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Introduction: Glucagon-like peptide 1 (GLP-1) therapeutics have experienced a meteoric rise in adoption, but our understanding of the endogenous systems that produce GLP-1 and how they regulate behavior remain incomplete. Preproglucagon neurons in the nucleus of the solitary tract (GcgNTS neurons) are the primary source of GLP-1 in the brain. In this study, we examined the neurophysiological and causal contributions of GcgNTS neurons to consummatory and valence behavior. Methods: electrophysiology, in vivo optogenetics, fiber photometry. Results: Using electrophysiology, we observed that GcgNTS neuron neural firing and excitability is reduced in response to 24-hour food deprivation that varied by sex. Conversely, GcgNTS neurons significantly increase their firing rate after a brief 1-hour chow refeed after food deprivation. Consistent with this, GcgNTS neurons display elevated Fos levels following binge-like consumption of palatable high-fat diet. Using in vivo optogenetics, we observed that optogenetic activation of GcgNTS neurons produced anxiety and negative valence that varied by sex. High-frequency activation of GcgNTS neurons also reduced feeding and appetitive behavior. Interestingly, high-frequency activation of GcgNTS neurons produced lasting effects that persisted after cessation of laser illumination. Using a novel transgenic mouse, Gcg-IRES-FlpO, crossed to Glp1r-Cre mice combined with viral and transgenic reporters, we found that GcgNTS neurons and Glp1r neurons in the hypothalamus and amygdala make reciprocal connections. Currently, we are measuring functional connections between GcgNTS neurons and Glp1r neurons in the paraventricular nucleus of the hypothalamus and amygdala. Conclusions: GcgNTS neurons control valence and consumption, interacting with an interconnected GLP-1R-expressing network in the hypothalamus and amygdala. Disclosure M. Duran: None. S. Virkus: None. K.A. McMichen: None. Y. Andrade Cavalcante Moraes: None. E. Yadav: None. J.K. Singh: None. Z. Fokakis: None. S.Q. Stocking: None. S.O. Poole: None. C.S. Hunter: None. K.M. Habegger: Research Support; Eli Lilly and Company. Consultant; Glyscend Inc. Stock/Shareholder; Glyscend Inc. Consultant; Merck Novo Nordisk. Advisory Panel; Abvance Therapeutics. J.A. Hardaway: None. Funding K01DK115902R03DK129561P30DK079626P30DK056336
Duran et al. (Fri,) studied this question.