Binding of phyto-oestrogen and oestradiol-17 beta by cytoplasmic receptors in the pituitary gland and hypothalamus of the ewe.
The binding of the phyto-oestrogens, genistein and coumestrol by oestrogen receptors in pituitary and hypothalamic cytosol of the ewe was studied in relation to the binding of [3H]-oestradiol-17 beta. It was determined that the interaction of these compounds was competitive. The apparent dissociation constant for oestradiol-17 beta in ewe pituitary cytosol was determined to be 0 x 26 +/- 0 x 12 (S.E.M.) nmol/l. Apparent inhibition constants for coumestrol and genistein were determined to be 60 and 170 nmol/l respectively. These results suggested that phyto-oestrogens can interfere with the normal oestrogen feedback mechanisms with respect to release of gonadotrophine in the ewe.
D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D003375:Coumestrol / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism*; D004968:Estrogens, Non-Steroidal / Q000378:metabolism*; D005260:Female; D019833:Genistein; D007031:Hypothalamus / Q000378:metabolism*; D007529:Isoflavones / Q000378:metabolism; D010902:Pituitary Gland / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D012756:Sheep / Q000378:metabolism*
D004968:Estrogens, Non-Steroidal; D007529:Isoflavones; D011960:Receptors, Estrogen; D004958:Estradiol; D019833:Genistein; D003375:Coumestrol