Melatonin receptors are coupled to the intracellular effectors via GTP-binding proteins. In the presence of GTP or non-hydrolysable GTP derivatives affinity of the melatonin receptors for 125I-melatonin is decreased (15). The effects of melatonin in the pituitary, including inhibition of LH release and the effects on 2nd messengers are abolished after preincubation with pertussis toxin (PTX; 27). This indicates that the receptors are coupled to G-protein(s) belonging to the Gi family. Also the effects of melatonin in SCN are mediated by Gi: preincubation with PTX blocks the effect of melatonin on spontaneous electric activity (8). Gi family consists of 5 subspecies: 3 Gi and 2 G0 proteins (2,17). It is not clear which of these G proteins is involved in transduction of the melatonin signal.
Was this article helpful?
How Would You Love To Finally Get A Decent Night's Sleep? Do you toss and turn all night long without getting much of a wink of sleep? Are you tired of counting sheep for hours without falling asleep? Wouldn't you love to be able to fall asleep simply, easily and naturally, without pills, potions or harmful medicine?