression could reverse the effect of PF on hepatoma cells and inhibit the expressions of Wnt/ß-catenin pathway-related proteins. CONCLUSION: PF may inhibit the progression of HCC by blocking Wnt/ß-catenin pathway expression through downregulating 5-HT1D.
Subject(s)
Down-Regulation/drug effects , Glucosides/pharmacology , Monoterpenes/pharmacology , Receptor, Serotonin, 5-HT1D/metabolism , Wnt Signaling Pathway/drug effects , Apoptosis/drug effects , Carcinoma, Hepatocellular/metabolism , Carcinoma, Hepatocellular/pathology , Cell Line, Tumor , Cell Movement/drug effects , Cell Proliferation/drug effects , Humans , Liver Neoplasms/metabolism , Liver Neoplasms/pathology , RNA, Messenger/metabolism , Receptor, Serotonin, 5-HT1D/genetics , Wnt Proteins/metabolism , beta Catenin/metabolismABSTRACT
Acute mesenteric ischemia (AMI) is caused by an abrupt cessation of blood flow to the small intestine. Reperfusion is the return of blood flow to the ischemic bowel. Intestinal ischemia/reperfusion (I/R) leads to the formation of reactive oxygen species, local inflammatory response, and may lead to the patient's death. Pre-treatment of the intestinal may reduce the high mortality associated with AMI. 5-Hydroxytryptamine 1B (5-HT1B) and 5-HT1D receptors have anti-inflammatory and neuroprotective effects in different experimental studies. We aimed to investigate the potential involvement of these receptors in intestinal I/R injury. Firstly, we assessed the expression and localization of 5-HT1B and 5-HT1D receptors in the enteric nervous system using an immunofluorescence-based method. Intestinal I/R in rats was induced by 30 min occlusion of superior mesenteric artery and reperfusion for 2 h. Rats were randomly divided in different control and I/R groups (n = 6) receiving either vehicle, sumatriptan (5-HT1B/1D receptors agonist; 0.1 mg/kg), GR127,935 (5-HT1B/1D receptors antagonist; 0.1 mg/kg) and combination of sumatriptan (0.1 mg/kg) + GR127,935 (0.1 mg/kg) before determination of biochemical and histological parameters. In the enteric nervous system, 5-HT1B and 5-HT1D receptors were expressed 17% and 11.5%, respectively. Pre-treatment with sumatriptan decreased 5-hydroxytryptamine (5HT) level by 53%, and significantly decreased calcitonin gene-related peptide (CGRP) levels, lipid pereoxidation, neutrophil infiltration, and level of pro-inflammatory markers in the serum. Histopathologic studies also showed a remarkable decrease in intestinal tissue injury. These findings suggest that sumatriptan may inhibit intestinal injury induced by I/R through modulating the inflammatory response by activation of 5-HT1B/1D receptors.
Subject(s)
Mesenteric Ischemia/metabolism , Receptor, Serotonin, 5-HT1B/metabolism , Receptor, Serotonin, 5-HT1D/metabolism , Reperfusion Injury/metabolism , Animals , Calcitonin Gene-Related Peptide/metabolism , Ileum/drug effects , Ileum/metabolism , Ileum/pathology , Inflammation/metabolism , Inflammation/pathology , Intestinal Mucosa/drug effects , Intestinal Mucosa/metabolism , Intestinal Mucosa/pathology , Male , Mesenteric Ischemia/pathology , Oxadiazoles/pharmacology , Oxidative Stress/drug effects , Piperazines/pharmacology , Rats, Wistar , Reperfusion Injury/pathology , Serotonin/metabolism , Serotonin 5-HT1 Receptor Agonists/pharmacology , Serotonin Antagonists/pharmacology , Sumatriptan/pharmacologyABSTRACT
This study was planned to evaluate the effects of sumatriptan, 5-HT1B/1D receptors agonist, on ischaemia/reperfusion injury in bilateral testes after unilateral testicular torsion/detorsion in rats. Male Wistar rats (n = 42) were allocated into a sham-operated group, a control group and treatment groups which were injected sumatriptan (0.1, 0.3 and 1 mg/kg), GR-127935 (0.01 mg/kg)-5-HT1B/1D receptors antagonist-and sumatriptan (0.1 mg/kg) + GR-127935 (0.01 mg/kg). Torsion was induced for 1 hr by rotating right testis 7200 in the clockwise direction, and after 7 days of detorsion, bilateral orchiectomy was conducted. While the level of TNF-α rose in testicular tissue after inducing torsion/detorsion, sumatriptan injection notably lowered TNF-α level in ipsilateral (torted) and contralateral (nontorted) testes (p < 0.001). Moreover, after inducing testicular torsion/detorsion, SOD activity was decreased, whereas administration of sumatriptan significantly increased SOD activity in bilateral testes (p < 0.001). After induction of torsion/detorsion, macroscopic and histological analyses also showed severe damages which were improved by sumatriptan injection. Interestingly, co-administration of sumatriptan with GR-127935 reversed the beneficial impacts of sumatriptan on macroscopic appearance, microscopic pattern and biochemical markers. It is concluded that sumatriptan presumably via stimulation of 5-HT1B/1D receptors decreased inflammation, oxidative stress and deteriorations induced by ischaemia/reperfusion injury following testicular torsion/detorsion.
Subject(s)
Reperfusion Injury/drug therapy , Serotonin 5-HT1 Receptor Agonists/administration & dosage , Spermatic Cord Torsion/complications , Sumatriptan/administration & dosage , Testis/drug effects , Animals , Disease Models, Animal , Humans , Male , Oxadiazoles/administration & dosage , Oxidative Stress/drug effects , Piperazines/administration & dosage , Rats , Rats, Wistar , Receptor, Serotonin, 5-HT1B/metabolism , Receptor, Serotonin, 5-HT1D/metabolism , Reperfusion Injury/etiology , Reperfusion Injury/pathology , Serotonin Antagonists/administration & dosage , Superoxide Dismutase/metabolism , Testis/pathology , Tumor Necrosis Factor-alpha/metabolismABSTRACT
The monosynaptic stretch reflex (MSR) plays an important role in feedback control of movement and posture but can also lead to unstable oscillations associated with tremor and clonus, especially when increased with spinal cord injury (SCI). To control the MSR and clonus after SCI, we examined how serotonin regulates the MSR in the sacrocaudal spinal cord of rats with and without a chronic spinal transection. In chronic spinal rats, numerous 5-HT receptor agonists, including zolmitriptan, methylergonovine, and 5-HT, inhibited the MSR with a potency highly correlated to their binding affinity to 5-HT1D receptors and not other 5-HT receptors. Selective 5-HT1D receptor antagonists blocked this agonist-induced inhibition, although antagonists alone had no action, indicating a lack of endogenous or constitutive receptor activity. In normal uninjured rats, the MSR was likewise inhibited by 5-HT, but at much higher doses, indicating a supersensitivity after SCI. This supersensitivity resulted from the loss of the serotonin transporter SERT with spinal transection, because normal and injured rats were equally sensitive to 5-HT after SERT was blocked or to agonists not transported by SERT (zolmitriptan). Immunolabeling revealed that the 5-HT1D receptor was confined to superficial lamina of the dorsal horn, colocalized with CGRP-positive C-fibers, and eliminated by dorsal rhizotomy. 5-HT1D receptor labeling was not found on large proprioceptive afferents or α-motoneurons of the MSR. Thus serotonergic inhibition of the MSR acts indirectly by modulating C-fiber activity, opening up new possibilities for modulating reflex function and clonus via pain-related pathways. NEW & NOTEWORTHY Brain stem-derived serotonin potently inhibits afferent transmission in the monosynaptic stretch reflex. We show that serotonin produces this inhibition exclusively via 5-HT1D receptors, and yet these receptors are paradoxically mostly confined to C-fibers. This suggests that serotonin acts by gating of C-fiber activity, which in turn modulates afferent transmission to motoneurons. We also show that the classic supersensitivity to 5-HT after spinal cord injury results from a loss of SERT, and not 5-HT1D receptor plasticity.
Subject(s)
Nerve Fibers, Unmyelinated/metabolism , Receptor, Serotonin, 5-HT1D/metabolism , Reflex, Stretch , Spinal Cord Injuries/metabolism , Animals , Female , Nerve Fibers, Unmyelinated/drug effects , Nerve Fibers, Unmyelinated/physiology , Rats , Serotonin 5-HT1 Receptor Agonists/pharmacology , Serotonin 5-HT1 Receptor Antagonists/pharmacology , Serotonin Plasma Membrane Transport Proteins/metabolism , Spinal Cord Injuries/physiopathologyABSTRACT
Serotonin and its receptors have been shown to play critical regulatory roles in cancer biology. Nevertheless, the contributions of 5-hydroxytryptamine 1D (5-HT1D), an indispensable member of the serotonergic system, to hepatocellular carcinoma (HCC) remain unknown. The present study demonstrated that the 5-HT1D expression level was significantly up-regulated in HCC tissues and cell lines. The 5-HT1D expression level was closely correlated with unfavorable clinicopathological characteristics. Survival analyses show that elevated 5-HT1D expression level predicts poor overall survival and high recurrence probability in HCC patients. Functional studies revealed that 5-HT1D significantly promoted HCC proliferation, epithelial-mesenchymal transition, and metastasis in vitro and in vivo. Mechanistically, 5-HT1D could stabilize PIK3R1 by inhibiting its ubiquitin-mediated degradation. The interaction between 5-HT1D and phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1) enhanced the expression of FoxO6 through the PI3K/Akt signaling pathway; FoxO6 could also be directly transcriptionally activated by 5-HT1D in an Akt-independent manner. MicroRNA-599 was found to be an upstream suppressive modulator of 5-HT1D. Additionally, 5-HT1D could attenuate tryptophan hydroxylase 1 expression through the PI3K/Akt/cut-like homeobox 1 axis in HCC. Conclusion: Herein, we uncovered the potent oncogenic effect of 5-HT1D on HCC by interacting with PIK3R1 to activate the PI3K/Akt/FoxO6 pathway, and provided a potential therapeutic target for HCC.
Subject(s)
Carcinoma, Hepatocellular/metabolism , Forkhead Transcription Factors/metabolism , Liver Neoplasms, Experimental/metabolism , Receptor, Serotonin, 5-HT1D/metabolism , Animals , Carcinoma, Hepatocellular/mortality , Carcinoma, Hepatocellular/pathology , China/epidemiology , Epithelial-Mesenchymal Transition , Female , Hep G2 Cells , Humans , Liver Neoplasms, Experimental/mortality , Liver Neoplasms, Experimental/pathology , Male , Mice, Inbred BALB C , Mice, Nude , MicroRNAs/metabolism , Middle Aged , Neoplasm Metastasis , Phosphatidylinositol 3-Kinases/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Tryptophan Hydroxylase/metabolismABSTRACT
Although depression and cardiovascular diseases are related, the role of antidepressants such as fluoxetine (increasing serotonin levels) within cardiac regulation remains unclear. We aimed to determine whether fluoxetine modifies the pharmacological profile of serotonergic influence on vagal cardiac outflow. Rats were treated with fluoxetine (10 mg/kg per day; p.o.) for 14 days or equivalent volumes of drinking water (control group); then, they were pithed and prepared for vagal stimulation. Bradycardic responses were obtained by electrical stimulation of the vagal fibers (3, 6, and 9 Hz) or i.v. acetylcholine (ACh; 1, 5, and 10 µg/kg). The i.v. administration of 5-hydroxytryptamine (5-HT; 10 and 50 µg/kg) inhibited the vagally induced bradycardia. 5-CT (5-HT1/7 agonist) and L-694,247 (5-HT1D agonist) mimicked the serotonin inhibitory effect while α-methyl-5-HT (5-HT2 agonist) was devoid of any action. SB269970 (5-HT7 antagonist) did not abolish 5-CT inhibitory action on the electrically induced bradycardia. Pretreatment with LY310762 (5-HT1D antagonist) blocked the effects induced by L-694,247 and 5-CT. 5-HT and 5-CT failed to modify the bradycardia induced by exogenous ACh. Our outcomes suggest that fluoxetine treatment modifies 5-HT modulation on heart parasympathetic neurotransmission in rats, evoking inhibition of the bradycardia via prejunctional 5-HT1D in pithed rats.
Subject(s)
Antidepressive Agents, Second-Generation/pharmacology , Bradycardia/drug therapy , Fluoxetine/pharmacology , Receptor, Serotonin, 5-HT1D/metabolism , Vagus Nerve/drug effects , Administration, Oral , Animals , Antidepressive Agents, Second-Generation/therapeutic use , Bradycardia/etiology , Depression/complications , Depression/drug therapy , Disease Models, Animal , Drug Evaluation, Preclinical , Fluoxetine/therapeutic use , Heart/innervation , Heart Rate/drug effects , Humans , Oxadiazoles/pharmacology , Phenols/pharmacology , Rats , Rats, Wistar , Serotonin/pharmacology , Serotonin 5-HT1 Receptor Antagonists/pharmacology , Serotonin Receptor Agonists/metabolism , Sulfonamides/pharmacology , Tryptamines/pharmacology , Vagus Nerve/metabolismABSTRACT
Methamphetamine (METH)-seeking relapse is associated with memory and synaptic plasticity changes. Serotonin is a key neuromodulator in this process. While there is a known distribution of 5-HT1D receptors in reward and memory areas, such as the hippocampus, its physiological function is currently unknown. Here, we evaluated effect of a 5-HT1D receptor agonist, PNU142633, on the reinstatement of METH-seeking behavior and long-term potentiation. Rats were implanted with a cannula into lateral ventricle, then treated with saline or METH (5â¯mg/kg) during the acquisition phase of the conditioned place preference (CPP) test. On day 13 of the extinction phase, METH groups were divided into four groups: METH (0: saline, 1, or 2.5 (priming METH) mg/kg; i.p.)â¯+â¯vehicle (5⯵l/rat) or a priming dose of METH (2.5â¯mg/kg; i.p.)â¯+â¯PNU (2⯵g/5⯵l; i.c.v.) and their preference scores were calculated on reinstatement day (day 14). Immediately following this, electrophysiology was performed to assay the field excitatory postsynaptic potential (fEPSP) slope and population spike (PS) amplitude between groups. The results showed that CPP induction by METH gradually declined to extinction on days 12 and 13. A priming METH treatment significantly increased preference for the METH-paired chamber when compared with other groups, but pre-treatment with PNU significantly attenuated this effect. PS amplitude and fEPSP slopes in vehicleâ¯+â¯priming METH rats were greater when compared with other groups. Furthermore, PNU attenuated the priming METH-induced increase in PS amplitude. These findings suggest that PNU can decrease synaptic transmission and prevent METH reinstatement in rats.
Subject(s)
Conditioning, Operant/drug effects , Long-Term Potentiation/drug effects , Methamphetamine/pharmacology , Receptor, Serotonin, 5-HT1D/metabolism , Serotonin 5-HT1 Receptor Agonists/pharmacology , Animals , Central Nervous System Stimulants/pharmacology , Conditioning, Classical/drug effects , Excitatory Postsynaptic Potentials/drug effects , Extinction, Psychological/drug effects , Hippocampus/drug effects , Hippocampus/physiology , Long-Term Potentiation/physiology , Male , Neuronal Plasticity/drug effects , Rats , Rats, Wistar , Reward , Serotonin/pharmacology , Synaptic Transmission/drug effectsABSTRACT
Stretchable electrochemical (EC) sensors have broad prospects in real-time monitoring of living cells and tissues owing to their excellent elasticity and deformability. However, the redox reaction products and cell secretions are easily adsorbed on the electrode, resulting in sensor fouling and passivation. Herein, we developed a stretchable and photocatalytically renewable EC sensor based on Au nanotubes (NTs) and TiO2 nanowires (NWs) sandwich nanonetworks. The external Au NTs are used for EC sensing, and internal TiO2 NWs provide photocatalytic performance to degrade contaminants, which endows the sensor with excellent EC performance, high photocatalytic activity, and favorable mechanical tensile property. This allows highly sensitive recycling monitoring of NO released from endothelial cells and 5-HT released from mast cells under their stretching states in real time, therefore providing a promising tool to unravel elastic and mechanically sensitive cells, tissues, and organs.
Subject(s)
Biosensing Techniques , Electrochemical Techniques , Human Umbilical Vein Endothelial Cells/chemistry , Mast Cells/chemistry , Nitric Oxide/analysis , Receptor, Serotonin, 5-HT1D/analysis , Catalysis , Gold/chemistry , Human Umbilical Vein Endothelial Cells/metabolism , Humans , Mast Cells/metabolism , Nanotubes/chemistry , Nanowires/chemistry , Nitric Oxide/metabolism , Particle Size , Photochemical Processes , Receptor, Serotonin, 5-HT1D/metabolism , Surface Properties , Time Factors , Titanium/chemistryABSTRACT
Sumatriptan has been among the top choices in the management of migraine headaches. The association between migraine and epilepsy highlights the possible effect of sumatriptan on seizures. In this regard, we investigated sumatriptan effects on PTZ-induced seizures thresholds and delineated the modulatory role of 5-HT1B/D receptors and NOS/NO pathway. Our data revealed the anti-convulsant effects of lower doses of sumatriptan, and pro-convulsant effects of higher doses of sumatriptan. GR 127935, a selective 5-HT1B/D antagonist, could abolish the sumatriptan anti-convulsant effects, but it was ineffective against the sumatriptan pro-convulsant effects. Serotonin depletion by consecutive administration of p-CPA, a selective irreversible inhibitor of tryptophan hydroxylase, could not affect the anti-convulsant effects of sumatriptan. The anti-convulsant effects of sumatriptan was potentiated by L-NAME, a non-selective NOS inhibitor, 7-NI, a selective nNOS inhibitor, but not AG, an iNOS inhibitor. It was also neutralized by L-ARG, a NO precursor. The pro-convulsant effects of sumatriptan were blocked by L-NAME and AG, but not 7-NI. It was also potentiated by L-ARG. Our data revealed that anti-convulsive effects of sumatriptan is mediated by interaction between non-serotonergic 5-HT1B/D receptors and nNOS/NO pathway. Besides, the pro-convulsive effect of sumatriptan is mediated by iNOS/NO pathway independent of 5-HT1B/D receptors. For the first time, this study reported the biphasic effect of sumatriptan on an animal model of GCS and its modulatory pathways.
Subject(s)
Nitric Oxide Synthase Type III/metabolism , Nitric Oxide Synthase Type II/metabolism , Nitric Oxide/metabolism , Receptor, Serotonin, 5-HT1B/metabolism , Receptor, Serotonin, 5-HT1D/metabolism , Seizures/metabolism , Sumatriptan/pharmacology , Animals , Anticonvulsants/pharmacology , Anticonvulsants/therapeutic use , Convulsants/pharmacology , Convulsants/therapeutic use , Dose-Response Relationship, Drug , Male , Mice , Pentylenetetrazole/adverse effects , Seizures/chemically induced , Seizures/drug therapy , Seizures/pathology , Signal Transduction/drug effects , Sumatriptan/therapeutic useABSTRACT
Chloroquine (CQ) induces histamine-independent itch in human and mice. We recently reported the role of intradermal nitric oxide (NO)/cyclic guanosine monophosphate pathway in CQ-evoked scratching in mice. Chloroquine stimulates neuronal nitric oxide synthase (nNOS) activity to over-producing NO in the skin. Sumatriptan, a 5-hydroxytryptamine 1b/1d receptors (5-HTR1b/1d) agonist, is involved in pain and used to treat migraine and cluster headaches. According to previous studies, sumatriptan inhibits NOS activity. Thus, we aimed to investigate the effect of sumatriptan on CQ-induced scratching. We used the rostral back model of itch. Chloroquine was injected intradermally into the rostral back of NMRI mice, and the scratching behavior was evaluated by measuring the number of bouts over 30 min. We evaluated the effect of sumatriptan and combination of sumatriptan and a non-selective NO synthase inhibitor, L-N-nitro arginine methyl ester (L-NAME), on the scratching behavior. Additionally, the changes of skin, hippocampus, and cortical nitrite level after different treatments were studied. Intraperitoneal and intradermal sumatriptan attenuates CQ-induced itch which reversed by GR-127935, the selective 5-HTR1b and 5-HTR1d antagonist. Co-administration of subeffective doses of sumatriptan and L-NAME significantly decreases the scratching behavior. Intradermal injection of CQ significantly increases the intradermal nitrite levels while it does not have any significant effects on hippocampal or cortical nitrite concentrations. Likewise, the effective doses of intraperitoneal and intradermal sumatriptan significantly reduce intradermal nitrite levels. We concluded that sumatriptan suppresses CQ-induced itch most likely by activating 5-HT1b/1d receptors. This effect probably mediates through NO pathway.
Subject(s)
Antipruritics/pharmacology , Chloroquine , Nitric Oxide/metabolism , Pruritus/prevention & control , Receptor, Serotonin, 5-HT1B/drug effects , Receptor, Serotonin, 5-HT1D/drug effects , Serotonin 5-HT1 Receptor Agonists/pharmacology , Skin/drug effects , Sumatriptan/pharmacology , Animals , Behavior, Animal/drug effects , Disease Models, Animal , Dose-Response Relationship, Drug , Enzyme Inhibitors/pharmacology , Male , Mice , Nitric Oxide Synthase/antagonists & inhibitors , Nitric Oxide Synthase/metabolism , Pruritus/chemically induced , Pruritus/metabolism , Pruritus/physiopathology , Receptor, Serotonin, 5-HT1B/metabolism , Receptor, Serotonin, 5-HT1D/metabolism , Serotonin 5-HT1 Receptor Antagonists/pharmacology , Signal Transduction/drug effects , Skin/metabolism , Time FactorsABSTRACT
5-hydroxytryptamine (5-HT) modulates noradrenergic activity in different cardiovascular territories, but its effect on the mesenteric vasopressor outflow has not yet been clarified. This study investigated the in vivo serotonergic influence, characterizing 5-HT receptors implicated, in sympathetic innervation of mesenteric vasculature. Wistar rats were anaesthetised and prepared for the in situ autoperfused rat mesentery, monitoring systemic blood pressure (SBP), heart rate (HR) and mesenteric perfusion pressure (MPP). Electrical stimulation of mesenteric sympathetic nerves resulted in frequency-dependent increases in MPP (9 ± 1.6, 25.7 ± 3.9 and 60.2 ± 5 mmHg for 2, 4 and 8 Hz, respectively), without altering SBP or HR. 5-HT (1-25 µg/kg), 5-carboxamidotryptamine (5-HT1/7 agonist; 25 µg/kg) or L-694,247 (5-HT1D agonist; 1-25 µg/kg) i.a. bolus inhibited vasopressor responses by mesenteric nerves electrical stimulation, unlike i.a. bolus of agonists 8-OH-DPAT (5-HT1A ), CGS-12066B (5-HT1B ), BRL 54443 (5-HT1e/1F ), α-methyl-5-HT (5-HT2 ), 1-PBG (5-HT3 ), cisapride (5-HT4 ) or AS-19 (5-HT7 ) (25 µg/kg each). Interestingly, i.a. L-694,247 (25 µg/kg) also reduced the exogenous norepinephrine-induced vasoconstrictions. Pretreatment with selective 5-HT1D receptor antagonist, LY310762 (1 mg/kg, i.v.), completely abolished L-694,247- and 5-HT-induced mesenteric sympathoinhibition. Furthermore, ELISA analysis confirmed 5-HT1D receptors expression in mesenteric artery. These findings suggest that serotonergic mechanisms-induced sympathoinhibition of mesenteric noradrenergic outflow is mediated by pre and/or postjunctional 5-HT1D receptors.
Subject(s)
Mesenteric Arteries/drug effects , Mesentery/drug effects , Receptor, Serotonin, 5-HT1D/metabolism , Serotonin/pharmacology , Splanchnic Circulation/drug effects , Sympathetic Nervous System/drug effects , Animals , Electric Stimulation , In Vitro Techniques , Male , Mesenteric Arteries/innervation , Mesenteric Arteries/metabolism , Mesentery/blood supply , Mesentery/metabolism , Oxadiazoles/pharmacology , Rats, Wistar , Tryptamines/pharmacology , Vasoconstrictor Agents/pharmacologyABSTRACT
Lerimazoline is a sympathomimetic drug that belongs to the imidazoline class of compounds, and is used as a nasal decongestant. Studies on lerimazoline are rare, and its pharmacological profile is not completely understood. Here, we analyzed the affinity of lerimazoline for dopamine receptor D2, serotonin 5-HT1A and 5-HT2A receptors and α1-adrenoceptor, and investigated lerimazoline contractile effects in isolated rat thoracic aorta. We also determined the effect of several antagonists on the contractile response to lerimazoline, including prazosin (α1-adrenoceptor antagonist), RX 821002 and rauwolscine (α2-adrenoceptor antagonists), JP 1302 (α2C-adrenoceptor antagonist), methiothepin (non-selective 5-HT receptor antagonist), SB 224289 (5-HT1B receptor antagonist), BRL 15572 (5-HT1D receptor antagonist), and ketanserin (5-HT2A receptor antagonist). Lerimazoline displayed high affinity for the 5-HT1A receptor (Ki = 162.5 nM), similar to the previously reported affinity for the 5-HT1D receptor. Binding affinity estimates (Ki) for α1, 5-HT2A, and D2 receptors were 6656, 4202 and 3437.5 nM, respectively (the literature reported Ki for 5-HT1B receptor is 3480 nM). Lerimazoline caused concentration-dependent contractions in 70% of preparations, varying in the range between 40% and 55% of the maximal contraction elicited by phenylephrine. While prazosin reduced the maximum contractile response to lerimazoline, rauwolscine showed a non-significant trend in reduction of the response. Both ketanserin (10 nM and 1 µM) and methiothepin strongly suppressed the maximum response to lerimazoline. Overall, our results suggest that 5-HT2A and, less distinctly, α1-adrenergic receptors are involved in the lerimazoline-induced contractions, which makes lerimazoline an "atypical" decongestant.
Subject(s)
Aorta, Thoracic/drug effects , Muscle, Smooth, Vascular/drug effects , Niacinamide/analogs & derivatives , Receptor, Serotonin, 5-HT2A/drug effects , Sympathomimetics/pharmacology , Animals , Dose-Response Relationship, Drug , In Vitro Techniques , Male , Muscle Contraction/drug effects , Niacinamide/antagonists & inhibitors , Niacinamide/metabolism , Niacinamide/pharmacology , Phenylephrine/pharmacology , Rats , Rats, Wistar , Receptor, Serotonin, 5-HT1D/drug effects , Receptor, Serotonin, 5-HT1D/metabolism , Receptor, Serotonin, 5-HT2A/metabolism , Receptors, Adrenergic, alpha-1/drug effects , Receptors, Adrenergic, alpha-1/metabolism , Serotonin Antagonists/pharmacology , Sympathomimetics/metabolism , Vasoconstrictor Agents/pharmacologyABSTRACT
Background: 5-HT1B receptor agonists enhance cocaine intake during daily self-administration sessions but decrease cocaine intake when tested after prolonged abstinence. We examined if 5-HT1B receptor agonists produce similar abstinence-dependent effects on methamphetamine intake. Methods: Male rats were trained to self-administer methamphetamine (0.1 mg/kg, i.v.) on low (fixed ratio 5 and variable ratio 5) and high (progressive ratio) effort schedules of reinforcement until intake was stable. Rats were then tested for the effects of the selective 5-HT1B receptor agonist, CP 94,253 (5.6 or 10 mg/kg), or the less selective but clinically available 5-HT1B/1D receptor agonist, zolmitriptan (10 mg/kg), on methamphetamine self-administration both before and after a 21-day forced abstinence period during which the rats remained in their home cages. Results: The inverted U-shaped, methamphetamine dose-response function for intake on the fixed ratio 5 schedule was shifted downward by CP 94,253 both before and after abstinence. The CP 94,253-induced decrease in methamphetamine intake was replicated in rats tested on a variable ratio 5 schedule, and the 5-HT1B receptor antagonist SB 224,289 (10 mg/kg) reversed this effect. CP 94,253 also attenuated methamphetamine intake on a progressive ratio schedule both pre- and postabstinence. Similarly, zolmitriptan attenuated methamphetamine intake on a variable ratio 5 schedule both pre- and postabstinence, and the latter effect was sustained after each of 2 more treatments given every 2 to 3 days prior to daily sessions. Conclusions: Unlike the abstinence-dependent effect of 5-HT1B receptor agonists on cocaine intake reported previously, both CP 94,253 and zolmitriptan decreased methamphetamine intake regardless of abstinence. These findings suggest that 5-HT1B receptor agonists may have clinical efficacy for psychostimulant use disorders.
Subject(s)
Amphetamine-Related Disorders/drug therapy , Serotonin 5-HT1 Receptor Agonists/pharmacology , Amphetamine-Related Disorders/metabolism , Animals , Central Nervous System Stimulants/administration & dosage , Conditioning, Operant , Disease Models, Animal , Dose-Response Relationship, Drug , Male , Methamphetamine/administration & dosage , Motor Activity/drug effects , Motor Activity/physiology , Oxazolidinones/pharmacology , Pyridines/pharmacology , Random Allocation , Rats, Sprague-Dawley , Receptor, Serotonin, 5-HT1B/metabolism , Receptor, Serotonin, 5-HT1D/metabolism , Reinforcement Schedule , Tryptamines/pharmacologyABSTRACT
Amongst the side effects of triptans, a substantial percentage of patients experience injection site pain and tenderness, the underlying mechanism of which is unknown. We found that the dose range from 10fg to 1000ng (intradermal) of sumatriptan induced a complex dose-dependent mechanical hyperalgesia in male rats, with distinct peaks, at 1pg and 10ng, but no hyperalgesia at 1ng. In contrast, in females, there was 1 broad peak. The highest dose (1000ng) did not produce hyperalgesia in either sex. We evaluated the receptors mediating sumatriptan hyperalgesia (1pg, 1 and 10ng). In males, the injection of an antagonist for the serotonin (5-HT) receptor subtype 1B (5-HT1B), but not 5-HT1D, markedly inhibited sumatriptan (1pg)-induced hyperalgesia, at 10ng a 5-HT1D receptor antagonist completely eliminated hyperalgesia. In contrast, in females, the 5-HT1D, but not 5-HT1B, receptor antagonist completely blocked sumatriptan (1pg and 10ng) hyperalgesia and both 5-HT1B and 5-HT1D receptor antagonists attenuated hyperalgesia (1ng) in females, which is GPR30 estrogen receptor dependent. While selective 5-HT1D or 5-HT1B, agonists produce robust hyperalgesia in female and male rats, respectively, when co-injected the hyperalgesia induced in both sexes was attenuated. Mechanical hyperalgesia induced by sumatriptan (1pg and 10ng) is dependent on the G-protein αi subunit and protein kinase A (PKA), in IB4-positive and negative nociceptors. Understanding the mechanisms responsible for the complex dose dependence for triptan hyperalgesia may provide useful information for the design of anti-migraine drugs with improved therapeutic profiles.