Cognitive & neuro
GPE (glycyl-prolyl-glutamate)
A three-amino-acid fragment of IGF-1 studied as a neuroprotective agent in Parkinson's and stroke models.
What it is
GPE is a tripeptide (glycine-proline-glutamate) released when IGF-1 is cleaved in the brain. It acts on the NMDA receptor complex rather than on IGF-1 receptors, which is why it drew interest as a neuroprotective agent for Parkinson's disease and stroke. It has been through only small early human studies.
How it works
- 1
Binds a site on the NMDA receptor complex, reducing glutamate-driven excitotoxicity.
- 2
Reduces inflammatory signalling in microglia in animal models.
- 3
Protects dopamine neurons in toxin models of Parkinson's disease.
- 4
Does not act through IGF-1 receptors, so it avoids that growth pathway.
- 5
Small enough to be given peripherally and still reach the brain.
What it's studied for
Reported and studied effects
- Tolerability shown in small early studies
- Efficacy in humans is unproven
- Neuroprotective effects in animals are consistent but untranslated
Research protocol notes
Research context onlyResearch context only - investigational. Published studies used intravenous doses in the milligram per kilogram range over days in animals and in small human safety work; no adequately powered efficacy trial has been reported.
These figures are described so you can understand what researchers did. They are not a dose, a schedule, or a suggestion — and they are not a substitute for a doctor.
Possible side effects and contraindications
Safety profile
Possible side effects
- Headache reported
- Transient blood pressure change
- No serious safety signal in the small studies
- Long-term safety unknown
Contraindications and cautions
- No approved use
- Pregnancy and childhood - untested
- Caution with conditions sensitive to NMDA receptor modulation
A side-effect list is never complete, and these are not the only situations that warrant caution. Anything unexpected, or anything you are unsure about, should be discussed with a doctor before use.
Evidence assessment
Small early-stage human safety studies plus consistent animal data, but no adequately powered trial of any clinical endpoint.
References
References link to published literature, regulator pages or literature indexes. Where a link points to a search, it collects the peer-reviewed work on that molecule rather than a single study.
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