melaninconcentrating

Melanin concentrating is a biological process by which pigment (melanin) is redistributed within pigment cells, notably melanophores and melanocytes, leading to changes in coloration. The term is often linked to melanin-concentrating hormone (MCH), a neuropeptide originally identified in fish that regulates pigment cell physiology as part of a broader system of light-dark adaptation and camouflage.

In non-mammalian vertebrates, melanophore pigment particles called melanosomes can move within the cell. Melanin-concentrating hormone promotes the aggregation of melanosomes toward the center of the cell, reducing pigment coverage on the cell surface and producing a lighter appearance. Conversely, melanocyte-stimulating hormone (MSH) promotes dispersion of melanosomes, increasing surface coverage and darkening coloration. The transitions occur over minutes to hours and can be triggered by light conditions, stress, hormones, or neuronal signals.

In mammals, pigmentation of skin and hair depends on melanin production in melanocytes and subsequent transfer to keratinocytes. While MCH functions as a brain neuropeptide involved in energy balance and feeding, its role in skin pigmentation is less central. Regulation of pigment distribution in mammals more commonly involves melanocyte-stimulating hormones and other signaling pathways. Nonetheless, the cellular mechanism—melanosome movement within pigment cells and the balance between aggregation and dispersion—underlies pigmentary responses across vertebrates.

Applications and relevance: Understanding melanin concentrating informs studies of camouflage and adaptive coloration in animals, pigmentary disorders, and the evolution of pigment systems. It also has practical relevance in aquaculture and research on neuropeptide regulation of physiology.