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Watts SW, Garver H, Morisset-Lopez S, Suzenet F, Fink GD. β-arrestin biased signaling is not involved in the hypotensive actions of 5-HT 7 receptor stimulation: use of Serodolin. Pharmacol Res 2024; 199:107047. [PMID: 38157998 DOI: 10.1016/j.phrs.2023.107047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 12/21/2023] [Accepted: 12/21/2023] [Indexed: 01/03/2024]
Abstract
The 5-hydroxytryptamine 7 receptor (5-HT7) is necessary for 5-HT to cause a concentration-dependent vascular relaxation and hypotension. 5-HT7 is recognized as having biased signaling, transduced through either Gs or β -arrestin. It is unknown whether 5-HT7 signals in a biased manner to cause vasorelaxation/hypotension. We used the recently described β-arrestin selective 5-HT7 receptor agonist serodolin to test the hypothesis that 5-HT7 activation does not cause vascular relaxation or hypotension via the β -arrestin pathway. Isolated abdominal aorta (no functional 5-HT7) and vena cava (functional 5-HT7) from male Sprague Dawley rats were used in isometric contractility studies. Serodolin (1 nM - 10 μM) did not change baseline tone of isolated tissues and did not relax the endothelin-1 (ET-1)-contracted vena cava or aorta. In the aorta, serodolin acted as a 5-HT2A receptor antagonist, evidenced by a rightward shift in 5-HT-induced concentration response curve [pEC50 5-HT [M]: Veh = 5.2 +/- 0.15; Ser (100 nM) = 4.49 +/- 0.08; p < 0.05]. In the vena cava, serodolin acted as a 5-HT7 receptor antagonist, shifting the concentration response curve to 5-HT left and upward (%10 μM NE contraction; Veh = 3.2 +/- 1.7; Ser (10 nM) = 58 +/- 11; p < 0.05) and blocking relaxation of pre-contracted tissue to the 5-HT1A/7 agonist 5-carboxamidotryptamine. In anesthetized rats, 5-HT or serodolin was infused at 5, 25 and 75 μg/kg/min, iv. Though 5-HT caused concentration-dependent depressor responses, serodolin caused an insignificant small depressor responses at all three infusion rates. With the final dose of serodolin on board, 5-HT was unable to reduce blood pressure. Collectively the data indicate that serodolin functions as a 5-HT7 antagonist with additional 5-HT2A blocking properties. 5-HT7 activation does not cause vascular relaxation or hypotension via the β -arrestin pathway.
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Affiliation(s)
- Stephanie W Watts
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824-1317, USA.
| | - Hannah Garver
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824-1317, USA
| | - Severine Morisset-Lopez
- Centre de Biophysique Moléculaire, CNRS, Unité Propre de Recherche 4301, Université d'Orléans, Orléans Cedex 2 45071 France
| | - Franck Suzenet
- Institut de Chimie Organique et Analytique, Université d'Orléans, CNRS UMR 7311, rue de Chartres, 45067 Orléans, France
| | - Gregory D Fink
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824-1317, USA
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Thompson JM, Tragge W, Flood ED, Schulz S, Lisabeth E, Watts SW. Development of a 5-HT 7 receptor antibody for the rat: the good, the bad, and the ugly. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2023; 396:2599-2611. [PMID: 37071157 PMCID: PMC10497691 DOI: 10.1007/s00210-023-02482-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 03/30/2023] [Indexed: 04/19/2023]
Abstract
Our laboratory has a vested interest in measuring the location and expression of the 5-hydroxytryptamine (5-HT, serotonin) 7 (5-HT7) receptor in the rat. Determining tissue-specific receptor expression would aid in validating understood and potentially new tissues that support the 5-HT7 receptor-mediated fall in blood pressure, an event we are committed to understand. We contracted with 7TM Antibodies to develop deliberately and rigorously a rat 5-HT7 (r5-HT7) receptor specific antibody. Three antigens, two targeting the third internal loop and one the C terminus, were used in three rabbits to generate antibodies. As a positive control, HEK293(T or AD) cells were transfected with a plasmid for the r5-HT7 receptor also expressing a C terminus 3xFLAG tag. Naïve rat tissues were also used in Western and immunohistochemical analyses. Nine antibodies (3 from three different rabbits) detected a ~ 75 kDa protein absent in homogenates of vector control HEK293T cells. Only antibodies that recognized the C terminus of the 5-HT7 receptor [ERPERSEFVLQNSDH(Abu)GKKGHDT; antibodies 3, 6, and 9] positively and concentration-dependently identified the r5-HT7 receptor expressed in Westerns of transfected HEK293T cells. These same C terminus antibodies also successfully detected the r5-HT7 receptor in immunocytochemical test of the transfected HEK293AD cells, colocalizing with the detected FLAG sequence. In naive tissue, antibody 6 performed the best, identifying specific bands in the brain cortex in Western analysis. These same antibodies produced a more diverse band profile in the vena cava, identifying 6 major proteins. In immunohistochemical experiments, the same C-terminus antibodies, with antibody 3 performing the best, detected the 5-HT7 receptor in rat veins. This deliberate work has given rise to at least three antibodies that can be used with good confidence in r5-HT7 transfected cells, two antibodies that can be used in immunohistochemical analyses of rat tissues and in Westerns of rat brain; we are less confident of the use of these same antibodies in rat veins.
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Affiliation(s)
- Janice M Thompson
- Department of Pharmacology and Toxicology, Michigan State University, 1355 Bogue Street, Rm B445, East Lansing, MI, 48824-1317, USA
| | - Will Tragge
- Department of Pharmacology and Toxicology, Michigan State University, 1355 Bogue Street, Rm B445, East Lansing, MI, 48824-1317, USA
| | - Emma D Flood
- Department of Pharmacology and Toxicology, Michigan State University, 1355 Bogue Street, Rm B445, East Lansing, MI, 48824-1317, USA
| | - Stefan Schulz
- Department of Pharmacology and Toxicology, Jena University Hospital, 07747, Jena, Germany
- 7TM Antibodies, 07745, Jena, Germany
| | - Erika Lisabeth
- Department of Pharmacology and Toxicology, Michigan State University, 1355 Bogue Street, Rm B445, East Lansing, MI, 48824-1317, USA
| | - Stephanie W Watts
- Department of Pharmacology and Toxicology, Michigan State University, 1355 Bogue Street, Rm B445, East Lansing, MI, 48824-1317, USA.
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Jackson WF, Daci A, Thompson JM, Fink GD, Watts SW. 5-HT 7 receptors mediate dilation of rat cremaster muscle arterioles in vivo. Microcirculation 2023; 30:e12808. [PMID: 37204759 PMCID: PMC11409460 DOI: 10.1111/micc.12808] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 04/07/2023] [Accepted: 04/28/2023] [Indexed: 05/20/2023]
Abstract
OBJECTIVE Serotonin (5-HT) infusion in vivo causes hypotension and a fall in total peripheral resistance. However, the vascular segment and the receptors that mediate this response remain in question. We hypothesized that 5-HT7 receptors mediate arteriolar dilation to 5-HT in skeletal muscle microcirculation. METHODS Cremaster muscles of isoflurane-anesthetized male Sprague-Dawley rats were prepared for in vivo microscopy of third- and fourth-order arterioles and superfused with physiological salt solution at 34°C. Quantitative real-time PCR (RT-PCR) was applied to pooled samples of first- to third-order cremaster arterioles (2-4 rats/sample) to evaluate 5-HT7 receptor expression. RESULTS Topical 5-HT (1-10 nmols) or the 5-HT1/7 receptor agonist, 5-carboxamidotryptamine (10-30 nM), dilated third- and fourth-order arterioles, responses that were abolished by 1 μM SB269970, a selective 5-HT7 receptor antagonist. In contrast, dilation induced by the muscarinic agonist, methacholine (100 nmols) was not inhibited by SB269970. Serotonin (10 nmols) failed to dilate cremaster arterioles in 5-HT7 receptor knockout rats whereas arterioles in wild-type litter mates dilated to 1 nmol 5-HT, a response blocked by 1 μM SB269970. Quantitative RT-PCR revealed that cremaster arterioles expressed mRNA for 5-HT7 receptors. CONCLUSIONS 5-HT7 receptors mediate dilation of small arterioles in skeletal muscle and likely contribute to 5-HT-induced hypotension, in vivo.
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Affiliation(s)
- William F Jackson
- Department of Pharmacology & Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Armond Daci
- Department of Pharmacology & Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
- Department of Pharmacy, Faculty of Medicine, University of Prishtina "Hasan Prishtina", Prishtina, Kosovo
| | - Janice M Thompson
- Department of Pharmacology & Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Gregory D Fink
- Department of Pharmacology & Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Stephanie W Watts
- Department of Pharmacology & Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA
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Rodnyy AY, Kondaurova EM, Bazovkina DV, Kulikova EA, Ilchibaeva TV, Kovetskaya AI, Baraboshkina IA, Bazhenova EY, Popova NK, Naumenko VS. Serotonin 5-HT 7 receptor overexpression in the raphe nuclei area produces antidepressive effect and affects brain serotonin system in male mice. J Neurosci Res 2022; 100:1506-1523. [PMID: 35443076 DOI: 10.1002/jnr.25055] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 03/28/2022] [Accepted: 04/03/2022] [Indexed: 12/15/2022]
Abstract
Heterodimerization between 5-HT7 and 5-HT1A receptors seems to play an important role in the mechanism of depression and antidepressant drug action. It was suggested that the shift of the ratio between 5-HT1A /5-HT7 hetero- and 5-HT1A /5-HT1A homodimers in presynaptic neurons toward 5-HT1A /5-HT1A homodimers is one of the reasons of depression. Consequently, the artificial elevation of 5-HT7 receptor number in presynaptic terminals might restore physiological homo-/heterodimer ratio resulting in antidepressive effect. Here we showed that adeno-associated virus (AAV)-based 5-HT7 receptor overexpression in the midbrain raphe nuclei area produced antidepressive effect in male mice of both C57Bl/6J and genetically predisposed to depressive-like behavior ASC (antidepressant sensitive cataleptics) strains. These changes were accompanied by the elevation of 5-HT7 receptor mRNA level in the frontal cortex of C57Bl/6J and its reduction in the hippocampus of ASC mice. The presence of engineered 5-HT7 receptor in the midbrain of both mouse strains was further demonstrated. Importantly that 5-HT7 receptor overexpression resulted in the reduction of 5-HT1A receptor level in the membrane protein fraction from the midbrain samples of C57Bl/6J, but not ASC, mice. 5-HT7 receptor overexpression caused an increase of 5-HIAA/5-HT ratio in the midbrain and the frontal cortex of C57Bl/6J and in all investigated brain structures of ASC mice. Thus, 5-HT7 receptor overexpression in the raphe nuclei area affects brain 5-HT system and causes antidepressive effect both in C57Bl/6J and in "depressive" ASC male mice. Obtained results indicate the involvement of 5-HT7 receptor in the mechanisms underlying depressive behavior.
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Affiliation(s)
- Alexander Ya Rodnyy
- Federal Research Center Institute of Cytology and Genetics, Siberian Division of the Russian Academy of Science, Novosibirsk, Russia
| | - Elena M Kondaurova
- Federal Research Center Institute of Cytology and Genetics, Siberian Division of the Russian Academy of Science, Novosibirsk, Russia
| | - Darya V Bazovkina
- Federal Research Center Institute of Cytology and Genetics, Siberian Division of the Russian Academy of Science, Novosibirsk, Russia
| | - Elisabeth A Kulikova
- Federal Research Center Institute of Cytology and Genetics, Siberian Division of the Russian Academy of Science, Novosibirsk, Russia
| | - Tatiana V Ilchibaeva
- Federal Research Center Institute of Cytology and Genetics, Siberian Division of the Russian Academy of Science, Novosibirsk, Russia
| | - Alexandra I Kovetskaya
- Federal Research Center Institute of Cytology and Genetics, Siberian Division of the Russian Academy of Science, Novosibirsk, Russia
| | - Irina A Baraboshkina
- Federal Research Center Institute of Cytology and Genetics, Siberian Division of the Russian Academy of Science, Novosibirsk, Russia
| | - Ekaterina Yu Bazhenova
- Federal Research Center Institute of Cytology and Genetics, Siberian Division of the Russian Academy of Science, Novosibirsk, Russia
| | - Nina K Popova
- Federal Research Center Institute of Cytology and Genetics, Siberian Division of the Russian Academy of Science, Novosibirsk, Russia
| | - Vladimir S Naumenko
- Federal Research Center Institute of Cytology and Genetics, Siberian Division of the Russian Academy of Science, Novosibirsk, Russia
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Shi Y, Sobrinho CR, Soto-Perez J, Milla BM, Stornetta DS, Stornetta RL, Takakura AC, Mulkey DK, Moreira TS, Bayliss DA. 5-HT7 receptors expressed in the mouse parafacial region are not required for respiratory chemosensitivity. J Physiol 2022; 600:2789-2811. [PMID: 35385139 PMCID: PMC9167793 DOI: 10.1113/jp282279] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 03/23/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract A brainstem homeostatic system senses CO2/H+ to regulate ventilation, blood gases and acid–base balance. Neurons of the retrotrapezoid nucleus (RTN) and medullary raphe are both implicated in this mechanism as respiratory chemosensors, but recent pharmacological work suggested that the CO2/H+ sensitivity of RTN neurons is mediated indirectly, by raphe‐derived serotonin acting on 5‐HT7 receptors. To investigate this further, we characterized Htr7 transcript expression in phenotypically identified RTN neurons using multiplex single cell qRT‐PCR and RNAscope. Although present in multiple neurons in the parafacial region of the ventrolateral medulla, Htr7 expression was undetectable in most RTN neurons (Nmb+/Phox2b+) concentrated in the densely packed cell group ventrolateral to the facial nucleus. Where detected, Htr7 expression was modest and often associated with RTN neurons that extend dorsolaterally to partially encircle the facial nucleus. These dorsolateral Nmb+/Htr7+ neurons tended to express Nmb at high levels and the intrinsic RTN proton detectors Gpr4 and Kcnk5 at low levels. In mouse brainstem slices, CO2‐stimulated firing in RTN neurons was mostly unaffected by a 5‐HT7 receptor antagonist, SB269970 (n = 11/13). At the whole animal level, microinjection of SB269970 into the RTN of conscious mice blocked respiratory stimulation by co‐injected LP‐44, a 5‐HT7 receptor agonist, but had no effect on CO2‐stimulated breathing in those same mice. We conclude that Htr7 is expressed by a minor subset of RTN neurons with a molecular profile distinct from the established chemoreceptors and that 5‐HT7 receptors have negligible effects on CO2‐evoked firing activity in RTN neurons or on CO2‐stimulated breathing in mice. Key points Neurons of the retrotrapezoid nucleus (RTN) are intrinsic CO2/H+ chemosensors and serve as an integrative excitatory hub for control of breathing. Serotonin can activate RTN neurons, in part via 5‐HT7 receptors, and those effects have been implicated in conferring an indirect CO2 sensitivity. Multiple single cell molecular approaches revealed low levels of 5‐HT7 receptor transcript expression restricted to a limited population of RTN neurons. Pharmacological experiments showed that 5‐HT7 receptors in RTN are not required for CO2/H+‐stimulation of RTN neuronal activity or CO2‐stimulated breathing. These data do not support a role for 5‐HT7 receptors in respiratory chemosensitivity mediated by RTN neurons.
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Affiliation(s)
- Yingtang Shi
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Cleyton R Sobrinho
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Jaseph Soto-Perez
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Brenda M Milla
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Daniel S Stornetta
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Ruth L Stornetta
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Ana C Takakura
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Thiago S Moreira
- Department of Physiology and Biophysics, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Douglas A Bayliss
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
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Sato M, Nakamura S, Inada E, Takabayashi S. Recent Advances in the Production of Genome-Edited Rats. Int J Mol Sci 2022; 23:ijms23052548. [PMID: 35269691 PMCID: PMC8910656 DOI: 10.3390/ijms23052548] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/17/2022] [Accepted: 02/21/2022] [Indexed: 12/14/2022] Open
Abstract
The rat is an important animal model for understanding gene function and developing human disease models. Knocking out a gene function in rats was difficult until recently, when a series of genome editing (GE) technologies, including zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and the type II bacterial clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated Cas9 (CRISPR/Cas9) systems were successfully applied for gene modification (as exemplified by gene-specific knockout and knock-in) in the endogenous target genes of various organisms including rats. Owing to its simple application for gene modification and its ease of use, the CRISPR/Cas9 system is now commonly used worldwide. The most important aspect of this process is the selection of the method used to deliver GE components to rat embryos. In earlier stages, the microinjection (MI) of GE components into the cytoplasm and/or nuclei of a zygote was frequently employed. However, this method is associated with the use of an expensive manipulator system, the skills required to operate it, and the egg transfer (ET) of MI-treated embryos to recipient females for further development. In vitro electroporation (EP) of zygotes is next recognized as a simple and rapid method to introduce GE components to produce GE animals. Furthermore, in vitro transduction of rat embryos with adeno-associated viruses is potentially effective for obtaining GE rats. However, these two approaches also require ET. The use of gene-engineered embryonic stem cells or spermatogonial stem cells appears to be of interest to obtain GE rats; however, the procedure itself is difficult and laborious. Genome-editing via oviductal nucleic acids delivery (GONAD) (or improved GONAD (i-GONAD)) is a novel method allowing for the in situ production of GE zygotes existing within the oviductal lumen. This can be performed by the simple intraoviductal injection of GE components and subsequent in vivo EP toward the injected oviducts and does not require ET. In this review, we describe the development of various approaches for producing GE rats together with an assessment of their technical advantages and limitations, and present new GE-related technologies and current achievements using those rats in relation to human diseases.
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Affiliation(s)
- Masahiro Sato
- Department of Genome Medicine, National Center for Child Health and Development, Tokyo 157-8535, Japan
- Correspondence: (M.S.); (S.T.); Tel.: +81-3-3416-0181 (M.S.); +81-53-435-2001 (S.T.)
| | - Shingo Nakamura
- Division of Biomedical Engineering, National Defense Medical College Research Institute, Saitama 359-8513, Japan;
| | - Emi Inada
- Department of Pediatric Dentistry, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544, Japan;
| | - Shuji Takabayashi
- Laboratory Animal Facilities & Services, Preeminent Medical Photonics Education & Research Center, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka 431-3192, Japan
- Correspondence: (M.S.); (S.T.); Tel.: +81-3-3416-0181 (M.S.); +81-53-435-2001 (S.T.)
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7
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Gonzalez-Pons R, McRae K, Thompson JM, Watts SW. 5-HT7 Receptor Restrains 5-HT-induced 5-HT2A Mediated Contraction in the Isolated Abdominal Vena Cava. J Cardiovasc Pharmacol 2021; 78:319-327. [PMID: 34029269 PMCID: PMC8460595 DOI: 10.1097/fjc.0000000000001057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 05/04/2021] [Indexed: 11/26/2022]
Abstract
ABSTRACT Although discovered as a vasoconstrictor, 5-hydroxytryptamine (5-HT, serotonin) infused into man and rodent reduces blood pressure. This occurs primarily through activation of 5-HT7 receptors and, at least in part, venodilation. Vascular mechanisms by which this could occur include direct receptor activation leading to vasodilation and/or suppression of contractile 5-HT receptor activation. This study tests the hypothesis that the 5-HT7 receptor restrains activation of the 5-HT2A receptor. A subhypothesis is whether agonist-induced activation-independent of constitutive activity-of the 5-HT7 receptor is necessary for this restraint. The isolated abdominal aorta and vena cava from the normal male Sprague-Dawley rat was our model. Studies used real-time PCR and a pharmacological approach in the isolated tissue bath for measurement of isometric tone. Although 5-HT2A receptor mRNA expression in both aorta and vena cava was significantly larger than that of the 5-HT7 receptor mRNA, the 5-HT7/5-HT2A receptor mRNA ratio was greater in the vena cava (0.30) than in the aorta (0.067). 5-HT7 receptor antagonism by SB266970 and DR 4458 increased maximum contraction to 5-HT in the isolated vein by over 50% versus control. The 5-HT2A receptor agonists TCB-2 and NBOH were more potent in the aorta compared with 5-HT but less efficacious, serving as partial agonists. By contrast, these same three agonists caused no contraction in the vena cava isolated from the same rats up to 10 μM agonist. Antagonism of the 5-HT7 receptor by SB269970 did not increase either the potency or efficacy of TCB-2 or NBOH. These data support that the 5-HT7 receptor itself needs to be stimulated to reduce contraction and suggest there is little constitutive activity of the 5-HT7 receptor in the isolate abdominal vena cava.
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MESH Headings
- Animals
- Aorta, Abdominal/drug effects
- Aorta, Abdominal/metabolism
- In Vitro Techniques
- Male
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT2A/drug effects
- Receptor, Serotonin, 5-HT2A/genetics
- Receptor, Serotonin, 5-HT2A/metabolism
- Receptors, Serotonin/drug effects
- Receptors, Serotonin/genetics
- Receptors, Serotonin/metabolism
- Serotonin/pharmacology
- Serotonin Antagonists/pharmacology
- Serotonin Receptor Agonists/pharmacology
- Vasoconstriction/drug effects
- Vasodilation/drug effects
- Vena Cava, Inferior/drug effects
- Vena Cava, Inferior/metabolism
- Rats
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Affiliation(s)
- Romina Gonzalez-Pons
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI
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8
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Seitz BM, Watts SW, Fink GD. Reduction in Hindquarter Vascular Resistance Supports 5-HT 7 Receptor Mediated Hypotension. Front Physiol 2021; 12:679809. [PMID: 34248666 PMCID: PMC8264506 DOI: 10.3389/fphys.2021.679809] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/25/2021] [Indexed: 11/13/2022] Open
Abstract
The 5-HT7 receptor is the primary mediator of both the acute (<hours) and chronic (day-week) decreases in mean arterial pressure (MAP) during low dose 5-HT infusion in rats. Previous data show the hypotensive response during chronic 5-HT infusion is due to a decrease total peripheral resistance (TPR) and specifically splanchnic vascular resistance. We hypothesized that changes in vascular resistance in both the splanchnic and skeletal muscle vascular beds are critical to the cardiovascular effects mediated by the 5-HT7 receptor. Systemic and regional hemodynamic data were collected in conscious and anesthetized male rats using radiotelemetry, vascular catheters and transit-time flowmetry. Reversible antagonism of the 5-HT7 receptor was achieved with the selective antagonist SB269970 (33 μg/kg, iv). From the very beginning and throughout the duration (up to 5 days) of a low dose (25 μg/kg) infusion of 5-HT, TPR, and MAP were decreased while cardiac output (CO) was increased. In a separate group of rats, the contribution of the 5-HT7 receptor to the regional hemodynamic response was tested during 5-HT-induced hypertension. The decrease in MAP after 24 h of 5-HT (saline 83 ± 3 vs. 5-HT 72 ± 3 mmHg) was associated with a significant decrease in skeletal muscle vascular resistance (saline 6 ± 0.2 vs. 5-HT 4 ± 0.4 mmHg/min/mL) while splanchnic vascular resistance was similar in 5-HT and saline-treated rats. When SB269970 was administered acutely, MAP and skeletal muscle vascular resistance rapidly increased, whereas splanchnic resistance was unaffected. Our work suggests the most prominent regional hemodynamic response to 5-HT7 receptor activation paralleling the fall in MAP is a decrease in skeletal muscle vascular resistance.
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Affiliation(s)
- Bridget M Seitz
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, United States
| | - Stephanie W Watts
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, United States
| | - Gregory D Fink
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, United States
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9
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Seitz BM, Demireva EY, Xie H, Fink GD, Krieger-Burke T, Burke WM, Watts SW. 5-HT does not lower blood pressure in the 5-HT 7 knockout rat. Physiol Genomics 2019; 51:302-310. [PMID: 31125292 DOI: 10.1152/physiolgenomics.00031.2019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The fall in mean arterial pressure (MAP) after 24 h of 5-HT infusion is associated with a dilation of the portal vein (PV) and abdominal inferior vena cava (Ab IVC); all events were blocked by the selective 5-HT7 receptor antagonist SB269970. Few studies have investigated the contribution of the 5-HT7 receptor in long-term cardiovascular control, and this requires an understanding of the chronic activation of the receptor. Using the newly created 5-HT7 receptor knockout (KO) rat, we presently test the hypothesis that continuous activation of the 5-HT7 receptor by 5-HT is necessary for the chronic (1 wk) depressor response and splanchnic venodilation. We also address if the 5-HT7 receptor contributes to endogenous cardiovascular regulation. Conscious MAP (radiotelemeter), splanchnic vessel diameter (ultrasound), and cardiac function (echocardiogram) were measured in ambulatory rats during multiday 5-HT infusion (25 μg·kg-1·min-1 via minipump) and after pump removal. 5-HT infusion reduced MAP and caused splanchnic venodilation of wild-type (WT) but not KO rats at any time point. The efficacy of 5-HT-induced contraction was elevated in the isolated abdominal inferior vena cava from the KO compared with WT rats, supporting loss of a relaxant receptor. Similarly, the efficacy of 5-HT causing an acute pressor response to higher doses of 5-HT in vivo was also increased in the KO vs. WT rat. Our work supports a novel mechanism for the cardiovascular effects of 5-HT, activation of 5-HT7 receptors mediating venodilation in the splanchnic circulation, which could prove useful in the treatment of cardiovascular disease.
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Affiliation(s)
- Bridget M Seitz
- Department of Pharmacology and Toxicology, Michigan State University , East Lansing, Michigan
| | - Elena Y Demireva
- Transgenic and Genome Editing Facility, and Institute for Quantitative Health Science and Engineering, Michigan State University , East Lansing, Michigan
| | - Huirong Xie
- Transgenic and Genome Editing Facility, and Institute for Quantitative Health Science and Engineering, Michigan State University , East Lansing, Michigan
| | - Gregory D Fink
- Department of Pharmacology and Toxicology, Michigan State University , East Lansing, Michigan
| | - Teresa Krieger-Burke
- Department of Pharmacology and Toxicology, Michigan State University , East Lansing, Michigan
| | - William M Burke
- Department of Pharmacology and Toxicology, Michigan State University , East Lansing, Michigan
| | - Stephanie W Watts
- Department of Pharmacology and Toxicology, Michigan State University , East Lansing, Michigan
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