Figure 2.

The attenuated LH surge is rescued by Kp-10 and correlates with reduced production of Kiss1 mRNA under estradiol-positive feedback conditions. A, Kiss1 mRNA in the anterior hypothalamus, which includes the AVPV. Data are expressed as mean ± sem from OVX young (Y) rats primed with estradiol and progesterone (E2 + P; n = 4) or oil (n = 4) and OVX middle-aged (MA) rats primed with E2 + P or oil and killed at 4 h (oil; n = 4, E2 + P; N 4) or 7 h (oil; n = 4, E2 + P; n = 4) after the P or last oil injection. There was no statistical difference in Kiss1 mRNA levels in E2-primed MA rats killed at 4 (n = 4) or 7 h (n = 4) after P; therefore, these data were pooled. The same was true for MA rats primed with oil (n = 4/time point). There was a significant main effect of hormone treatment (F = 44, P < 0.0001), age (F = 5, P < 0.03), and an interaction between hormone treatment and age (F = 7, P < 0.01). a, P < 0.005 vs. all E2 + P groups; b, P < 0.05 vs. Y E2 + P. B–F, Plasma LH levels are expressed as mean ± sem from OVX and E2 + P primed young control rats (Y; n = 6) and middle-aged control rats (MA; n = 7) dialyzed with ACSF and young (Y + Kp-10; n = 6) and middle-aged rats (MA + Kp-10; n = 10) dialyzed with 10 nm Kp-10. Progesterone was injected at 0900 h (time 0). B, LH surge in control rats. C, LH surge in Kp-10-treated rats. D, Total LH (AUC); there was a main effect of age (F = 11, P < 0.01) and an interaction between age and Kp-10 (F = 12, P < 0.001). E, Peak LH; there was a main effect of age (F = 11, P < 0.005) and an interaction between age and Kp-10 (F = 5.5, P < 0.05). F, LH surge onset (h relative to P injection) (Kruskal Wallis = 21.8, P < 0.005). a, P < 0.05 vs. Y; b, P < 0.05 vs. Y + Kp-10; c, P < 0.01 vs. MA + Kp-10.