title: Autoradiographic distribution and physiological regulation of 2-[125I]iodomelatonin binding in rat epididymis.
abstract: Autoradiographic study was conducted to localize 2-[125I]iodomelatonin binding in the rat epididymis. In the peripubertal (6 weeks old), postpubertal (8 weeks old) and adult (3 months old) rats, intense specific 2-[125I]iodomelatonin labelling of the corpus epididymidis was observed. The intensity of 2-[125I]iodomelatonin binding in the distal epididymal segment was significantly decreased in orchidectomized rats but the effect could be reversed with testosterone replacement. The intensity of 2-[125I]iodomelatonin binding in the distal rat epididymal segment did not show any diurnal rhythmicity when mid-light period and mid-dark period levels were compared, and was unaffected by constant lighting. Our data suggest androgen-dependent expression of 2-[125I]iodomelatonin binding sites, independent of light-induced changes in circulating melatonin, in the rat corpus epididymidis. A novel role of melatonin and its receptor in the regulation of the functions of rat corpus epididymidis is strongly implicated.
authors.affiliation: Department of Physiology, University of Hong Kong, Hong Kong. sywshiu@hkucc.hku.hk
authors.forename: S Y
authors.initials: SY
authors.lastname: Shiu
authors.forename: P H
authors.initials: PH
authors.lastname: Chow
authors.forename: Z H
authors.initials: ZH
authors.lastname: Yu
authors.forename: F
authors.initials: F
authors.lastname: Tang
authors.forename: S F
authors.initials: SF
authors.lastname: Pang
mesh_terms: D000818:Animals; D001345:Autoradiography; D002940:Circadian Rhythm; D004822:Epididymis / Q000378:metabolism*; D007457:Iodine Radioisotopes; D008027:Light; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D009919:Orchiectomy; D017440:Photoperiod; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution
chemical_list: D007457:Iodine Radioisotopes; D008550:Melatonin