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Wang J, Liu B, Sun F, Xu Y, Luan H, Yang M, Wang C, Zhang T, Zhou Z, Yan H. Histamine H3R antagonist counteracts the impaired hippocampal neurogenesis in Lipopolysaccharide-induced neuroinflammation. Int Immunopharmacol 2022; 110:109045. [DOI: 10.1016/j.intimp.2022.109045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/24/2022] [Accepted: 07/07/2022] [Indexed: 11/05/2022]
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Berlin M, Boyce CW, de Lera Ruiz M. Histamine H3 Receptor as a Drug Discovery Target. J Med Chem 2010; 54:26-53. [DOI: 10.1021/jm100064d] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Michael Berlin
- Chemical Research, Merck Research Laboratories, 2015 Galloping Hill Road, Kenilworth, New Jersey 07033, United States
| | - Christopher W. Boyce
- Chemical Research, Merck Research Laboratories, 2015 Galloping Hill Road, Kenilworth, New Jersey 07033, United States
| | - Manuel de Lera Ruiz
- Chemical Research, Merck Research Laboratories, 2015 Galloping Hill Road, Kenilworth, New Jersey 07033, United States
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Histamine in Normal and Malignant Cell Proliferation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 709:109-23. [DOI: 10.1007/978-1-4419-8056-4_11] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Medina VA, Croci M, Mohamad NA, Massari N, Garbarino G, Cricco GP, Núñez MA, Martín GA, Crescenti EJV, Bergoc RM, Rivera ES. Mechanisms underlying the radioprotective effect of histamine on small intestine. Int J Radiat Biol 2009; 83:653-63. [PMID: 17729160 DOI: 10.1080/09553000701570238] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
PURPOSE To examine the protective effects of histamine on intestinal damage produced by gamma-radiation. MATERIALS AND METHODS 56 mice were divided into 4 groups. Histamine and Histamine-10 Gy groups received a daily subcutaneous histamine injection (0.1 mg/kg) starting 20 hours before irradiation and continued until the end of the experimental period; the untreated group received saline. Histamine-10 Gy and untreated-10 Gy groups were irradiated with a single dose on whole-body using Cesium-137 source (7 Gy/min) and were sacrificed 3 days after irradiation. Small intestine was removed, fixed and stained with hematoxylin and eosin. The number of intestinal crypts per circumference, and other histological characteristics of intestinal cells were evaluated. We further determined by immunohistochemistry the expression of proliferating cell nuclear antigen (PCNA), Bax, Bcl-2 (pro- and anti-apoptotic protein, respectively), antioxidant enzymes (Superoxide dismutase (SOD), Catalase and Glutathione peroxidase), histamine content and apoptosis by terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate biotin nick end labeling (TUNEL) assay. Cells in the S phase of the cell cycle were identified by immunohistochemical detection of 5-bromo-2'-deoxyuridine (BrdU) incorporation. RESULTS Histamine treatment reduced mucosal atrophy, edema and preserved villi, crypts and nuclear and cytoplasmic characteristics of small intestine after radiation exposure. Additionally, histamine treatment increased PCNA expression and the BrdU-positive cell number, histamine content, decreased the number of apoptotic cells and significantly increased Catalase and copper-zinc-containing SOD of irradiated mice. CONCLUSIONS Histamine prevents radiation-induced toxicity by increasing proliferation of damaged intestinal mucosa and suppressing apoptosis that was associated with an increase in SOD and Catalase levels. This effect might be of clinical value in patients undergoing radiotherapy.
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Affiliation(s)
- Vanina A Medina
- Radioisotopes Laboratory, School of Pharmacy and Biochemistry, University of Buenos Aires
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Davenas E, Rouleau A, Morisset S, Arrang JM. Autoregulation of McA-RH7777 hepatoma cell proliferation by histamine H3 receptors. J Pharmacol Exp Ther 2008; 326:406-13. [PMID: 18474684 DOI: 10.1124/jpet.107.135368] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Previous studies have suggested that histamine (HA) acts as an autocrine growth factor. We have explored the modulation of cell proliferation by HA using McA-RH7777 hepatoma cells. High L-histidine decarboxylase (HDC) expression and HA synthesis were found in McA-RH7777 cells. Whereas extracellular HA reached submicromolar concentrations, intracellular levels were very low, indicating that HA was secreted by the cells. McA-RH7777 cells also express H3-receptor (H3R) transcripts and proteins. Reverse transcriptase-polymerase chain reaction analysis detected only transcripts for the long isoform. Immunocytochemistry performed with a selective H3R antibody showed that most cells were immunoreactive. H3R binding sites (Bmax approximately 30 fmol/mg protein) were identified when [125I] iodoproxyfan binding was displaced by the agonist imetit. High-affinity binding also occurred at cytochrome P450 enzymes. This binding was not inhibited by HA, H3R agonists, or by a nonimidazole H3R antagonist but was displaced by imidazole H3R antagonists or by ketoconazole, a imidazole-containing cytochrome inhibitor. HA inhibited proliferation of McA-RH7777 hepatoma cells. The absence of uptake system, its much higher potency at H3Rs, and its low intracellular levels suggested that HA interacted with H3Rs rather than cytochromes. In agreement, both imidazole H3R antagonists, a nonimidazole H3R antagonist, and the HDC inhibitor alpha-monofluoromethyl histidine increased cell proliferation (up to approximately 60%), revealing a H3R-mediated inhibition by endogenous HA. Moreover, exogenous HA inhibited the increase induced by alpha-FMH or H3R antagonists with a nanomolar potency. In conclusion, our findings show that HA regulates proliferation of McA-RH7777 hepatoma cells by interacting with autoinhibitory H3Rs.
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Affiliation(s)
- E Davenas
- Laboratoire de Neurobiologie et Pharmacologie Moléculaire, Centre de Psychiatrie et Neurosciences de l'INSERM, 2 ter rue d'Alésia, 75014 Paris, France
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6
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Demorrow S, Francis H, Alpini G. Biogenic amine actions on cholangiocyte function. Exp Biol Med (Maywood) 2007; 232:1005-13. [PMID: 17720946 DOI: 10.3181/0703-mr-51] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Biogenic amines, such as serotonin, histamine, dopamine, and the catecholamines epinephrine and norepinephrine, regulate a multitude of cellular responses. A great deal of effort has been invested into understanding the effects of these molecules and their corresponding receptor systems on cholangiocyte secretion, apoptosis, and growth. This review summarizes the results of these efforts and highlights the importance of these regulatory molecules on the physiology and pathophysiology of cholangiocytes.
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Affiliation(s)
- Sharon Demorrow
- The Division of Research and Education, Medical Research Building, Scott and White Hospital, 702 S.W. H.K. Dodgen Loop, Temple, TX 76504,USA.
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Francis H, Franchitto A, Ueno Y, Glaser S, DeMorrow S, Venter J, Gaudio E, Alvaro D, Fava G, Marzioni M, Vaculin B, Alpini G. H3 histamine receptor agonist inhibits biliary growth of BDL rats by downregulation of the cAMP-dependent PKA/ERK1/2/ELK-1 pathway. J Transl Med 2007; 87:473-87. [PMID: 17334413 PMCID: PMC3751000 DOI: 10.1038/labinvest.3700533] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Histamine regulates many functions by binding to four histamine G-coupled receptor proteins (H1R, H2R, H3R and H4R). As H3R exerts their effects by coupling to Galpha(i/o) proteins reducing adenosine 3', 5'-monophosphate (cAMP) levels (a key player in the modulation of cholangiocyte hyperplasia/damage), we evaluated the role of H3R in the regulation of biliary growth. We posed the following questions: (1) Do cholangiocytes express H3R? (2) Does in vivo administration of (R)-(alpha)-(-)-methylhistamine dihydrobromide (RAMH) (H3R agonist), thioperamide maleate (H3R antagonist) or histamine, in the absence/presence of thioperamide maleate, to bile duct ligated (BDL) rats regulate cholangiocyte proliferation? and (3) Does RAMH inhibit cholangiocyte proliferation by downregulation of cAMP-dependent phosphorylation of protein kinase A (PKA)/extracellular signal-regulated kinase 1/2 (ERK1/2)/ets-like gene-1 (Elk-1)? The expression of H3R was evaluated in liver sections by immunohistochemistry and immunofluorescence, and by real-time PCR in cholangiocyte RNA from normal and BDL rats. BDL rats (immediately after BDL) were treated daily with RAMH, thioperamide maleate or histamine in the absence/presence of thioperamide maleate for 1 week. Following in vivo treatment of BDL rats with RAMH for 1 week, and in vitro stimulation of BDL cholangiocytes with RAMH, we evaluated cholangiocyte proliferation, cAMP levels and PKA, ERK1/2 and Elk-1 phosphorylation. Cholangiocytes from normal and BDL rats express H3R. The expression of H3R mRNA increased in BDL compared to normal cholangiocytes. Histamine decreased cholangiocyte growth of BDL rats to a lower extent than that observed in BDL RAMH-treated rats; histamine-induced inhibition of cholangiocyte growth was partly blocked by thioperamide maleate. In BDL rats treated with thioperamide maleate, cholangiocyte hyperplasia was slightly higher than that of BDL rats. In vitro, RAMH inhibited the proliferation of BDL cholangiocytes. RAMH inhibition of cholangiocyte growth was associated with decreased cAMP levels and PKA/ERK1/2/Elk-1 phosphorylation. Downregulation of cAMP-dependent PKA/ERK1/2/Elk-1 phosphorylation (by activation of H3R) is important in the inhibition of cholangiocyte growth in liver diseases.
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MESH Headings
- Animals
- Bile Ducts/surgery
- Bile Ducts, Intrahepatic/drug effects
- Bile Ducts, Intrahepatic/growth & development
- Bile Ducts, Intrahepatic/pathology
- Cell Proliferation/drug effects
- Cyclic AMP/metabolism
- Cyclic AMP-Dependent Protein Kinases
- Disease Models, Animal
- Down-Regulation/drug effects
- Drug Therapy, Combination
- Gene Expression Regulation, Enzymologic/drug effects
- Histamine/pharmacology
- Histamine Agonists/pharmacology
- Hyperplasia/chemically induced
- Hyperplasia/pathology
- Ligation
- Liver/drug effects
- Liver/metabolism
- Liver/pathology
- MAP Kinase Signaling System
- Male
- Methylhistamines/pharmacology
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3/metabolism
- Mitogen-Activated Protein Kinases/metabolism
- Phosphorylation
- Piperidines/pharmacology
- Protein Serine-Threonine Kinases/metabolism
- Rats
- Rats, Inbred F344
- Receptor, EphA8/metabolism
- Receptors, Histamine H3/genetics
- Receptors, Histamine H3/metabolism
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Affiliation(s)
- Heather Francis
- Department of Research and Education, College of Medicine, Scott & White Hospital and The Texas A & M University System Health Science Center, Temple, TX 76504, USA
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8
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Grandi D, Schunack W, Morini G. Epithelial cell proliferation is promoted by the histamine H3 receptor agonist (R)-α-methylhistamine throughout the rat gastrointestinal tract. Eur J Pharmacol 2006; 538:141-7. [PMID: 16682020 DOI: 10.1016/j.ejphar.2006.03.049] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Revised: 03/15/2006] [Accepted: 03/16/2006] [Indexed: 01/08/2023]
Abstract
The temporal effect of (R)-alpha-methylhistamine on epithelial cell proliferation throughout the rat gastrointestinal tract was investigated. (R)-alpha-methylhistamine was administered at 100 mg/kg orally and the rats were sacrificed 1, 24, 48, 72 and 144 h later. All the animals received 5-bromo-2'-deoxyuridine, (BrdU), 200 mg/kg i.p., 2 h before sacrifice. Gastrointestinal tissue was processed for histology and immunohistochemistry. (R)-alpha-methylhistamine caused a progressive increase in mucosal thickness of gastric fundus, distal small intestine and distal colon. Statistically significant differences from control values were found between 48 and 72 h after (R)-alpha-methylhistamine. (R)-alpha-methylhistamine significantly increased the number of BrdU-positive cells in the gastric fundus and antrum, intermediate and distal small intestine and distal colon. Peak effects were observed between 1 and 24 h after (R)-alpha-methylhistamine administration. Proliferating cell number and mucosal thickness were comparable to those of control rats at 144 h. (R)-alpha-methylhistamine exerts a long lasting growth-promoting effect on the stomach, distal small intestine and distal colon. Present data support a role of histamine H(3) receptors in the normal regulation of cell cycle in epithelial tissue.
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Affiliation(s)
- Daniela Grandi
- Department of Human Anatomy, Pharmacology and Forensic Medicine, University of Parma, 43100 Parma, Italy
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Dembiński A, Warzecha Z, Ceranowicz P, Brzozowski T, Dembiński M, Konturek SJ, Pawlik WW. Role of capsaicin-sensitive nerves and histamine H1, H2, and H3 receptors in the gastroprotective effect of histamine against stress ulcers in rats. Eur J Pharmacol 2004; 508:211-21. [PMID: 15680274 DOI: 10.1016/j.ejphar.2004.11.059] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2004] [Accepted: 11/26/2004] [Indexed: 11/24/2022]
Abstract
UNLABELLED It is assumed that an overproduction of gastric acid is the most important factor in the development of peptic ulcer. However, it has been also demonstrated that gastric defense mechanisms, which prevent mucosal injury, are enhanced by the same factors that increase acid secretion. The aim of this study was to examine the role of capsaicin-sensitive sensory nerves and histamine H1, H2, and H3 receptors in histamine-induced gastroprotection against stress ulcers. Studies were performed on rats with intact or ablated sensory nerves. Ablation of sensory nerves was induced by neurotoxic doses of capsaicin. Gastric ulcers were induced by water immersion and restrain stress. Before exposure to stress, rats were pretreated with saline (control), histamine (10 micromol/kg), histamine H1 receptor antagonist pyrilamine (100 micromol/kg), histamine H2 receptor antagonist ranitidine (100 micromol/kg), histamine H3 receptor antagonist thioperamide (100 micromol/kg), or a combination of histamine with these histamine receptor antagonists. RESULTS Histamine alone reduced ulcer area evoked by stress and this effect was accompanied by an increase in gastric mucosal blood flow and mucosal DNA synthesis, as well as a decrease in serum pro-inflammatory interleukin-1beta concentration. Treatment with combination of pyrilamine plus histamine caused an increase in gastric ulcer area and serum interleukin-1beta above the value observed in animals treated with saline, and this effect was accompanied by a decrease in gastric mucosal DNA synthesis. Ranitidine, in combination with histamine, reduced the ulcer area and serum interleukin-1beta to a minimal value, whereas gastric mucosal blood flow and DNA synthesis reached a maximal value. Pretreatment with thioperamide before histamine administration abolished the histamine-evoked reduction in gastric ulcer area. Ablation of sensory nerves increased the ulcer area in animals treated with saline or histamine, or histamine in combination with pyrilamine or ranitidine. In animals with sensory nerves ablation combined with administration of thioperamide plus histamine, the ulcer area was similar to that in saline-treated animals with intact sensory nerves. We conclude that: (1) histamine exhibits protective effect against stress-induced gastric ulcer and that this gastroprotection is related to stimulation of histamine H1 and H3 receptors; (2) blockade of histamine H2 receptors exhibited beneficial effect on gastric mucosa against stress-induced gastric ulcers; and (3) ablation of sensory nerves aggravates stress-induced gastric ulcer and reduces histamine-evoked gastroprotection related to stimulation of histamine H3 receptors.
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MESH Headings
- Animals
- Capsaicin/pharmacology
- DNA/biosynthesis
- Gastric Mucosa/blood supply
- Gastric Mucosa/drug effects
- Gastric Mucosa/innervation
- Histamine/pharmacology
- Histamine Antagonists/pharmacology
- Histamine H1 Antagonists/pharmacology
- Immersion/adverse effects
- Interleukin-1/blood
- Male
- Neurons, Afferent/drug effects
- Neurons, Afferent/physiology
- Piperidines/pharmacology
- Pyrilamine/pharmacology
- Rats
- Rats, Wistar
- Receptors, Histamine/physiology
- Receptors, Histamine H1/physiology
- Receptors, Histamine H2/physiology
- Receptors, Histamine H3/physiology
- Regional Blood Flow/drug effects
- Restraint, Physical/adverse effects
- Stomach Ulcer/metabolism
- Stomach Ulcer/pathology
- Stomach Ulcer/prevention & control
- Stress, Physiological/etiology
- Stress, Physiological/physiopathology
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Affiliation(s)
- Artur Dembiński
- Department of Physiology, Jagiellonian University Medical School, 16 Grzegórzecka Street, Kraków 31-531, Poland.
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Nakamura E, Kataoka T, Furutani K, Jimbo K, Aihara T, Tanaka S, Ichikawa A, Ohtsu H, Okabe S. Lack of histamine alters gastric mucosal morphology: comparison of histidine decarboxylase-deficient and mast cell-deficient mice. Am J Physiol Gastrointest Liver Physiol 2004; 287:G1053-61. [PMID: 15271653 DOI: 10.1152/ajpgi.00353.2003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Histamine plays an important role in the regulation of gastric acid secretion; however, its role in maintenance of gastric morphology remains unclear. To clarify the necessity of histamine for gastric mucosal development and maintenance, we evaluated two different kinds of mice that lacked either mast cells (one of the gastric histamine-producing cell types) or histidine decarboxylase (HDC; a histamine-synthesizing enzyme). Measurements of stomach weight, intragastric pH, mucosal histamine levels, as well as serum gastrin and albumin levels were performed in mice. Gastric mucosal appearance was examined by immunohistochemical techniques. Although gastric mucosal histamine levels in mast cell-deficient mice were half of those observed in the wild-type mice, intragastric pH, serum gastrin levels, and gastric morphology at 12 mo were unchanged compared with the wild-type mice. In contrast, HDC-deficient mice possessed no detectable gastric histamine, but did exhibit hypergastrinemia, as well as marked increases in intragastric pH and stomach weight compared with the wild-type mice. Histological analysis revealed that 9-mo-old HDC-deficient mice demonstrated hyperplasia in the oxyntic glandular base region, as well as increased numbers of parietal and enterochromaffin-like cells. These results indicate that enterochromaffin-like cell-derived histamine is potentially involved in gastric mucosal morphology regulation.
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Affiliation(s)
- Eiji Nakamura
- Department of Applied Pharmacology, Kyoto Pharmaceutical University, Misasagi, Yamashina, Kyoto 607-8414, Japan
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Liu J, Li ZS, Wan XJ, Wang W. Effect of nNOS/iNOS expression on cell apoptosis during stress ulcer of gastric mucosa in mice. Shijie Huaren Xiaohua Zazhi 2004; 12:2127-2130. [DOI: 10.11569/wcjd.v12.i9.2127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To determine the effect of different type of NOS expression on gastric mucosal cell apoptosis during stress ulcer in mice.
METHODS: Apoptotic cells were quantitated in gastric mucosa by terminal deoxynucleatidyl transferase mediated dUTP nick and labelling (TUNEL) techniques. The expression of nNOS/iNOS proteins was detected by immunohistochemical method. The effects of different dose of nitric oxide inhibitor NG-nitro-L-arginine methyl ester (L-NAME) on gastric mucosal apoptosis was investigated in immersion-restraint stress model of mice.
RESULTS: The expression of iNOS was highly correlated with the apoptotic cell quantities of gastric mucosa. In contract to the high dose of L-NAME (20.0 mg/kg) that increased the quantity of apoptosis 25.8% (P <0.05), small dose of L-NAME (2.0 mg/kg) decreased the quantity of apoptosis 34.6% (P <0.01).
CONCLUSION: The expression of NO is a double-edged sword, a low amount of NO produced by neuronal forms of NOS performs many physiological functions. On the contrary, higher concentration of NO produced by inducible form of NOS induces the epithelial cell apoptosis under stress condition.
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Charles J, Angus JA, Wright CE. Central endogenous histamine modulates sympathetic outflow through H3 receptors in the conscious rabbit. Br J Pharmacol 2003; 139:1023-31. [PMID: 12839877 PMCID: PMC1573916 DOI: 10.1038/sj.bjp.0705322] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. This study examined the role of histamine H(3) receptors in vagal and sympathetic autonomic reflexes in the conscious rabbit, and in rabbit and guinea-pig isolated right atria. 2. The baroreceptor-heart rate reflex (baroreflex), Bezold-Jarisch-like and nasopharyngeal reflexes were assessed after these treatments (i.v.; with H(1) and H(2) receptor block): (i) vehicle (saline; n=11); (ii) H(3) receptor agonist, (R)-alpha-methylhistamine (R-alpha-MH) 100 micro g kg(-1)+100 micro g kg(-1) h(-1) (n=9); (iii) H(3) receptor antagonist, thioperamide 1 mg kg(-1)+1 mg kg(-1) h(-1) (n=11); (iv) R-alpha-MH and thioperamide (n=6); and (v) H(2) and H(3) antagonist, burimamide 6.3 mg kg(-1)+6.3 mg kg(-1) h(-1) (n=4). 3. R-alpha-MH caused a thioperamide-sensitive fall in mean arterial pressure (MAP) of 8+/-1 mmHg and tachycardia of 18+/-2 bpm (P<0.0005). Burimamide was without effect, however thioperamide elicited an increase in MAP of 4+/-1 mmHg (P<0.01), but no change in heart rate (HR). 4. R-alpha-MH caused a 44% decrease in the average gain of the baroreflex (P=0.0001); this effect was antagonised by thioperamide. Thioperamide caused a parallel rightward shift in the barocurve with an increase in MAP of 5 mmHg (P<0.05). Burimamide had no effect on the baroreflex. The vagally mediated bradycardia elicited by the Bezold-Jarisch and nasopharyngeal reflexes was unaffected by H(3) receptor ligand administration. 5. R-alpha-MH (<or=10 micro M) caused a thioperamide-sensitive depression of both sympathetic and vagal responses in guinea-pig atria, but had no effect in rabbit atria. 6. As H(3) receptor activation caused a significant decrease in baroreflex gain without affecting HR range, the former is unlikely to be simply due to peripheral sympatholysis (supported by the lack of effect in isolated atria). Central H(3) receptors may have a tonic role in the baroreflex as thioperamide caused a rightward resetting of the barocurve. In contrast, the peripherally acting H(3) antagonist burimamide was without effect. These findings suggest a role for central histamine H(3) receptors in cardiovascular homeostasis in the rabbit.
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Affiliation(s)
- Julian Charles
- Department of Pharmacology, The University of Melbourne, Victoria 3010, Australia
| | - James A Angus
- Department of Pharmacology, The University of Melbourne, Victoria 3010, Australia
| | - Christine E Wright
- Department of Pharmacology, The University of Melbourne, Victoria 3010, Australia
- Author for correspondence:
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