Overview
PT-141 (bremelanotide) is a cyclic heptapeptide and synthetic analogue of the naturally occurring melanocortin peptide alpha-melanocyte-stimulating hormone (alpha-MSH). It was originally derived from Melanotan II by removal of the C-terminal amide group, converting it from a cyclic lactam to a free carboxylic acid. Unlike Melanotan II, PT-141 does not produce significant tanning effects in research models, as its primary receptor activity is directed toward the melanocortin 3 receptor (MC3R) and melanocortin 4 receptor (MC4R) rather than the MC1R responsible for melanogenesis. PT-141 acts centrally through the nervous system rather than through the vascular system, making it a distinct research tool for studying melanocortin signaling in the brain.
Mechanism
PT-141 is a non-selective melanocortin receptor agonist with activity at MC1R, MC3R, and MC4R, with the highest research interest focused on its MC3R and MC4R agonism. MC4R is expressed in the hypothalamus and limbic system and plays a well-characterized role in energy homeostasis and autonomic nervous system regulation. Research in rodent models has demonstrated that central melanocortin receptor activation by PT-141 and related analogues engages dopaminergic and oxytocinergic pathways in brain regions associated with motivation and reward. The peptide crosses the blood-brain barrier in animal models, enabling direct CNS engagement.
Research Areas
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Melanocortin Receptor Research
PT-141 is used as a pharmacological tool to study the distribution, signaling, and physiological roles of MC3R and MC4R in the central and peripheral nervous systems.
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Hypothalamic Circuit Research
Research has examined PT-141's effects on hypothalamic neuronal activity, neuropeptide release, and downstream autonomic outputs in rodent models.
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Dopaminergic Pathway Research
Studies have explored the relationship between melanocortin receptor activation and dopamine release in mesolimbic reward circuits using PT-141 as a probe compound.
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Energy Homeostasis Research
Given MC4R's established role in energy balance, PT-141 has been used in research models to study feeding behavior, energy expenditure, and body weight regulation.
Storage
Store lyophilized at -20°C. Reconstitute with sterile bacteriostatic water. Store reconstituted peptide at 4°C and use within 14 days. Protect from light.