TY - JOUR
T1 - Feedback on LH in testosterone-clamped men depends on the mode of testosterone administration and body composition
AU - Roelfsema, Ferdinand
AU - Yang, Rebecca J.
AU - Liu, Peter Y.
AU - Takahashi, Paul Y.
AU - Veldhuis, Johannes D.
PY - 2019/1/1
Y1 - 2019/1/1
N2 - Context: Quantitative studies of the short-term feedback of testosterone (T) on luteinizing hormone (LH) secretion in healthy men are relatively rare. Such studies require the shutting down of endogenous T secretion and the imposition of experimentally controlled IV T addback. Objective: To evaluate whether pulsatile and continuous T delivery confers equivalent negative feedback on LH secretion. Design: This was a placebo-controlled, blinded, and prospectively randomized crossover study comprising 16 healthy men [age range 23 to 54 years and a body mass index (BMI) between 22.3 and 34.2 kg/m2]. Subjects received ketoconazole to block endogenous T secretion and received continuous or 90-minute pulses of IV T addback. Setting: The study was performed in a Clinical Translational Research Unit. Interventions: Subjects underwent 14 hours of blood sampling at 10-minute intervals, with a bolus IV injection of 33 ng/kg gonadotropin-releasing hormone (GnRH). Main Outcome Measures: Log-transformed LH and T concentration ratios before and after GnRH administration. Results: Despite higher T concentrations during pulsatile T feedback, LH concentrations and secretion rates, whether driven by endogenous or exogenous GnRH, were similar to those during continuous T infusion, indicating diminished pulsatile T feedback. Feedback correlated negatively with BMI. Under controlled T feedback, basal but not pulsatile LH secretion correlated negatively with CT-estimated visceral fat mass. Conclusion: Feedback by pulsatile T delivery has diminished inhibitory strength compared with continuous infusion. Feedback is negatively correlated with BMI.
AB - Context: Quantitative studies of the short-term feedback of testosterone (T) on luteinizing hormone (LH) secretion in healthy men are relatively rare. Such studies require the shutting down of endogenous T secretion and the imposition of experimentally controlled IV T addback. Objective: To evaluate whether pulsatile and continuous T delivery confers equivalent negative feedback on LH secretion. Design: This was a placebo-controlled, blinded, and prospectively randomized crossover study comprising 16 healthy men [age range 23 to 54 years and a body mass index (BMI) between 22.3 and 34.2 kg/m2]. Subjects received ketoconazole to block endogenous T secretion and received continuous or 90-minute pulses of IV T addback. Setting: The study was performed in a Clinical Translational Research Unit. Interventions: Subjects underwent 14 hours of blood sampling at 10-minute intervals, with a bolus IV injection of 33 ng/kg gonadotropin-releasing hormone (GnRH). Main Outcome Measures: Log-transformed LH and T concentration ratios before and after GnRH administration. Results: Despite higher T concentrations during pulsatile T feedback, LH concentrations and secretion rates, whether driven by endogenous or exogenous GnRH, were similar to those during continuous T infusion, indicating diminished pulsatile T feedback. Feedback correlated negatively with BMI. Under controlled T feedback, basal but not pulsatile LH secretion correlated negatively with CT-estimated visceral fat mass. Conclusion: Feedback by pulsatile T delivery has diminished inhibitory strength compared with continuous infusion. Feedback is negatively correlated with BMI.
KW - bioavailable testosterone
KW - body composition
KW - feedback
KW - human
KW - LH
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U2 - 10.1210/js.2018-00317
DO - 10.1210/js.2018-00317
M3 - Article
SN - 2472-1972
VL - 3
SP - 235
EP - 249
JO - Journal of the Endocrine Society
JF - Journal of the Endocrine Society
IS - 1
ER -