Developmental programming: excess weight gain amplifies the effects of prenatal testosterone excess on reproductive cyclicity--implication for polycystic ovary syndrome

Abstract

Sheep exposed to testosterone (T) during early to midgestation exhibit reproductive defects that include hypergonadotropism, functional hyperandrogenism, polycystic ovaries, and anovulatory infertility, perturbations similar to those observed in women with polycystic ovary syndrome. Obesity increases the severity of the phenotype in women with polycystic ovary syndrome. To determine whether prepubertal weight gain would exaggerate the reproductive disruptions in prenatal T-treated sheep, pregnant sheep were injected with 100 mg T propionate ( approximately 1.2 mg/kg) im twice weekly, from d 30-90 of gestation. Beginning about 14 wk after birth, a subset of control and prenatal T-treated females were overfed to increase body weight to 25% above that of controls. Twice-weekly progesterone measurements found no differences in timing of puberty, but overfed prenatal T-treated females stopped cycling earlier. Detailed characterization of periovulatory hormonal dynamics after estrous synchronization with prostaglandin F(2alpha) found 100% of controls, 71% of overfed controls, 43% of prenatal T-treated, and 14% of overfed prenatal T-treated females had definable LH surges. Only one of seven overfed prenatal T-treated female vs. 100% of control, 100% of overfed control, and seven of eight prenatal T-treated females exhibited a luteal progesterone increase. Assessment of LH pulse characteristics during the anestrous season found both overfeeding and prenatal T excess increased LH pulse frequency without an interaction between these two variables. These findings agree with the increased prevalence of anovulation observed in obese women with polycystic ovary syndrome and indicate that excess postnatal weight gain amplifies reproductive disruptions caused by prenatal T excess.

Figure 1

Changes in body weight (kilograms) for control (C), OFC, T, and OFT females from birth to 59 wk of age. Beginning at 14 wk of age, a subset of control and T animals were overfed (OFC and OFT). Weights were taken at weekly intervals up to 39 wk and at 2- to 4-wk intervals thereafter. The vertical black line indicates when overfeeding began. The horizontal gray bar indicates the period of twice-weekly P₄ sampling. The arrow indicates the time when a detailed cycle characterization was undertaken.

Figure 2

Plasma P₄ profiles, first P₄ rise (age at puberty; mean ± sem), and end of the first breeding season for control (C), OFC, T, and OFT females. Biweekly P₄ levels were measured starting a few weeks before the expected time of puberty and ending a few weeks after the expected end of the breeding season. The vertical gray line indicates when sampling began during the periovulatory dynamics assessment. Bar graphs show first P₄ rise (puberty) and end of breeding season. Bars with different letters (a vs. b and x vs. y) differed; P < 0.05.

Figure 3

Circulating patterns of daily P₄ in control (C), OFC, T, and OFT females after induction of luteolyis with PGF_2α. Bar graphs show percentage of females with high P₄ levels at the second PGF_2α injection, percentage of females that exhibited a rise in P₄ after PGF_2α, duration of luteal P₄ secretion, and mean peak levels of P₄. Asterisks indicate significant treatment differences: *, P < 0.05; **, P < 0.01.

Figure 4

Circulating patterns of LH (white circles), FSH (black circles), and E₂ (shaded areas) in control, OFC, T, and OFT females after induction of luteolyis with PGF_2α.

Figure 5

LH pulse patterns during the nonbreeding season of control (C), OFC, T, and OFT females are shown on the left. Black circles depict LH pulses identified by the Cluster algorithm. Bar graphs show mean ± sem circulating levels of LH, LH pulse frequency (number of pulses/12 h), interpulse interval, and pulse amplitude (note one T and one OFT died before the anestrus study). White bar, control; gray striped bar, OFC; black bar, T; black striped bar, OFT. Ob, over-fed.