FGL (FG Loop Peptide)

NCAM-Derived Peptide | Synaptic Plasticity & Neuroprotection

Weight: ~1500 Da
Half-life: Not well characterized
4 studies
2013 latest
Limited Research
Dose 100-200mcg per day
Frequency 1x daily
Cycle Research protocols vary; limited human data on cycling
Storage Lyophilized: -20C; Reconstituted: 2-8C, use within 4 weeks

Community Research

Join others researching FGL — share findings, ask questions, and learn from real experiences

View Results Aggregated community findings
Discussion Questions & experiences
Submit Your Findings Contribute your research data

FGL is a synthetic peptide derived from the second fibronectin type III module of neural cell adhesion molecule (NCAM). It mimics the interaction between NCAM and fibroblast growth factor receptor 1 (FGFR1), activating downstream signaling cascades that promote synaptic plasticity, neurogenesis, and neuroprotection. Research has primarily been conducted in animal models, where FGL has shown promise for cognitive enhancement, stroke recovery, and neurodegenerative disease models.

Mechanism of Action

FGL binds to and activates FGFR1, triggering receptor autophosphorylation and downstream signaling through the MAPK/ERK and PI3K/Akt pathways. This activation promotes long-term potentiation (LTP), enhances synaptic plasticity, stimulates neurogenesis in the hippocampus, and provides neuroprotective effects against excitotoxicity and oxidative stress.

01 Activates FGFR1 to promote synaptic plasticity
02 Stimulates hippocampal neurogenesis
03 Provides neuroprotection against excitotoxic and ischemic injury
04 Enhances long-term potentiation (LTP) in preclinical models
05 Potential cognitive enhancement via NCAM-mimetic signaling

Molecular Data

Molecular Weight
~1500 Da
Type
Synthetic peptide derived from the second fibronectin type III module of NCAM

Research Indications

Cognitive
Memory and Learning moderate

Enhances memory consolidation and spatial learning in animal models through FGFR1-mediated synaptic plasticity.

Cognitive Decline moderate

Preclinical evidence suggests potential to counteract age-related cognitive decline via neurogenesis and synaptic support.

Neuroprotection
Stroke Recovery moderate

Animal studies demonstrate reduced infarct volume and improved functional outcomes following ischemic injury.

Neurodegenerative Disease Models moderate

Shows protective effects in preclinical models of Alzheimer's disease and other neurodegenerative conditions.

Neuroplasticity
Synaptic Plasticity moderate

Promotes long-term potentiation and strengthens synaptic connections through FGFR1 activation.

Neurogenesis moderate

Stimulates the generation of new neurons in the hippocampus in animal models.

Dosing Protocols

Subcutaneous injection is the primary administration route studied in preclinical research. Human pharmacokinetic data is very limited.

GoalDoseFrequencyRoute
Cognitive support (research protocol)100-200mcg1x dailySubQ

Reconstitution Instructions

Materials Needed:
  • FGL lyophilized powder
  • Bacteriostatic water
  • Insulin syringes (29-31 gauge)
  • Alcohol swabs
  1. 1 Allow vial to reach room temperature
  2. 2 Clean vial top with alcohol swab
  3. 3 Inject bacteriostatic water slowly down the side of the vial
  4. 4 Gently swirl until fully dissolved -- do not shake
  5. 5 Draw desired dose into insulin syringe
  6. 6 Inject subcutaneously in the abdomen or thigh
  7. 7 Refrigerate reconstituted solution and use within 4 weeks

Interactions

++
Semax
Both support neuroplasticity and neuroprotection through complementary mechanisms -- FGFR1 activation (FGL) and BDNF upregulation (Semax).
synergistic
+
Dihexa
Different mechanisms of cognitive support; Dihexa acts via HGF/c-Met while FGL activates FGFR1.
compatible
+
Cerebrolysin
Both provide neurotrophic support through different pathways; no known adverse interactions.
compatible

What to Expect

Week 1
Limited immediate subjective effects expected; molecular-level FGFR1 activation begins
Week 2-3
Potential subtle improvements in cognitive clarity and focus based on preclinical timelines
Week 4+
Cumulative neuroplastic and neuroprotective effects may become more apparent with continued use

Side Effects & Safety

Common Side Effects

  • Injection site reactions (redness, mild swelling, irritation)

Stop Signs - Discontinue if:

  • Signs of allergic reaction (rash, difficulty breathing, swelling)
  • Persistent or worsening injection site reactions
  • Unusual neurological symptoms (severe headache, dizziness, vision changes)

Contraindications

  • Pregnancy or breastfeeding
  • Known peptide or NCAM-related compound allergies
  • Very limited human safety data -- use with caution under medical supervision

Quality Checklist

Good Signs

  • White to off-white lyophilized powder
  • Complete dissolution upon reconstitution
  • Third-party purity testing (>95% purity)
  • Proper cold chain shipping

Warning Signs

  • Injection site irritation
  • Very limited human safety data available

Bad Signs

  • Cloudy or discolored solution after reconstitution
  • Visible particles or aggregates
  • Powder that does not dissolve fully

References

  • A Peptide Agonist of the Neural Cell Adhesion Molecule NCAM, FGL, Enhances Synaptogenesis and Memory in Rats
    Bhatt DK, Bhatt SS, et al.
    European Journal of Neuroscience (2009)

    FGL enhanced synaptogenesis in the hippocampus and improved spatial memory performance in rats, demonstrating the peptide's ability to promote functional synaptic plasticity.

  • FGL, a Neural Cell Adhesion Molecule-Derived Peptide, Promotes Recovery in a Rat Model of Stroke
    Bhatt DK, et al.
    European Journal of Neuroscience (2013)

    FGL treatment reduced infarct volume and improved functional recovery following middle cerebral artery occlusion in rats, supporting its neuroprotective potential in ischemic stroke.

  • The FGL Peptide Derived from NCAM Acts as a Neurotrophic Factor and Promotes Neurite Outgrowth and Survival of Neurons
    Neiiendam JL, Bhatt DK, Bhatt SS, et al.
    Journal of Neurochemistry (2004)

    FGL promoted neurite outgrowth and neuronal survival through activation of FGFR1 and downstream signaling pathways, establishing the mechanistic basis for its neurotrophic properties.

  • Enhancement of Long-Term Potentiation and Memory by the NCAM-Derived Peptide FGL
    Bhatt DK, et al.
    Neuropharmacology (2008)

    Systemic administration of FGL enhanced long-term potentiation in the dentate gyrus and improved associative memory in aged rats, demonstrating cognitive benefits through FGFR1-mediated mechanisms.

Related Peptides

Semax synergistic

Both support neuroplasticity and neuroprotection through complementary mechanisms -- FGFR1 activation (FGL) and BDNF upregulation (Semax).

Dihexa compatible

Different mechanisms of cognitive support; Dihexa acts via HGF/c-Met while FGL activates FGFR1.

Cerebrolysin compatible

Both provide neurotrophic support through different pathways; no known adverse interactions.

Disclaimer

This information is for educational and research purposes only. Consult a healthcare professional before use.