PT-141, also referred to in the scientific literature as bremelanotide, is a synthetic cyclic heptapeptide that has attracted considerable attention in peptide research circles for its interactions with the melanocortin receptor system. Derived from the naturally occurring alpha-melanocyte-stimulating hormone (α-MSH), PT-141 has been investigated primarily in preclinical models for its ability to engage central melanocortin pathways — a system that governs a broad range of physiological signaling cascades well beyond pigmentation alone. Researchers studying neuropeptide biology, hypothalamic signaling, and autonomic regulation have positioned PT-141 as a valuable tool compound for exploring how melanocortin receptors modulate complex behavioral and physiological outputs.
As interest in melanocortin receptor agonism has expanded across multiple research disciplines, PT-141 has emerged as one of the more structurally studied peptides in this class. Its cyclic structure confers greater metabolic stability compared to linear analogs, making it a useful reference molecule for laboratory scientists examining receptor selectivity, downstream signaling cascades, and peptide pharmacodynamics in controlled research settings.
Research-only notice: This content is provided for educational discussion and laboratory research purposes only. No medical claims are made or implied. PT-141 is a reference compound intended solely for in-vitro and preclinical laboratory research. It is not intended for human or animal use.
PT-141 - 10MG — Research-Grade Reference Material PT-141 - 10MG is supplied as a lyophilized powder for in-vitro laboratory research use only. SourcePeptides supplies this material strictly as a laboratory reference standard.…
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Pfizer Hospira Bacteriostatic Water – 30 mL
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Ipamorelin - 10MG
$55.00$41.25 with 1st order
BPC-157 - 10MG / TB-500 - 10MG (Wolverine 20MG)
$110.00$82.50 with 1st order
MT-2 - 10MG
$45.00$33.75 with 1st order
Frequently Asked Questions
What is PT-141 and how is it classified in peptide research?
PT-141 (bremelanotide) is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (α-MSH). In research contexts, it is classified as a melanocortin receptor agonist, studied primarily for its activity at MC1R, MC3R, and MC4R receptor subtypes in preclinical models.
Which melanocortin receptors does PT-141 interact with in preclinical studies?
Preclinical research has investigated PT-141’s binding affinity across multiple melanocortin receptor subtypes, with particular focus on MC3R and MC4R, which are distributed throughout the central nervous system and have been linked to autonomic and behavioral signaling pathways in animal models.
How does PT-141 differ structurally from alpha-MSH?
PT-141 is a cyclic analog derived from α-MSH, modified to improve metabolic stability and receptor binding. The cyclization of the peptide backbone reduces enzymatic degradation compared to the linear α-MSH sequence, making it a more tractable molecule for preclinical receptor binding and signaling studies.
What biological pathways has PT-141 been studied in connection with?
Research has investigated PT-141 in relation to hypothalamic melanocortin signaling, autonomic nervous system pathways, and central nervous system receptor biology. Preclinical models have examined its interactions with reward circuitry, neuroendocrine axes, and downstream cAMP-mediated signaling cascades.
Is PT-141 the same compound as Melanotan-2?
PT-141 and Melanotan-2 (MT-2) are structurally related but distinct compounds. MT-2 is a cyclic analog of α-MSH studied for its melanotropic properties, while PT-141 was developed from MT-2 as a metabolite and is studied for its more selective central melanocortin receptor activity in preclinical models.
What does MC4R activation represent in basic neuroscience research?
MC4R (melanocortin-4 receptor) is expressed in hypothalamic and limbic brain regions and has been studied in preclinical neuroscience as a regulator of autonomic tone, energy homeostasis signaling, and reward-related behavioral circuits. PT-141’s activity at this receptor makes it a useful tool compound for probing these pathways in laboratory settings.
Where can researchers source PT-141 for laboratory use?
Research-grade PT-141 is available from specialized peptide suppliers for in-vitro and preclinical laboratory applications. It is supplied as a lyophilized reference compound intended exclusively for scientific research purposes.
The Melanocortin System: A Research Foundation
To appreciate PT-141’s place in contemporary peptide research, it is essential to first understand the breadth of the melanocortin system. The melanocortin family encompasses five G-protein-coupled receptor (GPCR) subtypes — MC1R through MC5R — each with distinct tissue distributions and downstream signaling profiles. Endogenous ligands for these receptors include α-MSH, β-MSH, γ-MSH, and adrenocorticotropic hormone (ACTH), all derived from the proopiomelanocortin (POMC) precursor protein.
PT-141 - 10MG — Research-Grade Reference Material PT-141 - 10MG is supplied as a lyophilized powder for in-vitro laboratory research use only. SourcePeptides supplies this material strictly as a laboratory reference standard.…
View Research Data
Pfizer Hospira Bacteriostatic Water – 30 mL
$45.00$33.75 with 1st order
Ipamorelin - 10MG
$55.00$41.25 with 1st order
BPC-157 - 10MG / TB-500 - 10MG (Wolverine 20MG)
$110.00$82.50 with 1st order
MT-2 - 10MG
$45.00$33.75 with 1st order
In the central nervous system, MC3R and MC4R subtypes have been the focus of extensive research. MC4R in particular is densely expressed in hypothalamic nuclei, and preclinical studies have linked its activation to modulation of autonomic outflow, neuroendocrine regulation, and behavioral signaling. MC3R, expressed in hypothalamic and limbic structures, has been explored in preclinical models for its role in energy homeostasis pathways and reward-related signaling. Together, these receptors represent a compelling research target for investigators studying neuropeptide signaling and central nervous system biology.
POMC-Derived Peptides and Receptor Selectivity
A key challenge in melanocortin research has been achieving receptor subtype selectivity, since endogenous peptides such as α-MSH bind across multiple receptor subtypes with varying affinity. Synthetic analogs like PT-141 have been engineered to provide researchers with tools for interrogating specific receptor subtypes more precisely. Studies have examined PT-141’s binding kinetics at recombinant melanocortin receptors, helping map the structural determinants of selectivity within the His-Phe-Arg-Trp (HFRW) core pharmacophore — the tetrapeptide sequence critical for melanocortin receptor engagement.
PT-141 Molecular Structure and Stability Profile
PT-141 is a cyclic heptapeptide with the amino acid sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH. The cyclization between aspartic acid and lysine residues forms a lactam bridge that constrains the peptide into a bioactive conformation. This structural feature is a primary focus of peptide chemistry research because it substantially reduces susceptibility to proteolytic cleavage, enhancing the molecule’s utility as a stable laboratory reference compound compared to its linear precursors.
The D-Phe substitution at position 7 — replacing the native L-Phe found in α-MSH — is another structurally significant modification that researchers have noted for its role in increasing receptor binding affinity and extending the duration of receptor engagement in preclinical binding assays. This substitution is shared with related compounds such as Melanotan-2, and understanding the structure-activity relationship at this position has been an active area of peptide chemistry investigation. Researchers interested in the broader landscape of nasal spray peptide delivery and structural stability may also find the role of mannitol in peptide formulation relevant to understanding how compounds like PT-141 are stabilized as lyophilized reference materials.
Preclinical Research Findings: Central Nervous System Pathways
Hypothalamic Signaling Studies
A substantial body of preclinical research has examined PT-141’s engagement with hypothalamic melanocortin circuits. Animal model studies have demonstrated that melanocortin receptor agonism in hypothalamic nuclei — particularly the paraventricular nucleus (PVN) and the medial preoptic area (MPOA) — influences autonomic nervous system outflow. Preclinical studies using rodent models have provided evidence that MC4R activation in these regions initiates downstream cAMP signaling cascades that modulate physiological responses associated with autonomic regulation.
Research has also explored the intersections between melanocortin signaling and dopaminergic reward circuits. Preclinical data from animal models suggest that MC4R agonism can modulate mesolimbic dopamine activity, offering researchers a molecular lens through which to study the interface between hypothalamic peptide signaling and reward-related neural circuitry. This line of inquiry connects to broader neuroscience research examining how neuropeptides regulate motivational states at the neurobiological level.
Autonomic and Cardiovascular Research Observations
Several preclinical studies have investigated the cardiovascular correlates of central melanocortin receptor activation. Animal model research has observed transient changes in blood pressure parameters following central administration of melanocortin agonists, an effect attributed to MC4R-mediated modulation of sympathetic nervous system outflow. These findings have been of interest to researchers mapping the neuroendocrine-cardiovascular axis, though they remain confined to preclinical observations and require further mechanistic investigation. It is worth noting that researchers working with related peptide systems — such as those exploring oxytocin’s mechanisms in preclinical social behavior models — encounter parallel questions about how neuropeptides interface with autonomic regulation.
PT-141 vs. Melanotan-2: Distinguishing Two Related Research Compounds
| Feature | PT-141 (Bremelanotide) | Melanotan-2 (MT-2) |
|---|---|---|
| Structural class | Cyclic heptapeptide (lactam-bridged) | Cyclic heptapeptide (disulfide analog) |
| Primary receptor focus | MC3R / MC4R (central CNS focus) | MC1R / MC3R / MC4R (broader profile) |
| Research area emphasis | Hypothalamic, autonomic, CNS signaling | Melanogenesis, pigmentation biology, CNS |
| Metabolic stability | Enhanced via lactam cyclization + D-Phe | Enhanced via cyclization |
| Origin | Derived as a metabolite/analog of MT-2 | Derived from α-MSH |
| Key preclinical model use | Autonomic modulation, reward circuitry | Pigmentation, metabolic signaling |
While PT-141 and MT-2 share a common structural lineage and both engage the melanocortin receptor family, their research profiles diverge meaningfully. MT-2 has been more extensively studied in melanogenesis and pigmentation biology models, whereas PT-141 research has concentrated on central melanocortin receptor biology. Researchers selecting between these compounds for laboratory applications should consider the specific receptor subtypes and biological pathways under investigation.
Choose PT-141 if…
- The research focus is on MC3R or MC4R receptor biology in central nervous system preparations
- Studies involve hypothalamic signaling, autonomic nervous system circuitry, or reward pathway biology
- Greater metabolic stability in aqueous assay conditions is a priority for the experimental design
- The investigation centers on structure-activity relationships within the HFRW pharmacophore in a CNS receptor context
Choose MT-2 if…
- The research focus is on melanogenesis, pigmentation biology, or MC1R-mediated signaling in melanocyte preparations
- Studies require a broader melanocortin receptor binding profile across MC1R through MC4R subtypes
- Investigations involve metabolic signaling correlates of melanotropic peptide activity
PT-141 – 10MG Nasal Spray (research use only) →
MT-2 – 10MG (research use only) →
Melanocortin Receptor Agonism and Neuropeptide Research Context
PT-141’s research significance extends beyond its own receptor binding profile. As a tool compound, it has helped investigators map the functional architecture of melanocortin receptor subtypes, contributing to a growing body of knowledge about how central neuropeptide systems coordinate complex physiological responses. Researchers working in adjacent areas — such as those investigating neuropeptide analogs like Selank and Semax in preclinical cognitive models — will recognize the shared conceptual framework: that synthetic peptide analogs, by virtue of their structural precision, provide researchers with pharmacological levers to dissect receptor-mediated signaling with greater specificity than endogenous ligands alone.
PT-141 has also informed research into the broader melanocortin-opioid receptor interaction hypothesis, given evidence from animal model studies suggesting cross-talk between melanocortin signaling and endogenous opioid pathways. This area of neuropeptide interaction biology remains an active frontier for basic science investigation, with PT-141 serving as a useful reference molecule for probing the relevant receptor systems.
In-Vitro Applications and Receptor Binding Assays
In laboratory settings, PT-141 is frequently employed in competitive binding assays using recombinant melanocortin receptor preparations, allowing researchers to characterize binding kinetics, IC₅₀ values, and receptor occupancy dynamics. Cell-based functional assays measuring cAMP accumulation downstream of MC4R activation represent another common application, helping researchers quantify agonist potency and compare PT-141’s efficacy profile against other synthetic melanocortin analogs. These types of assay systems require high-purity peptide reference materials, underscoring the importance of sourcing research-grade compounds from reputable suppliers. Researchers reconstituting lyophilized peptides for assay work will also want to consult resources on bacteriostatic water quality standards for peptide reconstitution.
Related Research Compounds for Melanocortin and Neuropeptide Studies
Researchers building out a comprehensive neuropeptide or melanocortin-focused library may find value in exploring related compounds that intersect with PT-141’s biological territory. For scientists studying GH secretagogue biology alongside neuropeptide signaling, ipamorelin’s mechanisms and GH biology represent a complementary research domain that highlights how different GPCR-targeting peptides modulate distinct but overlapping neuroendocrine axes.
MT-2 – 10MG Nasal Spray (research use only) →
Oxytocin – 5MG (research use only) →
Kisspeptin – 10MG (research use only) →
Where These Fit in Your Research Library
PT-141 occupies a distinct niche within the broader melanocortin peptide research toolkit. For investigators assembling a comprehensive neuropeptide reference library, it pairs naturally with MT-2 for comparative receptor binding studies, and with neuropeptides such as oxytocin and kisspeptin for multi-system autonomic and neuroendocrine signaling research. Browse the full catalog for additional research-grade peptide reference compounds:
Final Takeaway: PT-141 as a Melanocortin Research Tool Compound
PT-141 represents one of the most structurally refined and extensively studied synthetic melanocortin receptor agonists available to preclinical researchers today. Its cyclic architecture, D-Phe substitution, and selective engagement of MC3R and MC4R subtypes make it a valuable tool for dissecting central melanocortin signaling pathways in hypothalamic, limbic, and autonomic research contexts. Preclinical studies have established a foundation of mechanistic data connecting PT-141 to cAMP-mediated receptor signaling, hypothalamic neuroendocrine biology, and reward circuit modulation in animal models — all areas that continue to attract significant scientific interest. For laboratory investigators seeking a well-characterized melanocortin reference compound, PT-141 remains one of the more compelling options in the current research peptide landscape.
Sources & Further Reading
- Molinoff PB et al. — “PT-141: A Melanocortin Agonist for the Treatment of Sexual Dysfunction” — Annals of the New York Academy of Sciences (2003)
- Wikberg JE — “Melanocortin Receptors: Perspectives for Novel Drugs” — European Journal of Pharmacology (1999)
- Giuliano F et al. — “Neurophysiology and Pharmacology of Female Genital Sexual Response” — Journal of Sex & Marital Therapy (2004)
- Hadley ME & Dorr RT — “Melanocortin Peptide Therapeutics: Historical Milestones, Clinical Studies, and Future Directions” — Peptides (2006)
- PubMed Search — PT-141 Melanocortin Receptor Research Literature
