Quick summary
MIF-1 (Pro-Leu-Gly-NH2) is an oxytocin-derived tripeptide that modulates dopaminergic neurotransmission. It showed promise in early Parkinson's disease trials in the 1970s-1980s by potentiating D2 receptor signaling, though research has been largely dormant since the 1990s.
Overview
MIF-1 (Melanocyte Inhibiting Factor 1), also designated Pro-Leu-Gly-NH2 or PLG, is a cyclic tripeptide endogenously derived from oxytocin. It has been studied for its ability to modulate dopaminergic neurotransmission and has shown potential in early Parkinson's disease research, as well as mood modulation. Its small size and CNS penetration make it a model compound for neuropeptide pharmacology.
Mechanism of action
MIF-1 (Pro-Leu-Gly-NH2) modulates dopamine receptor sensitivity, particularly potentiating D2 receptor signaling in the striatum without acting as a direct receptor agonist. It is thought to act as an allosteric modulator of dopamine receptors and may inhibit dopamine breakdown by modulating MAO-B activity. MIF-1 also influences oxytocin receptor systems and has been reported to affect GABA and serotonin pathways. Its mechanism is complex and not fully characterized.
Dosing protocols
| Purpose | Route | Dosage | Frequency | Notes |
|---|---|---|---|---|
| dopaminergic research | intravenous | 20–200 mcg | per experimental protocol |
Dosing information is for educational purposes only. Consult a qualified healthcare professional before using any peptide.
Research summary
Early clinical trials in the 1970s–1980s showed modest improvement in Parkinson's disease motor symptoms in small patient cohorts receiving intravenous MIF-1. Rodent studies demonstrated reversal of reserpine-induced akinesia and potentiation of L-DOPA effects. Interest has also extended to mood disorders, with some data suggesting antidepressant-like effects in animal models. Research has been largely dormant since the 1990s, with no modern large-scale clinical trials completed.[1][2][3][4]
Evidence grading
Each claimed benefit is graded by the strength of available evidence. Grades reflect study quality, not effect size.
Strong = multiple RCTs · Moderate = limited trials or observational · Preliminary = animal or in vitro only · Insufficient = anecdotal or no published data
Side effects
Side effects vary by individual. This is not an exhaustive list. Report unusual symptoms to a healthcare professional.
Common stacks
Peptides commonly paired with MIF-1 for synergistic effects.
Legal status
MIF-1 (Pro-Leu-Gly-NH2) is not FDA-approved for any indication and is classified as a research compound. Available from peptide synthesis suppliers for laboratory use.
Sourcing & access
Research compound
MIF-1 is classified as a research compound. Regulatory status varies by jurisdiction. Always verify current legal status and source from vendors providing third-party certificates of analysis (COA).
Frequently asked questions
MIF-1 (Melanocyte Inhibiting Factor 1, also known as Pro-Leu-Gly-NH2 or PLG) is a cyclic tripeptide endogenously derived from oxytocin. It modulates dopaminergic neurotransmission and has been studied for Parkinson's disease and mood disorders.
MIF-1 acts as an allosteric modulator of dopamine D2 receptors in the striatum, potentiating their signaling without directly activating them. It may also modulate MAO-B activity, and influence oxytocin receptor, GABA, and serotonin pathways.
In the small clinical trials conducted in the 1970s–1980s, MIF-1 was generally well-tolerated, with only mild nausea reported anecdotally and no significant adverse events in Parkinson's disease patient cohorts receiving intravenous doses. It remains classified as a research compound, is not FDA-approved for any indication, and lacks modern large-scale safety data — long-term human safety has never been formally evaluated.
Early clinical trials in the 1970s-1980s showed only modest improvement in Parkinson's motor symptoms in small cohorts. No modern large-scale clinical trials have been completed since the 1990s, though the compound's CNS-penetrating properties and unique dopamine-modulating mechanism remain of academic interest.
Research references
- MIF-1 (Pro-Leu-Gly-NH2) potentiation of dopamine effects in the CNSPubMed
- Melanocyte-inhibiting factor-1: neuropeptide interaction with dopamine receptorPubMed
- MIF-1 anti-Parkinson effects and mechanisms of actionPubMed
- Pro-Leu-Gly-amide (MIF-1) as a neuromodulator: CNS effects and therapeutic potentialPubMed