【作者】 张权；

【导师】 邓慧华；

【作者基本信息】 东南大学 ， 生物医学工程（学习科学）， 2017， 博士

【摘要】 皮质醇是维持生命的必需糖皮质激素,可的松是皮质醇的主要代谢物。机体循环系统中的皮质醇水平受到下丘脑—垂体—肾上腺皮质(HPA)轴和11β-羟基类固醇脱氢酶(11β-HSD)等多重方式的调节,其中HPA轴主要负责皮质醇的分泌,11β-HSD负责皮质醇的代谢,即皮质醇与可的松之间的相互转化。以往研究常用血液、唾液、尿液基质中皮质醇与可的松的比值(Rbcc,Rscc和Rucc)来评估11β-HSD的长期活性。然而,唾液和尿液生物标记仅能反映即时状态或短期的11β-HSD活性,不能可靠地反映长期的11ββ-HSD活性;而且Rscc和Rucc主要反映唾液腺和肾脏内2型11β-HSD活性,不能反映1型和2型11β-HSD整体活性。尽管Rbcc主要反映机体内11β-HSD整体活性,但不能反映11β-HSD长期活性。值得注意的是,头发皮质醇能够反映HPA轴的长期功能,且其主要来源于血液中游离皮质醇的主动运输或被动扩散。据此推测,头发中R(Rhcc)可能适合用以反映11β-HSD的长期活性和整体活性。因此,本文旨在探索Rhcc作为11β-HSD生物标记的有效性、稳定性和适用性。首先,研究Rhcc作为11β-HSD生物标记的有效性。通过检验头发中类固醇与唾液中类固醇的关联性来验证头发中类固醇的内在生理来源主要为血液中自由类固醇的主动运输或被动扩散。结果发现,头发中类固醇含量和唾液中类固醇含量线性相关显著,这表明血液中自由类固醇的主动运输或被动扩散机制是头发中类固醇的主要内在生理来源。此外,通过检验Rhcc与Rscc的关联性来探索Rhcc反映的11β-HSD整体活性与Rscc反映的唾液腺中11β-HSD2活性之间的关系。结果发现,Rhcc与Rscc线性相关显著,其相关系数小于0.3。这可能是因为Rscc主要反映唾液腺中11β-HSD2的活性,而Rhcc可能反映机体内11β-HSD1和I1β-HSD2的综合活性。其次,研究Rhcc作为11β-HSD生物标记的稳定性。通过前测一后测的追踪研究设计,以单点、单天Rscc和单天Rucc为参照,验证Rhcc的长期稳定性。单点Rscc是反映11β-HSD2活性的急性生物标记,单天Rcc和Rucc是反映11β-HSD2活性的短期生物标记,Rhcc是反映11β-HSD整体活性的长期生物标记。结果发现,单点Rscc在1到2周上的稳定性差;单天Rscc和Rucc在1到2周上具有中等程度的稳定性;Rhcc在6到12个月时间间隔上具有中等程度的稳定性。这些结果表明Rhcc的跨时间相对稳定性优于Rscc和Rucc。最后,通过检验Rhcc能否灵敏地区分四类慢性应激模型人群与正常人群,探索Rh作为11β-HSD长期的回溯性生物标记的适用性。慢性应激模型分别是HPA轴功能异常的慢性心理应激模型(如美沙酮脱毒维持治疗人群)、HPA轴功能正常的慢性持续性心理应激模型(如孤独症患者的照顾者)、HPA轴功能正常的慢性间断性心理应激模型(如A型行为人群),以及HPA轴功能正常的慢性生理应激模型(如肥胖人群)。结果发现,MMT人群、孤独症患者的照顾者和A型行为人群的Rhcc均显著高于对照组,但肥胖人群的Rhcc与对照组无显著性差异。这些结果表明处于慢性心理应激人群的11β-HSD活性可能低下,而处于慢性生理应激人群的11β-HSD活性可能正常。总之,Rhcc可能是能够可靠地反映11β-HSD长期整体活性的、一种新型的、可回溯的生物标记。这将为研究11β-HSD长期活性与慢性应激的关系提供一个新的思路和新的工具。更多还原

【Abstract】 Cortisol is a necessary glucocorticoid hormone to maintain life,and cortisone is its inactive metabolite.Circulating cortisol levels are modulated by hypothalamic-pituitary-adrenocortical(HPA)axis and 11β-hydroxysteroid dehydrogenase(11β-HSD)where HPA axis is responsible for cortisol secretion and 11β-HSD is responsible for the interconversion of cortisone to cortisol.In the previous,the ratios of cortisol to cortisone(Rcc)in blood,saliva and urine were used as the biomarkers to assess the activity of 11β-HSD.However,Rcc in blood,saliva and urine(Rbcc,Rscc and Rucc)are not long-term biomarkers to reliably assess the activity of 11β-HSDs because they are acute,short-term biomarkers.Moreover,Rscc and Rucc may mainly reflect local activity of 11β-HSD2 in salivary glands and kidney rather than integrated activity of 11β-HSDs.More importently,cortisol in hair has been proven to be a reliable biomarker reflecting the long-term activity of the HPA axis,and the blood-related diffusion is its biologically endogenous source.It was assumed that the Rcc value in hair(Rhcc)may be a potential biomarker to reflect the long-term integrated activity of 11β-HSDs.Therefore,this paper aimed to explore the validity,intraindividual relative stability and availability of Rhcc as a biomarker of 11β-HSDs.Firstly,the present study aimed to examine the validity of Rhc in reflecting the long-term activity of 11β-HSD by exploring whether there is bivariate correlation of hair steroids with salivary steroids.The results revealed that there was significantly positive correlation between hair levels and saliva levels for both cortisol and cortisone,indicating that blood steroids are the major source of hair steroids.Additionally,the present study aimed to examine the relationship between the integrated activity of all 11β-HSDs and the activity of 11β-HSD2 in salivary gland by exploring whether there is a direct correlation between Rhcc and Rscc.The results revealed that there was significantly positive correlation between Rhcc and Rscc,but its coefficient was less than 0.3,which may be because Rscc might mainly represent the local activity of 11β-HSD2 in salivary gland,and Rhcc reflect the integrated activity of 11β-HSDs.Secondly,the present study aimed to examine the long-term intraindividual relative stability of Rhcc based on a longitudinal test-retest design.Single-point and single-day Rscc and single-day Rucc were taken as references to validate the long-term stability of Rhcc where single-point Rscc is a acute biomarker to reflect the activity of 11β-HSD2,single-day Rscc and Rucc are short-term biomarkers to reflect the activity of 11β-HSD2,and Rhcc is a long-term biomarker to reflect the integrated activity of 11β-HSDs.The results revealed that single-point Rscc showed weak long-term relative stability within a two-week period,and single-day level Rscc and Rucc showed moderate long-term relative stability within a two-week period,and Rhcc showed moderate long-term relative stability in a 12-month period.These results indicated that Rhcc have better long-term relative stability than Rscc and Rucc.Finally,the present study aimed to examine the avalibility of Rhcc in reflecting the long-term activity of 11β-HSD by exploring association between Rhcc and psychological and physiological chronic stress among four diffenrnt kinds of populations,patients in methanadone-maintenance treatment(MMT),mothers of children with autism,college students with type A behavior pattern(TABP)and with obesity.The results revealed that MMT patients,mothers of children with autism,college students with type A behavior pattern have significantly higher Rhcc than controls,but there is no significant difference in Rhc between college students with obesity and controls.These results implied that psychological chronic stress might show lower activity of 11β-HSD,but physiological chronic stress might show normal activity of 11β-HSD.In conclusion,Rhcc was a novel retrospective biomarker reliably reflecting the long-term integrated activity of 11β-HSDs.This finding will prompt the reliability and effectiveness of Rhcc and extend the application of Rhcc to chronic stress research.更多还原