Hirobe Tomohisa, Kiuchi Megumi, Wakamatsu Kazumasa, Ito Shosuke
Radiation Effect Mechanism Research Group, National Institute of Radiological Sciences, Chiba 263-8555, Japan.
Zoolog Sci. 2010 Jun;27(6):470-6. doi: 10.2108/zsj.27.470.
Murine recessive yellow (Mc1r(e)) is a loss-of-function mutation in the receptor for alpha-melanocyte-stimulating hormone, melanocortin receptor 1 (Mc1r), and results in a yellow coat by inducing pheomelanin synthesis in hair follicular melanocytes. We previously showed that eumelanin and pheomelanin content in dorsal hair in female Mc1r(e)/Mc1r(e) mice 5 weeks after birth was greater than that in male mice. To better understand the sex difference in hair pigmentation, estrogen, progesterone, and androgen were injected subcutaneously to newborn mice, and the effects of these sex hormones on hair pigmentation at 8.5 days were investigated. Although these sex hormones failed to affect the ratio of pheomelanic to eumelanic hair, they increased total hair pigmentation. Chemical analyses showed that total melanin content was increased by a low dose of estrogen in female mice. Moreover, estrogen increased pheomelanin content in female hair, whereas the hormone greatly decreased both eumelanin and pheomelanin content in male hair. High doses of progesterone, in contrast, increased total melanin content in both female and male hair. Moreover, a high dose of androgen increased total melanin content exclusively in male hair. These results suggest that estrogen is the main factor in determining the higher content of eumelanin and pheomelanin in female hair of Mc1r(e)/Mc1r(e) mice.
小鼠隐性黄色（Mc1r(e)）是α-黑素细胞刺激素受体黑素皮质素受体1（Mc1r）的功能丧失突变，通过诱导毛囊黑素细胞合成褐黑素导致毛发呈黄色。我们之前发现，出生5周后的雌性Mc1r(e)/Mc1r(e)小鼠背部毛发中的真黑素和褐黑素含量高于雄性小鼠。为了更好地理解毛发色素沉着的性别差异，将雌激素、孕酮和雄激素皮下注射到新生小鼠体内，并研究这些性激素对8.5天时毛发色素沉着的影响。尽管这些性激素未能影响褐黑素毛发与真黑素毛发的比例，但它们增加了毛发的总色素沉着。化学分析表明，低剂量雌激素可增加雌性小鼠的总黑色素含量。此外，雌激素增加了雌性毛发中的褐黑素含量，而该激素大大降低了雄性毛发中的真黑素和褐黑素含量。相比之下，高剂量孕酮增加了雌性和雄性毛发中的总黑色素含量。此外，高剂量雄激素仅增加了雄性毛发中的总黑色素含量。这些结果表明，雌激素是决定Mc1r(e)/Mc1r(e)小鼠雌性毛发中真黑素和褐黑素含量较高的主要因素。
