PT-141 — Melanocortin Receptor Research

Last updated: May 2026

PT-141, also called bremelanotide, is a cyclic synthetic peptide. It triggers pigment signal receptors in the central nervous system. It is structurally linked to Melanotan II but modified with a lactam bridge that improves stability. PT-141 is studied as a pigment signal receptor agonist, in particular at MC3R. MC4R receptor subtypes. According to a review in the Journal of Sexual Medicine (2006). Early trial-based research on PT-141 examined MC3R. MC4R triggers pathways in the brain base as part of central nervous system signaling studies. All research using PT-141 is conducted under lab terms only.

Next Level Pharm supplies research-grade PT-141 tested to at least 99 percent purity by HPLC. Mass spec on every batch. HPLC confirms compound purity. Mass spec confirms the peptide molecule weight. A Certificate of Test ships with every lot.

The sections below cover PT-141’s structure, the pigment signal receptor system, and MC3R. MC4R research shows how PT-141 differs from PDE5-pathway compounds functionally, and sourcing standards.

Key Takeaways

What it is: PT-141 (bremelanotide) is a cyclic synthetic pigment signal peptide. It triggers MC3R and MC4R receptors in the central nervous system in research models.
Pathway: PT-141 acts centrally through brain-based pigment signal receptor pathways. Is functionally different from distally acting compounds.
Receptor specificity: PT-141 shows action at many pigment signal receptor subtypes (MC1R, MC3R, MC4R). MC3R and MC4R are the CNS-relevant subtypes in published research.
Research context: PT-141 has been studied in trial-based contexts. The research-grade compound is for lab research only. Is not the same as any approved drug.
Sourcing standard: Research-grade PT-141 needs HPLC purity above 99 percent. Mass spec proof of the cyclic peptide structure. A lot-exact Certificate of Test.

Here is a closer look at the pigment signal receptor system, what studies show. What to check when sourcing.

What Is PT-141 and How Is It Structured?

PT-141 is a cyclic heptapeptide. Its cyclic structure comes from a lactam bridge between two amino acids in the chain. This bridge makes the molecule more rigid and metabolically stable than linear analogs. PT-141 was derived from Melanotan II,. It is a linear cyclic peptide studied for pigmentation effects through MC1R trigger.

The key structural change in PT-141 compared to Melanotan II is a substitution. It shifts receptor preference toward MC3R and MC4R. Reduces the strong MC1R action that drives pigmentation effects. According to a study in Peptides (2003), PT-141 showed selective binding to MC3R. MC4R in radioligand binding assays, with a different selectivity profile than Melanotan II. This receptor selectivity shift is what defines PT-141’s research context as CNS-pathway focused rather than pigmentation focused.

What Is the Melanocortin Receptor System?

The pigment signal receptor family includes five subtypes: MC1R through MC5R. Each subtype has a different tissue distribution and living function. MC1R is on melanocytes and controls pigmentation. MC2R is on the adrenal cortex and binds ACTH. MC3R and MC4R are in the brain base and other CNS regions. MC5R is in exocrine glands.

PT-141 research focuses on MC3R and MC4R since these receptors are linked to CNS signaling pathways. It affects appetite control, energy balance, and other brain-based functions in animal models. According to a review in Endocrine Reviews (2006). MC4R trigger in the brain base is one of the key regulators of energy balance. Downstream CNS signaling studied in rodent and primate models. This receptor biology context explains why PT-141 is studied in brain-based signaling research.

Browse sexual health peptides for COA-tested PT-141 and linked research compounds.

What Does MC3R and MC4R Research Show for PT-141?

MC3R and MC4R are both expressed in brain-based nuclei. Triggers of these receptors change downstream signaling through cAMP and other second-messenger pathways. The brain base is a master control center that integrates many physical signals. MC3R. MC4R action in this region has been linked to many downstream CNS effects in animal model studies.

Published PT-141 research examined MC3R. MC4R trigger in rodent models using receptor link assays, intracellular signaling measurements, and behavioral outcomes. According to a study in the Journal of Sexual Medicine (2004), PT-141 produced MC3R. MC4R-dependent CNS action in rat models. This CNS-mediated pathway is distinct from compounds that act on peripheral tissue without brain-based involvement.

How Does PT-141 Differ from PDE5 Compounds in Studies?

PDE5 inhibitors (such as sildenafil) act distally by blocking the phosphodiesterase type 5 enzyme in vascular smooth muscle. This increases cyclic GMP and promotes vasodilation in exact tissues. The pathway is entirely peripheral and does not involve direct CNS receptor trigger.

PT-141 acts centrally through brain-based MC3R and MC4R triggers. This is a fundamentally different pathway at a different anatomical site. Experts studying the CNS aspects of pigment signal signaling use PT-141 in particular since it allows review of brain-based pathway triggers without peripheral vascular effects. Published research distinguishes these two mechanistic pathways in the research on pigment signal agonists. PDE5 pathway biology.

What Does Receptor Binding Data Show for PT-141?

Receptor link assays measure how tightly a compound attaches to an exact receptor. For PT-141. Binding studies used radiolabeled peptide competition assays to determine affinity at each pigment signal receptor subtype. The binding data shows that PT-141 has measurable affinity at MC1R, MC3R. MC4R, with the strongest research focus on MC3R and MC4R.

The binding affinity at MC4R is mainly well-studied since MC4R knockout animal models have been used to confirm. MC4R is needed for PT-141’s CNS effects. Studies using MC4R knockout mice showed reduced PT-141 CNS action compared to wild-type controls. This confirms that MC4R is a primary target in the mechanistic pathway. According to a review in Research-grade Reviews (2007). Pigment signal receptor link assays for synthetic peptides including PT-141 showed consistent receptor preference profiles across many lab groups.

How Is Research-Grade PT-141 Sourced?

Research-grade PT-141 needs HPLC purity at 99 percent or above. Mass spec proof of the cyclic heptapeptide molecule weight. A lot-exact Certificate of Test. The cyclic structure of PT-141 means standard linear peptide mass spec values do not apply. experts should confirm that the COA reflects the correct molecule weight for the cyclic form.

PT-141 is supplied as a lyophilized powder. Lyophilization removes moisture through freeze-drying under vacuum, extending shelf life and allowing room-temperature shipping. Products from unverified sources have shown incorrect molecule weights or purity shortfalls in independent testing. Lot-level records are needed for reproducible receptor link and CNS pathway research.

Receptor	Tissue distribution	PT-141 activity	Research context
MC1R	Melanocytes, skin	Moderate	Pigmentation pathway
MC2R	Adrenal cortex	Low / none	ACTH axis
MC3R	Hypothalamus, limbic	High	CNS signaling studies
MC4R	Hypothalamus, brainstem	High	Energy homeostasis, CNS
MC5R	Exocrine glands	Low	Exocrine function

Frequently Asked Questions

What is PT-141?

PT-141 (bremelanotide) is a cyclic synthetic peptide. It triggers pigment signal receptors, in particular MC3R and MC4R, in the central nervous system. It is used in receptor link and CNS pathway research. PT-141 is for lab research only. It is not approved for human use as a research compound. Purity is tested to at least 99 percent by HPLC and mass spec on every batch.

How is PT-141 different from Melanotan II?

PT-141 and Melanotan II are both pigment signal receptor agonists, but their receptor selectivity differs. Melanotan II has strong MC1R action. Drives pigmentation effects studied in cell and animal models. PT-141 was modified with a lactam bridge. Amino acid substitution to shift selectivity toward MC3R and MC4R. This makes PT-141 more suitable for CNS pathway research. Less focused on pigmentation biology compared to Melanotan II.

What is the melanocortin receptor system?

The pigment signal receptor family has five subtypes (MC1R through MC5R). MC1R controls pigmentation in melanocytes. MC2R is the ACTH receptor on the adrenal cortex. MC3R and MC4R are in the brain base and other CNS regions. MC5R is in exocrine glands. Each subtype has different tissue distribution and function. PT-141 research focuses on MC3R. MC4R since these are the CNS-relevant subtypes linked to brain-based signaling pathways in animal models.

What is MC4R and why is it studied with PT-141?

MC4R (pigment signal-4 receptor) is expressed in the brain base and brainstem. It is linked to energy balance, appetite control, and downstream CNS signaling in rodent research. PT-141 shows high binding affinity at MC4R in radioligand assays. MC4R knockout mouse studies confirmed that MC4R is needed for PT-141’s CNS effects in animal models. This receptor is one of the most studied targets in the pigment signal system research research.

How does PT-141 differ from PDE5 inhibitors mechanistically?

PDE5 inhibitors act distally by blocking phosphodiesterase type 5 in vascular smooth muscle, increasing cyclic GMP. Promoting vasodilation. PT-141 acts centrally by activating MC3R and MC4R in brain-based tissue. These are functionally distinct pathways at different anatomical locations. Experts studying brain-based pigment signal signaling use PT-141 in particular since it provides CNS pathway triggers without peripheral vascular pathway interference.

Has PT-141 been studied in clinical research?

PT-141 has been studied in trial-based research contexts. Early-phase human studies examined pigment signal receptor trigger and downstream CNS pathway changes. The research-grade compound is not the same as any approved pharmaceutical product. It is intended for lab research use only. Experts should note the distinction between the research compounds studied in early trial-based trials. Any approved therapeutic formulation used in trial-based medicine.

What purity is required for research-grade PT-141?

Research-grade PT-141 is tested to at least 99 percent purity by HPLC. Mass spec confirms the molecular weight of the cyclic heptapeptide structure. The cyclic lactam bridge changes the molecule weight compared to a linear peptide of the same chain. A Certificate of Test for the exact lot records purity and type. Full lot records ships with every PT-141 order to all 50 states.

Does PT-141 require special storage conditions?

Lyophilized PT-141 is stable at room temperature during shipping. Lyophilization removes moisture under vacuum, keeping the peptide stable without refrigeration during transit. After receipt, refrigerated storage at 2 to 8 degrees Celsius is standard for medium-term storage. Long-term storage at minus 20 degrees Celsius is acceptable. The exact storage terms for each lot are listed on the Certificate of Test. PT-141 ships to all 50 states in the United States.

Summary

PT-141 (bremelanotide) is a cyclic synthetic pigment signal peptide. It triggers MC3R and MC4R receptors in the central nervous system. Its CNS-mediated pathway is functionally distinct from distally acting compounds.

Published research covers receptor link assays, MC4R knockout proof studies. Brain-based CNS pathways trigger in rodent models. PT-141 has also been studied in early-phase trial-based research contexts. The research-grade compound is for lab use only. Sourcing needs HPLC purity above 99 percent, cyclic peptide mass spec proof, and lot-exact COA records.

What Should You Do Next?

If you are studying PT-141 for pigment signal receptor or CNS pathway research. Here is how to approach sourcing:

Confirm that mass spec records accounts for the cyclic lactam structure. Molecule weight for the cyclic form differs from a linear peptide of the same chain.
Review MC4R and MC3R receptor link research to understand the research context. What lab systems are most often used.
Browse research-grade PT-141 at Next Level Pharm for COA-tested options with full lot records.

About the Author

Next Level Pharm Research Team

Alex M covers peer-reviewed findings in peptide science for Next Level Pharm, a US-based supplier of research-grade peptides verified to >=99% purity via HPLC and mass spectrometry on every batch.

Disclaimer: The information provided on this page is for educational and research purposes only. Next Level Pharm’s products are intended for laboratory research use only. They are not intended for human consumption, diagnostic, therapeutic, or medicinal purposes. This content does not constitute medical advice. Always consult a licensed healthcare professional before making any health-related decisions.

What Is PT-141? Melanocortin Receptor Research Explained