title: Characterization of 2-[125I]iodomelatonin-binding sites in quail testes at mid-light and mid-dark.
abstract: The binding and pharmacological characteristics of 2-[125I]iodomelatonin binding sites in testis membrane preparations of quails were examined. Scatchard analyses yielded an equilibrium dissociation constant (Kd) of 46.6 +/- 8.6 pmol/l and maximum binding capacity (Bmax) of 2.77 +/- 0.20 fmol/mg protein for the gonadal 2-[125I]iodomelatonin binding sites. Except for melatonin, 6-chloromelatonin, 2-iodomelatonin and N-acetylserotonin, all compounds tested elicited no significant inhibition of radioligand binding. Significant diurnal variations were detected in serum melatonin levels of 24-week-old quails while no diurnal difference was detected in the affinities or densities of the gonadal 2-[125I]iodomelatonin binding sites in quails. Results of the present study suggest possible direct gonadal action by pineal melatonin in birds.
authors.affiliation: Neuroendocrinology Research Section, Clarke Institute of Psychiatry, Toronto, Ont., Canada.
authors.forename: Z P
authors.initials: ZP
authors.lastname: Wang
authors.forename: K M
authors.initials: KM
authors.lastname: Cheng
authors.forename: G M
authors.initials: GM
authors.lastname: Brown
authors.forename: C S
authors.initials: CS
authors.lastname: Pang
authors.forename: S F
authors.initials: SF
authors.lastname: Pang
mesh_terms: D000818:Animals; D003370:Coturnix / Q000378:metabolism*; D003624:Darkness; D007700:Kinetics; D008027:Light; D008297:Male; D008550:Melatonin / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism; D044094:Receptors, Melatonin; D017981:Receptors, Neurotransmitter / Q000378:metabolism* / Q000502:physiology; D013737:Testis / Q000033:anatomy & histology / Q000378:metabolism* / Q000502:physiology
chemical_list: D044094:Receptors, Melatonin; D017981:Receptors, Neurotransmitter; C044556:2-iodomelatonin; D008550:Melatonin