A bizarre receptor mediating stimulatory effect of histamine on cyclic AMP formation in duck pineal gland

• Published in: Neuroscience letters 1995-12, Vol.202 (1), p.65-68
• Main Authors: Nowak, Jerzy Z, Sȩk, Barbara, Zawilska, Jolanta B
• Format: Article
• Language: English
• Subjects: Anas platyrhynchos; Animals; Biological and medical sciences; cAMP; Cyclic AMP - metabolism; Duck pineal gland; Ducks - physiology; Fundamental and applied biological sciences. Psychology; Histamine - pharmacology; Histamine Agonists - pharmacology; Histamine Antagonists - pharmacology; Histamine H1 Antagonists - pharmacology; Histamine H2 Antagonists - pharmacology; Histamine receptors; Hypothalamus. Hypophysis. Epiphysis. Urophysis; Methylhistamines - pharmacology; Morphology. Functional localizations; Pineal Gland - enzymology; Pineal Gland - ultrastructure; Pyrilamine - pharmacology; Ranitidine - pharmacology; Receptors, Histamine - metabolism; Vertebrates: endocrinology
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/0304-3940(95)12215-X

In agreement with our previous findings in chick pineal, histamine also appeared to be a potent stimulator of cAMP formation in intact duck pineal gland (about ten-fold increase above control at 100 μM), showing an EC 50 value of 3–5 μM. The effect of histamine in the duck pineal was mimicked by several histaminergic drugs, with the following order of potency: histamine = 4-methylhistamine > 2-methylhistamine > R-α-methylhistamine > amthamine > 2-thiazolylethylamine = immepip > imetit > dimaprit. The effect of 100 μM histamine was unaffected by H 1-, H 2- and H 3-receptor selective antagonists, mepyramine, ranitidine and thioperamide, respectively; yet, two other Hz-antagonists, aminopotentidine and tiotidine, reduced the histamine effect by only 40%. Thus, these results, being in line with our previous chick data, give support to a suggestion that histamine may be considered a modulator of the pineal activity, and that the avian pineal may contain a novel or avian-specific histamine receptor modulating cAMP formation, whose pharmacology is different from that typical for H 1-, H 2-, or H 3-type receptor.