The site of action for \(\alpha-\mathrm{MSH}\) is a. muopioid receptors b. melanocortin-1 receptors c. glucocorticoid receptors d. melatonin receptors e. ACTH receptors

α-MSH, or alpha-Melanocyte Stimulating Hormone, is a hormone involved in the regulation of skin and hair color by stimulating the production of melanin, which is responsible for pigmentation. It also plays a role in appetite regulation and immune system modulation.

Given the function of α-MSH, it is necessary to determine which of the options (a to e) corresponds to the target receptors for this hormone. a. muopioid receptors: These receptors are involved in pain and analgesic response. They are not related to α-MSH function. b. melanocortin-1 receptors: These receptors play an important role in melanin production, which is the main function of α-MSH. c. glucocorticoid receptors: These receptors are involved in the regulation of glucose metabolism, inflammation response, and stress response. They are not related to α-MSH function. d. melatonin receptors: These receptors are involved in the regulation of sleep and circadian rhythm. They are not related to α-MSH function. e. ACTH receptors: These receptors are related to the function of Adrenocorticotropic hormone (ACTH), which is involved in the regulation of cortisol production and stress response. They are not related to α-MSH function.

Based on the information above, the correct site of action for α-MSH is melanocortin-1 receptors, as they are involved in melanin production, which is the main function of α-MSH. Therefore, the correct option is: b. melanocortin-1 receptors