Gap junction amplification in rat ovarian granulosa cells: I. A direct response to follicle-stimulating hormone☆

[摘要] Theabilityoffollicle-stimulatinghormone(FSH),theestrogens,estradiol-17βanddiethylstilbestrol,andtheestrogenantagonists,clomipheneandenclomiphenecitratetoaffectthegrowthandinternalizationofhypophysectomizedratgranulosacellgapjunctionmembraneswascomparedinovarianfolliclesassignedtooneoffourfolliclesizeclasses(60–149,150–249,250–319,and320–450μmdiameter).Intheabsenceofexogenoushormonestimulation,atresiapreventsfolliclegrowthbeyond320μmindiameterbutsurfacegapjunctionmembraneincreasesthroughoutthisearlyfolliclegrowth.Internalizationofgapjunctionmembraneisfirstdetectedatthe150-to249-μmfolliclestageandalsoincreaseswithfolliclesize.Therefore,growthandturnoverofgapjunctionmembraneoccuratabasalrateintheabsenceofgonadotropinorsteroidhormonestimulation.Estrogenandestrogenantagonistinjectionsresultinnosignificantdifferencesintheamountofsurfaceorinternalizedjunctionmembraneinthethreesmallestfolliclesizeclasseswhencomparedtotheuntreatedhypophysectomizedanimals.However,estrogenbutnotestrogenantagonistsrescuesgrowingfolliclesfromatresiaandpermitstheirfurthergrowthintothe320-to450-μmfolliclesizeclass.Asaresultoftheadditionalfolliclegrowth,bothsurfaceandinternalizedjunctionmembraneincreasebeyondthatseeninthelargestfolliclesfromhypophysectomizedanimals.Incontrasttoothertreatments,FSHstimulationpromotesamplificationofgapjunctionmembraneinallsizeclassesand,likeestrogen,rescuesfolliclesfromatresiaandpromotestheirentryintothe320-to450-μmfolliclesizeclass.Surfacegapjunctionmembraneisamplifiedtwo-tofourfoldoverothertreatmentsinthefirstthreefolliclesizeclasses,butreachesmaximallevelsinthe250-to319-μmfollicles.Theinternalizedjunctionmembranewhichfirstappearsinthe150-to249-μmsizeclassisdramaticallyincreasedoverothertreatmentsinthe250-to319-and320-to450-μmsizeclasses.Thesestudiesindicatethatexogenousestrogenstimulationpromotesgapjunctiongrowthindirectlybysustainingthebasalrateofjunctionsynthesisinfolliclesrescuedfromatresia.Incontrast,exogenousFSHstimulationdirectlyamplifiesthedevelopmentalsequenceofgapjunctiongrowthandturnover.Duringearlyfolliclegrowth,FSHstimulationpreferentiallypromotesincreasesinsurfacegapjunctionswhileinternalizationofsurfacejunctionsisincreasedduringlaterfolliclegrowth.

[学科分类] 生物科学（综合）