PT-141 Research Guide (Preclinical Overview)
PT-141 (Bremelanotide) is a synthetic cyclic heptapeptide derivative of alpha-melanocyte-stimulating hormone (α-MSH) that functions as a potent melanocortin receptor agonist. Investigated extensively for its role in central nervous system pathway activation rather than direct vascular dynamics, this compound provides a valuable tool for neuroendocrine research. This comprehensive PT-141 research guide reviews the molecule's chemical structure, receptor selectivity profiles, preclinical model data, and laboratory quality standards.
Quick answer
PT-141 (Bremelanotide) is a synthetic cyclic heptapeptide derivative of alpha-melanocyte-stimulating hormone (α-MSH) that functions as a potent melanocortin receptor agonist. Investigated extensively for its role in central nervous system pathway activation rather than direct vascular dynamics, this compound provides a valuable tool for neuroendocrine research. This comprehensive PT-141 research guide reviews the molecule's chemical structure, receptor selectivity profiles, preclinical model data, and laboratory quality standards.
Key takeaways
- [PT-141](/research-peptides/pt-141), chemically designated as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, is a synthetic cyclic heptapeptide with a molecular weight of 1024.2 g/mol.
- The biological activities of [PT-141](/research-peptides/pt-141) are mediated through its interaction with the melanocortin receptor (MCR) family, a group of five distinct G-protein coupled receptors (MC1R through MC5R).
- [PT-141](/research-peptides/pt-141) was originally identified during structural activity relationship (SAR) studies of [Melanotan II](/product/melanotan-ii), a non-selective melanocortin receptor agonist developed for photoprotection research.
- Unlike classic therapeutic compounds for cardiovascular or smooth muscle modulation that rely on nitric oxide donor pathways or phosphodiesterase type 5 (PDE5) inhibition, [PT-141](/research-peptides/pt-141) operates directly within the central nervous system.
Chemical Structure and Physical Properties of PT-141
PT-141, chemically designated as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, is a synthetic cyclic heptapeptide with a molecular weight of 1024.2 g/mol. Derived structurally from the active core sequence of alpha-melanocyte-stimulating hormone (α-MSH), PT-141 incorporates a lactam bridge between the side chains of aspartic acid and lysine. This conformational constraint significantly enhances resistance to enzymatic cleavage by serum peptidases compared to linear peptide counterparts.
The presence of a D-phenylalanine residue at position 4 is critical for its receptor interaction kinetics, imparting higher binding affinity and prolonging receptor activation profiles in experimental assays. Researchers utilizing PT-141 in biochemical investigations evaluate its distinct physicochemical stability across varying pH environments and temperature ranges. Understanding these structural parameters is essential for designing valid in vitro binding studies and maintaining peptide integrity in solution.
Melanocortin Receptor Binding Kinetics and Signaling
The biological activities of PT-141 are mediated through its interaction with the melanocortin receptor (MCR) family, a group of five distinct G-protein coupled receptors (MC1R through MC5R). Preclinical binding assays indicate that PT-141 acts primarily as a high-affinity agonist at MC3R and MC4R, with moderate affinity for MC1R and minimal interaction with MC2R or MC5R.
Ligand binding to MC3R and MC4R triggers the activation of adenylate cyclase via Gs protein coupling, leading to an intracellular elevation of cyclic adenosine monophosphate (cAMP). This signal cascade activates protein kinase A (PKA) and downstream transcription factors. Investigators utilizing the PX1 Research library frequently examine these intracellular pathways to map central neuroendocrine signals without eliciting the glucocorticoid responses associated with MC2R stimulation.
Evolution from Melanotan II to Bremelanotide
PT-141 was originally identified during structural activity relationship (SAR) studies of Melanotan II, a non-selective melanocortin receptor agonist developed for photoprotection research. While Melanotan II exhibited broad activity across MC1R, MC3R, MC4R, and MC5R, early preclinical models revealed that a metabolite, later isolated and synthesized as PT-141, demonstrated refined receptor target selectivity.
By modifying the N-terminal region and eliminating specific non-target interactions, scientists synthesized PT-141 to isolate central behavioral and neuroendocrine pathways from peripheral skin pigmentation effects associated with heavy MC1R stimulation. This structural refinement allowed laboratory researchers to isolate central melanocortin dynamics, creating a cleaner pharmacological probe for central nervous system investigations.
Central Neurological Mechanism vs. Peripheral Vasodilation
Unlike classic therapeutic compounds for cardiovascular or smooth muscle modulation that rely on nitric oxide donor pathways or phosphodiesterase type 5 (PDE5) inhibition, PT-141 operates directly within the central nervous system. Preclinical autoradiography and microdialysis studies demonstrate that PT-141 targets the medial preoptic area (mPOA) and the paraventricular nucleus (PVN) of the hypothalamus.
Activation of MC4R in these central nuclei leads to downstream release of dopamine in the nucleus accumbens, modulating central autonomic and behavioral responses. Because PT-141 does not directly relax vascular smooth muscle, in vitro models comparing central melanocortin agonists against peripheral vasodilators provide critical insights into neurogenic control pathways independent of direct local hemodynamics.
Preclinical Model Systems and Laboratory Applications
In vitro and animal model systems have provided substantial data regarding the behavioral and physiological outputs of PT-141 signaling. In rodent research, central administration (icv) or systemic administration of PT-141 demonstrates quantifiable changes in appetitive and consummatory behavior patterns, social interactions, and energy homeostasis parameters.
Non-human primate models have been utilized to evaluate autonomic tone, central temperature regulation, and neuroendocrine hormone secretion following melanocortin stimulation. These experimental frameworks allow researchers to analyze how central MC3R/MC4R activation influences broader metabolic and autonomic networks, establishing baseline metrics for comparative neurobiology.
Comparative Analysis within the Melanocortin Class
To understand the unique profile of PT-141, it is beneficial to compare it against other structural analogues in the melanocortin peptide class. While Melanotan II exhibits potent affinity for MC1R (driving melanogenesis) alongside central receptor activity, PT-141 demonstrates reduced skin-pigmentation pathways while retaining central MC3R/MC4R activity.
Furthermore, when contrasted with metabolic peptides like CJC-1295 No DAC or growth factor secretagogues, PT-141 acts through entirely distinct GPCR signaling cascades that do not directly stimulate the somatotropic axis. Reviewing these structural and functional divergences within an institutional research program ensures that the appropriate molecular tools are selected for specific experimental endpoints. Laboratories sourcing research peptides can explore bulk institutional accounts to support comparative multi-compound studies.
Purity Verification and HPLC/MS Analytical Standards
In preclinical laboratory settings, compound purity is paramount to prevent confounding experimental data resulting from residual peptide fragments, counter-ions, or synthetic side products. PT-141 research requires strict analytical confirmation utilizing High-Performance Liquid Chromatography (HPLC) coupled with Mass Spectrometry (MS).
PX1 Research ensures that every batch of PT-141 undergoes independent testing in an ISO 17025 accredited laboratory. Our peptide purity standards guarantee a minimum of 99% purity by HPLC area, with tandem mass spectrometry confirming the precise molecular weight of 1024.2 Da. Every lot is accompanied by a publicly verifiable Certificate of Analysis (COA), verifying molecular identity and chemical uniformity.
Endotoxin Testing and Reconstitution Parameters
For cell culture assays and sensitive in vivo animal models, lipopolysaccharide (LPS) endotoxin contamination can trigger inflammatory cascades, altering baseline gene expression and neuroendocrine responses. PX1 Research subjects all peptide lots to chromogenic Limulus Amebocyte Lysate (LAL) testing, verifying endotoxin levels remain strictly below threshold limits (<0.01 EU/mg).
When preparing PT-141 for laboratory protocols, proper solvent selection and aseptic technique are required. The peptide is typically supplied as a lyophilized powder. Researchers should consult standard laboratory reconstitution protocols to determine appropriate buffer selection, such as sterile bacteriostatic water or phosphate-buffered saline (PBS), ensuring complete dissolution without vortex-induced mechanical shear.
Storage, Degradation Pathways, and Handling Protocols
Lyophilized PT-141 exhibits excellent long-term stability when stored at -20°C or -80°C in a desiccated environment, shielded from direct light exposure. Repeated freeze-thaw cycles must be avoided to prevent peptide aggregation and oxidation of the tryptophan residue at position 6.
Once reconstituted, aqueous solutions of PT-141 should be stored at 2°C to 8°C and utilized within a defined experimental timeframe to prevent hydrolytic cleavage. Standard operating procedures in the laboratory should dictate aliquoting reconstituted stock solutions into single-use microcentrifuge tubes to maintain consistency across long-term experimental series. Sourcing from domestic suppliers with fast fulfillment from CA and AZ facilities minimizes ambient temperature exposure during transit.
Frequently Asked Questions
What is PT-141 and what is its primary target in laboratory research?
PT-141 (Bremelanotide) is a synthetic cyclic heptapeptide melanocortin receptor agonist. In preclinical research, it is studied primarily for its binding selective affinity to central MC3R and MC4R receptors involved in neuroendocrine signaling pathways.
How does PT-141 differ from Melanotan II in preclinical models?
While Melanotan II binds strongly to MC1R (stimulating melanogenesis and skin pigmentation), PT-141 exhibits reduced relative affinity for MC1R while maintaining robust activity at central MC3R and MC4R sites, allowing researchers to study central pathways with minimal pigmentary influence.
What analytical methods are used to confirm PT-141 purity?
PT-141 purity and identity are verified using High-Performance Liquid Chromatography (HPLC) to establish chemical purity (≥99%) and Mass Spectrometry (MS) to confirm exact molecular mass (1024.2 Da).
Why is endotoxin testing critical for PT-141 in laboratory assays?
Bacterial endotoxins (LPS) can induce inflammatory cytokine expression in cell cultures and animal models, confounding experimental results. Testing ensures endotoxin levels are below rigorous research thresholds (<0.01 EU/mg).
What solvents are recommended for reconstituting PT-141 for laboratory use?
Lyophilized PT-141 is typically reconstituted using sterile bacteriostatic water or laboratory-grade phosphate-buffered saline (PBS), depending on the specific in vitro or in vivo protocol requirements.
How should reconstituted PT-141 solutions be stored?
Reconstituted solutions should be stored at 2°C to 8°C for short-term use, or aliquoted and stored at -20°C to -80°C for extended research timelines to avoid degradation and freeze-thaw fatigue.
Does PX1 Research provide lot-specific COAs for PT-141?
Yes. Every lot of PT-141 synthesized and distributed by PX1 Research includes a third-party Certificate of Analysis (COA) from an ISO 17025 accredited laboratory detailing HPLC purity and mass spec verification.
Can PT-141 be ordered for institutional bulk research projects?
PX1 Research offers wholesale and bulk institutional accounts for qualified academic and corporate research laboratories conducting large-scale preclinical studies.
All products are sold strictly for laboratory and research use only. Not for human or veterinary use, diagnosis, treatment or consumption. Statements have not been evaluated by the FDA.