Identification of a histamine H(3)-like receptor in the zebrafish (Danio rerio) brain.
The distribution of histaminergic fibers in the zebrafish brain was recently shown to resemble that in mammals. Expression of L-histidine decarboxylase (HDC) mRNA was shown only in the area corresponding to that expressing HDC in mammals. This indicates that the zebrafish could be a useful model for studies on the function of the brain histaminergic system. In this study an H(3)-like receptor is identified in zebrafish brain. With binding studies using N-alpha-[(3)H]methylhistamine on zebrafish brain sections, signals were observed in several regions. Highest densities were detected in optic tectum and hypothalamus. The autoradiographic signal was abolished completely by the H(3)-specific antagonist clobenpropit and significantly reduced by another H(3) antagonist, thioperamide. Histamine and immepip induced an increase of guanosine 5'-(gamma-[(35)S]thio)triphosphate binding in several areas of the zebrafish brain. The activation was blocked with clobenpropit but not with cimetidine or mepyramine. These results indicate that the zebrafish has a histamine H(3)-like receptor that functionally interacts with the inhibitory, G(i)/G(o), class of G proteins. No previous evidence for a histamine receptor in zebrafish exists. The receptor described here is apparently similar to the mammalian H(3) receptor, making this the first description of a histamine H(3)-like receptor in a lower vertebrate.
Peitsaro
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Department of Biology, Abo Akademi University, Turku, Finland.
Anichtchik
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Panula
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D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D002927:Cimetidine / Q000494:pharmacology; D005260:Female; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000493:pharmacokinetics; D017442:Histamine Agonists / Q000493:pharmacokinetics; D006633:Histamine Antagonists / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D008761:Methylhistamines / Q000493:pharmacokinetics; D010880:Piperidines / Q000494:pharmacology; D011738:Pyrilamine / Q000494:pharmacology; D011869:Radioligand Assay; D018100:Receptors, Histamine H3 / Q000032:analysis / Q000378:metabolism*; D013462:Sulfur Radioisotopes; D013890:Thiourea / Q000031:analogs & derivatives / Q000494:pharmacology; D014316:Tritium; D015027:Zebrafish
D017442:Histamine Agonists; D006633:Histamine Antagonists; D007093:Imidazoles; D008761:Methylhistamines; D010880:Piperidines; D018100:Receptors, Histamine H3; D013462:Sulfur Radioisotopes; D014316:Tritium; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C069357:alpha-methylhistamine; D002927:Cimetidine; D013890:Thiourea; D011738:Pyrilamine; C052075:thioperamide; C086108:clobenpropit