Li Li, Hu Dan-Ning, Zhao Huiquan, McCormick Steven A, Nordlund James J, Boissy Raymond E
Department of Dermatology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0592, USA.
Invest Ophthalmol Vis Sci. 2006 Oct;47(10):4507-12. doi: 10.1167/iovs.06-0391.
Whereas cutaneous pigmentation increases after exposure to ultraviolet (UV) irradiation, ocular pigmentation does not. This study was designed to examine the evidence that alpha-melanocyte-stimulating hormone (alpha-MSH), which is thought to be the mediator of UV response in the skin, has any role to play in uveal melanocytes.
Human uveal melanocytes derived from the choroid and the iris were cultivated by using eyes harvested from adult cadaveric donors and were assessed by Northern blot analysis for growth and melanogenic response to alpha-MSH and expression of the receptor for alpha-MSH (MC1-R). In addition, expression of alpha-MSH was evaluated in ocular tissue by immunocytochemistry.
Uveal melanocytes, unlike cutaneous melanocytes in vitro, exhibited no stimulation of proliferation in response to alpha-MSH at dosages ranging from 0.1 to 100 muM. In addition, tyrosine hydroxylase, DOPA oxidase, and protein levels for tyrosinase, TRP-1, and TRP-2 were not influenced by alpha-MSH. Associated with the lack of alpha-MSH response in cultured uveal melanocytes was the absence of expression of the receptor for alpha-MSH (MC1-R), as assessed by Northern blot analysis. Also in contrast to the skin, pigmented ocular tissue lacked expression of the alpha-MSH ligand, as assessed by immunocytochemistry.
In conclusion, ocular pigmentation does not appear to be regulated by melanocyte stimulating hormone.
皮肤在暴露于紫外线（UV）照射后色素沉着会增加，而眼部色素沉着却不会。本研究旨在检验这样的证据，即被认为是皮肤紫外线反应介质的α-黑素细胞刺激素（α-MSH）在葡萄膜黑素细胞中是否发挥任何作用。
使用从成年尸体供体获取的眼睛培养源自脉络膜和虹膜的人葡萄膜黑素细胞，并通过Northern印迹分析评估其对α-MSH的生长和黑素生成反应以及α-MSH受体（MC1-R）的表达。此外，通过免疫细胞化学评估眼部组织中α-MSH的表达。
与体外培养的皮肤黑素细胞不同，葡萄膜黑素细胞在0.1至100μM剂量范围内对α-MSH无增殖刺激反应。此外，酪氨酸羟化酶、多巴氧化酶以及酪氨酸酶、TRP-1和TRP-2的蛋白水平不受α-MSH影响。通过Northern印迹分析评估，培养的葡萄膜黑素细胞缺乏α-MSH受体（MC1-R）的表达，这与缺乏α-MSH反应相关。同样与皮肤相反，通过免疫细胞化学评估，有色眼部组织缺乏α-MSH配体的表达。
总之，眼部色素沉着似乎不受黑素细胞刺激素调节。
