Cortisol Metabolism in the Bolivian Squirrel Monkey (Saimiri boliviensis boliviensis)

摘要

NewWorldsquirrelmonkeys(Saimirispp.)havehighcirculatingcortisollevelsbutnormalelectrolytesandbloodpressures.ThegoalofthepresentstudywastogaininsightintoadaptivemechanismsusedbyBoliviansquirrelmonkeystominimizetheeffectsofhighcortisolonmineralocorticoidreceptor(MR)activityandelectrolyteandwaterbalance.Aldosteronelevelsinserumfrom10squirrelmonkeyswere17.7±3.4ng/dl(normalrangeinhumans,4to31ng/dl),suggestingthatsquirrelmonkeysdonotexhibitacompensatoryincreaseinaldosterone.ThesquirrelmonkeyMRwasclonedandexpressedinCOS-7cellsandfoundtohavesimilarresponsivenesstocortisolandaldosteroneashumanMR,suggestingthatsquirrelmonkeyMRisnotinherentlylessresponsivetocortisol.TodeterminewhetheralteredmetabolismofcortisolmightcontributetoMRprotectioninsquirrelmonkeys,serumandurinarycortisolandcortisoneweremeasured,andacomprehensiveurinarycorticosteroidmetaboliteprofilewasperformedinsamplesfromanesthetizedandawakesquirrelmonkeys.Thelevelsofcortisoneexceededthoseofcortisolinserumandurine,suggestingincreasedperipheral11#59137;-hydroxysteroiddehydrogenase2activityinsquirrelmonkeys.Inaddition,asignificantfraction(approximately20%)oftotalcorticosteroidsexcretedintheurineofsquirrelmonkeysappearedas6#59137;-hydroxycortisol,comparedwiththatinman(1%).Therefore,changesincortisolmetabolismlikelycontributetoadaptivemechanismsusedbyBoliviansquirrelmonkeystominimizeeffectsofhighcortisol.