Abstract: The present invention describes that neurotrophins undergo post-translational modifications, and that these post-translational modifications mediate the pro-apoptotic and/or pro-neurite activity of neurotrophins. These post-translational modifications notably include nitration and the formation of conformationally-different dimers, as well as of abnormal oligomers, such as tetramers and octamers. The invention further relates to compounds that compete with such modified neurotrophins, as well as to compounds that binds to said modified neurotrophins. The invention thus provides useful agents for the treatment of the conditions or diseases involving chronic pain and/or neuron loss.