Studies on the developmental pattern of the enzymes converting glucose 6-phosphate to myo-inositol in the rat☆

[摘要] Themyo-inositollevelofplasmawasdeterminedduringpre-andpostnataldevelopmentoftherat.Fetalconcentrationsexceededthoseofmaternalratsbynearly10-fold.Immediatelyafterbirth,themyo-inositolleveldecreasedbutwasmaintainedatvalues3–4timesthatofthelactatingdams.Thecyclitolcontentofratmilkwashighandroseduringlactationtoamaximumof1.6mM.Thebiosynthesisofmyo-inositolfromglucose6-phosphateiscatalyzedbyglucose6-phosphate:l-myo-inositol-1-phosphatecyclaseandl-myo-inositol-1-phosphatephosphatase.Theactivityofbothenzymeswasmonitoredinfetalandneonatalliver,maternalliver,placenta,andmammarygland.Resultsindicatedthatthefetalliveraccountedforover48%ofthetotalcarcasscyclaseand26%ofthetotalcarcassphosphataseactivity.Developmentalchangescorrelatedwellwiththepatternofmyo-inositolinfetalratplasma.Similarly,theenzymesofthemyo-inositolbiosyntheticpathwayincreasedinratmammaryglandincloseagreementwiththemyo-inositolcontentofmilkanddiminishedtoprelactationactivitieswithin24hraftertheonsetofinvolution.Themyo-inositollevelofcolostrumandmilkoffivehumansubjectswashighest(2.8mM)beforebirthanddecreasedto40%ofthatlevel5dayspostpartum,whereitremainedforatleast3weeks.Evenafter7monthsoflactation,themilkofonesubjectcontained3–4-foldmoremyo-inositolthanallcommercialinfantformulasanalyzed.

[学科分类] 生物科学（综合）