THESPECIFICITY OFOESTROGEN RECEPTORINBRAIN,PITUITARY AND UTERUS

I Thespecificity ofoestrogen receptor inratbrain regions (hypothalamus, amygdala andcortex), pituitary anduterus was studied bymeasurement oftheinhibition of17#-oestradiol highaffinity binding incytosol, inthepresenceofunlabelled putative inhibitors ofbinding. 2 Binding was inhibited onlybythose ofthecompounds tested thatpossessed oestrogen agonist or antagonist activity. Theaffinities were estimated andtheranking orderofthecompounds was the same inalltissue sourcesofcytosol andcorresponded totheranking orderofagonist orantagonist potency. 3 There weresome significant differences between some oftheestimated affinities indifferent tissues, these being seenmostcommonly between pituitary andhypothalamus on onehandanduterus on-the other. 4 Thepossibility ofheterogeneity ofoestrogen receptor isdiscussed.