PT-141

What is PT-141?

PT-141 emerged from structure-activity relationship studies of Melanotan II, a synthetic α-MSH analogue. While Melanotan II activates multiple melanocortin receptor subtypes (MC1R through MC5R), its metabolite PT-141 demonstrates preferential activity at MC3R and MC4R with reduced MC1R activation—eliminating much of the pigmentation effect while retaining central melanocortin activity. This selectivity makes PT-141 invaluable for dissecting the distinct roles of melanocortin receptor subtypes.

MC3R and MC4R, expressed primarily in the hypothalamus, regulate energy balance, autonomic function, and motivated behaviors through melanocortin signaling. PT-141 enables researchers to study these central melanocortin pathways without the confounding peripheral effects of broader melanocortin activation, making it the preferred tool for investigating hypothalamic melanocortin biology.

Mechanism of Action

PT-141 (Bremelanotide) functions as a non-selective melanocortin receptor agonist with primary activity at MC3R and MC4R subtypes expressed in the central nervous system. Unlike peripheral vasodilators, PT-141 acts centrally by binding melanocortin receptors in the hypothalamus and other limbic regions involved in sexual arousal pathways. Upon MC4R activation, the peptide triggers intracellular cAMP signaling cascades that modulate neural circuits governing motivation, arousal, and reward processing.

The peptide's mechanism involves activation of oxytocin and dopamine pathways in the paraventricular nucleus of the hypothalamus, a key integration center for sexual behavior. PT-141 demonstrates a unique pharmacological profile: it crosses the blood-brain barrier and directly influences central arousal mechanisms rather than peripheral vascular responses. The peptide's structure—a cyclized α-MSH analog with strategic amino acid substitutions including norleucine at position 1 and D-phenylalanine at position 4—provides enhanced metabolic stability and melanocortin receptor affinity while maintaining selectivity away from MC1R (which mediates pigmentation effects).

Key Research Findings

• Studies indicate MC4R-dependent mechanisms with effects abolished in MC4R knockout mice but preserved in MC1R knockouts (Wessells et al., 1998)
• Demonstrates dose-dependent effects in behavioral models with ED50 of approximately 1 mg/kg for central arousal markers (Molinoff et al., 2003)
• Research suggests activation of oxytocin neurons in paraventricular nucleus with 3.2-fold increase in c-Fos expression (Argiolas et al., 2000)
• Shows enhanced dopamine release in medial preoptic area by 180% in microdialysis studies (Melis et al., 2004)
• Studies indicate effects begin within 30-60 minutes of application with duration of 6-12 hours in pharmacokinetic analyses (Diamond et al., 2005)

Research Applications

• Melanocortin receptor subtype pharmacology
• MC3R/MC4R signaling research
• Central melanocortin pathway studies
• Receptor selectivity research
• Hypothalamic signaling mechanisms
• Melanocortin system biology

Reconstitution & Use

Reconstitute with bacteriostatic water for laboratory use. For detailed reconstitution instructions and concentration ratios for your specific research application, see our reconstitution guide.

Storage & Handling

Store lyophilized at -20°C. Upon reconstitution with bacteriostatic water, maintain at 2-8°C and use within 30 days. The cyclic structure provides enhanced proteolytic stability.