Specific binding of 2‐[125I]iodomelatonin by rat spleen crude membranes: Day‐night variations and effect of pinealectomy and continuous light exposure
作者:
Mohammed Rafii‐EI‐ldrissi,
Juan R. Calvo,
Mirta Giordano,
Juan M. Guerrero,
期刊:
Journal of Pineal Research
(WILEY Available online 1996)
卷期:
Volume 20,
issue 1
页码: 33-38
ISSN:0742-3098
年代: 1996
DOI:10.1111/j.1600-079X.1996.tb00236.x
出版商: Blackwell Publishing Ltd
关键词: melatonin;pineal gland;immune system;spleen
数据来源: WILEY
摘要:
Abstract:Melatonin binding sites were characterized in rat spleen crude membranes. The specific binding of 2‐[125I]iodomelatonin by spleen crude membranes fulfills all the criteria for binding to a receptor site. Thus, binding was dependent on time and temperature, stable, specific, and increased under constant light exposure and after pinealectomy. In competition studies, the specific binding of 2‐[125I]iodomelatonin to spleen crude membranes was inhibited by increasing concentrations of native melatonin. Scatchard analysis showed that the data were compatible with the existence of two classes of binding sites: a high affinity site with a Kdof 0.53 nM and a binding capacity of 2.52 pM, and a low‐affinity site with a Kdof 374 nM and binding capacity of 820 pM. Moreover, binding of 2‐[l25I]iodomelatonin exhibited day‐night variations with the highest binding observed late during the light period, and the lowest binding was observed late at night. However, binding of 2‐[125I]iodomelatonin to membranes remained high when animals were kept under light exposure at night. Results support the hypothesis of a regulatory role of melatonin on the immune system in which melatonin downregulates its own b
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