Psycho-pharmacological peptides

Peptide of the formula:

• A-R-L-Ser-R.sub.1 -L-Thr-L-Pro-L-Leu-L-Val-L-Thr-B
• wherein
• R represents the amino acid residue L-Lys or L-Arg,
• R.sub.1 represents the amino acid residue L-Glu or L-Gln,
• B represents one of the following amino acid or peptide-radicals:
• L-Leu-OH, (.alpha.-dehydro) Leu-OH
• D-Leu-OH
• L-Leu-L-Phe-OH
• L-Leu-L-Phe-L-Lys-OH
• L-MeLeu-OH
• or the radical ##STR3## and A represents one of the following radicals or residues:
• hydrogen
• H-L-Glu
• Z.sub.1 -L-Glu
• Z.sub.2 -L-Ser-L-Glu-
• H-Q.sub.1 -L-Thr-L-Ser-L-Glu-
• Q.sub.2 -L-Thr-L-Ser-L-Glu-
• Z.sub.3 -Q.sub.1 -L-Thr-L-Ser-L-Glu- or
• H.sub.2 N-ALK-CO-L-Phe-Q.sub.1 -L-Ser-L-Glu-
• in which
• Z.sub.1 represents H-L-Ser, H-D-Ser, desamino-Ser, 2,3-dihydroxy propanoyl or H.sub.2 N-ALK-CO-,
• Z.sub.2 represents H-L-Thr, H-D-Thr, desamino-Thr, 2,3-dihydroxybutanoyl or H.sub.2 N-ALK-CO;
• Q.sub.1 represents L-Met, L-Met (O), L-Met (O.sub.2) or L-Leu
• Q.sub.2 represents H-D-Met, H-D-Met (O), H-D-Leu, H-D-Met (O.sub.2), desamino MET, desamino Met (O), desamino Met (O.sub.2), desamino Leu, 2-hydroxy-4-methylthiobutanoyl, 2-hydroxy-4-methylpentanoyl or the radical H.sub.2 N-ALK-CO,
• Z.sub.3 represents H-L-Phe, H-D-Phe, desamino Phe, 2-hydroxy-3-phenyl-propanoyl and H.sub.2 N-ALK-CO-,
• and ALK represents an alkylene or alkylidene group with 1-6 carbon atoms,
• as well as derivative thereof selected from acid addition salts, metal salts, aliphatic esters having from 1 to 18 carbon atoms in the alkanol moiety, unsubstituted amides, mono- or di-alkyl substituted amides, wherein the alkyl group contains from 1 to 6 carbon atoms, N-acyl derivatives wherein the acyl group contains from 1 to 6 carbons atoms, N-alkyl or N,N-dialkyl derivatives wherein the alkyl group has from 1 to 6 carbon atoms, and metal complexes.