Mean ± SEM LH concentrations (ng/ml) in male (A) and (C) and female (B) and (D) adult WT and homozygous Kiss1Cre/Cre (i.e., Kiss1 KO) mice. Blood samples were collected before (basal) and 25 min after ICV injection of senktide (an NK3R-specific agonist; 600 pmol diluted in 5 µl 0.9% NaCl). (A, B) Mean ± SEM LH concentrations (ng/ml) in adult WT male and female mice gonadectomized (WTORX or WTOVX, respectively) and studied in parallel to hypogonadal (with low sex steroid levels) Kiss1Cre/Cre (i.e., Kiss1 KO) littermates (n = 7–10/group). (C, D) Mean ± SEM LH concentrations (ng/ml) in adult gonadectomized WT and Kiss1Cre/Cre (i.e., Kiss1 KO) male and female mice supplemented with testosterone or estradiol, respectively (WTORX+T, WTOVX+E2, Kiss1 KO+T, Kiss1 KO+E2; n = 5–10/group). Basal versus after senktide injection LH concentrations were compared with a paired t-test ****p < 0.0001, **p < 0.007. T = testosterone, E2 = estradiol.