Characterization of melatonin binding sites in the Harderian gland and median eminence of the rat

Journal Article · Tue Jan 01 00:00:00 EST 1991 · Life Sciences; (USA)

DOI:https://doi.org/10.1016/0024-3205(91)90454-J· OSTI ID:5924749

Lopez-Gonzalez, M A; Calvo, J R; Rubio, A; Goberna, R; Guerrero, J M ^[1]

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1. Univ. of Seville School of Medicine, Sevilla (Spain)

The characterization of specific melatonin binding sites in the Harderian gland (HG) and median eminence (ME) of the rat was studied using ({sup 125}I)melatonin. Binding of melatonin to membrane crude preparations of both tissues was dependent on time and temperature. Thus, maximal binding was obtained at 37{degree}C after 30-60 min incubation. Binding was also dependent on protein concentration. The specific binding of ({sup 125}I)melatonin was saturable, exhibiting only the class of binding sites in both tissues. The dissociation constants (Kd) were 170 and 190 pM for ME and HG, respectively. The concentration of the binding sites in ME was 8 fmol/mg protein, and in the HG 4 fmol/mg protein. In competition studies, binding of ({sup 125}I)melatonin to ME or HG was inhibited by increasing concentration of native melatonin; 50% inhibition was observed at about 702 and 422 nM for ME and HG, respectively. Additionally, the ({sup 125}I)melatonin binding to the crude membranes was not affected by the addition of different drugs such as norepinephrine, isoproterenol, phenylephrine, propranolol, or prazosin. The results confirm the presence of melatonin binding sites in median eminence and show, for the first time, the existence of melatonin binding sites in the Harderian gland.

• OSTI ID: 5924749
• Journal Information: Life Sciences; (USA), Vol. 48:12; ISSN 0024-3205
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
MELATONIN
RECEPTORS
CHEMICAL COMPOSITION
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL LOCALIZATION
CELL MEMBRANES
IODINE 125
PINEAL GLAND
RATS
TRACER TECHNIQUES
AMINES
ANIMALS
AROMATICS
AZAARENES
AZOLES
BETA DECAY RADIOISOTOPES
BODY
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
GLANDS
HETEROCYCLIC COMPOUNDS
INDOLES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PROTEINS
PYRROLES
RADIOISOTOPES
REACTION KINETICS
RODENTS
TRYPTAMINES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques