Effects of GnRH-specific deletion of CREB on estrogen negative feedback mechanisms. A, Chart summarizing the serum LH levels in mice before OVX (intact), 1 week after OVX, and 3 h after treatment with E2. B, C, Intact serum LH levels (B) and the increment from basal LH level (C) after OVX. D, LH levels decrease after treatment with E2 normalized to post-OVX LH levels. The histograms show the means (+SEM); n = 9–16. *p < 0.05; **p < 0.01; ***p < 0.001 (ANOVA with Tukey's post hoc test).