两项新成果关注消化道疾病

　　

生物通报道：消化道系统与我们每天的生活密切相关，消化道疾病对于机体的影响也是巨大的，近期来自国内和国外的两项成果发现了两种重要的消化道疾病：大肠癌，以及十二指肠溃疡的新疾病机理，这对于预防，治疗这些疾病具有重要的意义。

来自遵义医学院，以及美国加州大学圣地亚哥分校的的研究人员发表了题为“Estrogen Regulation of Duodenal Bicarbonate Secretion and Sex-Specific Protection of Human Duodenum”的文章，揭示了成年女性罹患十二指肠溃疡明显低于男性的原因，这一成果公布在Gastroenterology杂志封面上。

这项研究是对我国西南地区“十二指肠溃疡”病的发病情况调查统计的基础上，发现该病的发生率存在着明显的性别差异，即成年女性罹患十二指肠溃疡的比例显著低于男性（4-5倍），但绝经以后女性的发病率就与男性相差无几了。为了弄清楚其中的原因，研究人员进一步进行了深入研究，发现了其中机理。

分泌碳酸氢盐是十二指肠粘膜用来抵御胃酸损害的重要屏障，碳酸氢盐分泌的减少与十二指肠溃疡的发生、发展相关。这项研究发现，绝经前的女性，其十二指肠粘膜碳酸氢盐的分泌在基础和酸刺激条件下均明显高于同龄对照组的男性，而两性间的此种差异在女性绝经后就消失了；而且，性成熟期女性十二指肠粘膜碳酸氢盐的分泌是随血液中雌激素水平的变化而变化的，位于十二指肠粘膜上皮的雌激素受体介导了这一过程。

在另外一项成果，来自日本岐阜大学的研究人员发现一种在自然界并不存在、而是以氧化镁为原料人工合成而得的水溶性镁，抑制了大肠癌细胞的增殖，这说明这一物质可能具有抗癌的作用。

研究人员首先向实验鼠腹腔投放微量致癌物质，并配合使用能诱发严重炎症的物质，使实验鼠患上大肠癌。之后又向部分实验鼠投放3种浓度分别为7ppm、35ppm和175ppm的水溶性镁，并与未接受任何处置的实验鼠进行对比。结果发现接受7ppm水溶性镁治疗的实验鼠体内癌细胞数量只有未接受任何处置的对照组实验鼠的一半，而接受175ppm水溶性镁治疗的实验鼠，癌细胞数量已降到对照组的四分之一。

这项研究表明了水溶性镁在抑制大肠癌方面的作用，研究人员推测这可能由于水溶性镁能减轻癌细胞分裂时染色体呈不均衡分布的不稳定性，从而抑制癌细胞增殖。

原文摘要：

Estrogen Regulation of Duodenal Bicarbonate Secretion and Sex-Specific Protection of Human Duodenum

Background & Aims The reason that women have a lower prevalence of duodenal ulcer is not clear. We investigated whether estrogen regulates human duodenal bicarbonate secretion (DBS) and whether this process accounts for sex differences in the prevalence of duodenal ulcer. Methods We performed an epidemiologic study to correlate duodenal ulcer prevalence with sex and age. Proximal DBS was measured from healthy subjects. Estrogen-receptor expression was examined in human duodenal mucosa by immunoblot and immunohistochemical analyses. Results Among women, the prevalence of duodenal ulcer was significantly lower than among men. The reduced prevalence was greatest among premenopausal women (20—49 y), who were 3.91- to 5.09-fold less likely to develop duodenal ulcers than age-matched men; the difference was reduced to 1.32-fold or less among subjects aged 60 years or older. Premenopausal (20—29 y), but not postmenopausal (60—69 y), women had significantly higher basal and acid-stimulated DBS than the age-matched men. Basal and acid-stimulated DBS in premenopausal women (20—29 y) were significantly higher than in postmenopausal women (60—69 y), whereas there were no significant differences in basal or acid-stimulated DBS between men who were aged 20—29 years or 60—69 years. Serum levels of estradiol changed in parallel with basal and acid-stimulated DBS during the physiological menstrual cycle in premenopausal women. 17β-estradiol–stimulated DBS was independent of age or sex. Estrogen receptors α and β were detected on plasma membranes and in the cytosol of human duodenal epithelial cells. Conclusions Estrogen regulates human DBS, which could reduce the risk for duodenal ulcer in women and contribute to sex differences in the prevalence of duodenal ulcer.