Selank

Selank is a synthetic analogue of the immunomodulatory peptide tuftsin; as such, it mimics many of its effects. It has been shown to modulate the expression of Interleukin-6 (IL-6) and affect the balance of T helper cell cytokines.  It has been shown to influence the concentration of monoamine neurotransmitters and induce metabolism of serotonin.  Selank has also been found to rapidly elevate the expression of brain-derived neurotropic factor (BDNF) in the hippocampus of rats.
Selank, as well as a related peptide drug, Semax, have been found to inhibit enzymes involved in the degradation of enkephalins and other endogenous regulatory peptides, and this action may be involved in their effects.  It has also been found to affect the activity of carboxypeptidase H and phenylmethylsulfonylfluoride-inhibited carboxypeptidase in rat nervous system tissue.
Selank has been found to produce antidepressant-like effects in animal models of depression and anhedonia.