Pharmacological characterization, molecular subtyping, and autoradiographic localization of putative melatonin receptors in uterine endometrium of estrous rats

Citation
H. Zhao et al., Pharmacological characterization, molecular subtyping, and autoradiographic localization of putative melatonin receptors in uterine endometrium of estrous rats, LIFE SCI, 66(17), 2000, pp. 1581-1591
Citations number
50
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biochemistry & Biophysics
Journal title
LIFE SCIENCES
ISSN journal
0024-3205 → ACNP
Volume
66
Issue
17
Year of publication
2000
Pages
1581 - 1591
Database
ISI
SICI code
0024-3205(20000317)66:17<1581:PCMSAA>2.0.ZU;2-A
Abstract
The objective of this study was to determine the biochemical characteristic s, subtypes, and localization of melatonin receptors in the rat uterus in e strous stage. Autoradiography with the melatonin ligand, 2-[I-125]iodomelat onin, showed that melatonin receptors were localized in the rat uterine end ometrium. Binding of 2-[I-125]iodomelatonin in crude membrane preparations of rat uterine endometrium in estrous stage was stable, saturable, reversib le and of high affinity. Rosenthal analysis yielded an equilibrium dissocia tion constant (Kd) of 28.9 +/- 3.59 pmol/l (n = 8) and a maximum number of binding sites (Bmax) of 1.6 +/- 0.15 fmol/mg protein (n = 8). The Kd value determined from kinetic analysis was 16.5 +/- 3.02 pmol/l (n = 3). Competit ion studies using various indoles and neurotransmitters demonstrated that 2 -iodomelatonin, melatonin, 6-chloromelatonin, 6-hydroxymelatonin and N-acet ylserotonin showed significant inhibition of the 2-[I-125]iodomelatonin bin ding, while the other indole compounds tested had no significant inhibition . The expression of rat uterine endometrial melatonin receptor subtypes was studied by reverse transcription-polymerase chain reaction (RT-PCR) using mt, and MT, receptor gene-specific primers. mt, receptor cDNA was amplified and confirmed by nucleotide sequencing. These findings indicate that mt, r eceptors were present in the rat uterine endometrium, and suggest that mela tonin plays an integral part in uterine physiology.