GLP-1 (Glucagon-Like Peptide-1) has evolved from a mere glucose-lowering target into a phenomenal sector within global biomedicine. With the success of drugs like Semaglutide and Tirzepatide, the market for GLP-1 Receptor Agonists (GLP1RAs) is projected to exceed $100 billion by 2030. The core logic behind these drugs lies in activating the GLP-1 Receptor (GLP-1R) to drive glucose-lowering, weight-loss, and organ-protective effects. Currently, the R&D focus is shifting from single-target agents to multi-target drugs like GLP-1R/GIPR and GLP-1R/GCGR agonists. This article provides an in-depth analysis of the molecular mechanisms of GLP-1R and explores research progress and preclinical model applications for this target across multiple organ systems.
 

Target Introduction
 

The Glucagon-Like Peptide-1 Receptor (GLP-1R) belongs to the Class B G protein-coupled receptor (GPCR) family and is a core effector molecule of the incretin system. The discovery of GLP-1R dates back to the 1980s when researchers isolated exendin-4 from the saliva of the Gila monster—a peptide hormone sharing 53% sequence homology with mammalian GLP-1 but resistant to degradation by Dipeptidyl Peptidase-4 (DPP-4).
 

GLP-1R is widely expressed in pancreatic β-cells, α-cells, the gastrointestinal tract, the central nervous system (especially the hypothalamus and brainstem), the heart, kidneys, and vascular endothelial cells. This systemic expression pattern dictates the multi-organ protective effects of GLP-1R agonists (GLP1RAs)—regulating blood glucose and body weight while influencing cardiovascular, renal, and neurological functions.
 

Activation of GLP-1R couples to Gs proteins, elevating intracellular cAMP levels, which in turn activates PKA and EPAC signaling pathways. In pancreatic β-cells, this signaling promotes glucose-dependent insulin secretion and inhibits glucagon release, achieving precise glycemic control. In the CNS, GLP-1R activation stimulates appetite-regulating neurons in the hypothalamus (e.g., POMC neurons), enhances satiety, and inhibits gastric emptying, thereby reducing food intake. Furthermore, in the cardiovascular system, GLP-1R exerts protective effects on vascular endothelial function by inhibiting oxidative stress and inflammatory responses.
 

Core Diseases and Mechanisms
 

Type 2 Diabetes Mellitus (T2DM) and Obesity:
 

During the progression of T2DM and obesity, defects in endogenous GLP-1 secretion and downregulation of GLP-1R expression in β-cells lead to impaired Gs-cAMP-PKA/Epac signaling cascades. This results in the loss of Glucose-Dependent Insulinotropic Polypeptide (GDIS) function and abnormal glucagon suppression. Concurrently, against a backdrop of chronic hyperinsulinemia and leptin resistance, GLP-1R-mediated satiety signaling in the hypothalamic appetite center is obstructed. This manifests as inhibited POMC neuron activation and excessive excitation of AgRP/NPY neurons, ultimately triggering central appetite dysregulation.

 

Image source: Glucagon-like peptide-1 receptor: mechanisms and advances in therapy
 

Cardiovascular Disease (CVD):
 

Beyond direct regulation of glucose and lipid metabolism, GLP-1R signaling plays a vital role in maintaining vascular homeostasis. In diabetic and obese states, systemic chronic inflammation and oxidative stress continuously attack the vascular endothelium, potentially leading to downregulation of GLP-1R within the vascular system. Weakened receptor function reduces the efficiency of eNOS-mediated vasodilatory signaling and diminishes anti-inflammatory pathway activity, potentially accelerating atherosclerotic plaque formation and destabilization.
 

Non-Alcoholic Fatty Liver Disease (NAFLD/NASH):
 

The liver, as a core metabolic organ, is also regulated by GLP-1R signaling. Insulin resistance drives excessive peripheral fat breakdown, causing a massive influx of Free Fatty Acids (FFA) into the liver and triggering ectopic lipid deposition. Within this sustained lipotoxic microenvironment, GLP-1R expression on the surface of hepatic sinusoidal endothelial cells may be downregulated, depriving the liver of crucial metabolic buffering and protective signals. Meanwhile, unchecked lipotoxicity may activate Hepatic Stellate Cells (HSCs) and the TGF-β/Smad pathway, promoting the rapid progression from NAFLD to NASH and cirrhosis.
 

Alzheimer's Disease (AD) and Parkinson's Disease (PD):
 

In recent years, the role of GLP-1R in the central nervous system has garnered increasing attention, with abnormal signaling potentially linked to neurodegenerative diseases. In the context of brain insulin resistance, weakened GLP-1R signaling in neurons may impair the normal regulatory function of the PI3K/Akt pathway. Notably, the PI3K/Akt pathway primarily exerts inhibitory effects on autophagy regulation; thus, diminished GLP-1R signaling may indirectly weaken the negative regulation of autophagy, leading to impaired clearance of toxic proteins (Aβ, tau, α-syn). Additionally, impaired GLP-1R function in astrocytes may reduce the secretion of neurotrophic factors, exacerbating synaptic damage.
 

Research Landscape
 

Based on the aforementioned multi-organ protective mechanisms, GLP-1R has evolved from a simple glucose-lowering target into a "versatile player" in metabolic disease therapy, with R&D pipelines and clinical translation strategies adapting accordingly. Currently, the global R&D pipeline is highly active, involving over 700 drugs and nearly 5,000 development statuses, covering the entire lifecycle from preclinical to marketed stages. Existing drugs primarily activate the Gs-cAMP-PKA pathway to achieve glucose-dependent insulin secretion, appetite suppression, and cardiovascular protection. The development trend has shifted from single-target (GLP-1R) to dual/triple agonist agents (e.g., GLP-1/GIP, GLP-1/GCG), achieving stronger weight loss and metabolic improvements through multi-hormonal synergy.
 

In this R&D wave, preclinical animal models serve as a critical bridge connecting basic mechanisms to clinical translation, and their importance is increasingly prominent. Future GLP-1R R&D will focus on two directions: First, precision medicine—developing tissue-specific or allosteric modulators based on receptor distribution differences in the central nervous system, pancreas, etc., to mitigate gastrointestinal side effects. Second, cross-domain applications—expanding indications to neurodegenerative diseases (e.g., Alzheimer's), chronic kidney disease, and MASH (Metabolic Dysfunction-Associated Steatotic Hepatitis, formerly NAFLD/NASH). Coupled with breakthroughs in AI drug design and oral peptide technology, the GLP-1R target is poised to provide safer, long-acting solutions in the fields of metabolism and its associated diseases. Validating these complex multi-target mechanisms and cross-indication adaptations heavily relies on preclinical animal model verification.
 

Application of Preclinical Mouse Models
 

In the R&D of GLP-1R-targeted drugs, genetically engineered mouse models are core tools for validating target function and evaluating the efficacy and safety of candidate drugs. Two models are particularly critical:
 

GLP-1R KO Mice:​ Global knockout of the Glp1rgene, used to study the fundamental impact of receptor deficiency on glucose metabolism, insulin secretion, and appetite regulation. It is a core tool for validating GLP-1 pathway functionality.
 

GLP-1R Humanized Mice:​ Replacement of the mouse Glp1rgene with the human GLP1Rgene, specifically used to evaluate the in vivo efficacy and safety of agonists or antagonists targeting human GLP-1R.
 

Supporting Mechanism Research and Drug Development
 

In the current fiercely competitive GLP-1 sector, R&D speed is the deciding factor for success. MingCeler Biotech's self-developed TurboMice™ technology overcomes the bottlenecks of traditional modeling, enabling efficient editing at almost any target gene locus. By bypassing traditional breeding and screening, it allows for the preparation of complete homozygous gene-edited mouse models directly from embryonic stem cells in as little as two months.
 

MingCeler Biotech​ supports the customization of various GLP-1R-related mouse models according to client needs, such as GLP-1R KO mice and GLP-1R humanized mice, assisting you in rapidly seizing the critical R&D window period.
 

References:
 

1.Zheng, Z., Zong, Y., Ma, Y. et al. Glucagon-like peptide-1 receptor: mechanisms and advances in therapy. Sig Transduct Target Ther9, 234 (2024). https://doi.org/10.1038/s41392-024-01931-z

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