a, Schematic of Mc4r-t2a-Cre locus. b, Single cell RNA sequencing validation of individual PVHGFP (n=31), PVHnon-GFP (n=5) and ARC (n=30) neurons demonstrating endogenous Mc4r mRNA only in PVHGFP cells. c–f, CRACM from ARCAgRP neurons (red) onto putative post-synaptic PVH neurons demonstrating monosynaptic inhibitory input onto 83% of PVHMC4R (c), 20% of non-MC4R PVH (d), but not onto PVHOXT (e) or PVHCRH (f) neurons. g, In vivo optogenetic occlusion schematic involving concomitant stimulation of MC4R/OXT soma and ARCAgRP terminals in the PVH. h, ARCAgRP→PVH (n=7) ChR2-driven light-cycle food intake was significantly attenuated by simultaneous activation of PVHMC4R (n=10), but not PVHOXT (n=8), soma (Repeated measures ANOVA, main effect of treatment (F(1,22)=240.99, p<0.0001), main effect of genotype (F(2,22)=16.88, p<0.0001) and interaction (F(2,22)=25.95, p<0.0001); post-hoc: ARCAgRP→PVH (pre vs stim), ****p<0.0001; ARCAgRP→PVHMC4R (pre vs stim), **p=0.0036; ARCAgRP→PVHOXT (pre vs stim), ****p<0.0001; ARCAgRP→PVH vs ARCAgRP→PVHMC4R, ****p<0.0001). i, All mice in (h) exhibited comparable levels of ARCAgRP ChR2-mCherry transduction (One-way ANOVA, F(3,23)=0.41, p=0.66). Abbreviations, 3v, third ventricle; PTX, picrotoxin. Scale bar in panel c, 100 μm and relates to all images. All values presented as mean±SEM.