title: 2-[125I]iodomelatonin binding sites in the rat vas deferens.
abstract: To further understand the mechanism by which melatonin potentiates noradrenergic transmission in the rat vas deferens, we localized and partially characterized 2-[125I]-iodomelatonin-binding sites in tissue sections of the rat vas deferens using quantitative autoradiography. High-affinity 2-[125I]-iodomelatonin-binding sites were localized around the lumen of the prostatic portion, but not in the epididymal portion of the rat vas deferens. The binding of 2-[125I]-iodomelatonin to sections of the prostatic portion was stable, reversible and saturable. Saturation studies revealed a single class of high-affinity binding sites with a dissociation constant (Kd) of 104.2 +/- 23.7 pM (n = 4) and a binding capacity (Bmax) of 2.07 +/- 0.19 fmol/mg of protein (n = 4). These results suggest that melatonin may regulate sympathetic neurotransmission through activation of specific melatonin receptors in the prostatic portion of the rat vas deferens.
authors.affiliation: Department of Pharmacology, Northwestern University Medical School, Chicago, Ill. 60611.
authors.forename: R C
authors.initials: RC
authors.lastname: Carneiro
authors.forename: R P
authors.initials: RP
authors.lastname: Markus
authors.forename: M L
authors.initials: ML
authors.lastname: Dubocovich
mesh_terms: D000818:Animals; D001345:Autoradiography; D001665:Binding Sites; D007457:Iodine Radioisotopes; D008297:Male; D008550:Melatonin / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism; D051381:Rats; D011956:Receptors, Cell Surface / Q000032:analysis / Q000378:metabolism; D044094:Receptors, Melatonin; D014649:Vas Deferens / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D007457:Iodine Radioisotopes; D011956:Receptors, Cell Surface; D044094:Receptors, Melatonin; C044556:2-iodomelatonin; D008550:Melatonin