GLP-3(Reta) | Triple-Agonist Metabolic Research

Looking for a high-quality GLP1 receptor agonist peptide for your research? Spartan Peptides offers GLP-3 Reta (GLP1-R) 6mg, a cutting-edge tri-agonist peptide that activates GLP-1, GIP, and glucagon receptors. This unique mechanism has made GLP-3 Reta a focal point in metabolic research, particularly in studies related to weight management, glucose regulation, and cardiovascular health.

Form: Lyophilized peptide powder

Molecular Formula: C₂₂₃H₃₄₃F₃N₄₆O₇₀

Molecular Weight: 4,731.33 g/mol

Synonyms: LY-3437943, NOP2Y096GV, Triple Agonist GLP-3 Reta

CAS Number: 2,381,089-83-2

Why Researchers Choose GLP-3 Reta

GLP-3 Reta is known as a triple agonist peptide, meaning it simultaneously stimulates:

GLP-1 receptors – supports insulin signaling, slows gastric emptying, and influences satiety.

GIP receptors – assists with glucose regulation and metabolic balance.

Glucagon receptors – plays a key role in energy expenditure and glucose metabolism.

By targeting three receptors instead of one, GLP-3 Reta is being studied for its potential synergistic benefits in metabolic and obesity-related research models.

Storage & Stability

Short-Term Storage: Stable for several weeks at room temperature.

Refrigerated Storage: Up to 4 °C (39 °F) for short-term use.

Long-Term Storage: Store at −80 °C (−112 °F) to maintain peptide integrity.

Form: Supplied as a white, lyophilized powder for maximum stability during shipping and storage.

Intended Use

This peptide is sold strictly for laboratory and research purposes only. It is not for human consumption, medical, or veterinary use.

Key Takeaways

High-purity GLP-3 Reta (GLP1-R) 6mg & 8mg available at Spartan Peptides

Advanced tri-agonist peptide for research applications

Bulk discounts for larger research orders

Secure and stable lyophilized peptide format

GLP-3(Reta): Research Overview

GLP-3(Reta) refers to a tri-agonist research peptide acting simultaneously on three incretin and gut hormone receptors: GLP-1R (glucagon-like peptide-1 receptor), GIPR (glucose-dependent insulinotropic polypeptide receptor), and GLP-2R (glucagon-like peptide-2 receptor) or alternatively the glucagon receptor in some compound iterations. This represents a third-generation incretin research platform beyond single-axis GLP-1R agonists and dual-axis GIP/GLP-1R agonists — engaging three distinct but metabolically interconnected receptor systems simultaneously.

Key mechanistic and research interests include:

• Triple-Axis Incretin Engagement: Simultaneous activation of GLP-1R, GIPR, and a third receptor (GLP-2R or glucagon receptor) produces broader metabolic effects than dual or single agonism — including greater energy expenditure, enhanced glucagon suppression, and potential intestinal trophic effects (via GLP-2R).
• Energy Expenditure Research: The addition of glucagon receptor agonism to the GLP-1/GIP platform may amplify thermogenic effects through cAMP-mediated hepatic and adipose energy expenditure — an active area of preclinical metabolic research.
• Intestinal Biology: GLP-2R activation drives intestinal epithelial proliferation, gut barrier integrity research, and nutrient absorption modulation — a distinct biological research dimension not present in single or dual GLP-1/GIP agonists.
• Comparative Metabolic Platform: GLP-3(Reta) serves as a research comparator against GLP-2(Tirz) and GLP-1(Sema) to isolate the contribution of each additional receptor in the incretin research cascade.

This compound is most meaningfully studied alongside GLP-1(Sema) and GLP-2(Tirz) to construct the incretin single → dual → triple agonism research ladder. For metabolic peptide stacking design, see our Stacking Peptides Research Guide.

Research Context: GLP-3(Reta) in the Incretin Receptor Agonist Research Landscape

The incretin peptide research landscape has evolved from single-receptor to multi-receptor agonism, providing a tiered platform for dissecting the contribution of each receptor system. GLP-3(Reta) represents the apex of this research ladder:

• GLP-3(Reta) — Triple GLP-1R/GIPR/GLP-2R (or glucagon) agonist; next-generation metabolic research platform, broadest incretin receptor coverage
• GLP-2(Tirz) — Dual GIP/GLP-1 receptor agonist; superior to single GLP-1 agonism, serves as comparator for triple vs. dual agonism
• GLP-1(Sema) — Single GLP-1 receptor agonist; foundational incretin reference peptide
• MOTS-c — Mitochondrial metabolic peptide; AMPK-mediated metabolic regulation (non-receptor-agonist mechanism, complementary research)
• AOD-9604 — hGH fragment; selective lipolysis via beta-3 AR (adipose-targeted, non-incretin mechanism)

GLP-1(Sema), GLP-2(Tirz), and GLP-3(Reta) together form the definitive incretin agonism comparative research set.

Related Research Resources

• What Are Peptides: The Complete 2026 Research Guide
• Peptide Stacking Research Guide: Synergistic Combinations
• How to Reconstitute Peptides Safely for R&D
• Quality Control in Peptide Research: Interpreting Purity
• Peptide Safety 101: Finding the Safest Place to Buy Peptides

Frequently Asked Questions

What is GLP-3 Reta and how is it classified in research?

GLP-3 Reta (LY3437943) is a novel synthetic triple agonist peptide that simultaneously activates glucose-dependent insulinotropic polypeptide (GIP) receptor, glucagon-like peptide-1 (GLP-1) receptor, and glucagon receptor. In research settings, it represents the next generation of poly-agonist incretin peptides, extending dual-agonist pharmacology by incorporating glucagon receptor activity for enhanced metabolic modulation. All laboratory studies are conducted under controlled experimental conditions.

What is the mechanism of action of GLP-3 Reta in preclinical models?

GLP-3 Reta's triple receptor agonism combines GLP-1R-mediated appetite suppression and glucose-dependent insulin secretion, GIPR-mediated incretin enhancement and adipose tissue metabolism, and glucagon receptor-mediated hepatic glucose output regulation and energy expenditure. This multi-receptor pharmacology is studied using receptor binding assays, cell signaling studies, and metabolic rodent models to characterize metabolic effects.

How does GLP-3 Reta differ from dual agonists in research pharmacology?

Unlike dual GIP/GLP-1 receptor agonists such as GLP-2(Tirz), GLP-3 Reta adds glucagon receptor activation, which in preclinical models contributes to increased basal energy expenditure through hepatic glucose mobilization and thermogenic signaling. Research pharmacology studies have characterized the receptor selectivity profile and signaling bias of GLP-3 Reta compared to both mono-agonist and dual-agonist reference compounds in controlled laboratory settings.

What molecular characteristics define GLP-3 Reta as a research compound?

GLP-3 Reta is a fatty acid-acylated peptide with modifications that extend its half-life through albumin binding, enabling once-weekly dosing in clinical research settings. Its molecular weight is approximately 4,726 Da. The triple receptor engagement design represents a sophisticated approach to multi-incretin pathway pharmacology studied in both preclinical and clinical research settings.

How should GLP-3 Reta be stored for laboratory research?

Research-grade GLP-3 Reta in lyophilized form should be stored at -20 degrees C or lower, protected from light and moisture. Reconstitution with sterile water per research protocol specifications should be performed immediately before use. Given its lipophilic modification, researchers should follow validated preparation procedures to ensure complete dissolution and maintain structural integrity.

What research evidence has characterized GLP-3 Reta's metabolic effects?

Published research including systematic reviews and meta-analyses of randomized controlled trials has characterized GLP-3 Reta's effects on body weight reduction, glycemic control, and cardiometabolic parameters. Preclinical mechanism-of-action studies have complemented clinical data by characterizing receptor pharmacology and metabolic pathway engagement. All findings represent controlled research investigations.

References

1. Abdrabou Abouelmagd A, Abdelrehim AM, Bashir MN, et al. “Efficacy and safety of GLP-3(Reta), a novel GLP-1, GIP, and glucagon receptor agonist for obesity treatment: a systematic review and meta-analysis of randomized controlled trials.” Proc (Bayl Univ Med Cent). 2025;38(3):291-303.. PubMed
2. Katsi V, Koutsopoulos G, Fragoulis C, Dimitriadis K, Tsioufis K. “GLP-3(Reta)-A Game Changer in Obesity Pharmacotherapy.” Biomolecules. 2025;15(6):796.. PubMed
3. Melson E, et al. “What is the pipeline for future medications for obesity?” Int J Obes (Lond). 2025;49(3):433-451.. PubMed
4. Hong SH, Choi KM. “Gut hormones and appetite regulation.” Curr Opin Endocrinol Diabetes Obes. 2024;31(3):115-121.. PubMed

Research and Clinical Studies

Phase 2 Trial of Retatrutide in Adults with Obesity

Jastreboff, Kaplan, Frías et al. reported phase 2 trial results for retatrutide, a novel triple co-agonist of the glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon receptors, in adults with obesity. The investigators characterized dose-dependent weight reductions of up to approximately 24% from baseline over 48 weeks with the highest dose studied, with continued weight loss trajectory observed at trial completion suggesting the plateau had not yet been reached. Researchers noted that these findings represented the largest pharmacologically-induced weight reductions reported in a clinical trial at the time of publication (Jastreboff et al., 2023; PMID: 37366315).

Triple Receptor Agonism: GIP, GLP-1, and Glucagon Pathways

Research characterizing retatrutide's pharmacological mechanism established its unique triple receptor engagement as the molecular basis for its enhanced metabolic activity compared to dual or single incretin agonists. Investigators noted that glucagon receptor co-agonism adds thermogenic and lipolytic effects to the appetite suppression and insulin-stimulatory properties of GLP-1 and GIP receptor engagement, respectively. Researchers characterized the combination of these three receptor activities as producing synergistic effects on energy balance that may account for the greater weight reduction observed with retatrutide compared to GLP-1 receptor agonists alone (Jastreboff et al., 2023; PMID: 37366315).

Cardiometabolic Biomarker Changes

Clinical characterization of retatrutide's effects on cardiometabolic risk factors demonstrated significant improvements in fasting lipids, blood pressure, fasting glucose, and liver fat content alongside the primary weight reduction endpoint. Investigators observed that the magnitude of cardiometabolic improvements correlated with, but appeared to exceed, what would be predicted from weight loss alone, suggesting direct organ-level effects of the triple agonist mechanism. Researchers noted that the hepatic fat reductions were particularly notable and warranted further investigation given the high prevalence of metabolic-associated steatohepatitis in the obesity research population (Jastreboff et al., 2023; PMID: 37366315).

Dose-Response Characterization and Safety Profile

The phase 2 program for retatrutide characterized a clear dose-response relationship for both weight reduction and cardiometabolic outcomes across the dose range studied. Investigators noted that gastrointestinal adverse effects—nausea, vomiting, and diarrhea—were the most commonly reported, consistent with the known class effects of incretin-based therapies, and that most events were transient and mild to moderate in severity. Researchers characterized the compound's overall safety profile in this early-phase study as consistent with the mechanism of action and supportive of advancing to phase 3 investigation (Jastreboff et al., 2023; PMID: 37366315).