TY - JOUR
T1 - Steroidal regulation of biologically active luteinizing hormone secretion in men and women
AU - Veldhuis, Johannes D.
N1 - Funding Information:
We thank Patsy Craig for her skilful preparation of the manuscript; Paul P. Azimi for the artwork; and Sandra Jackson and the expert nursing staff at the University of Virginia General Clinical Research Center for conduct of the research protocols. This work was supported in part by NIH Grant RR-00847 to the General Clinical Research Center of the University of Virginia; RCDA 1-KO4-HD00634 (J.D.V.); Diabetes and Research Training Center Grant NIH DK-38942; the Pratt Foundation; NIH-supported Clinfo Data Reduction Systems; the University of Virginia Academic Enhancement Fund; and the NSF Science Center for Biological Timing (J.D.V.).
PY - 1993/11
Y1 - 1993/11
N2 - The biological activity of circulating luteinizing hormone (LH)molecules can be assessed with high sensitivity, specificity, and precision by the in-vitro rat interstitial (Leydig)-cell testosterone (RICT) bioassay. Compared to immunoreactive estimates of the LH content of plasma, the living Leydig-cell bioassay integrates the functional in-vitro potency of all circulating LH isoforms, while simultaneously reflecting the effects of otherwise potentially confounding in-vivo antagonists of LH action on steroidogenesis. Here, we review the pathophysiological regulation by steroid hormones of bioactive LH secretion and clearance in men and women. Our investigations and those in the available literature indicate that: (i) Exogenous (non-aromatizable) 5-±-dihydrotestosterone infusion suppresses LH bioactivity, whereas blockade of the endogenous androgen receptor with flutamide increases secretion of biopotent LH in men; (ii) endogenous androgen excess due to a masculinizing testosterone-secreting adrenal tumour in a post-menopausal woman reversibly suppressed plasma LH bioactivity markedly; (iii) exogenous oestradiol infusion will reduce whereas the antioestrogen, tamoxifen-HC1, can increase bioactive LH secretion in young men; (iv) the effect of anti-oestrogen is blunted in healthy older men; (v) endogenous hyperoestrogenism due to an adrenal oestrogen-secreting tumour in a middle-aged man with gynaecomastia profoundly but reversibly inhibited bioactive LH secretion; (vi) in post-menopausal women, exogenous oestrogen administration, whether oral (diethylstilbestrol), percutaneous (oestradiol), or intravaginal (oestradiolimpregnated silastic ring), exerts a temporally biphasic effect on basal bioactive LH secretion, i.e. acute suppression (within 24 h), subacute escape (at 5-10 days), and longer-term inhibition (30 days); (vii) during the normal menstrual cycle, bioactive LH secretion is pulsatile and both frequency and amplitude regulated; and (viii) oestrogen exposure can enhance gonadotrophin releasing hormone (GnRH)'s stimulatory action on biologically active LH secretion, resulting in so-called GnRH self-priming. Oestrogen's facilitative effects are achieved by a novel mechanism, in 84 which oestrogen augments LH secretory burst mass and duration. Moreover, GnRH dose-LH secretory response studies show that oestrogen promotes an increase in GnRH efficacy (maximal effects) but not GnRH sensitivity (potency or half-maximally effective doses of GnRH We conclude that steroid hormones are primary regulator o physiologically pulsatile bioactive LH secretion in healthy men and women. Moreover, steroids exert potent pathological effects on biologically active LH release in conditions of selective hyperandrogenism or hyperoestrogenism due to steroid-secreting adrenal or gonadal tumours.
AB - The biological activity of circulating luteinizing hormone (LH)molecules can be assessed with high sensitivity, specificity, and precision by the in-vitro rat interstitial (Leydig)-cell testosterone (RICT) bioassay. Compared to immunoreactive estimates of the LH content of plasma, the living Leydig-cell bioassay integrates the functional in-vitro potency of all circulating LH isoforms, while simultaneously reflecting the effects of otherwise potentially confounding in-vivo antagonists of LH action on steroidogenesis. Here, we review the pathophysiological regulation by steroid hormones of bioactive LH secretion and clearance in men and women. Our investigations and those in the available literature indicate that: (i) Exogenous (non-aromatizable) 5-±-dihydrotestosterone infusion suppresses LH bioactivity, whereas blockade of the endogenous androgen receptor with flutamide increases secretion of biopotent LH in men; (ii) endogenous androgen excess due to a masculinizing testosterone-secreting adrenal tumour in a post-menopausal woman reversibly suppressed plasma LH bioactivity markedly; (iii) exogenous oestradiol infusion will reduce whereas the antioestrogen, tamoxifen-HC1, can increase bioactive LH secretion in young men; (iv) the effect of anti-oestrogen is blunted in healthy older men; (v) endogenous hyperoestrogenism due to an adrenal oestrogen-secreting tumour in a middle-aged man with gynaecomastia profoundly but reversibly inhibited bioactive LH secretion; (vi) in post-menopausal women, exogenous oestrogen administration, whether oral (diethylstilbestrol), percutaneous (oestradiol), or intravaginal (oestradiolimpregnated silastic ring), exerts a temporally biphasic effect on basal bioactive LH secretion, i.e. acute suppression (within 24 h), subacute escape (at 5-10 days), and longer-term inhibition (30 days); (vii) during the normal menstrual cycle, bioactive LH secretion is pulsatile and both frequency and amplitude regulated; and (viii) oestrogen exposure can enhance gonadotrophin releasing hormone (GnRH)'s stimulatory action on biologically active LH secretion, resulting in so-called GnRH self-priming. Oestrogen's facilitative effects are achieved by a novel mechanism, in 84 which oestrogen augments LH secretory burst mass and duration. Moreover, GnRH dose-LH secretory response studies show that oestrogen promotes an increase in GnRH efficacy (maximal effects) but not GnRH sensitivity (potency or half-maximally effective doses of GnRH We conclude that steroid hormones are primary regulator o physiologically pulsatile bioactive LH secretion in healthy men and women. Moreover, steroids exert potent pathological effects on biologically active LH release in conditions of selective hyperandrogenism or hyperoestrogenism due to steroid-secreting adrenal or gonadal tumours.
KW - Bioactive
KW - Gonadotrophin
KW - Human
KW - Pituitary
KW - Pulsatile
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U2 - 10.1093/humrep/8.suppl_2.84
DO - 10.1093/humrep/8.suppl_2.84
M3 - Article
C2 - 8276976
AN - SCOPUS:0027491348
SN - 0268-1161
VL - 8
SP - 84
EP - 96
JO - Human Reproduction
JF - Human Reproduction
ER -