Semax (ACTH 4-10 Analog)

Semax is a synthetic heptapeptide derived from the ACTH (adrenocorticotropic hormone) fragment 4-10, with a Pro-Gly-Pro tripeptide extension at the C-terminus. Developed at the Institute of Molecular Genetics in Russia, it has been approved as a prescription nootropic and neuroprotective medication in Russia and several other countries. Unlike full-length ACTH, Semax lacks hormonal activity and does not stimulate cortisol release. The modifications enhance metabolic stability while retaining and amplifying the cognitive-enhancing properties associated with the ACTH(4-10) fragment, known as the "active core" for neurotropic effects.

Semax exerts its effects through several neurobiological mechanisms: **Neurotrophic Factor Regulation:** Semax significantly increases expression of BDNF, NGF, and their receptors (TrkA, TrkB). These neurotrophins are essential for neuronal survival, differentiation, and synaptic plasticity. **Dopaminergic System Modulation:** The peptide affects dopamine and serotonin neurotransmission, particularly in frontal cortex regions involved in attention, working memory, and executive function. **Neuroprotection:** Semax provides protection against various neurological insults including hypoxia, ischemia, and neurotoxicity through antioxidant effects and mitochondrial stabilization. **Gene Expression Effects:** Studies show Semax modulates expression of hundreds of genes involved in neurotransmission, immune function, vascular regulation, and cellular stress responses.