Cyclic Glycine-Proline (cGP)
IGF-1 Bioavailability Regulator & Neuroprotective Peptide
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.
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.
Higher cGP levels correlate with improved memory retention in elderly populations
Protects neural stem cells from oxidative stress; efficacy demonstrated in stroke models
Mouse studies show reduced amyloid plaque load and improved spatial memory
Clinical study showed increased CSF cGP and reduced anxiety/depression scores
Mechanism
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.
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.
Higher cGP levels correlate with improved memory retention in elderly populations
Research areas
- 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.
- 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.
- Higher cGP levels correlate with improved memory retention in elderly populations
- Protects neural stem cells from oxidative stress; efficacy demonstrated in stroke models
- Mouse studies show reduced amyloid plaque load and improved spatial memory
- Clinical study showed increased CSF cGP and reduced anxiety/depression scores
- Clinical trial improved vascular complications and normalized HbA1c%
- Demonstrated systolic blood pressure reduction in clinical observations
- Higher cGP/IGF-1 ratios associated with favorable clinical outcomes
- Maintained ratios correlate with preserved cognitive function with age
Research notes
- Allergic reactions (rash, difficulty breathing, swelling)
- Unexpected blood glucose changes
- Unusual fatigue or weakness
- Consult healthcare provider if taking IGF-1 or growth hormone medications
- Limited long-term human data available
- Not studied in pregnancy
Pharmacokinetics
- 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.
FAQs
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.