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ID:14271267
大小:352.50 KB
页数:79页
时间:2018-07-27
《adrenocortical insufficiency - stud:肾上腺皮质功能不全-螺柱》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、ADRENOCORTICALINSUFFICIENCYTHEADRENALCORTEXBASISCONCEPTSADRENOCORTICALHISTOLOGYTheadrenalcortexiscomposedofthreeconcentriczoneswithdistinctsteroidbiosyntheticcapacities.Zonaglomerulosa–biosynthesisofmineralocorticoidsZonafasciculata–biosynthesisofglucocorticoidsZonareticularis–biosynthesisofadren
2、alandrogens.STEROIDBIOSYNTHESISSteroidogenesisresultsfromspecificsequentialenzymaticconversionsofcholesterolsubstrateintosteroidhormones,whichexertawidevarietyofbiologicalactivities.STEROIDBIOSYNTHESISAseriesofsteroidogenicenzymesarecompartmentalizedeitherinthemitochondriaorintheendoplasticreticulum
3、.SeveraloftheseenzymesbelongtothesuperfamilyofmixedfunctionoxidaseenzymesknownascytochromeP450.STEROIDBIOSYNTHESISApproximately~80%ofadrenalcholesterolsourcesareprovidedbycirculatinglowdensitylipoprotein(LDL).TheadrenalcellscanalsosynthesizecholesteroldenovofromacetylcoenzymeA.STEROIDBIOSYNTHESISThe
4、firstrate-limitingstepinsteroidogenesisinvolvestheremovalofsixcarbonsfromthelateralchainofcholesterolbyintegralinnermitochondrialmembraneP450sidechaincleavage(CYP11A1)enzymetogeneratepregnenolone.NomenclatureforsteroidogenicenzymesnowutilizedTrivialnamePastCurrentCholesterolside-chaincleavageenzyme;
5、desmolaseP450sccCYP11A13β-Hydroxysteroiddehydrogenase3β-HSD3β-HSD17α-Hydroxylase/17,20-lyaseP450c17CYP1721-HydroxylaseP450c21CYP21A211β-HydroxylaseP450c11CYP11B1Aldosteronesynthase;corticosterone18-methylcorticosteroneoxidase/lyaseP450C11ASCYP11B2Mainsteroidbiosyntheticpathways(mineralocorticoidsand
6、glucocorticoids).cholesterolpregnenoloneprogesterone11-deoxycorticosterone(DOC)corticosterone(B)18OH-corticosteroneALDOSTERONE3β-HSDIICYP21A2CYP11B217αOH-pregnenoloneCYP1717α-hydroxylase17,20-lyase17αOH-progesterone11-deoxycortisol(S)CORTISOL(F)CYP11B1ZONAFASTICULATAZONAGLOMERULOSA11β-hydroxylaseCYP
7、11A118-hydroxylase18-methyloxidaseMainsteroidbiosyntheticpathways(adernalandrogens).cholesterolpregnenoloneprogesterone3β-HSDII17αOH-pregnenolone17α-hydroxylase17,20-lyase17αOH-progesteroneZONARETICUL
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