Characterization of Melatonin Binding Sites in the Pars Tuberalis of the European Hamster

1992 ◽  
Vol 4 (2) ◽  
pp. 189-192 ◽  
Author(s):  
D. J. Skene ◽  
M. Masson-Pévet ◽  
P. Pévet
Keyword(s):  
Binding Sites ◽  
Pars Tuberalis

Characterization of melatonin receptors in the ram pars tuberalis: influence of light

1990 ◽  
Vol 123 (5) ◽  
pp. 557-562 ◽  
Author(s):  
Jean Pelletier ◽  
Bertrand Castro ◽  
Georges Roblot ◽  
Renée Wylde ◽  
Marie-Madeleine de Reviers
Keyword(s):  
Median Eminence ◽  
Binding Sites ◽  
Melatonin Receptors ◽  
Scatchard Analysis ◽  
Pars Tuberalis

Abstract. The present study was conducted to assess the binding of [125I]melatonin to frozen unfixed sections of pars tuberalis/median eminence tissue from Ile-de-France rams exposed or not exposed to light before slaughter. The specificity of [125I]melatonin binding to the pars tuberalis tissue was revealed by autoradiography and the magnitude of binding as related to the pars tuberalis area was determined after incubation and counting of pars tuberalis/median eminence sections. Subsequent studies with sections incubated with [125I]melatonin indicated that 1. the binding sites were saturable; 2. binding was stable for 24 h at 20°C, but unstable at 28 or 37°C; 3. melatonin and [12 7I]melatonin had a similar potency to compete with [125I]melatonin for binding sites, whereas other ligands such as serotonin or N-acetylserotonin were devoid of activity, and 4. by Scatchard analysis, the constant affinity Ka was found to be high in the 1010 l/mol range. Rams exposed to light throughout the night prior to slaughter presented a significant increase in the apparent number of [125I]melatonin binding sites in comparison to animals maintained under darkness (2.25±0.30 vs 1.01±0.17 fmol/mm2 pars tuberalis, p<0.01), whereas Ka values were similar in both groups. These results indicate the presence of true melatonin receptors in the pars tuberalis of the ram. Furthermore, they suggest that their apparent number is light-dependent.

Characterization of Thromboxane A2/Prostaglandin H2 Receptors in Porcine Coronary Artery -The Inhibitory Effect of a Novel Dibenzoxepin Derivative, KW-3635

1992 ◽  
Vol 67 (05) ◽  
pp. 582-584 ◽  
Author(s):  
Ichiro Miki ◽  
Akio Ishii
Keyword(s):  
Coronary Artery ◽  
Binding Sites ◽  
Thromboxane A2 ◽  
Inhibitory Effect ◽  
Scatchard Analysis ◽  
Single Class ◽  
Porcine Coronary Artery ◽  
Equilibrium Binding ◽  
H2 Receptors

SummaryWe characterized the thromboxane A2/prostaglandin H2 receptors in porcine coronary artery. The binding of [3H]SQ 29,548, a thromboxane A2 antagonist, to coronary arterial membranes was saturable and displaceable. Scatchard analysis of equilibrium binding showed a single class of high affinity binding sites with a dissociation constant of 18.5 ±1.0 nM and the maximum binding of 80.7 ± 5.2 fmol/mg protein. [3H]SQ 29,548 binding was concentration-dependently inhibited by thromboxane A2 antagonists such as SQ 29,548, BM13505 and BM13177 or the thromboxane A2 agonists such as U46619 and U44069. KW-3635, a novel dibenzoxepin derivative, concentration-dependently inhibited the [3H]SQ 29,548 binding to thromboxane A2/prosta-glandin H2 receptors in coronary artery with an inhibition constant of 6.0 ± 0.69 nM (mean ± S.E.M.).

Characterization of [3H]5-hydroxytryptamine and [3H]spiperone binding sites in clathrin-coated vesicles from bovine brain

1998 ◽  
Vol 794 (2) ◽  
pp. 291-298 ◽  
Author(s):  
Kayoko Moroi ◽  
Naoko Ozaki ◽  
Tomoko Kadota ◽  
Ken Kadota
Keyword(s):  
Binding Sites ◽  
Bovine Brain ◽  
Coated Vesicles
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