Reduced estradiol negative feedback in GKirKO mice. A and B, Serum LH and FSH levels in intact WT control mice in metestrus and intact GKirKO mice (noncycling) compared with OVX WT control mice and OVX GKirKO mice, respectively (n = 4–11). C and D, Kiss1 mRNA in AVPV nucleus and ARC nucleus of intact WT control mice in metestrus and intact GKirKO mice compared with OVX WT control mice and OVX GKirKO mice, respectively (n = 4–5). Significant differences compared with intact WT and GKirKO control groups: *, P ≤ .05; **, P ≤ .01; ***, P ≤ .001. Two-way ANOVA showed an interaction between genotype and treatment in A (P ≤ .001) and B (P ≤ .001), an effect of treatment in A, B, C, and D (P ≤ .001) and an effect of genotype in A and B (P ≤ .001).