<unk> s are analogues of<unk>  that bind to and activate the<unk> s of the<unk>  receptor have a number of therapeutic applications including treatment of sleep disorders and depression. The discovery and development of<unk> s was motivated by the need for more potent analogues than<unk> , with better pharmacokinetics and longer half-lives.<unk> s were developed with the<unk>  structure as a model. The<unk>  receptors are G protein-coupled receptors and are expressed in various tissues of the body. There are two subtypes of the receptor in humans,<unk>  receptor 1 (MT1) and<unk>  receptor 2 (MT2).<unk>  and<unk> s, on market or in clinical trials, all bind to and activate both receptor types. The binding of the agonists to the receptors has been investigated since 1986, yet is still not fully understood. When<unk> s bind to and activate their receptors it causes numerous physiological processes.
Melatonin receptor agonist
Serotonin receptor agonist
Dopamine agonist
Monoamine reuptake inhibitor
Dopamine reuptake inhibitor
Serotonin releasing agent
Serotonin–dopamine reuptake inhibitor
Norepinephrine reuptake inhibitor