Glucagon-like peptide-1 drives energy metabolism on the synaptic highway

The effect of GLP-1R agonists on the medical triad of obesity, diabetes, and cancer

Glucagon-like peptide-1 receptor (GLP-1R) agonists have garnered significant attention for their therapeutic potential in addressing the interconnected health challenges of diabetes, obesity, and cancer. The role of GLP-1R in type 2 diabetes mellitus (T2DM) is highlighted, emphasizing its pivotal contribution to glucose homeostasis, promoting β-cell proliferation, and facilitating insulin release. GLP-1R agonists have effectively managed obesity by reducing hunger, moderating food intake, and regulating body weight. Beyond diabetes and obesity, GLP-1R agonists exhibit a multifaceted impact on cancer progression across various malignancies. The mechanisms underlying these effects involve the modulation of signaling pathways associated with cell growth, survival, and metabolism. However, the current literature reveals a lack of in vivo studies on specific GLP-1R agonists such as semaglutide, necessitating further research to elucidate its precise mechanisms and effects, particularly in cancer. While other GLP-1R agonists have shown promising outcomes in mitigating cancer progression, the association between some GLP-1R agonists and an increased risk of cancer remains a topic requiring more profound investigation. This calls for more extensive research to unravel the intricate relationships between the GLP-1R agonist and different cancers, providing valuable insights for clinicians and researchers alike.

Neuron-glia crosstalk and inflammatory mediators in migraine pathophysiology

Migraine is a complex neurological disorder with neuroinflammation playing a crucial role in its pathogenesis. This review provides an overview of the neuroinflammation mechanisms in migraine, focusing on both cellular and molecular aspects. At the cellular level, we examine the role of glial cells, including astrocytes, microglia, oligodendrocytes in the central nervous system, and Schwann cells and satellite glial cells in the peripheral nervous system. On the molecular level, we explore the signaling pathways, including IL-1β, TNF-α, IL-6, and non-coding RNAs, that mediate cell interactions or independent actions. Some of the molecular signaling pathways mentioned, such as TNF-α and IL-1β, have been investigated as druggable targets. Recent advancements, such as [11C] PBR28-targeted imaging for visualizing astrocyte activation and single-cell sequencing for exploring cellular heterogeneity, represent breakthroughs in understanding the mechanisms of neuroinflammation in migraine. By considering factors for personalized treatments, estrogen and TRPM8 emerge as promising therapeutic targets regarding sexual dimorphism. These advancements may help bridge the gap between preclinical findings and clinical applications, ultimately leading to more precise and personalized options for migraine patients.

Populations of Hindbrain Glucagon-Like Peptide 1 (GLP1) Neurons That Innervate the Hypothalamic PVH, Thalamic PVT, or Limbic Forebrain BST Have Axon Collaterals That Reach All Central Regions Innervated by GLP1 Neurons

Neurons in the caudal nucleus of the solitary tract (cNTS) and intermediate reticular nucleus (IRt) that express the glucagon gene (Gcg) give rise to glucagon-like peptide 1 (GLP1)-immunopositive axons in the spinal cord and many subcortical brain regions. Central GLP1 receptor signaling contributes to motivated behavior and stress responses in rats and mice, in which hindbrain GLP1 neurons are activated to express c-Fos in a metabolic state-dependent manner. The present study examined whether GLP1 inputs to distinct brain regions arise from distinct subsets of Gcg-expressing neurons, and mapped the distribution of axon collaterals arising from projection-defined GLP1 neural populations. Using our Gcg-Cre knock-in rat model, Cre-dependent adeno-associated virus (AAV) tracing was conducted in adult male and female rats to compare axonal projections of IRt versus cNTS GLP1 neurons. Overlapping projections were observed in all brain regions that receive GLP1 input, with the caveat that cNTS injections produced Cre-dependent labeling of some IRt neurons, and vice versa. In additional experiments, specific diencephalic or limbic forebrain nuclei were microinjected with Cre-dependent retrograde AAVs (AAVrg) that expressed reporters to fully label the axon collaterals of transduced GLP1 neurons. AAVrg injected into each forebrain site labeled Gcg-expressing neurons in both the cNTS and IRt. The collective axon collaterals of labeled neurons entered the spinal cord and every brain region previously reported to contain GLP1-positive axons. These results indicate that the axons of GLP1 neural populations that innervate the thalamic paraventricular nucleus, paraventricular nucleus of the hypothalamus, and/or bed nucleus of the stria terminalis collectively innervate all central regions that receive GLP1 axonal input.

Pharmacological Advances in Incretin-Based Polyagonism: What We Know and What We Don't

The prevalence of obesity continues to rise in both adolescents and adults, in parallel obesity is strongly associated with the increased incidence of type 2 diabetes, heart failure, certain types of cancer, and all-cause mortality. In relation to obesity, many pharmacological approaches of the past have tried and failed to combat the rising obesity epidemic, particularly due to insufficient efficacy or unacceptable side effects. However, while the history of antiobesity medication is plagued by failures and disappointments, we have witnessed over the last 10 years substantial progress, particularly in regard to biochemically optimized agonists at the receptor for glucagon-like peptide-1 (GLP-1R) and unimolecular coagonists at the receptors for GLP-1 and the glucose-dependent insulinotropic polypeptide (GIP). Although the GIP receptor:GLP-1R coagonists are being heralded as premier pharmacological tools for the treatment of obesity and diabetes, uncertainty remains as to why these drugs testify superiority over best-in-class GLP-1R monoagonists. Particularly with regard to GIP, there remains great uncertainty if and how GIP acts on systems metabolism and if the GIP system should be activated or inhibited to improve metabolic outcome in adjunct to GLP-1R agonism. In this review, we summarize recent advances in GLP-1- and GIP-based pharmacology and discuss recent findings and open questions related to how the GIP system affects systemic energy and glucose metabolism.

Activation of arcuate nucleus glucagon-like peptide-1 receptor-expressing neurons suppresses food intake

BACKGROUND

Central nervous system (CNS) control of metabolism plays a pivotal role in maintaining energy balance. In the brain, Glucagon-like peptide 1 (GLP-1), encoded by the proglucagon 'Gcg' gene, produced in a distinct population of neurons in the nucleus tractus solitarius (NTS), has been shown to regulate feeding behavior leading to the suppression of appetite. However, neuronal networks that mediate endogenous GLP-1 action in the CNS on feeding and energy balance are not well understood.

RESULTS

We analyzed the distribution of GLP-1R-expressing neurons and axonal projections of NTS GLP-1-producing neurons in the mouse brain. GLP-1R neurons were found to be broadly distributed in the brain and specific forebrain regions, particularly the hypothalamus, including the arcuate nucleus of the hypothalamus (ARC), a brain region known to regulate energy homeostasis and feeding behavior, that receives dense NTS^Gcg neuronal projections. The impact of GLP-1 signaling in the ARC GLP-1R-expressing neurons and the impact of activation of ARC GLP-1R on food intake was examined. Application of GLP-1R specific agonist Exendin-4 (Exn-4) enhanced a proportion of the ARC GLP-1R-expressing neurons and pro-opiomelanocortin (POMC) neuronal action potential firing rates. Chemogenetic activation of the ARC GLP-1R neurons by using Cre-dependent hM3Dq AAV in the GLP-1R-ires-Cre mice, established that acute activation of the ARC GLP-1R neurons significantly suppressed food intake but did not have a strong impact on glucose homeostasis.

CONCLUSIONS

These results highlight the importance of central GLP-1 signaling in the ARC that express GLP-1R that upon activation, regulate feeding behavior.

Dose titration with the glucagon-like peptide-1 agonist, liraglutide, reduces cue- and drug-induced heroin seeking in high drug-taking rats

Opioid use disorder (OUD), like other substance use disorders (SUDs), is widely understood to be a disorder of persistent relapse. Despite the use of three FDA-approved medications for OUD, typically in conjunction with behavioral treatments, relapse rates remain unacceptably high. Whereas medication assisted therapy (MAT) reduces the risk of opioid overdose mortality, the benefits of MAT are negated when people discontinue the medications. Currently approved medications present barriers to efficient use, including daily visits to a treatment center or work restrictions. With spiking increases in opioid relapse and death, it is imperative to identify new treatments that can reduce the risk of relapse. Recent evidence suggests that glucagon-like peptide-1 receptor agonists (GLP-1RAs), currently FDA-approved to treat obesity and type two diabetes, may be promising candidates to reduce relapse. GLP-1RAs have been shown to reduce relapse in rats, whether elicited by cues, drug, and/or stress. However, GLP-1RAs also can cause gastrointestinal malaise, and therefore, in humans, the medication typically is titrated up to full dose when initiating treatment. Here, we used a rodent model to test whether cue- and drug-induced heroin seeking can be reduced by the GLP-1RA, liraglutide, when the dose is titrated across the abstinence period and prior to test. The results show this titration regimen is effective in reducing both cue-induced heroin seeking and drug-induced reinstatement of heroin seeking, particularly in rats with a history of high drug-taking. Importantly, this treatment regimen had no effect on either circulating glucose or insulin. GLP-1RAs, then, appear strong candidates for the non-opioid prevention of relapse to opioids.

The neuroprotective effects of glucagon-like peptide 1 in Alzheimer's and Parkinson's disease: An in-depth review

Currently, there is no disease-modifying treatment available for Alzheimer's and Parkinson's disease (AD and PD) and that includes the highly controversial approval of the Aβ-targeting antibody aducanumab for the treatment of AD. Hence, there is still an unmet need for a neuroprotective drug treatment in both AD and PD. Type 2 diabetes is a risk factor for both AD and PD. Glucagon-like peptide 1 (GLP-1) is a peptide hormone and growth factor that has shown neuroprotective effects in preclinical studies, and the success of GLP-1 mimetics in phase II clinical trials in AD and PD has raised new hope. GLP-1 mimetics are currently on the market as treatments for type 2 diabetes. GLP-1 analogs are safe, well tolerated, resistant to desensitization and well characterized in the clinic. Herein, we review the existing evidence and illustrate the neuroprotective pathways that are induced following GLP-1R activation in neurons, microglia and astrocytes. The latter include synaptic protection, improvements in cognition, learning and motor function, amyloid pathology-ameliorating properties (Aβ, Tau, and α-synuclein), the suppression of Ca2+ deregulation and ER stress, potent anti-inflammatory effects, the blockage of oxidative stress, mitochondrial dysfunction and apoptosis pathways, enhancements in the neuronal insulin sensitivity and energy metabolism, functional improvements in autophagy and mitophagy, elevated BDNF and glial cell line-derived neurotrophic factor (GDNF) synthesis as well as neurogenesis. The many beneficial features of GLP-1R and GLP-1/GIPR dual agonists encourage the development of novel drug treatments for AD and PD.

Semaglutide early intervention attenuated testicular dysfunction by targeting the GLP-1-PPAR-α-Kisspeptin-Steroidogenesis signaling pathway in a testicular ischemia-reperfusion rat model

Testicular torsion is a serious emergency and a well-known cause of male infertility. It represents 10 %-15 % of scrotal diseases in children. Kisspeptin (KISS1) is a hormone secreted from the hypothalamic nuclei and testis, but its role in testis is not fully understood. Semaglutide is a novel antidiabetic glucagon-like peptide 1 (GLP-1) analog. Hence, we designed the current study to elucidate the possible ameliorative effect of semaglutide on ischemia/reperfusion-induced testicular dysfunction in rats and highlight the role of the testicular GLP-1/PCG-1α-PPAR-α-KISS1 signaling pathway. We randomly divided 50 male Sprague Dawley into five equal groups (10 rats each): SHAM, exendin 9-39 -treated (EX), testicular torsion/detorsion (T/D), testicular torsion/detorsion and semaglutide-treated (SEM + T/D), and testicular torsion/detorsion, exendin, and semaglutide-treated (EX + SEM + T/D). We quantified serum follicle-stimulating hormone, luteinizing hormone, total testosterone, testicular oxidative stress markers, testicular gene expression of GLP-1/KISS1 pathway-related genes (KISS1, KISS1R, GLP-1, GLP-1R, PGC-1α, PPAR-α), steroidogenesis pathway-related genes (STAR, CYP11A1, CYP17A1, HSD17B3, CYP19A1), HO-1, Nrf-2, and testicular protein expression of HIF-1α, TNF-α, NF-κβ, Caspase-3, FAS, proliferating cell nuclear antigen, and KISS1 through testicular histopathology and immunohistochemistry assays. Testicular torsion/detorsion markedly elevated proapoptotic, proinflammatory, and oxidative stress marker levels, noticeably downregulating the expression of GLP-1/KISS1 and steroidogenesis pathway-related proteins. Semaglutide administration significantly ameliorated all these deleterious effects. Nevertheless, injecting exendin, a GLP1-R antagonist, before semaglutide abolished all the documented improvements. We concluded that semaglutide ameliorated ischemia/reperfusion-induced testicular dysfunction by modulating the GLP-1/PGC-1α-PPAR-α/KISS1/steroidogenesis signaling pathway, improving testicular oxidative state, and suppressing testicular inflammation and apoptosis.

The role of glucagon-like peptide 1 (GLP-1) in addictive disorders

Drug-, alcohol- and tobacco use disorders are a global burden affecting millions of people. Despite decades of research, treatment options are sparse or missing, and relapse rates are high. Glucagon-like peptide-1 (GLP-1) is released in the small intestines, promotes blood glucose homeostasis, slows gastric emptying, and reduces appetite. GLP-1 receptor agonists approved for treating type 2 diabetes mellitus and obesity, have received attention as a potential anti-addiction treatment. Studies in rodents and non-human primates have demonstrated a reduction in intake of alcohol and drugs of abuse, and clinical trials have been initiated to investigate whether the preclinical findings can be translated to patients. This review will give an overview of current findings and discuss the possible mechanisms of action. We suggest that effects of GLP-1 in alcohol- and substance use disorder is mediated centrally, at least partly through dopamine signalling, but precise mechanisms are still to be uncovered.

Activation of microglial GLP-1R in the trigeminal nucleus caudalis suppresses central sensitization of chronic migraine after recurrent nitroglycerin stimulation

Background

Central sensitization is considered a critical pathogenic mechanism of chronic migraine (CM). Activation of microglia in the trigeminal nucleus caudalis (TNC) contributes to this progression. Microglial glucagon-like peptide-1 receptor (GLP-1R) activation can alleviate pain; however, whether it is involved in the mechanism of CM has not been determined. Thus, this study aims to investigate the precise role of GLP-1R in the central sensitization of CM.

Methods

Repeated nitroglycerin injection-treated mice were used as a CM animal model in the experiment. To identify the distribution and cell localization of GLP-1R in the TNC, we performed immunofluorescence staining. Changes in the expression of GLP-1R, Iba-1, PI3K and p-Akt in the TNC were examined by western blotting. To confirm the effect of GLP-1R and PI3K/Akt in CM, a GLP-1R selective agonist (liraglutide) and antagonist (exendin(9–39)) and a PI3K selective antagonist (LY294002) were administered. Mechanical hypersensitivity was measured through von Frey filaments. To investigate the role of GLP-1R in central sensitization, calcitonin gene-related peptide (CGRP) and c-fos were determined using western blotting and immunofluorescence. To determine the changes in microglial activation, IL-1β and TNF-α were examined by western blotting, and the number and morphology of microglia were measured by immunofluorescence. We also confirmed the effect of GLP-1R on microglial activation in lipopolysaccharide-treated BV-2 microglia.

Results

The protein expression of GLP-1R was increased in the TNC after nitroglycerin injection. GLP-1R was colocalized with microglia and astrocytes in the TNC and was fully expressed in BV-2 microglia. The GLP-1R agonist liraglutide alleviated basal allodynia and suppressed the upregulation of CGRP, c-fos and PI3K/p-Akt in the TNC. Similarly, the PI3K inhibitor LY294002 prevented nitroglycerin-induced hyperalgesia. In addition, activating GLP-1R reduced Iba-1, IL-1β and TNF-α release and inhibited TNC microglial number and morphological changes (process retraction) following nitroglycerin administration. In vitro, the protein levels of IL-1β and TNF-α in lipopolysaccharide-stimulated BV-2 microglia were also decreased by liraglutide.

Conclusions

These findings suggest that microglial GLP-1R activation in the TNC may suppress the central sensitization of CM by regulating TNC microglial activation via the PI3K/Akt pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10194-021-01302-x.

The role of linagliptin, a selective dipeptidyl peptidase-4 inhibitor, in the morphine rewarding effects in rats

Linagliptin is a selective dipeptidyl peptidase-4 (DPP-4) inhibitor which suppresses the rapid degradation of endogenous glucagon-like peptide-1 (GLP-1). In clinical practice, it is used as an antidiabetic drug, but recent studies have confirmed its role in the activity of the central nervous system (CNS). The reported study focused on the role of linagliptin (10 and 20 mg/kg, ip) in the morphine rewarding effect, analyzing how the agent had influenced the conditioned place preference (CPP) in rats via the expression, acquisition, extinction and reinstatement of the morphine rewarding effect. The obtained results clearly demonstrated linagliptin to inhibit the expression and acquisition, to accelerate the extinction and, eventually, to reduce the reinstatement of morphine-induced CPP. The undertaken experiments significantly extended our knowledge on the mechanisms behind the morphine rewarding effect.

Glucagon-Like Peptide-1 Receptor Agonist Treatment Does Not Reduce Abuse-Related Effects of Opioid Drugs

Dependence on opioids and the number of opioid overdose deaths are serious and escalating public health problems, but medication-assisted treatments for opioid addiction remain inadequate for many patients. Glucagon-like pepide-1 (GLP-1) is a gut hormone and neuropeptide with actions in peripheral tissues and in the brain, including regulation of blood glucose and food intake. GLP-1 analogs, which are approved diabetes medications, can reduce the reinforcing and rewarding effects of alcohol, cocaine, amphetamine, and nicotine in rodents. Investigations on effects of GLP-1 analogs on opioid reward and reinforcement have not been reported. We assessed the effects of the GLP-1 receptor agonist Exendin-4 (Ex4) on opioid-related behaviors in male mice, i.e., morphine-conditioned place preference (CPP), intravenous self-administration (IVSA) of the short-acting synthetic opioid remifentanil, naltrexone-precipitated morphine withdrawal, morphine analgesia (male and female mice), and locomotor activity. Ex4 treatment had no effect on morphine-induced CPP, withdrawal, or hyperlocomotion. Ex4 failed to decrease remifentanil self-administration, if anything reinforcing effects of remifentanil appeared increased in Ex4-treated mice relative to saline. Ex4 did not significantly affect analgesia. In contrast, Ex4 dose dependently decreased oral alcohol self-administration, and suppressed spontaneous locomotor activity. Taken together, Ex4 did not attenuate the addiction-related behavioral effects of opioids, indicating that GLP-1 analogs would not be useful medications in the treatment of opioid addiction. This difference between opioids and other drug classes investigated to date may shed light on the mechanism of action of GLP-1 receptor treatment in the addictive effects of alcohol, central stimulants, and nicotine.

Resistance Exercise Training Attenuates the Loss of Endogenous GLP-1 Receptor in the Hypothalamus of Type 2 Diabetic Rats

The aim of this study was to investigate the effects of resistance exercise training on hypothalamic GLP-1R levels and its related signaling mechanisms in T2DM. The animals were separated into three groups: a non-diabetic control (CON), diabetic control (DM), and diabetic with resistance exercise (DM + EXE) group. The resistance exercise training group performed ladder climbing (eight repetitions, three days per week for 12 weeks). Body weight was slightly lower in the DM + EXE group than the DM group, but difference between the groups was not significant. Food intake and glucose were significantly lower in the DM + EXE group than in the DM group. The blood insulin concentration was significantly higher and glucagon was significantly lower in the DM + EXE group. The DM + EXE group in the hypothalamus showed significant increases in GLP-1R mRNA, protein kinase A (PKA), glucose transporter 2 (GLUT2), and protein kinase B (AKT) and significant decrease in protein kinase C-iota (PKC-iota). Antioxidant enzymes and apoptosis factors were significantly improved in the DM + EXE group compared with the DM group in the hypothalamus. The results suggest that resistance exercise contributes to improvements the overall health of the brain in diabetic conditions.

Inhibition of DPP4 enhances inhibitory synaptic transmission through activating the GLP-1/GLP-1R signaling pathway in a rat model of febrile seizures

Dipeptidyl peptidase-IV (DPP4) is a cell surface serine peptidase widely expressed in the brain. Recent studies suggest that DPP4 contributes to the development of febrile seizures (FS); however, the underlying mechanism is still unclear. Thus, we investigated the role of DPP4 in the progression of FS at the molecular and electrophysiological levels using FS models in vivo and in vitro. Herein, we found that both the mRNA and protein levels of DPP4 were upregulated in the FS model. Administration of the pharmacological DPP4 inhibitor sitagliptin suppressed the hyperthermia-induced neuronal excitability as determined via whole-cell patch-clamp recordings in vitro. Interestingly, sitagliptin administration activated the glucagon-like peptide-1 (GLP-1)/GLP-1 receptor (GLP-1R) pathway by increasing the expression of GLP-1 and GLP-1R in a rat model of FS. Moreover, administration of the GLP-1R inhibitor exendin9-39 increased seizure severity, and sitagliptin reversed the effect, as shown in the electroencephalogram (EEG) and patch-clamp results in a rat model of FS. Furthermore, the GLP-1R-mediated reduction in GABAergic transmission was enhanced by sitagliptin and DPP4 knockdown through increasing miniature inhibitory post-synaptic currents (mIPSCs) in vitro accompanied by increased synaptic release of GABA in vivo. Taken together, our results demonstrate a role of DPP4 in regulating GABAergic transmission via the GLP-1/GLP-1R pathway. These findings indicated that DPP4 may represent a novel therapeutic strategy and target for FS.

Cognitive dysfunction and metabolic comorbidities in mood disorders: A repurposing opportunity for glucagon-like peptide 1 receptor agonists?

Major depressive disorder and bipolar disorder are highly prevalent and disabling conditions. Cognition is considered a core domain of their psychopathology and a principle mediator of psychosocial impairment, disproportionately accounting for overall illness-associated costs. There are few interventions with replicated evidence of efficacy in treating cognitive deficits in mood disorders. Evidence also indicates that cognitive deficits are associated with obesity and involve significant impairment across multiple domains. Conversely, weight-loss interventions, such as physical exercise and bariatric surgery, have been shown to beneficially affect cognitive function. This convergent phenomenology suggests that currently available agents that target metabolic systems may also be capable of mitigating deficits in cognitive functions, and are, therefore, candidates for repurposing. The incretin glucagon-like peptide-1 (GLP-1) is a hormone secreted by intestinal epithelial cells. GLP-1 receptors (GLP-1R) are widely expressed in the central nervous system. Activation of GLP-1R leads to facilitation of glucose utilization and antiapoptotic effects in various organs. Pre-clinical trials have demonstrated significant neuroprotective effects of GLP-1, including protection from cell death, promotion of neuronal differentiation and proliferation; and facilitation of long-term potentiation. Liraglutide is a GLP-1R agonist that has been approved for the treatment of type 2 diabetes mellitus and obesity. Convergent preclinical and clinical evidence, including a proof-of-concept pilot study from group, has suggested that liraglutide may improve objective measures of cognitive function in adults with mood disorders. The safety and availability of GLP-1R agonists indicate that they are promising candidates for repurposing, and that they may be viable therapeutic options for mood disorders. This article is part of the Special Issue entitled 'Metabolic Impairment as Risk Factors for Neurodegenerative Disorders.'

Exenatide exerts cognitive effects by modulating the BDNF-TrkB neurotrophic axis in adult mice

Modulation of insulin-dependent signaling is emerging as a valuable therapeutic tool to target neurodegeneration. In the brain, the activation of insulin receptors promotes cell growth, neuronal repair, and protection. Altered brain insulin signaling participates in the cognitive decline seen in Alzheimer's disease patients and the aging brain. Glucagon-like peptide-1 (GLP-1) regulates insulin secretion and, along with GLP-1 analogues, enhances neurotrophic signaling and counteracts cognitive deficits in preclinical models of neurodegeneration. Moreover, recent evidence indicates that GLP-1 modulates the activity of the brain-derived neurotrophic factor (BDNF). In this study, in adult wild-type mice, here employed as a model of mid-life brain aging, we evaluated the effects of a 2-month treatment with exenatide, a GLP-1 analogue. We found that exenatide promotes the enhancement of long-term memory performances. Biochemical and imaging analyses show that the drug promotes the activation of the BDNF-TrkB neurotrophic axis and inhibits apoptosis by decreasing p75NTR-mediated signaling. The study provides preclinical evidence for the use of exenatide to delay age-dependent cognitive decline.

Enhanced AMPA Receptor Trafficking Mediates the Anorexigenic Effect of Endogenous Glucagon-like Peptide-1 in the Paraventricular Hypothalamus

Glucagon-like Peptide 1 (GLP-1)-expressing neurons in the hindbrain send robust projections to the paraventricular nucleus of the hypothalamus (PVN), which is involved in the regulation of food intake. Here, we describe that stimulation of GLP-1 afferent fibers within the PVN is sufficient to suppress food intake independent of glutamate release. We also show that GLP-1 receptor (GLP-1R) activation augments excitatory synaptic strength in PVN corticotropin-releasing hormone (CRH) neurons, with GLP-1R activation promoting a protein kinase A (PKA)-dependent signaling cascade leading to phosphorylation of serine S845 on GluA1 AMPA receptors and their trafficking to the plasma membrane. Finally, we show that postnatal depletion of GLP-1R in the PVN increases food intake and causes obesity. This study provides a comprehensive multi-level (circuit, synaptic, and molecular) explanation of how food intake behavior and body weight are regulated by endogenous central GLP-1. VIDEO ABSTRACT.