Mete A, Hendriks H G, Klaren P H M, Dorrestein G M, van Dijk J E, Marx J J M
Department of Pathology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands.
Avian Pathol. 2003 Dec;32(6):625-32. doi: 10.1080/03079450310001610659.
Iron overload is a very frequent finding in several animal species and a genetic predisposition is suggested. In one of the most commonly reported species with susceptibility for iron overload (mynah bird), it was recently shown that the cause of this pathophysiology is high uptake and retention of dietary iron. Here we compare susceptible (mynahs) with non-susceptible avian species (chickens) by evaluating iron uptake at the intestinal absorptive cell level. Enterocytes from mynahs and chickens were isolated and uptake of Fe(II) and Fe(III) was studied in vitro. It was found that Fe(III) uptake is much lower than Fe(II) uptake for both species. Although liver iron, present only in hepatocytes, was at least 10-fold higher in mynahs than chickens, enterocyte Fe(II) uptake was considerably higher in mynahs. Fe(II) uptake showed saturation at the studied concentrations in both species. Kinetic studies revealed a three-fold increase in Vmax for mynahs. Calculated values for the uptake kinetics of the probable membrane transporter suggest that mynah bird enterocytes have a significantly higher limiting uptake rate, due to the possible increase in the number of transporters when compared with chicken enterocytes. The susceptibility of this species is due to intestinal iron uptake despite hepatic iron accumulation, implicating a 'mis-sensing' of body iron similarly to human hereditary haemochromatosis.
铁过载在多种动物物种中是一种非常常见的现象，提示存在遗传易感性。在最常报道的易发生铁过载的物种之一（八哥）中，最近发现这种病理生理学的原因是膳食铁的高摄取和潴留。在这里，我们通过评估肠道吸收细胞水平的铁摄取，将易感物种（八哥）与非易感鸟类物种（鸡）进行比较。分离出八哥和鸡的肠上皮细胞，并在体外研究Fe(II)和Fe(III)的摄取。结果发现，两种物种的Fe(III)摄取均远低于Fe(II)摄取。虽然仅存在于肝细胞中的肝脏铁含量，八哥比鸡至少高10倍，但八哥肠上皮细胞的Fe(II)摄取却明显更高。在研究的浓度下，两种物种的Fe(II)摄取均显示出饱和现象。动力学研究表明，八哥的Vmax增加了三倍。对可能的膜转运蛋白摄取动力学的计算值表明，与鸡的肠上皮细胞相比，八哥的肠上皮细胞可能由于转运蛋白数量的增加而具有显著更高的极限摄取率。该物种的易感性是由于尽管肝脏铁蓄积，但肠道仍摄取铁，这与人类遗传性血色素沉着症类似，意味着对体内铁的“误判”。
