Multifunctional Roles of Melanocyte-Stimulating Hormone and Melanin-Concentrating Hormone in Fish: Evolution from Classical Body Color Change

© 2014 TERRAPUB, Tokyo. All rights reserved. doi:10.5047/absm.2014.00701.0001 Abstract The representative role of melanocyte-stimulating hormone (MSH) and melaninconcentrating hormone (MCH) in fish is regulation of pigment migration. However, our studies using barfin flounder Verasper moseri, a flatfish as a major experimental fish, have revealed that MSH and MCH are multifunctional because their receptors are widely distributed not only in the melanophores but also in the brain and systemic body. Their biological roles other than control of pigment migration would be regulation of feeding behavior, energy metabolism, cortisol release, etc. Among them, an interesting biological process on molecular level has been observed in the role of α-MSH. A fine difference in the structure—presence or absence of one acetyl group—modified the activities. Namely, desacetyl-α-MSH having no acetyl group at N-terminal stimulates pigment dispersion in melanophore and cortisol release from the interrenal gland, while α-MSH having one acetyl group has negligible effects. On the whole body level, MCH probably transfers information about photic conditions from the external environment to the body. MCH production is changeable, depending on the difference in the intensity of the light. A white background enhances production of MCH, and MCH turns body color pale by aggregating pigments in scales. It is suggested that this peptide stimulates feeding behavior. This monograph reveals molecular characteristic and biological significance of MSH and MCH systems in fish. Multifunctional Roles of Melanocyte-Stimulating Hormone and Melanin-Concentrating Hormone in Fish: Evolution from Classical Body Color Change