Effects of KNDy neuron ablation on Serum LH (mean ± SEM, n = 6–8 rats/ group). On day 0, rats were ovariectomized (OVX) and injected with NK3-SAP (KNDy ablated) or Blank-SAP in the arcuate nucleus. From 20 to 23 days later and they were implanted s.c. with E2 capsules and sacrificed 11 days later. In Blank-SAP controls, serum LH was markedly increased after ovariectomy and reduced by E2 treatment. In KNDy-ablated rats, LH did not significantly rise three weeks after OVX. Serum LH was also lower in KNDy ablated rats, vs Blank-SAP controls after estrogen treatment. These data show that KNDy neurons are essential for the rise in LH secretion after ovariectomy and tonic LH secretion in estrogen-treated rats. # Significantly different, Blank-SAP vs. NK3-SAP. + Significantly different from intact values on day 0. * Significantly reduced after E2 treatment (compared to OVX). Modified with permission from Mittelman-Smith et al. (2012b).