Characterization of melatonin receptors in the brain of four avian species: duck, goose, pigeon, and turkey.
Melatonin receptor sites were characterized in the brains of four avian species (duck, goose, pigeon, and turkey) by an in vitro binding technique, using 2-[125I]iodomelatonin as a labeled ligand. The specific binding of 2-[125I]iodomelatonin to avian brain membranes was found to be stable, saturable, reversible, and of high affinity. Scatchard analysis revealed that 2-[125I]iodomelatonin binds to a single class of sites in brain membrane preparations of these species with high affinity (affinity constants Kd between 153 and 289 pM) and low capacity (total number of binding sites B(max) between 5.07 and 10.15 fmol/mg protein). Competition studies showed the following relative order of potency of indolic compounds to inhibit the specific 2-[125I]iodomelatonin binding: melatonin >> N-acetyltryptamine > N-acetyl-5-hydroxytryptamine > 5-hydroxytryptamine >>> 5-methoxytryptamine. We conclude that the 2-[125I]iodomelatonin-binding sites in brains of duck, goose, pigeon, and turkey have similar binding and pharmacological characteristics, and may represent ML-1 melatonin receptor sites.
Zawilska
J B
JB
Department of Biogenic Amines, Polish Academy of Sciences, Lódź, Poland.
Nowak
J Z
JZ
D000818:Animals; D001717:Birds / Q000378:metabolism*; D001923:Brain Chemistry / Q000502:physiology*; D010856:Columbidae; D004372:Ducks; D005260:Female; D005777:Geese; D006207:Half-Life; D007457:Iodine Radioisotopes; D007700:Kinetics; D008550:Melatonin / Q000031:analogs & derivatives / Q000378:metabolism; D008566:Membranes / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000187:drug effects / Q000378:metabolism*; D044094:Receptors, Melatonin; D013045:Species Specificity; D014422:Turkeys
D007457:Iodine Radioisotopes; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D044094:Receptors, Melatonin; C044556:2-iodomelatonin; D008550:Melatonin