Extrahypothalamic GABAergic nociceptin–expressing neurons regulate AgRP neuron activity to control feeding behavior
Mark A. Smith, … , Hanns Ulrich Zeilhofer, Dominic J. Withers
Mark A. Smith, … , Hanns Ulrich Zeilhofer, Dominic J. Withers
Published September 26, 2019
Citation Information: J Clin Invest. 2020;130(1):126-142. https://doi.org/10.1172/JCI130340.
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Research Article Metabolism Neuroscience

Extrahypothalamic GABAergic nociceptin–expressing neurons regulate AgRP neuron activity to control feeding behavior

Abstract

Arcuate nucleus agouti–related peptide (AgRP) neurons play a central role in feeding and are under complex regulation by both homeostatic hormonal and nutrient signals and hypothalamic neuronal pathways. Feeding may also be influenced by environmental cues, sensory inputs, and other behaviors, implying the involvement of higher brain regions. However, whether such pathways modulate feeding through direct synaptic control of AgRP neuron activity is unknown. Here, we show that nociceptin-expressing neurons in the anterior bed nuclei of the stria terminalis (aBNST) make direct GABAergic inputs onto AgRP neurons. We found that activation of these neurons inhibited AgRP neurons and feeding. The activity of these neurons increased upon food availability, and their ablation resulted in obesity. Furthermore, these neurons received afferent inputs from a range of upstream brain regions as well as hypothalamic nuclei. Therefore, aBNST GABAergic nociceptin neurons may act as a gateway to feeding behavior by connecting AgRP neurons to both homeostatic and nonhomeostatic neuronal inputs.

Authors

Mark A. Smith, Agharul I. Choudhury, Justyna A. Glegola, Paulius Viskaitis, Elaine E. Irvine, Pedro Caldas Custodio de Campos Silva, Sanjay Khadayate, Hanns Ulrich Zeilhofer, Dominic J. Withers

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Figure 6

Activity of aBNST nociceptin neurons increases during the initiation of feeding.

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Activity of aBNST nociceptin neurons increases during the initiation of ...
(A) Diagram illustrating injection of DOGCre and jRGECO1a AAVs into the aBNST of Pnoc-EGFP mice for ex vivo imaging and recording. (B) Simultaneous measurements of electrical excitability (Vm, top) and fluorescence intensity (ΔF/F, bottom) in aBNST jRGECO1a–expressing neurons (n = 3). Action potential firing was evoked by depolarizing current injections (I-Inj.) and correlated with increased fluorescence. (C and D) Image of aBNST neuron (C) and corresponding changes in spontaneous jRGECO1a fluorescence (ΔF/F) (D) at 590 nm but not 488 nm (n = 5). (E) Diagram illustrating injection of DOGCre and jRGECO1a AAVs into the aBNST of Pnoc-EGFP mice, with implantation of optical fibers into the aBNST. (F) jRGECO1a expression in the aBNST and optical fiber location. (G) Illustration of the open-field arena containing 2 pots (with a novel object or food). (H) Fluorescence intensity (ΔF/F) in mice approaching a novel object (blue) or initiating feeding (red). Data represent the mean ± SEM. n = 7 mice. Two-way repeated-measures ANOVA [interaction: f (239,2868) = 1.44, P < 0.0001; time: f (239,2868) = 1.35, P < 0.001; feeding versus object: f (1,12) = 2.70, P = 0.14]. (I) Diagram of intercrossed Pnoc-EGFP and Agrp-Cre mice injected with DOG-flpo and flp-dependent ChR2-mCherry AAVs into the aBNST and Cre-dependent jRGECO1a AAV into the arcuate nucleus. Optical fibers were placed in the aBNST for ChR2 stimulation and in the arcuate nucleus for jRGECO1a activity recording. (J) Fluorescence intensity (ΔF/F) in AgRP neurons before and after aBNST photostimulation, where indicated. Data indicate the mean ± SEM. n = 5 mice. (K) AgRP activity (ΔF/F) for mice shown in J before (Ctrl.) and after stimulation (Stim.). Data represent the mean ± SEM. *P < 0.05, by paired t test [t (4) = 2.97, P = 0.041]. Scale bars: 20 μm (C) and 200 μm (F).