Semax and Selank: Nootropic Peptide Research and Neuroprotection Studies
A comparative analysis of Semax and Selank — synthetic neuropeptides derived from ACTH and tuftsin, respectively — and their applications in cognitive function and neuroprotection research.
Semax: The ACTH-Derived Nootropic
Semax is a synthetic heptapeptide (Met-Glu-His-Phe-Pro-Gly-Pro) derived from the N-terminal fragment of adrenocorticotropic hormone (ACTH 4-10). The addition of the Pro-Gly-Pro tripeptide at the C-terminus confers resistance to enzymatic degradation, extending its half-life significantly compared to the native ACTH fragment.
Proposed Mechanisms
Semax influences multiple neurological pathways:
- Neurotrophic factor expression: Upregulates brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) mRNA levels in the hippocampus
- Melanocortin receptor modulation: Acts as a partial agonist at MC4 and MC5 receptors, which are expressed in brain regions involved in learning and memory
- Dopaminergic and serotonergic systems: Modulates neurotransmitter levels without direct receptor binding
- Enkephalin degradation: Inhibits enkephalin-degrading enzymes, enhancing endogenous opioid peptide signaling
- Cerebral blood flow: Increases brain microcirculation without systemic hemodynamic effects
Research Applications
- Learning and memory tasks (Morris water maze, passive avoidance, novel object recognition)
- Ischemic stroke models for neuroprotection research
- Optic nerve and retinal ganglion cell protection
- Attention and cognitive performance under fatigue conditions
- Nerve regeneration after peripheral nerve injury
Selank: The Tuftsin Analog
Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro) is a synthetic analog of the endogenous immunomodulatory peptide tuftsin. Like Semax, the Pro-Gly-Pro tail provides enzymatic stability.
Proposed Mechanisms
- GABAergic modulation: Modulates GABA receptor function without direct agonism
- Anti-anxiety effects: Increases exploratory behavior and reduces anxiety-like behavior in elevated plus maze and open field tests
- Immune-neural interaction: Retains tuftsin's immunomodulatory properties while adding central effects
- Monoamine neurotransmitter balance: Stabilizes serotonin and dopamine turnover
Research Applications
- Anxiety models (elevated plus maze, light-dark box, novelty-suppressed feeding)
- Stress-induced cognitive impairment studies
- Immune-brain axis research
- Antidepressant screening models
Semax vs. Selank: Research Comparison
| Property | Semax | Selank |
|---|---|---|
| Origin | ACTH fragment | Tuftsin analog |
| Primary effect | Cognitive enhancement | Anxiolysis |
| BDNF upregulation | Strong | Moderate |
| Melanocortin activity | Yes (MC4/MC5) | No |
| GABAergic effects | Minimal | Significant |
| Anxiolytic profile | Mild | Pronounced |
Malice Research Lab supplies Semax (XA10) and Selank (SK10) for neurological and neuroprotection research.