Abstract: The invention relates to compounds having either agonist or antagonist activities for the neurotrophins NGF and BDNF and represented by monomeric or dimeric substituted dipeptides that are analogs of the exposed portions of loop 1 or loop 4 regions of these neurotrophins near or at a beta-turn of the respective loop. N-acylated substituents of these dipeptides are biostereoisomers of the amino acid residues preceding these dipeptide sequences in the neurotrophin primary structure. The dimeric structure is produced advantageously by using hexamethylenediamine to which dipeptides are attached via their carboxyl groups. The claimed compounds displayed neuroprotective and differentiation-inducing activities in cellular models and enhanced the amount of phosphorylated tyrosine kinase A and the heat shock proteins Hsp32 and Hsp70 in the concentration range of 10?9 to 10?5 M.