Thomson A B, Keelan M, Lam T, Cheeseman C I, Walker K, Clandinin M T
Department of Medicine, University of Alberta, Edmonton, Canada.
Am J Physiol. 1989 Jan;256(1 Pt 1):G178-87. doi: 10.1152/ajpgi.1989.256.1.G178.
Adult female Sprague-Dawley rats were fed isocaloric semipurified diets containing a high content of either polyunsaturated (P) or saturated (S) fatty acids; these diets were nutritionally adequate, providing for all known essential nutrient requirements. On day 3 after beginning S or P, one group of animals was exposed to a single 6-Gy dose of abdominal radiation, and the other half was sham irradiated. S or P diets were continued for a further 14 days. Brush-border membrane purification and sucrase-specific activities were unaffected by diet or by abdominal irradiation. In rats fed P, irradiation was associated with an increase in jejunal brush-border membrane total phospholipid and the ratio of phospholipid to cholesterol; these changes were not observed in animals fed S. In irradiated rats, ileal brush-border membrane phospholipid per cholesterol was high in animals fed S compared with P. In irradiated animals fed P, there was reduced jejunal and ileal uptake of several medium- and long-chain saturated and unsaturated fatty acids and cholesterol, and the ileal uptake of higher concentrations of glucose was reduced in irradiated animals fed P. In contrast, lipid uptake was similar in control and irradiated animals fed S except for cholesterol uptake, which was reduced. Ileal uptake of higher concentrations of glucose was increased in irradiated animals fed S. Quantitative autoradiography failed to demonstrate any change in the distribution of leucine or lysine transport sites along the villus 1 or 2 wk after abdominal irradiation or in response to feeding S or P. Also, these differences in transport achieved by feeding S to radiated animals were not explained by variations in the animals' food consumption or intestinal mucosal surface area. Thus the use of short-term feeding with a saturated fatty acid diet in the prevention of acute irradiation damage to the intestine warrants further investigation in humans.
成年雌性Sprague-Dawley大鼠被喂食等热量的半纯化日粮，这些日粮含有高含量的多不饱和（P）或饱和（S）脂肪酸；这些日粮营养充足，能满足所有已知的必需营养需求。在开始摄入S或P日粮后的第3天，一组动物接受单次6 Gy剂量的腹部辐射，另一半进行假辐射。S或P日粮再持续喂食14天。刷状缘膜的纯化和蔗糖酶特异性活性不受日粮或腹部辐射的影响。在喂食P日粮的大鼠中，辐射导致空肠刷状缘膜总磷脂增加以及磷脂与胆固醇的比例增加；在喂食S日粮的动物中未观察到这些变化。在接受辐射的大鼠中，与喂食P日粮的动物相比，喂食S日粮的动物回肠刷状缘膜中每单位胆固醇的磷脂含量较高。在喂食P日粮的受辐射动物中，几种中链和长链饱和及不饱和脂肪酸以及胆固醇的空肠和回肠摄取减少，并且喂食P日粮的受辐射动物中较高浓度葡萄糖的回肠摄取减少。相比之下，喂食S日粮的对照动物和受辐射动物的脂质摄取相似，但胆固醇摄取减少。喂食S日粮的受辐射动物中较高浓度葡萄糖的回肠摄取增加。定量放射自显影未能显示腹部辐射后1或2周沿绒毛的亮氨酸或赖氨酸转运位点分布的任何变化，也未显示对喂食S或P的反应。此外，给受辐射动物喂食S日粮所实现的这些转运差异不能通过动物食物摄入量或肠黏膜表面积的变化来解释。因此，在预防肠道急性辐射损伤方面使用短期饱和脂肪酸日粮喂养值得在人类中进一步研究。
