(A) Schematic showing experimental protocol with GnRH-Cre mice injected with Cre-dependent Flex-hM4D(Gi)-mCherry AAVs bilaterally into the region of the median eminence and CNO given into the same region. MS, medial septum. CNO, Clozapine N-oxide. (B) Fluorescence images of GnRH neuron projections in the vicinity of the median eminence expressing GnRH (green) and mCherry (red) in GnRH::Flex-hM4D(Gi)-mCherry mice. Scale bar, 20 μm. (C,D) LH surge profiles in all GnRH-Cre OVX+E+P female mice following MBH injection of saline (C, n = 12) or CNO (D, n = 12). (E) Mean (± SEM) LH levels. ***p<0.001, two-way repeated measures ANOVA with Holm-Sidak test. F-J. Representative examples of pulsatile LH secretion in OVX GnRH-Cre mice given saline (F,G) or CNO (I,J). LH pulses are indicated by asterisks. Mean (± SEM) amplitude (H) and frequency (K) of LH pulses in saline (n = 8) and CNO (n = 7). ***p<0.001,*p<0.05 Mann-Whitney U-tests.