摘要
【目的】研究锌在肉仔鸡十二指肠、空肠和回肠中的吸收机理。【方法】观测不同水平锌在肉仔鸡小肠不同部位中的吸收速率,对数据进行非线性回归拟合,研究锌吸收动力学特点,采用Real-time PCR检测肉仔鸡小肠中MT、ZnT1、ZnT2和ZnT5 mRNA相对表达量。【结果】在不同锌添加水平下,回肠锌吸收均极显著高于十二指肠和空肠(P<0.005),十二指肠和空肠的锌吸收类似;吸收动力学特点表明,十二指肠、空肠锌的最大吸收速度(Jmax)分别为5.32±1.46、2.57±0.39nmol·min-1·cm-1,米氏常数(Km)分别为1.44±0.33、0.51±0.17mmol·L-1,回肠的扩散系数(P)为5.72±0.11cm2·min-1;添加40μg·ml-1锌与未添加锌相比,显著提高肉仔鸡十二指肠(P=0.018)及空肠和回肠(P≤0.0037)的MT mRNA水平,显著降低回肠ZnT5 mRNA水平(P=0.034),且添加锌后十二指肠和回肠的ZnT1、ZnT2及十二指肠ZnT5的mRNA水平有降低趋势,空肠的3个基因表达量略有增加。添加40μg·ml-1锌,肉仔鸡十二指肠的MT、ZnT1 mRNA水平极显著高于空肠和回肠(P≤0.0001),回肠MT、ZnT1和ZnT5的mRNA水平在3个肠段中均趋于最低。【结论】回肠是肉仔鸡锌吸收的主要部位,锌的吸收不同于十二指肠和空肠,为非饱和扩散过程,而十二指肠和空肠锌的吸收为饱和载体调节过程;各肠段几种锌转运蛋白的基因表达差异进一步说明回肠锌吸收以扩散为主,十二指肠和空肠的锌吸收与多种锌转运蛋白密切相关。
[Objective] This study was conducted to investigate mechanisms of zinc absorption in the duodenum, the jejunum and the ileum of broilers. [Method] The absorption velocities of zinc in different intestinal segments of broilers at different zinc concentrations were observed. Non-linear regression was used to fit the data to study the kinetic absorption of zinc, and determined the mRNA expression of MT, ZnT1, ZnT2 and ZnT5 in different intestinal segments by Real-time PCR. [Results] At the different zinc supplemental concentrations, zinc absorption velocities in the ileum were most significantly higher than those in other two intestinal segments （P〈0.005）, and the absorption velocities in other two intestinal segments were similar. The kinetic absorption of zinc indicated that the maximum absorption velocity of zinc （Jmax） in the duodenum and the jejunum were 5.32±1.46, 2.57±0.39 nmol·min^-l·cm^-1, respectively, Michaelis-Menten constant （Kin） were 1.44±0.33, 0.51±0.17 mmol·L^-1, respectively, diffusive constant （P） of ileum was 5.72±0.11 cm^2.min^-1. Zinc supplementation improved MT mRNA level significantly in the duodenum （P=0.018） and most significantly in the jejunum, the ileum （P≤0.0037）, reduced ZnT5 mRNA level significantly in the ileum （P=0.034）. Moreover, ZnT1, ZnT2 and ZnT5 mRNA levels in the duodenum and the ileum tended to be decreased with zinc supplementation, but the mRNA levels of three zinc transporters in the jejunum was increased little. At 40 μg·ml^-lzinc supplemental group, MT and ZnT1 mRNA levels in the duodenum were significantly higher than that in the jejunum and the ileum （P≤0.0001）. Moreover, MT,ZnT1 and ZnT5 mRNA levels in the ileum were lowest among three intestinal segments, the difference was not obvious. [Conclusion] Ileum is the major site of zinc absorption in broiler intestine, zinc absorption in the ileum is a non-saturable diffuse process, but other two intestinal segments are saturable carrier-mediated processes. The different exp
出处
《中国农业科学》
CAS
CSCD
北大核心
2008年第9期2789-2797,共9页
Scientia Agricultura Sinica
基金
国家"973"项目(2004CB117501)
动物营养学国家重点实验室自主研究课题[2004DA125184(团)0812]
关键词
锌
吸收
肉仔鸡
小肠
Zinc
Absorption
Broiler chicken
Intestine
