Progesterone-Mediated Inhibition of the GnRH Pulse Generator: Differential Sensitivity as a Function of Sleep Status

Abstract

Context: During normal, early puberty, luteinizing hormone (LH) pulse frequency is low while awake but increases during sleep. Mechanisms underlying such changes are unclear, but a small study in early pubertal girls suggested that differential wake-sleep sensitivity to progesterone negative feedback plays a role.

Objective: To test the hypothesis that progesterone acutely reduces waking LH pulse frequency more than sleep-associated pulse frequency in late pubertal girls.

Design: Randomized, placebo-controlled, double-blinded crossover study.

Setting: Academic clinical research unit.

Participants: Eleven normal, postmenarcheal girls, ages 12 to 15 years.

Intervention: Subjects completed two 18-hour admissions in separate menstrual cycles (cycle days 6 to 11). Frequent blood sampling for LH assessment was performed at 1800 to 1200 hours; sleep was encouraged at 2300 to 0700 hours. Either oral micronized progesterone (0.8 mg/kg/dose) or placebo was given at 0700, 1500, 2300, and 0700 hours, before and during the first admission. A second admission, performed at least 2 months later, was identical to the first except that placebo was exchanged for progesterone or vice versa (treatment crossover).

Main outcome measures: LH pulse frequency during waking and sleeping hours.

Results: Progesterone reduced waking LH pulse frequency by 26% (P = 0.019), with no change observed during sleep (P = 0.314). The interaction between treatment condition (progesterone vs placebo) and sleep status (wake vs sleep) was highly significant (P = 0.007).

Conclusions: In late pubertal girls, progesterone acutely reduced waking LH pulse frequency more than sleep-associated pulse frequency. Differential wake-sleep sensitivity to progesterone negative feedback may direct sleep-wake LH pulse frequency changes across puberty.

Trial registration: ClinicalTrials.gov NCT00929006.

Figures

Figure 1.

Study schematic. Vertical arrows indicate the times when either oral micronized progesterone (P4) or placebo (PBO) was given. PBO was exchanged for P4 or vice versa for the second admission (treatment crossover). Horizontal arrows indicate wake (1900 to 2300 and 0700 to 1100 hours) and sleep (2300 to 0300 and 0300 to 0700 hours) blocks.

Figure 2.

Sex steroid changes between progesterone (P4) and placebo (PBO) conditions. Data points indicate the change in (a) mean P4, (b) estradiol, (c) total testosterone, and (d) free testosterone concentrations from the PBO to the P4 condition. Change in hormone concentration in individual subjects (○); these data are also summarized using box-and-whisker plots, which show median (line inside the box); mean (open square); 25th and 75th percentiles (bottom and top of box); and minimum and maximum (bottom and top whiskers). P values relate to the mean changes between the treatment conditions. E2, estradiol; T, testosterone.

Figure 3.

LH pulse frequency as a function of sleep status and treatment condition. (a) Individual average LH pulse frequency under the placebo (PBO) and progesterone (P4) conditions during both (left) wake periods and (right) sleep periods. An individual subject’s data are represented by connected ○. Note that wake LH pulse frequency was lower with P4 than with PBO in most (10 of 11) subjects, whereas sleep-related LH pulse frequency was lower with P4 in less than one-half (five of 11) of subjects. (b) Mean LH pulse frequency (denoted by ●) in each treatment condition during (left) wake and (right) sleep blocks, with vertical lines denoting 95% confidence intervals. P values in each column relate to the change in LH pulse frequency between treatment conditions. P values relating to the interaction between treatment (PBO vs P4) and sleep status (wake vs sleep) are also shown.

Figure 4.

Secondary outcomes: LH pulse mass, mean LH, and mean FSH as a function of sleep status and treatment condition. Rows illustrate data for (a and b) LH pulse mass, (c and d) mean LH, and (e and f) mean FSH. (a, c, and e) (left) Individual mean data (denoted by connected ○) with placebo (PBO) and progesterone (P4) during wake blocks; (right) individual mean data during sleep blocks. (b, d, and f) (left) Mean data (denoted by ●) for PBO and P4 conditions during wake blocks; (right) mean data during sleep blocks. Vertical lines identify 95% confidence intervals for the mean. P values relate to changes between PBO and P4 conditions. Although not significant, P values relating to the interaction between treatment condition and sleep status are shown.

Figure 5.

Post hoc analyses. (a) Mean LH pulse frequency with placebo (PBO) and progesterone (P4) in each 4-hour time block. Wake time blocks are 1900 to 2300 and 0700 to 1100 hours; sleep time blocks are 2300 to 0300 and 0300 to 0700 hours. Box-and-whisker plots denote the median (line inside the box); mean (open square); 25th and 75th percentiles (bottom and top of box); and minimum and maximum (bottom and top whiskers). (b) The relationship between the percent change in waking LH pulse frequency related to P4 administration and free testosterone measured during the PBO admission (calculated using SHBG and total testosterone measured by LC-MS/MS).