Specific 2-[125I]iodomelatonin binding sites in the duck adrenal gland.
Using 2-[125I]iodomelatonin as the radioligand, putative melatonin receptors in the duck adrenal gland were investigated. 2-[125I]Iodomelatonin binding to the membrane preparations of duck adrenals collected at mid-light was specific, rapid, saturable, stable, reversible and of high affinity. Scatchard analyses showed one class of binding sites with an equilibrium dissociation constant of 27.4 +/- 2.9 pmol/l and a maximum number of binding sites of 3.38 +/- 0.26 fmol/mg protein. Binding of 2-[125I]iodomelatonin in different subcellular fractions demonstrated the following descending order of density: mitochondrial > nuclear > microsomal >>> cytosol. Pharmacological studies indicated that these sites were highly specific to melatonin. As 2-[125I]iodomelatonin is a specific agonist of melatonin, it is proposed that the sites studied are adrenal melatonin receptors.
Pang
C S
CS
Clarke Institute of Psychiatry, Toronto, Ont., Canada.
Tsang
K F
KF
Brown
G M
GM
Pang
S F
SF
D000311:Adrenal Glands / Q000378:metabolism*; D000818:Animals; D004372:Ducks / Q000378:metabolism*; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D007700:Kinetics; D008550:Melatonin / Q000031:analogs & derivatives* / Q000378:metabolism; D008566:Membranes / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*; D044094:Receptors, Melatonin; D013347:Subcellular Fractions / Q000378:metabolism; D013816:Thermodynamics
D007457:Iodine Radioisotopes; D011956:Receptors, Cell Surface; D044094:Receptors, Melatonin; C044556:2-iodomelatonin; D008550:Melatonin