MSH, Cyclic AMP, and Melanocyte Differentiation

Publisher Summary This chapter discusses that the melanin-containing pigment cells, melanocytes, and melanophores have been favorite targets of study because of the fact that the pigment melanin serves as a built-in cytochemical marker and facilitates microscopic examinations. It has been found through embryological studies that these cells are derived from specific unpigmented cells of the neural crest that migrate to specific locations during a specific phase of embryonic development and give rise, at a much later stage, to pigmented cells. The melanocyte-stimulating hormone (MSH), and other structurally related polypeptides, including adrenocorticotropic hormone (ACTH), cause dispersion of the pigment granules, melanosomes, and therefore, produce visible darkening of the cell or of skin containing these cells. This effect is mediated via second messenger, cyclic adenosine monophosphate (cAMP), and, as in the case of most other polypeptide hormones, probably involves membrane-bound complexes of adenyl cyclase and hormone receptor molecules. Results discussed in the chapter indicate that the mythical inductor for melanocytogenesis is the well-known hormone MSH acting via the second messenger, cAMP. The chapter also discusses some future avenues of experimental approaches.