Melanin-concentrating hormone (MCH), originally isolated from salmon pituitary glands, has also been found in the mammalian CNS. In lower vertebrates, salmon MCH alters pigmentation by inducing melanosome aggregation within melanocytes of teleost fish, whereas it causes melanosome dispersion in amphibians and reptiles. The biological role of MCH in higher vertebrates, however, is not yet fully understood, but it may function as a neuromodulator and hypophysiotropic agent in the secretion of α-MSH, ACTH, and GH.

This derivative suitable for iodination is a further development of natural MCH, which loses its activity upon iodination. The labeled compound enabled to establish the first radioreceptor assay for MCH. Saturation binding experiments with this peptide, radioiodinated, revealed a Bmax of 1090 and a Kd of 1 · 10⁻¹⁰M for receptors in G4F-7 mouse melanoma cells.