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Tropmann K, Seibel-Ehlert U, Littmann T, Strasser A. Shining light on the histamine H 2 receptor: Synthesis of carbamoylguanidine-type agonists as a pharmacological tool to study internalization. Bioorg Med Chem Lett 2021; 52:128388. [PMID: 34600035 DOI: 10.1016/j.bmcl.2021.128388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 09/22/2021] [Accepted: 09/25/2021] [Indexed: 11/23/2022]
Abstract
So far, only little is known about the internalization process of the histamine H2 receptor (H2R). One promising approach to study such dynamic processes is the use of agonistic fluorescent ligands. Therefore, a series of carbamoylguanidine-type H2R agonists containing various fluorophores, heterocycles, and linkers (28-40) was synthesized. The ligands were pharmacologically characterized in several binding and functional assays. These studies revealed a significantly biased efficacy (Emax) for some of the compounds, e.g. 32: whereas 32 acted as strong partial (Emax: 0.77, mini-Gs recruitment) or full agonist (Emax: 1.04, [35S]GTPγS binding) with respect to G protein activation, it was only a weak partial agonist regarding β-arrestin1/2 recruitment (Emax: 0.09-0.12) and failed to promote H2R internalization (confocal microscopy). On the other hand, H2R internalization was observed for compounds that exhibited moderate agonistic activity in the β-arrestin1/2 pathways (Emax ≥ 0.22). The presented differently-biased fluorescent ligands are versatile molecular tools for future H2R studies on receptor trafficking and internalization e.g. using fluorescence microscopy.
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Biselli S, Bresinsky M, Tropmann K, Forster L, Honisch C, Buschauer A, Bernhardt G, Pockes S. Pharmacological characterization of a new series of carbamoylguanidines reveals potent agonism at the H 2R and D 3R. Eur J Med Chem 2021; 214:113190. [PMID: 33548637 DOI: 10.1016/j.ejmech.2021.113190] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/31/2020] [Accepted: 01/08/2021] [Indexed: 12/12/2022]
Abstract
Even today, the role of the histamine H2 receptor (H2R) in the central nervous system (CNS) is widely unknown. In previous research, many dimeric, high-affinity and subtype-selective carbamoylguanidine-type ligands such as UR-NK22 (5, pKi = 8.07) were reported as H2R agonists. However, their applicability to the study of the H2R in the CNS is compromised by their molecular and pharmacokinetic properties, such as high molecular weight and, consequently, a limited bioavailability. To address the need for more drug-like H2R agonists with high affinity, we synthesized a series of monomeric (thio)carbamoylguanidine-type ligands containing various spacers and side-chain moieties. This structural simplification resulted in potent (partial) agonists (guinea pig right atrium, [35S]GTPγS and β-arrestin2 recruitment assays) with human (h) H2R affinities in the one-digit nanomolar range (pKi (139, UR-KAT523): 8.35; pKi (157, UR-MB-69): 8.69). Most of the compounds presented here exhibited an excellent selectivity profile towards the hH2R, e.g. 157 being at least 3800-fold selective within the histamine receptor family. The structural similarities of our monomeric ligands to pramipexole (6), a dopamine receptor agonist, suggested an investigation of the binding behavior at those receptors. The target compounds were (partial) agonists with moderate affinity at the hD2longR and agonists with high affinity at the hD3R (e.g. pKi (139, UR-KAT523): 7.80; pKi (157, UR-MB-69): 8.06). In summary, we developed a series of novel, more drug-like H2R and D3R agonists for the application in recombinant systems in which either the H2R or the D3R is solely expressed. Furthermore, our ligands are promising lead compounds in the development of selective H2R agonists for future in vivo studies or experiments utilizing primary tissue to unravel the role and function of the H2R in the CNS.
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Affiliation(s)
- Sabrina Biselli
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany; Agrolab Labor GmbH, 84079, Bruckberg, Germany
| | - Merlin Bresinsky
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Katharina Tropmann
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Lisa Forster
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Claudia Honisch
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany; Institute of Biomolecular Chemistry - National Research Council (ICB-CNR), Padua Unit Via F. Marzolo, 1, 35131, Padova, Italy
| | - Armin Buschauer
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Günther Bernhardt
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Steffen Pockes
- Institute of Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany; Department of Neurology, University of Minnesota, Minneapolis, MN, 55455, USA; Department of Medicinal Chemistry, Institute for Therapeutics Discovery and Development, University of Minnesota, Minneapolis, MN, 55414, USA.
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Davies S, Ballesteros-Merino C, Allen NA, Porch MW, Pruitt ME, Christensen KH, Rosenberg MJ, Savage DD. Impact of moderate prenatal alcohol exposure on histaminergic neurons, histidine decarboxylase levels and histamine H 2 receptors in adult rat offspring. Alcohol 2019; 76:47-57. [PMID: 30557779 DOI: 10.1016/j.alcohol.2018.07.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 07/16/2018] [Accepted: 07/17/2018] [Indexed: 10/28/2022]
Abstract
We have reported that moderate prenatal alcohol exposure (PAE) elevates histamine H3 receptor-mediated inhibition of glutamatergic neurotransmission in dentate gyrus (DG), and that the H3 receptor antagonist ABT-239 ameliorates PAE-induced deficits in DG long-term potentiation. Here, we investigated whether PAE alters other markers of histaminergic neurotransmission. Long-Evans rat dams voluntarily consumed either a 0% or a 5% ethanol solution 4 h each day throughout gestation. Young adult female offspring from each prenatal treatment group were used in histidine decarboxylase (HDC) immunohistochemical studies of histamine neuron number in ventral hypothalamus, quantitative Western blotting studies of HDC expression in multiple brain regions, radiohistochemical studies of H2 receptor density in multiple brain regions, and in biochemical studies of H2 receptor-effector coupling in dentate gyrus. Rat dams consumed a mean of 1.90 g of ethanol/kg/day during pregnancy. This level of consumption did not affect maternal weight gain, offspring birth weight, or litter size. PAE did not affect the number of HDC-positive neurons in ventral hypothalamus. However, HDC expression was reduced in frontal cortex, dentate gyrus, and cerebellum of PAE rats compared to controls. Specific [125I]-iodoaminopotentidine binding to H2 receptors was not altered in any of the brain regions measured, nor was basal or H2 receptor agonist-stimulated cAMP accumulation in DG altered in PAE rats compared to controls. These results suggest that not all markers of histaminergic neurotransmission are altered by PAE. However, the observation that HDC levels were reduced in the same brain regions where elevated H3 receptor-effector coupling was observed previously raises the question of whether a cause-effect relationship exists between HDC expression and H3 receptor function in affected brain regions of PAE rats. This relationship, along with the question of why these effects occur in some, but not all brain regions, requires more-detailed investigation.
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Díaz Nebreda A, Zappia CD, Rodríguez González A, Sahores A, Sosa M, Burghi V, Monczor F, Davio C, Fernández N, Shayo C. Involvement of histamine H 1 and H 2 receptor inverse agonists in receptor's crossregulation. Eur J Pharmacol 2019; 847:42-52. [PMID: 30685431 DOI: 10.1016/j.ejphar.2019.01.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 01/11/2019] [Accepted: 01/23/2019] [Indexed: 12/31/2022]
Abstract
Histamine [2-(4-Imidazolyl)-ethylamine] modulates different biological processes, through histamine H1 and H2 receptors, and their respective blockers are widely used in treating allergic and gastric acid-related disorders. Histamine H1 and H2 receptor crossdesensitization and cointernalization induced by its agonists have been previously described. In this study, we show how this crosstalk determines the response to histamine H1 and H2 receptor inverse agonists and how histamine H1 and H2 receptor inverse agonists interfere with the other receptor's response to agonists. By desensitization assays we demonstrate that histamine H1 and H2 receptor inverse agonists induce a crossregulation between both receptors. In this sense, the histamine H1 receptor inverse agonists desensitize the cAMP response to amthamine, a histamine H2 receptor agonist. In turn, histamine H2 receptor inverse agonists interfere with histamine H1 receptor signaling. We also determine that the crossdesensitization induced by histamine H1 or H2 receptor agonists alters the histamine inverse agonists receptor response: activation of histamine H1 receptor affects cAMP response induced by histamine H2 receptor inverse agonists, whereas histamine H2 receptor agonist induces a negative regulation on the anti-inflammatory response of histamine H1 receptor inverse agonists. Binding studies revealed that histamine H1 and H2 receptors cointernalize after stimulus with histamine receptor inverse agonists. In addition, the inhibition of the internalization process prevents receptor crossregulation. Our study provides new insights in the mechanisms of action of histamine H1 and H2 receptors that explain the effect of histamine H1 and H2 receptor inverse agonists and opens up new venues for novel therapeutic applications.
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Affiliation(s)
- Antonela Díaz Nebreda
- Laboratorio de Patología y Farmacología Molecular, Instituto de Biología y Medicina Experimental (IBYME, CONICET), Buenos Aires, Argentina
| | - Carlos Daniel Zappia
- Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Angela Rodríguez González
- Laboratorio de Patología y Farmacología Molecular, Instituto de Biología y Medicina Experimental (IBYME, CONICET), Buenos Aires, Argentina
| | - Ana Sahores
- Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Máximo Sosa
- Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Valeria Burghi
- Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Federico Monczor
- Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Carlos Davio
- Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Natalia Fernández
- Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Carina Shayo
- Laboratorio de Patología y Farmacología Molecular, Instituto de Biología y Medicina Experimental (IBYME, CONICET), Buenos Aires, Argentina.
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Kagermeier N, Werner K, Keller M, Baumeister P, Bernhardt G, Seifert R, Buschauer A. Dimeric carbamoylguanidine-type histamine H2 receptor ligands: A new class of potent and selective agonists. Bioorg Med Chem 2015; 23:3957-69. [PMID: 25639885 DOI: 10.1016/j.bmc.2015.01.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Revised: 12/21/2014] [Accepted: 01/07/2015] [Indexed: 11/23/2022]
Abstract
The bioisosteric replacement of the acylguanidine moieties in dimeric histamine H2 receptor (H2R) agonists by carbamoylguanidine groups resulted in compounds with retained potencies and intrinsic activities, but considerably improved stability against hydrolytic cleavage. These compounds achieved up to 2500 times the potency of histamine when studied in [(35)S]GTPγS assays on recombinant human and guinea pig H2R. Unlike 3-(imidazol-4-yl)propyl substituted carbamoylguanidines, the corresponding 2-amino-4-methylthiazoles revealed selectivity over histamine receptor subtypes H1R, H3R and H4R in radioligand competition binding studies. H2R binding studies with three fluorescent compounds and one tritium-labeled ligand, synthesized from a chain-branched precursor, failed due to pronounced cellular accumulation and high non-specific binding. However, the dimeric H2R agonists proved to be useful pharmacological tools for functional studies on native cells, as demonstrated for selected compounds by cAMP accumulation and inhibition of fMLP-stimulated generation of reactive oxygen species in human monocytes.
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