Van Meulebroek Lieven, De Clercq Nathalie, Vanden Bussche Julie, Devreese Mathias, Fichant Eric, Delahaut Philippe, Croubels Siska, Vanhaecke Lynn
Faculty of Veterinary Medicine, Department of Veterinary Public Health & Food Safety, Laboratory of Chemical Analysis, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium.
Faculty of Veterinary Medicine, Department of Pharmacology, Toxicology and Biochemistry, Laboratory of Pharmacology and Toxicology, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium.
BMC Vet Res. 2017 Aug 14;13(1):236. doi: 10.1186/s12917-017-1158-5.
In Europe, synthetic corticosteroids are not allowed in animal breeding for growth-promoting purposes. Nevertheless, a high prevalence of non-compliant urine samples was recently reported for prednisolone, however, without any indication of unauthorized use. Within this context, 20β-dihydroprednisolone and the prednisolone/cortisol ratio have been suggested as potential tools to discriminate between exogenous and endogenous urinary prednisolone. In this study, the validity of these strategies was verified by investigating the plasma pharmacokinetic and urinary excretion profiles of relevant glucocorticoids in bovines, subjected to exogenous prednisolone treatment or tetracosactide hexaacetate administration to induce endogenous prednisolone formation. Bovine urine and plasma samples were analysed by liquid chromatography and mass spectrometry.
Based on the plasma pharmacokinetics and urinary profiles, 20β-dihydroprednisolone was confirmed as the main prednisolone-derived metabolite, being detected in the biological fluids of all 12 bovines (plasma AUC of 121 h μg L and urinary concentration > 0.695 μg L). However, this metabolite enclosed no potential as discriminative marker as no significant concentration differences were observed upon exogenous prednisolone treatment or tetracosactide hexaacetate administration under all experimental conditions. As a second marker tool, the prednisolone/cortisol ratios were assessed along the various treatments, taking into account that endogenous prednisolone formation involves the hypothalamic-pituitary-adrenal axis and is associated with an increased cortisol secretion. Significantly lower ratios were observed in case of endogenous prednisolone formation (i.e. ratios ranging from 0.00379 to 0.129) compared to the exogenous prednisolone treatment (i.e. ratios ranging from 0.0603 to 36.9). On the basis of these findings, a discriminative threshold of 0.260 was proposed, which allowed classification of urine samples according to prednisolone origin with a sensitivity of 94.2% and specificity of 99.0%.
The prednisolone/cortisol ratio was affirmed as an expedient strategy to discriminate between endogenous and exogenous prednisolone in urine. Although the suggested threshold value was associated with high specificity and sensitivity, a large-scale study with varying experimental conditions is designated to optimize this value.
在欧洲，合成皮质类固醇不允许用于促进动物生长的养殖目的。然而，最近有报道称泼尼松龙的尿液样本违规率很高，但没有任何未经授权使用的迹象。在此背景下，20β-二氢泼尼松龙和泼尼松龙/皮质醇比值被认为是区分外源性和内源性尿泼尼松龙的潜在工具。在本研究中，通过研究牛体内相关糖皮质激素的血浆药代动力学和尿排泄情况，验证了这些策略的有效性，这些牛接受了外源性泼尼松龙治疗或注射醋酸二十四肽促皮质素以诱导内源性泼尼松龙的形成。牛的尿液和血浆样本通过液相色谱和质谱进行分析。
基于血浆药代动力学和尿液分析结果，20β-二氢泼尼松龙被确认为泼尼松龙的主要代谢产物，在所有12头牛的生物样本中均被检测到（血浆曲线下面积为121 h·μg/L，尿液浓度>0.695 μg/L）。然而，这种代谢产物没有作为鉴别标志物的潜力，因为在所有实验条件下，外源性泼尼松龙治疗或注射醋酸二十四肽促皮质素后，均未观察到显著的浓度差异。作为第二个标志物工具，在各种治疗过程中评估了泼尼松龙/皮质醇比值，考虑到内源性泼尼松龙的形成涉及下丘脑-垂体-肾上腺轴，并与皮质醇分泌增加有关。与外源性泼尼松龙治疗相比（比值范围为0.0603至36.9），内源性泼尼松龙形成时观察到的比值显著较低（即比值范围为0.00379至0.129）。基于这些发现，提出了0.260的鉴别阈值，该阈值可根据泼尼松龙的来源对尿液样本进行分类，灵敏度为94.2%，特异性为99.0%。
泼尼松龙/皮质醇比值被确认为区分尿液中内源性和外源性泼尼松龙的便捷策略。尽管建议的阈值具有较高的特异性和灵敏度，但仍需开展一项在不同实验条件下的大规模研究以优化该值。
