MIF-1
Also known as: Pro-Leu-Gly-NH2 · melanocyte-inhibiting factor 1 · PLG
A tripeptide originally identified as an inhibitor of melanocyte-stimulating hormone release, with a distinctive research history spanning memory modulation, dopamine-receptor allosteric effects, and Parkinson's-disease-adjacent research applications.
MIF-1 (Pro-Leu-Gly-NH2) is a tripeptide dopamine D2 receptor allosteric modulator with distinctive research applications in Parkinson's disease and depression contexts.
Evidence tier: C — preclinical / mechanistic evidence only
- Category
- Cognitive Enhancement
- Half-life
- Short plasma half-life; CNS effects extend beyond exposure
Section 1
Overview
MIF-1 (Pro-Leu-Gly-NH2, also known as prolyl-leucyl-glycinamide or PLG) is a small endogenous tripeptide originally identified as an inhibitor of melanocyte-stimulating hormone (MSH) release from the pituitary. Its research history has since expanded far beyond the original endocrine-inhibitor characterisation into memory modulation, dopamine-receptor allosteric-modulator effects, and Parkinson's-disease-adjacent research applications.
The compound's most distinctive pharmacological property is its allosteric-modulator activity at dopamine D2 receptors — MIF-1 modulates D2 receptor pharmacology without direct receptor binding, providing a distinctive research-tool niche for probing dopamine-receptor allosteric modulation. This mechanism has motivated research applications in Parkinson's disease and depression contexts alongside the primary cognitive-endpoint research.
MIF-1 sits within the classical cognitive-peptide research canon alongside DGAVP, Org 2766, and other 1970s-90s research peptides. Its current research use is specialised rather than mainstream, but the compound retains research-tool relevance for its distinctive dopamine-D2-allosteric-modulator mechanism.
Section 2
Discovery & History
- Identified in the 1970s as the tripeptide from oxytocin's ring structure that inhibits melanocyte-stimulating hormone release, providing the original pharmacological characterisation and the compound's name.
- Characterised extensively for memory-modulation effects across the 1970s and 1980s classical cognitive-peptide research programme.
- The dopamine D2 receptor allosteric-modulator activity was characterised in the 1990s, opening a new mechanism-of-action research angle for the compound.
- Research applications extended into Parkinson's disease and depression contexts based on the dopamine-modulation mechanism through the 2000s and 2010s.
- No marketing authorisation for MIF-1 was found in the electronic medicines compendium (emc) or on the EMA's list of centrally authorised medicines on 17 October 2026. No clinical development towards marketing authorisation.
Section 3
Mechanism of Action
- 1Allosteric modulation of dopamine D2 receptors — the compound modulates D2 receptor pharmacology without direct receptor binding, providing a distinctive research-tool niche and the most-cited mechanism-of-action for MIF-1's current research applications.
- 2Inhibition of melanocyte-stimulating hormone (MSH) release from the pituitary — the original pharmacological characterisation and the mechanism-of-action that named the compound.
- 3Central memory-modulation effects via multiple downstream signalling pathways, though the mechanistic characterisation is less well-developed than for the ACTH-fragment or vasopressin-family cognitive peptides.
- 4Reported effects on the dopaminergic system beyond direct D2 allosteric modulation, providing a broader dopamine-modulation research angle relevant to Parkinson's disease and depression research contexts.
- 5Anti-Parkinsonian effects in preclinical animal models, extending the mechanism from the primary allosteric-modulator characterisation into disease-model research applications.
- 6Reported antidepressant-like effects in animal stress and depression models, providing a mood-relevance research application angle alongside the primary cognitive-endpoint research.
- 7Modulation of opioid-system activity in some research contexts, though this mechanism is less well-established than the primary dopaminergic modulation.
Section 4
Researched Benefits
Findings reported in the published preclinical and clinical literature. Effects in research contexts do not constitute claims of therapeutic benefit in humans.
- 1Distinctive dopamine D2 allosteric-modulator mechanism providing a research-tool niche unavailable to any other peptide on this reference — a mechanistically differentiated research-tool angle.
- 2Applications spanning cognitive-endpoint research, Parkinson's disease research, and depression research contexts, providing broad research applicability.
- 3Classical historical significance within the 1970s-90s cognitive-peptide research canon.
- 4Well-characterised acute-safety profile from decades of academic research use.
- 5Endogenous status providing a partial safety floor at physiological concentrations.
- 6Small tripeptide chemistry providing practical research handling and stability advantages.
Section 5
Theoretical Dosing & Protocols
| Route | Dosage | Frequency | Duration | Source |
|---|---|---|---|---|
| Intranasal / parenteral (research) | Microgram-to-milligram range in classical research protocols | Variable across research protocols | Short courses in most classical research contexts | None cited |
Note: MIF-1 research protocol standardisation is limited given the compound's specialised research applications rather than mainstream research-community usage.
Section 6
Administration Routes
- Intranasal administration — a common route in classical cognitive-peptide research.
- Subcutaneous and intramuscular administration in animal research contexts.
- Intravenous administration in some acute-pharmacology research contexts.
- Oral administration produces limited bioavailability owing to gastrointestinal proteolysis, though the small tripeptide structure provides modest protection relative to larger peptides.
Section 7
Safety Profile
Commonly reported
- · Generally well-tolerated in the classical research at studied doses.
- · Endogenous status provides a partial safety floor at physiological concentrations.
- · Injection-site reactions with parenteral administration.
- · No dependence, tolerance, or withdrawal phenomena documented in the reported research base.
Rare / theoretical
- · Long-term safety data at pharmacological doses above endogenous concentrations is limited.
- · Rare hypersensitivity reactions.
- · Theoretical interactions with dopaminergic pharmaceuticals given the D2 allosteric-modulation mechanism.
- · Theoretical off-target effects at other endogenous-peptide-binding systems.
Contraindications
- · No entry for MIF-1 was found in the electronic medicines compendium (emc) on 17 October 2026.
- · Pregnancy and lactation — no controlled data.
- · Concurrent use with dopaminergic pharmaceuticals should be evaluated for interaction.
Section 8
UK & EU Regulatory Context
United Kingdom
No entry for MIF-1 was found in the electronic medicines compendium (emc) on 17 October 2026. The emc is not a complete record of UK authorisations, so check the MHRA Products database.
European Union
Not approved by the EMA.
Section 9
Clinical Studies Summary
MIF-1 dopamine D2 allosteric-modulator characterisation
Molecular pharmacology characterisation of MIF-1's allosteric-modulator activity at dopamine D2 receptors, establishing the mechanism-of-action that dominates the compound's current research applications and provides the distinctive research-tool niche.
MIF-1 memory-modulation classical research
Classical 1970s-80s characterisation of MIF-1's memory-modulation effects across multiple learning and cognitive-endpoint paradigms, establishing the compound's cognitive-peptide research trajectory alongside the ACTH-fragment and vasopressin-family programmes.
MIF-1 anti-Parkinsonian effects in preclinical models
Preclinical evaluation of MIF-1's effects in animal Parkinson's disease models (MPTP-induced neurodegeneration), reporting reduced dopaminergic neurodegeneration and improved motor-endpoint outcomes in treated cohorts, extending the mechanism from allosteric-modulator characterisation into disease-model research applications.
MIF-1 in animal depression models
Behavioural pharmacology characterisation of MIF-1's effects in animal depression and stress models (forced swim, tail suspension), reporting antidepressant-like effects and providing the mood-relevance research application angle alongside the primary cognitive-and-Parkinsonian research.
Section 10
Frequently Asked Questions
Section 10a
Practical Research Guidance
Cycle guidance
Reconstitution & storage
UK sourcing notes
Section 11
Sourcing for Laboratory Research
Sourcing MIF-1 for laboratory research
Researchers in the United Kingdom and elsewhere typically obtain MIF-1 from specialist research-chemical suppliers. Purity, third-party testing, and supplier transparency are the principal differentiators worth evaluating before placing an order. The two suppliers below are commonly referenced in UK research contexts.
Reminder: this page is educational. Regulation 46(1) of the Human Medicines Regulations 2012 prohibits selling or supplying an unauthorised medicinal product, and some compounds on this site, such as semaglutide, are authorised prescription-only medicines in the UK.