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

Histamine H2‐like receptors in chick cerebral cortex: effects on cyclic AMP synthesis and characterization by [3H]tiotidine binding

“…4‐methylHA, dimaprit and amthamine (Van der Goot and Timmerman 2000), only 4‐methylHA strongly stimulated cAMP formation in the chick cerebral cortex, whereas amthamine and dimaprit were poorly active and inactive, respectively. Similar results have been obtained for the avian pineal gland (Nowak and Sek 1994; Nowak et al . 1995a,b).…”

“…This tissue is less sensitive to the studied action of HA than chick (and also duck) pineal gland, but clearly more sensitive than the cerebral cortex of mammals, such as guinea pigs and rabbits (Daly et al . 1982; Al‐Gadi and Hill 1985; Gannon and Hough 1988; Nowak and Sek 1994; Nowak et al . 1995a,b).…”

“…Although the ineffectiveness of dimaprit could be attributed to its possible lack of intrinsic activity in some CNS tissues (as previously demonstrated for the rabbit brain and avian pineal gland; Al‐Gadi and Hill 1985; Sek et al . 1988; Nowak and Sek 1994; Nowak et al . 1995a,b), to our knowledge there are no data on a similar lack of action for amthamine.…”

“…We have previously demonstrated that HA is a powerful stimulator of cAMP production in intact pineal glands of domestic fowls, i.e. hens, ducks, and geese; the amine did not, however, affect the nucleotide formation in the rat pineal gland (Nowak and Sek 1994; Nowak et al . 1995a,b, 1998).…”

“…The action of HA was mediated by a specific receptor, whose pharmacological profile is different from that of the H 1 , H 2 , H 3 and H 4 subtypes of HA receptor described for mammalian tissues. It has been suggested that this pineal HA receptor represents either an avian‐specific H 2 ‐like receptor or a novel HA receptor subtype (Nowak and Sek 1994; Nowak et al . 1995a,b).…”