Tri-, tetra-, penta- and polypeptides and their therapeutic use as an antidepressant agent

The present invention discloses novel peptides utilized to treat patients suffering from depression. These novel peptides are modifications of the tripeptide hormone MIF, including modification of amino terminus residues, carboxyl terminus residues and internal residues, including addition and substitution of amino acid residues and modification of the peptide bonds and functional side groups of respective amino acid residues. The tri-, tetra-, penta-, and polypeptides of the present invention may be utilized alone or in combination to treat patients suffering from depression.