Van Peer Els, De Bock Lies, Boussery Koen, Van Bocxlaer Jan, Casteleyn Christophe, Van Ginneken Chris, Van Cruchten Steven
Applied Veterinary Morphology, Department of Veterinary Sciences, University of Antwerp, Wilrijk, Belgium.
Laboratory of Medical Biochemistry and Clinical Analysis, Department of Bioanalysis, Ghent University, Ghent, Belgium.
Basic Clin Pharmacol Toxicol. 2015 Nov;117(5):350-7. doi: 10.1111/bcpt.12410. Epub 2015 May 18.
In view of paediatric drug development, regulatory authorities often request safety studies in juvenile animals, including minipigs. Unfortunately, knowledge on the ontogeny of the biotransformation processes in animal models remains scarce and impedes a correct interpretation of the toxicity findings. CYP3A4 is one of the most important drug-metabolizing enzymes in human beings and shows important similarities with CYP3A in the minipig. Therefore, the aim of this study was to assess the abundance and activity of CYP3A in liver microsomes from foetal, juvenile (days 1, 3, 7 and 28) and adult male and female Göttingen minipigs. CYP3A abundance was studied by an indirect enzyme-linked immunosorbent assay (ELISA), whereas CYP3A activity was assessed by a biotransformation assay with Luciferin-IPA. CYP3A abundance could not be detected until day 3. From day 7 onwards, a gradual increase in expression was noted, leading to the highest abundance in adult animals. CYP3A activity was not detectable in foetuses and 1-day-old animals. The CYP3A activity was detectable, but below the LLOQ in day 3 animals and increased gradually with age to reach the highest level in adults. The CYP3cide and ketoconazole inhibition, and testosterone and midazolam reduction of Luciferin-IPA metabolism in minipig liver microsomes substantiate that Luciferin-IPA is metabolized by CYP3A in minipigs. A positive correlation was found between CYP3A abundance and biotransformation of Luciferin-IPA (Pearson r = 0.863; p < 0.0001). In conclusion, both abundance and activity of CYP3A increased gradually in juvenile minipigs, but remained below the levels observed in adult animals.
鉴于儿科药物研发，监管机构通常要求在幼年动物（包括小型猪）中开展安全性研究。遗憾的是，关于动物模型中生物转化过程个体发育的知识仍然匮乏，这妨碍了对毒性研究结果的正确解读。CYP3A4是人类最重要的药物代谢酶之一，与小型猪的CYP3A具有重要的相似性。因此，本研究的目的是评估胎儿、幼年（第1、3、7和28天）以及成年雄性和雌性哥廷根小型猪肝微粒体中CYP3A的丰度和活性。通过间接酶联免疫吸附测定（ELISA）研究CYP3A丰度，而通过荧光素-IPA生物转化测定评估CYP3A活性。直到第3天才检测到CYP3A丰度。从第7天起，观察到表达逐渐增加，在成年动物中达到最高丰度。在胎儿和1日龄动物中未检测到CYP3A活性。在第3天的动物中可检测到CYP3A活性，但低于定量下限，并且随着年龄的增长逐渐增加，在成年动物中达到最高水平。小型猪肝微粒体中CYP3cide和酮康唑抑制以及荧光素-IPA代谢的睾酮和咪达唑仑还原证实荧光素-IPA在小型猪中由CYP3A代谢。发现CYP3A丰度与荧光素-IPA生物转化之间存在正相关（Pearson r = 0.863；p < 0.0001）。总之，幼年小型猪中CYP3A的丰度和活性均逐渐增加，但仍低于成年动物中观察到的水平。
