PT-141: Melanocortin Receptor Agonist Research Overview

PT-141 was originally developed as a sun-tanning research compound, derived from the melanotan-class of synthetic alpha-melanocyte stimulating hormone (alpha-MSH) analogs. During early preclinical investigations, researchers observed effects on sexual response signaling in animal models that were not accounted for by skin melanogenesis, prompting a redirection of research focus to those pathways.^[1]

The compound is a derivative of Melanotan II — a cyclic alpha-MSH analog with activity at multiple melanocortin receptors (MC1R, MC3R, MC4R, MC5R). PT-141 differs structurally from MT-II and shows a different selectivity profile, with research interest focused particularly on its MC4R activity.^[2]

PT-141 is studied as a research reference compound. While clinical formulations exist with approved indications in specific therapeutic contexts, research-grade material supplied for laboratory use is intended exclusively for in vitro research.

PT-141 structural features:

• Sequence: cyclic heptapeptide based on the alpha-MSH active core (His-Phe-Arg-Trp)

• Cyclization: lactam bridge providing conformational restriction

• Length: 7 amino acids

• Molecular formula: C₅₀H₆₈N₁₄O₁₀

• Molecular weight: approximately 1,025 Da

• C-terminus: free acid

Both Melanotan II and PT-141 are cyclic heptapeptide analogs of the alpha-MSH active core. They differ in C-terminal chemistry — MT-II has an amide C-terminus, while PT-141 has a free carboxylic acid. This single structural difference affects melanocortin receptor selectivity, particularly the relative activity at MC1R (which drives melanogenesis) vs MC4R (where the sexual response signaling localizes).^[2]

The cyclization in both peptides imposes a defined backbone geometry that mimics the active conformation of the alpha-MSH His-Phe-Arg-Trp motif, providing receptor agonist activity in a compact molecule.

PT-141 binds and activates multiple melanocortin receptor subtypes.

The melanocortin receptor family includes five subtypes (MC1R through MC5R), each with distinct tissue distribution and signaling consequences. PT-141 shows agonist activity at MC1R, MC3R, MC4R, and MC5R with varying potency. MC4R activity is the primary focus of central sexual response research.^[3]

MC4R is expressed predominantly in the central nervous system, including hypothalamic nuclei involved in appetite, autonomic regulation, and sexual response circuits. MC4R agonist activity triggers Gs-coupled cAMP signaling, with downstream consequences including modulation of pro-opiomelanocortin (POMC) neuron activity.^[4]

PT-141 research spans several preclinical domains.

The largest body of PT-141 preclinical literature examines central nervous system pathways involved in sexual response. Rodent models with standardized behavioral endpoints have been the principal substrate. The signaling is mediated through MC4R-expressing neurons in specific hypothalamic nuclei.^[5]

PT-141 is used as a tool compound in studies characterizing the broader melanocortin receptor family. Comparative studies pair PT-141 with subtype-selective agonists and antagonists to dissect MC1R-vs-MC4R contributions to various pathway readouts.^[3]

Because MC4R is centrally involved in appetite regulation, melanocortin agonists including PT-141 have been studied in rodent models of food intake and body weight. These studies are distinct from the sexual response research line but use overlapping receptor biology.^[4]

PT-141 is a small cyclic heptapeptide. The cyclization provides structural stability, and the compound is generally robust under standard handling conditions.

Lyophilized PT-141 is stored at minus 20 degrees Celsius for long-term preservation. Refrigerated storage at 4 degrees Celsius is acceptable short-term.

Bacteriostatic water or sterile water are standard reconstitution solvents. The cyclic structure dissolves cleanly in aqueous solvents.

HPLC for purity (≥99%), mass spectrometry for identity confirmation, and verification of intact cyclization. Each batch of Instant Peptides PT-141 ships with a full Certificate of Analysis.

Instant Peptides supplies PT-141 as a synthetic lyophilized reference compound. Material is supplied to qualified research professionals. Not for human or animal consumption.

View the product page for current pricing and the Certificate of Analysis for the active batch.