Kalliokoski Otto, Teilmann A Charlotte, Abelson Klas S P, Hau Jann
Department of Experimental Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Department of Experimental Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Gen Comp Endocrinol. 2015 Jan 15;211:147-53. doi: 10.1016/j.ygcen.2014.12.008. Epub 2014 Dec 31.
The physiological stress response is frequently gauged in animals, non-invasively, through measuring glucocorticoids in excreta. A concern with this method is, however, the unknown effect of variations in diets on the measurements. With an energy dense diet, leading to reduced defecation, will low concentrations of glucocorticoids be artificially inflated? Can this effect be overcome by measuring the total output of glucocorticoids in excreta? In a controlled laboratory setting we explored the effect in mice. When standard mouse chow - high in dietary fiber - was replaced with a 17% more energy-dense diet, fecal mass was significantly reduced. As circulating levels of corticosterone and the total output of corticosterone metabolites over time remained unaffected, the result was an overestimation - more than a doubling - of the corticosterone metabolite excretion if expressed as concentrations. Similar results were obtained for testosterone metabolites. Although measuring the total output is not feasible in, for example, wildlife studies, the present findings highlight the perilousness of relying on concentrations of hormones in excreta with no associated information of the dietary intake as even moderate changes can exert a great influence.
生理应激反应通常在动物身上通过非侵入性地测量排泄物中的糖皮质激素来衡量。然而，这种方法存在一个问题，即饮食变化对测量结果的未知影响。食用能量密集型饮食会导致排便减少，那么低浓度的糖皮质激素是否会被人为地夸大呢？通过测量排泄物中糖皮质激素的总排出量能否克服这种影响呢？在一个可控的实验室环境中，我们对小鼠进行了相关研究。当将膳食纤维含量高的标准小鼠饲料换成能量密度高17%的饲料时，粪便量显著减少。由于皮质酮的循环水平以及皮质酮代谢产物随时间的总排出量未受影响，结果是如果以浓度表示，皮质酮代谢产物的排泄量被高估了一倍多。睾酮代谢产物也得到了类似的结果。尽管例如在野生动物研究中测量总排出量不可行，但目前的研究结果凸显了在没有饮食摄入量相关信息的情况下依赖排泄物中激素浓度的危险性，因为即使是适度的变化也可能产生很大影响。
