Changing levels of estrogen alters the biophysical properties and morphology of Kiss1 neurons. A, B, Bar graphs of the mean steady-state capacitance of Kiss1 neurons of the preoptic area (AVPV/PeN) and Arc nuclei. Chronic estradiol treatment (OVX+E2) induces a significant increase in the mean steady-state capacitance of type I (firing) and type II (quiescent) AVPV/PeN Kiss1 neurons compared with lack of gonadal hormones (OVX). Opposite effect was observed in the Arc, where OVX+E2 induced a decrease in the mean steady-state capacitance of Arc Kiss1 neurons. C, D, Bar graphs showing the mean area of Kiss1 neurons of the AVPV/PeN (C) and Arc (D) from female mice at different estrogen milieu (ovariectomized/OVX and OVX+E2). E, F, Fluorescent photomicrographs showing examples of Kiss1 neurons (GFP immunoreactivity) in the Arc. Arc Kiss1 neurons from OVX mice exhibited increased neuronal area compared with OVX+E2. Data are presented as mean ± SEM, *p < 0.05. Scale bar, 10 μm.