FGL

preclinical

Also known as: FG Loop peptide, FGL(L)

**Mechanism of Action** FGL (FG Loop peptide) is a synthetic peptide derived from the neural cell adhesion molecule (NCAM) that mimics the homophilic binding interface of NCAM’s second fibronectin type III module. It selectively activates fibroblast growth factor receptor 1 (FGFR1) via the FG loop region, triggering downstream signaling cascades (e.g., MAPK/ERK and PLCγ pathways). This activation promotes neurite outgrowth, synaptogenesis, and long-term potentiation (LTP), thereby enhancing synaptic plasticity and memory consolidation in preclinical models. **Key Research Findings** Preclinical studies demonstrate that FGL improves spatial learning and memory in rodent models of aging, Alzheimer’s disease, and traumatic brain injury. For example, systemic or intracerebroventricular administration of FGL reverses cognitive deficits in APP/PS1 transgenic mice and enhances hippocampal LTP. The peptide also reduces amyloid-beta plaque burden and neuroinflammation in some models. Notably, FGL’s effects are dose-dependent and require intact FGFR1 signaling, as FGFR1 antagonists block its cognitive benefits. **Clinical Relevance** FGL remains in preclinical development, with no human trials reported. Its potential applications include age-related cognitive decline, Alzheimer’s disease, and other conditions involving synaptic dysfunction. Challenges include optimizing blood-brain barrier penetration and minimizing off-target FGFR activation (e.g., mitogenic effects). Further validation in higher-order species and long-term safety studies are needed before clinical translation. For research purposes only — not medical advice.

Key data

Category
Cognitive & Neuroprotective
Administration
intranasal, subcutaneous
Research status
preclinical
References
257
Tags
ncam, synaptic-plasticity

Research & studies

Regulatory Role of FGL-1 in Interorgan Communication by Controlling T Cell Homeostasis During the Onset of Sjögren Disease
Arthritis & rheumatology (Hoboken, N.J.) · 2025 · PubMed
Integrated molecular and clinical characterization of pulmonary large cell neuroendocrine carcinoma
Nature communications · 2025 · PubMed

Comparable overall survival across chemotherapy, chemoimmunotherapy, and immunotherapy without unexpected adverse events.; Distinct NSCLC-like (KEAP1, KRAS, STK11 mutations) and SCLC-like (RB1, TP53 mutations) LCNEC subtypes identified, with 80% aligning with SCLC transcriptional profiles.; Elevated FGL-1 and SPINK1 expression in NSCLC-like LCNECs, and higher DLL3 levels in SCLC-like LCNECs.; Fewer tumor-infiltrating lymphocytes in LCNECs compared to other lung cancers.

Effects of Bioconverted Guava Leaf (Psidium guajava L.) Extract on Skeletal Muscle Damage by Regulation of Ubiquitin-Proteasome System and Apoptosis in Type 2 Diabetic Mice
International journal of molecular sciences · 2025 · PubMed
Pan-cancer single-cell analysis reveals the heterogeneity and plasticity of cancer-associated fibroblasts in the tumor microenvironment
Nature communications · 2022 · PubMed

CAF activation trajectory is divided into three states with distinct cell interactions and immunotherapy prognosis associations.; Minor CAF components can originate from other TME components like endothelia and macrophages.; Endothelial-to-mesenchymal transition CAFs are ubiquitously present and may interact with SPP1+ tumor-associated macrophages, impacting survival stratification.; A browser for the integrated pan-cancer single-cell data is available online.

Moderated Network Models
Multivariate behavioral research · 2021 · PubMed
Peptides Acting as Cognitive Enhancers
Neuroscience · 2018 · PubMed
The Neural Cell Adhesion Molecule-Derived (NCAM)-Peptide FG Loop (FGL) Mobilizes Endogenous Neural Stem Cells and Promotes Endogenous Regenerative Capacity after Stroke
Journal of neuroimmune pharmacology : the official journal of the Society on NeuroImmune Pharmacology · 2016 · PubMed
The synthetic NCAM mimetic peptide FGL mobilizes neural stem cells in vitro and in vivo
Stem cell reviews and reports · 2014 · PubMed

FGL significantly enhanced NSC proliferation in vitro, with maximal effect at 10 μg/ml.; FGL induced oligodendroglial differentiation, while NCAM promoted neurogenesis.; In vivo, FGL increased proliferative activity of NSC in the subventricular zone.; Non-invasive PET imaging confirmed FGL-induced mobilization of NSC from the subventricular zone and hippocampus.

Frequently asked questions

What is FGL?

**Mechanism of Action** FGL (FG Loop peptide) is a synthetic peptide derived from the neural cell adhesion molecule (NCAM) that mimics the homophilic binding interface of NCAM’s second fibronectin type III module. It selectively activates fibroblast growth factor receptor 1 (FGFR1) via the FG loop region, triggering do

How does FGL work?

NCAM-derived FG-loop peptide that activates FGFR1 to enhance synaptic plasticity and memory in animal models.

What is the research status of FGL?

FGL is currently classified as preclinical, with 257 research references on record. This is for research purposes only and is not medical advice.

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