Melanotan I & II

Synthetic α-MSH analogues that stimulate melanin production for tanning/UV protection; MT-II also acts centrally to increase libido and may suppress appetite. MT-1 does not cross the BBB.

- Enhance pigmentation and reduce UV damage

- Boost libido/sexual function

Mechanism of Action

How this peptide works in the body

Melanocortin Receptor Activation:

Melanotan I binds to the melanocortin 1 receptor (MC1R) on melanocytes, stimulating melanogenesis (the process of melanin production). This activation triggers adenylate cyclase, leading to an increase in cyclic adenosine monophosphate (cAMP) levels, which in turn activates protein kinase A (PKA). PKA phosphorylates cAMP response element-binding protein (CREB), inducing the expression of microphthalmia-associated transcription factor (MITF). MITF then upregulates key melanogenic enzymes, including tyrosinase (TYR), tyrosinase-related protein-1 (TRP-1), and tyrosinase-related protein-2 (TRP-2), resulting in increased melanin synthesis. This leads to enhanced skin pigmentation and UV protection without the need for prolonged sun exposure.

Melanotan II (MT-2):

Melanotan II is a more potent melanocortin receptor agonist, binding not only to MC1R but also to MC3R and MC4R, leading to a broader range of physiological effects.

MC1R Activation: Similar to MT-1, MT-2 stimulates melanin production via the cAMP/PKA/MITF pathway, promoting a deeper and longer-lasting tan while enhancing UV protection.

MC4R Activation: MT-2 binds to melanocortin 4 receptors (MC4R) in the hypothalamus, which regulates energy balance, appetite suppression, and sexual function. This activation leads to a reduction in neuropeptide Y (NPY) signaling, decreasing hunger and caloric intake, contributing to metabolic regulation and weight loss.

MC3R Activation: MT-2 interacts with melanocortin 3 receptors (MC3R), influencing sexual function, mood, and energy balance. This results in the release of pro-opiomelanocortin (POMC)-derived peptides, stimulating dopaminergic and oxytocinergic pathways that enhance libido and erectile function. These effects make MT-2 a promising therapeutic agent for sexual dysfunction, particularly erectile dysfunction and hypoactive sexual desire disorder (HSDD).