More GnRH neurons express cFOS following high-fat diet (HFD). a Coronal sections of the preoptic area in the hypothalamus of GnRH-GFP mice following HFD stained for GFP (green) and cFOS (red). White arrows indicate GnRH neurons labeled with GFP and cFOS. Numbered squares correspond to enlarged areas below; 1, GnRH neurons green, cFOS red; arrows indicate GnRH neurons that express cFOS, an arrowhead points to the GnRH neuron without cFOS; 2–3, DAPI channel is included to facilitate cell count; nuclei blue, cFOS magenta. Arrows indicate cells labeled with cFOS and DAPI. b Quantification of neurons expressing cFOS in control (CTR, white bars) and HFD male mice (black bars): 1, increase in the percent of GnRH neurons with cFOS is observed in HFD compared to control. 2, quantification of the neurons that express cFOS, proximal to the OVLT delineated with #2 square; 3, quantification of the neurons that express cFOS, dorsally from the OVLT delineated with #3 square following control and HFD. Three hundred GnRH neurons were counted in each mouse. Statistical significance (p < 0.05), indicated by an asterisk, was determined with the t test.