Figure 4.

Progesterone regulation on secretin expression in vivo and in vitro. A, Real-time polymerase chain reaction (PCR) analysis of secretin messenger RNA (mRNA) level after ovariectomized mice were treated with progesterone (P4), estradiol-17β (E2), or a combination of progesterone and estradiol-17β (P4 + E2), respectively. B, Real-time PCR analysis of secretin mRNA level after ovariectomized mice were treated with progesterone for 1, 3, 12, and 24 hours, respectively. C, Real-time PCR analysis of secretin mRNA level in the uteri of ovariectomized mice injected with oil, P4, or P4 plus mifepristone (RU486) for 24 hours. The ovariectomized mice were injected subcutaneously with P4 (1 mg/mouse) once. For RU486 treatment, ovariectomized mice were injected with RU486 (0.75 mg/mouse) 1 hour before P4 treatment. The mice were killed to collect uteri after 24 hours. D, Real-time PCR of secretin expression after stromal cells were treated with P4, RU486, or P4 plus RU486 for 48 hours. Cultured stromal cells were treated with 1 μmol/L of progesterone (Sigma) for 48 hours or cells were pretreated with RU486 (1 mmol/L, Sigma) 1 hour before progesterone treatment. Then, the cells were collected 48 hours later. E₂ indicates estrogen; P₄, progesterone; *, statistical significance (P < .05; error bars, standard error [SE]).