How do these hormones increase melanin?

Melanocyte-stimulating hormones increase melanin production by acting on specific receptors in the skin cells that contain melanin-producing cells called melanocytes. These hormones bind to receptors on melanocytes, triggering a signaling cascade that leads to the production and release of melanin, the pigment responsible for skin color. This process not only affects the skin's coloration but is also a protective mechanism against ultraviolet (UV) light, as increased melanin can help absorb and reduce UV damage to the skin cells 1.