Genisteiniseffectiveagainstamyloid-βtoxicity,buttheunderlyingmechanismsareunclear.Wehypothesizedthatgenisteinmayprotectneuronsbyinhibitingthemitochondrialapoptoticpathway,andtherebyplayaroleinthepreventionofAlzheimer'sdisease.AratmodelofAlzheimer'sdiseasewasestablishedbyintraperitonealinjectionofD-galactoseandintracerebralinjectionofamyloid-βpeptide(25–35).Inthegenisteintreatmentgroups,a7-daypretreatmentwithgenistein(10,30,90mg/kg)wasgivenpriortoestablishingAlzheimer'sdiseasemodel,for49consecutivedays.Terminaldeoxyribonucleotidyltransferase-mediateddUTPnickendlabelingassaydemonstratedareductioninapoptosisinthehippocampusofratstreatedwithgenistein.Westernblotanalysisshowedthatexpressionlevelsofcapase-3,Baxandcytochromecweredecreasedcomparedwiththemodelgroup.Furthermore,immunohistochemicalstainingrevealedreductionsincytochromecandBaximmunoreactivityintheserats.MorriswatermazerevealedasubstantialshorteningofescapelatencybygenisteininAlzheimer'sdiseaserats.Thesefindingssuggestthatgenisteindecreasesneuronallossinthehippocampus,andimproveslearningandmemoryability.Theneuroprotectiveeffectsofgenisteinareassociatedwiththeinhibitionofthemitochondrialapoptoticpathway,asshownbyitsabilitytoreducelevelsofcaspase-3,Baxandcytochromec.
