Abstract
Effects of 10 and 50 mumol/l guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) on 2-[125I]iodomelatonin binding in the chicken bursa of Fabricius and spleen were tested. In the chicken bursa of Fabricius, GTP gamma S increased the Kd of 2-[125I]iodomelatonin binding sites without affecting the Bmax value. In contrast, GTP gamma S caused both an increase in Kd and a reduction in Bmax of 2-[125I]iodomelatonin binding sites in the chicken spleen. Our results suggest the existence of subtypes of melatonin receptors with different receptor-G protein-effector complexes in the avian primary and secondary lymphoid systems.
MeSH terms
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Animals
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Bursa of Fabricius / drug effects
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Bursa of Fabricius / metabolism*
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Chickens
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Down-Regulation / drug effects
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Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology*
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Guanosine Triphosphate / pharmacology
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In Vitro Techniques
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Iodine Radioisotopes
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Kinetics
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Melatonin / metabolism
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Membranes / drug effects
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Membranes / metabolism
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Receptors, Cell Surface / drug effects
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Receptors, Cell Surface / metabolism*
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Receptors, Melatonin
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Spleen / drug effects
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Spleen / metabolism*
Substances
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Iodine Radioisotopes
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Receptors, Cell Surface
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Receptors, Melatonin
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Guanosine 5'-O-(3-Thiotriphosphate)
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Guanosine Triphosphate
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Melatonin