Cyclic Glycine-Proline
Moderate researchIGF-1 Bioavailability Regulator & Neuroprotective Peptide
Endogenous cyclic dipeptide found in plasma, breast milk, and cerebrospinal fluid. Functions as metabolite of IGF-1, regulating its bioavailability through competitive binding to IGFBP-3.
Molecular & research data
- Sequence
- cyclo(Gly-Pro)
- Molecular weight
- 154.17 Da
- Half-life
- Extended stability (more stable than linear GPE precursor)
- Primary targets
- bdnf, gaba, igf1
- Routes (research)
- Oral
- Storage
- Room temperature in sealed container, protected from moisture and light
Overview
Endogenous cyclic dipeptide found in plasma, breast milk, and cerebrospinal fluid. Functions as metabolite of IGF-1, regulating its bioavailability through competitive binding to IGFBP-3. Demonstrates neuroprotective, cognitive-enhancing, and cardioprotective properties supported by clinical trials.
Mechanism of action
Competes with IGF-1 for IGFBP-3 binding, normalizing bioavailable IGF-1 levels. Acts as positive allosteric modulator of AMPA and GABA-A receptors. Increases BDNF levels via Akt/MDM2-p53 pathway activation.
Key research findings
- Neuroprotection and cognitive enhancement
- IGF-1 optimization
- Cardiovascular support
- Metabolic health improvement
- Blood-brain barrier penetration
- Convenient oral administration
Research applications
Neurological
- Cognitive Enhancement — Higher cGP levels correlate with improved memory retention in elderly populations
- Neuroprotection — Protects neural stem cells from oxidative stress; efficacy demonstrated in stroke models
- Alzheimer’s Disease — Mouse studies show reduced amyloid plaque load and improved spatial memory
- Parkinson’s Disease — Clinical study showed increased CSF cGP and reduced anxiety/depression scores
Metabolic
- Type-2 Diabetes — Clinical trial improved vascular complications and normalized HbA1c%
- Blood Pressure Regulation — Demonstrated systolic blood pressure reduction in clinical observations
Recovery
- Stroke Recovery — Higher cGP/IGF-1 ratios associated with favorable clinical outcomes
- Healthy Aging — Maintained ratios correlate with preserved cognitive function with age
Cyclic Glycine-Proline FAQ
Can cyclic glycine-proline improve cognitive function in healthy people, not just disease states?+
Yes, research shows higher cGP levels correlate with improved memory retention in healthy elderly populations. Clinical trials demonstrated enhanced cognitive function in normal aging, suggesting benefits for preserving mental sharpness beyond treating disease—relevant for anti-aging protocols.
What's the advantage of blackcurrant extract over pure cGP supplements?+
Blackcurrant extract provides cGP at approximately 300mg per serving in a natural, whole-food matrix that may improve bioavailability and provide additional antioxidants. Pure cGP comes in microgram quantities (20-100mcg), so extract forms offer higher doses though containing other compounds alongside cGP.
Does cGP actually help with Parkinson's disease or just animal models?+
One human clinical study showed blackcurrant supplementation (which raises CSF cGP by 74%) reduced anxiety and depression scores in Parkinson's patients. While animal models show more dramatic neuroprotection, the human evidence supports cognitive and mood benefits, though larger trials are needed.
Can cyclic glycine-proline be used long-term without breaks?+
Most protocols recommend 4-12 week cycles, though human safety data for long-term continuous use is limited. As cGP is an endogenous metabolite naturally found in cerebrospinal fluid and breast milk, extended use appears relatively safe, but cycling allows assessment of individual response and prevents potential tolerance.
References
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Last reviewed: 2026-06-26. Information is provided for research and educational reference only — see our disclaimer.