CerebrolysinvsSelank

Cerebrolysin is a complex biological preparation consisting of low-molecular-weight neuropeptides (approximately 75%) and free amino acids (approximately 25%), derived from enzymatic breakdown of porcine brain tissue. The peptide fraction contains fragments that mimic the activity of endogenous neurotrophic factors — BDNF, NGF, ciliary neurotrophic factor (CNTF), and glial cell line-derived neurotrophic factor (GDNF) — without being identical to any single neurotrophin.

The neurotrophic peptide components activate canonical neurotrophin signaling pathways. BDNF-mimetic peptides bind TrkB receptors, activating PI3K/Akt (cell survival) and Ras/MAPK/ERK (synaptic plasticity) cascades. NGF-mimetic peptides activate TrkA receptors on cholinergic neurons, supporting their survival and acetylcholine production. The combined neurotrophic activity promotes neuronal survival in ischemic and degenerative conditions, enhances synaptic plasticity and dendritic branching, and stimulates neurogenesis in the subgranular zone of the hippocampal dentate gyrus — one of the two brain regions where new neurons are produced in adults.

In Alzheimer's disease, Cerebrolysin has demonstrated multiple disease-modifying effects in preclinical and clinical studies. It reduces amyloid-beta aggregation by modulating the activity of amyloid precursor protein (APP) processing enzymes, shifting cleavage toward the non-amyloidogenic alpha-secretase pathway. It also reduces tau hyperphosphorylation by inhibiting glycogen synthase kinase-3β (GSK-3β) and cyclin-dependent kinase 5 (CDK5), the primary kinases responsible for the pathological phosphorylation of tau that leads to neurofibrillary tangle formation. In acute stroke, Cerebrolysin provides neuroprotection against glutamate excitotoxicity by modulating NMDA receptor activity — reducing excessive calcium influx through the receptor while preserving physiological glutamatergic signaling needed for normal neuronal function. Its approval in over 50 countries and large clinical evidence base (including meta-analyses of randomized controlled trials) make it one of the most clinically validated neuropeptide preparations, despite its lack of FDA approval.

Selank is a synthetic heptapeptide based on the endogenous immunomodulatory peptide tuftsin (Thr-Lys-Pro-Arg), with a stabilizing Pro-Gly-Pro extension at the C-terminus that dramatically increases its resistance to aminopeptidase degradation. Developed at the Institute of Molecular Genetics of the Russian Academy of Sciences, it was designed to combine the immune-enhancing effects of tuftsin with anxiolytic and nootropic properties.

The anxiolytic mechanism involves modulation of GABAergic neurotransmission. Selank acts as an allosteric modulator of GABA-A receptors, enhancing the inhibitory effects of GABA in anxiety-related brain regions including the amygdala, hippocampus, and prefrontal cortex. This produces a benzodiazepine-like anxiolytic effect without the sedation, cognitive impairment, or addiction potential associated with benzodiazepines — because Selank modulates rather than directly activates the receptor. Additionally, Selank stabilizes enkephalins (endogenous opioid pentapeptides) by inhibiting enkephalin-degrading enzymes (aminopeptidases and enkephalinase/neprilysin), prolonging their mood-regulating and anxiolytic signaling.

The nootropic effects are mediated through neurotrophic factor upregulation. Selank increases expression of brain-derived neurotrophic factor (BDNF) in the hippocampus and prefrontal cortex, promoting dendritic branching, synaptic plasticity, and long-term potentiation — the cellular mechanisms underlying memory formation and cognitive flexibility. It also modulates serotonergic (5-HT) metabolism, altering the balance between serotonin and its metabolite 5-HIAA in key brain regions. The immunomodulatory component derives from the tuftsin core: tuftsin naturally activates monocytes and macrophages through specific receptors, enhancing phagocytic activity and modulating IL-6, TNF-α, and other cytokine production. This immune regulation occurs at sub-anxiolytic doses, suggesting it is an independent pharmacological effect. The combined anxiolytic, cognitive-enhancing, and immunomodulatory profile is unique among available peptides.