Wynick D, Hammond P J, Akinsanya K O, Bloom S R
Department of Medicine, Hammersmith Hospital, London, UK.
Nature. 1993 Aug 5;364(6437):529-32. doi: 10.1038/364529a0.
Oestrogen, an essential physiological regulator of reproductive function, controls lactotroph proliferation and prolactin release. The neuropeptide galanin co-localizes to the lactotroph, but its physiological function is largely unknown. Pituitary galanin expression is extremely sensitive to the oestrogen status of the animal. A marked elevation occurs during pregnancy and lactation, and exogenous 17 beta-oestradiol can cause a 4,000-fold increase in messenger RNA levels. Here we report that galanin is secreted by a minority of lactotrophs and is essential for the regulation of basal and vasoactive-intestinal-polypeptide-stimulated prolactin release. Hyperoestrogenization increases the number of galanin-secreting cells and the resulting increase in basal prolactin release is completely abolished by treatment with galanin antiserum. Galanin is a potent lactotroph growth factor and galanin-immunoneutralization completely inhibits the previously reported mitogenic effects of oestrogen on the lactotroph. These findings represent direct evidence for paracrine regulation of lactotroph function and demonstrate that the effect of oestrogen on lactotroph proliferation and prolactin release are mediated by locally secreted galanin.
雌激素作为生殖功能的重要生理调节因子，控制着催乳素细胞的增殖和催乳素的释放。神经肽甘丙肽与催乳素细胞共定位，但其生理功能在很大程度上尚不清楚。垂体甘丙肽的表达对动物的雌激素状态极为敏感。在怀孕和哺乳期会显著升高，外源性17β-雌二醇可使信使RNA水平增加4000倍。我们在此报告，甘丙肽由少数催乳素细胞分泌，对基础催乳素释放以及血管活性肠肽刺激的催乳素释放的调节至关重要。雌激素过多会增加分泌甘丙肽的细胞数量，而用甘丙肽抗血清处理可完全消除由此导致的基础催乳素释放增加。甘丙肽是一种有效的催乳素细胞生长因子，甘丙肽免疫中和可完全抑制先前报道的雌激素对催乳素细胞的促有丝分裂作用。这些发现代表了旁分泌调节催乳素细胞功能的直接证据，并表明雌激素对催乳素细胞增殖和催乳素释放的作用是由局部分泌的甘丙肽介导的。
