Figure 1. AgRP neurons drive the HPA axis during fasting.

a, Schematic of Cre-dependent AAV-hM3Dq-mcherry or hM4Di-mCherry injection into the arcuate of Agrp-IRES-Cre mice. b, Time-line for chemogenetic activation of AgRP neurons. c, AgRP neuron stimulation increased corticosterone in fed mice (n = 4 AgRP^mCherry, n = 6 AgRP^hM3Dq. Two-tailed unpaired t-test- *P = 0.0309). d, Time-line for chemogenetic inhibition of AgRP neurons. e, AgRP neuron inhibition reduced fasting corticosterone (n = 7 Agrp^mCherry, n = 8 Agrp^hM4Di. Two-tailed unpaired t-test- **P = 0.0076). f, Schematic of photometry from PVH^Crh neurons and activation of AgRP neurons. g, Representative images of GCaMP6s expression in PVH^Crh neurons and hM3Dq-mCherry expression in AgRP neuron somas and terminals. h, Chemogenetic activation of AgRP neurons increased PVH^Crh neuron activity (n = 4 mice). i, Mean Ca²⁺ signal from PVH^Crh neurons after injection of CNO vs. vehicle (n = 4 mice. Two-tailed paired t-test- **P = 0.0012). j, Injection of vehicle or CNO did not affect Ca2+ signal in PVH^Crh neurons in mCherry-expressing mice (n = 5 mice). k, Mean Ca²⁺ signal from PVH^Crh neurons after injection of CNO vs. vehicle (n = 5 mice. Two-tailed paired t-test- P = 0.5297). l, Chemogenetic inhibition of AgRP neurons reduced PVH^Crh neuron activity (n = 5 mice). m, Mean Ca²⁺ signal from PVH^Crh neurons after injection of CNO vs. vehicle (n = 5 mice. Two-tailed paired t-test- **P = 0.0071). n, Schematic of optogenetic stimulation of AgRP neurons. o, Time-line for optogenetic stimulation of AgRP neurons. p, q, Optogenetic stimulation of AgRP neurons increased ACTH (n = 4 AgRP^GFP, n = 5 AgRP^ChR2. Two-tailed unpaired t-test- **P = 0.0068) (p) and corticosterone (n = 4 AgRP^GFP, n = 6 AgRP^ChR2, two-tailed unpaired t-test- **P = 0.0198) (q). Scale bar = 200 μm. Data represent = mean ± sem.