Differential effects of guanosine 5'-O-(3-thiotriphosphate) (GTPγS) on the 2-[125I]iodomelatonin binding sites in the chicken bursa of Fabricius and spleen

Abstract

Effects of 10 and 50 μmol/l guanosine 5'-0-(3-thiotriphosphate) (GTPγS) on 2-[125I]iodomelatonin binding in the chicken bursa of Fabricius and spleen were tested. In the chicken bursa of Fabricius, GTPγS increased the K(d) of 2-[125]iodomelatonin binding sites without affecting the B(max) value. In contrast, GTPγS caused both an increase in K(d) and a reduction in B(max) 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.link_to_subscribed_fulltex