Premium
EFFECT OF HIGH DOSE EXOGENOUS OESTROGEN ON MIDCYCLE LUTEINIZING HORMONE SURGE IN HUMAN SPONTANEOUS CYCLES
Author(s) -
MESSINIS I. E.,
TEMPLETON A.
Publication year - 1987
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1987.tb01173.x
Subject(s) - endocrinology , medicine , luteinizing hormone , follicular phase , endogeny , estrogen , gonadotropin , hormone , estrous cycle , biology
SUMMARY Induction of multiple follicular development in women results in supraphysiological serum oestradiol (E 2 ) levels and marked reduction of the endogenous LH surge. To examine whether high serum E 2 levels at midcycle can suppress gonadotrophin secretion during the LH surge, five normally ovulating women were given an intramuscular injection of 10 mg oestradiol benzoate 6‐42 h before the expected endogenous LH surge. The results were compared with the preceding untreated control cycle. Serum E 2 levels at the onset of the LH surge (mean ± SEM) were significantly higher in the oestrogen‐treated cycles (13 600 ± 1963 pmol/1) than in the control cycles(1012±116pmol/l)( P <0.001). The duration of the LH surge (64‐8 ± 2‐2 h) and LH peak levels (136 ± 9‐6 mIU/ ml) in the oestrogen treated cycles were similar to those in the control cycles (61.2 ± 3‐9 and 119 ± 9‐4 mlU/ml respectively) (mean ± SEM). The cycle day on which the LH surge started and the size of the dominant follicle, as assessed by ultrasound, did not differ significantly between the two groups of cycles. These results show that in spontaneous cycles the endogenous LH surge is neither reduced nor amplified by the induction of supraphysiological serum E 2 levels during the immediate preovulatory stage.