Effects of 2-hydroxyoestradiol-17 beta on plasma luteinizing hormone, follicle-stimulating hormone and prolactin, and nuclear translocation of pituitary oestrogen receptors in ovariectomized ewes.

The ability of oestradiol-17 beta (OE2) and 2-hydroxyoestradiol (2OH-OE2) to translocate pituitary oestrogen receptors to the nuclear compartment and to affect plasma concentrations of LH, FSH and prolactin was studied in ovariectomized ewes. Mean (+/- S.E.M.) nuclear oestrogen receptor levels (% of total pituitary oestrogen receptors) after intracarotid injections of 1.25 micrograms OE2, 400 micrograms 2OH-OE2 or vehicle were 8.7 +/- 2.3, 16.9 +/- 3.2 and 0.8 +/- 0.1% respectively. Whereas 1.25 or 12.5 micrograms OE2 significantly lowered plasma LH and FSH, 400 micrograms 2OH-OE2 did not affect plasma LH or FSH levels. Injection of 4000 micrograms 2OH-OE2 however, significantly affected plasma LH and FSH. Plasma prolactin levels were not significantly affected by the treatments. These data indicate a discrepancy between oestrogen receptor occupancy and effects on gonadotrophin and prolactin secretion after injection of catechol oestrogen.