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3 results on '"Histamine H4 receptors"'

1. Differential effects of functionally different histamine H4 receptor ligands on acute irritant dermatitis in mice.

Author

Adami, Maristella, Micheloni, Cristina, Grandi, Daniela, and Stark, Holger

Abstract

The anti-inflammatory effects of histamine H4 receptor (H4R) antagonists opened new therapeutic options for the treatment of inflammatory/allergic diseases, but the role of H4R in inflammation is far from being solved. Aim of the present study was to investigate the role of structurally related H4R ligands of the aminopyrimidine class with different efficacies and functionalities (neutral antagonist ST-994, partial agonist ST-1006, inverse agonist ST-1012, and partial inverse agonist ST-1124) on croton oil-induced ear edema and pruritus in mice. The H4R ligands were administered subcutaneously before topical application of croton oil. While ST-1006 and ST-1124 were ineffective at any dose tested (10-100 mg/kg), both ST-994 and ST-1012 (30 and 100 mg/kg) significantly reduced croton oil-induced ear edema. Moreover, ST-994, ST-1006, and ST-1124, but not ST-1012, significantly inhibited croton oil-induced ear pruritus at 30 mg/kg. In accordance with results obtained with the reference H4R antagonist JNJ7777120 (100 mg/kg), histological examination of inflamed ear tissue indicated that treatment with ST-994 (30 mg/kg) led to a significant reduction in the inflammatory severity score and in the number of eosinophils infiltrating the tissue, while the number of degranulated mast cells in inflamed tissues was increased in comparison with the number of intact mast cells. These data indicate that croton oil-induced ear inflammation and pruritus seem to be clearly, but variably, affected by the H4R ligands tested. The potential advantage of dual effect of the H4R neutral antagonist ST-994 has to be carefully considered as a new therapeutic approach to the treatment of inflammatory diseases. [ABSTRACT FROM AUTHOR]

Published
2018
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3. The involvement of central cholinergic system in the pressor effect of intracerebroventricularly injected U-46619, a thromboxane A2 analog, in conscious normotensive rats

Author

Murat Yalcin, Vahide Savci, M. Sertac Yilmaz, Sinan Cavun, Uludağ Üniversitesi/Veteriner Fakültesi/Fizyoloji Bölümü., Uludağ Üniversitesi/Tıp Fakültesi/Farmakoloji ve Klinik Farmakoloji Anabilim Dalı., Yalçın, Murat, Cavun, Sinan, Yılmaz, M. Sertaç, Savcı, Vahide, AAG-6956-2021, AAH-1571-2021, and AAC-9702-2019

Subjects
Central Nervous System, Male, Time Factors, Hypothalamus, Posterior, alpha7 Nicotinic Acetylcholine Receptor, Prostanoid receptors, Pressor response, Blood Pressure, Nicotinic Antagonists, Mecamylamine, Receptors, Nicotinic, Nicotinic, Animal tissue, Receptors, Thromboxane A2, Prostaglandin H2, Blood gas, Choline, Rats, Sprague-Dawley, Histamine H4 Receptors, Thioperamide, Chlorpheniramine Maleate, chemistry.chemical_compound, Heart Rate, Muscarinic acetylcholine receptor, Airways, Vasoconstrictor Agents, 7 [3 [(4 phenylsemicarbazido)methyl] 7 oxabicyclo[2.2.1]hept 2 yl] 5 heptenoic acid, Cholinergic, Neurons, Thromboxane A2 receptor blocking agent, Brain, Cardiovascular effect, General Medicine, Receptor antagonist, CDP-choline, Atropine, Nicotinic agonist, Hydrazines, Posterior hypothalamus, Nicotinic acetylcholine-receptors, Methyllycaconitine, Fatty Acids, Unsaturated, Blood-pressure, Acetylcholine, medicine.drug, Carbon dioxide tension, medicine.medical_specialty, Thromboxane A2 derivative, Consciousness, medicine.drug_class, Aconitine, Thromboxane A2, Nicotinic receptor blocking agent, Internal medicine, Dose response, Bradycardia, medicine, Animals, Animal experiment, Thromboxane A2 receptor, Alpha bungarotoxin, Cardiovascular response, Injections, Intraventricular, Pharmacology, Pharmacology & pharmacy, 15 hydroxy 11alpha,9alpha epoxymethanoprosta 5,13 dienoic acid, Cholinergic system, Bridged Bicyclo Compounds, Heterocyclic, Bungarotoxins, Rats, Endocrinology, chemistry, Release, 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid, A(2), Prostaglandins
Abstract

The aim of this study was to determine the involvement of the central cholinergic system in the rise in blood pressure evoked by the thromboxane A2 (TxA2) analog, U-46619, given centrally. Intracerebroventricular (i.c.v.) injections of U-46619 (0.5, 1.0 and 2.0 microg) caused dose- and time-related increases in blood pressure and decreased heart rate in awake rats. U-46619 (1 microg; i.c.v.) also produced an approximately 65% increase in posterior hypothalamic extracellular acetylcholine and choline levels. Pretreatment with SQ-29548 (8 microg; i.c.v.), selective TxA2 receptor antagonist, completely inhibited both the cardiovascular responses and the increase in acetylcholine and choline levels to subsequent injection of U-46619 (1 microg; i.c.v.). Atropine (10 microg; i.c.v.), nonselective muscarinic receptor antagonist, pretreatment did not affect the cardiovascular responses observed after U-46619 (1 microg; i.c.v.). Pretreatment with the nonselective nicotinic receptor antagonist, mecamylamine (50 microg; i.c.v.) attenuated the pressor effect of U-46619 (1 microg; i.c.v.). Higher doses of mecamylamine (75 and 100 microg; i.c.v.) pretreatments did not change the magnitude of the blockade of pressor response to U-46619; however, they abolished the bradycardic effect of U-46619 dose-dependently. Interestingly, pretreatment of rats with methyllycaconitine (10 microg; i.c.v.) or alpha-bungarotoxin (10 microg; i.c.v.), selective antagonists of alpha7 subtype of nicotinic acetylcholine receptors (alpha7nAChRs), partially abolished the pressor response to i.c.v. injection of U-46619 (1 microg). Similar to the mecamylamine data, the use of higher doses of methyllycaconitine (25 and 50 microg; i.c.v.) produced the same magnitude of blockade that was observed after the 10 microg methyllycaconitine pretreatment, but it completely abolished the bradycardic effect of U-46619 (1 microg; i.c.v.) at the dose of 25 microg. The present results show that central administration of U-46619 produces pressor and bradycardic effect and increase in hypothalamic acetylcholine and choline levels by activating central TxA2 receptors. The activation of central nicotinic receptors, predominantly alpha7nAChRs, partially mediates the cardiovascular responses to i.c.v. injection of U-46619.

Published
2005

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