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.
- Remains a research chemical in all jurisdictions; 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 |
|---|---|---|---|
| Intranasal / parenteral (research) | Microgram-to-milligram range in classical research protocols | Variable across research protocols | Short courses in most classical research contexts |
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
- · Not authorised for human use in the UK.
- · Pregnancy and lactation — no controlled data.
- · Concurrent use with dopaminergic pharmaceuticals should be evaluated for interaction.
Section 8
UK & EU Regulatory Context
United Kingdom
Not a licensed medicine in the UK. Research chemical only.
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: research peptides are sold strictly for in vitro and preclinical laboratory purposes. Importation or supply for human consumption is not permitted under UK medicines legislation.