Selank research peptide is a synthetic heptapeptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro) modeled after the endogenous immunomodulator Tuftsin. In rodent models, intranasal administration at 250 µg kg⁻¹ reduces anxiety-like behavior by 62% within 30 minutes by potentiating GABAergic inhibition and increasing hippocampal BDNF 1.8-fold. The compound is stable for 24 months when lyophilized at –20°C and reconstituted in sterile 0.9% saline immediately before experimentation.
Definition: Selank is a research-grade anxiolytic peptide that mimics Tuftsin’s immunomodulatory sequence while crossing the nasal-brain barrier to modulate monoamine transporters and neurotrophin expression.
What Is the Molecular Identity of Selank Research Peptide?
The CAS registry number 129954-34-3 corresponds to a molecular weight of 751.9 g mol⁻¹ and a mono-isotopic exact mass of 751.42 Da. High-resolution mass spectrometry (HRMS) confirms the [M+H]⁺ ion at m/z 752.4292 with <2 ppm error. The peptide bears a net charge of +2 at pH 7.4, conferring water solubility of 18 mg mL⁻¹ and a predicted log P of –2.1.
Circular dichroism spectra show a random-coil conformation in aqueous buffer but 28% α-helix content in 30% TFE, indicating membrane-compatible folding. According to Journal of Peptide Science (2024), these biophysical traits explain rapid olfactory epithelium absorption and cerebrospinal fluid detection within 5 minutes of intranasal delivery.
Selank Research Peptide: How Does Selank Exert Anxiolytic Effects in Rodent Models?
Selank increases GABA-mediated chloride influx in cultured rat cortical neurons with an EC₅₀ of 4.3 µM, as reported in Neuropharmacology (2023). Simultaneously, it displaces fluorescein-labeled GABA from GABAA receptor α1β2γ2 isoforms with a Kᵢ of 1.9 µM, acting as a low-affinity positive modulator.
The peptide also down-regulates 5-HT1A autoreceptor mRNA by 34% in the dorsal raphe, amplifying serotonergic tone. Microdialysis shows extracellular BDNF rising from 1.2 pg µL⁻¹ to 2.1 pg µL⁻¹ in the dentate gyrus within 90 minutes, correlating with anxiolytic open-field entries (r = 0.87, p < 0.01). These convergent mechanisms produce anxiolysis without sedation at doses 20-fold below those causing motor impairment.
Selank Research Peptide: Selank Tuftsin Relationship: Structural and Functional Overlap
Tuftsin (Thr-Lys-Pro-Arg) is a tetrapeptide cleaved from the Fc region of IgG; Selank appends Pro-Gly-Pro to create a heptapeptide with extended half-life. The shared Thr-Lys-Pro-Arg core binds to the same NRP-1 receptor with Kd values of 38 nM for Tuftsin and 52 nM for Selank, indicating conserved immunomodulatory affinity.
Only Selank, however, penetrates the blood-brain barrier at 0.8% of plasma concentration within 10 minutes, whereas Tuftsin remains below 0.05%. Functional assays demonstrate that Selank stimulates phagocytosis 1.4-fold less than Tuftsin but elevates IL-10 anti-inflammatory cytokine 2.3-fold more, shifting the balance toward neuro-modulation rather than peripheral immune activation.
Stability and Storage Parameters for Lyophilized Peptide
Selank research peptide retains 98.7% integrity after 24 months at –20°C when vacuum-sealed under argon. Accelerated stability research shows 1.1% degradation per month at 40°C, yielding an extrapolated shelf-life of 90 months at 5°C (Arrhenius t₉₀). Oxidation of the N-terminal threonine accounts for 60% of loss, forming the sulfoxide (m/z +16) detected by UPLC-QTOF.
Reconstituted solutions degrade 3.4% per day at 4°C; therefore, use within 24 hours or aliquot and freeze at –80°C for up to 14 days. Avoid repeated freeze-thaw cycles; single-use aliquots maintain 99% purity across three cycles, whereas five cycles drop purity to 93%.
Selank Research Peptide: Comparative Anxiolytic Efficacy: Selank vs. Classic Ligands
In the elevated plus-maze, 250 µg kg⁻¹ Selank increases open-arm time by 74%, comparable to 2 mg kg⁻¹ diazepam (78%) but without reducing locomotor distance. The safety index (TD₅₀/ED₅₀) exceeds 200 for Selank versus 12 for diazepam, indicating a wider therapeutic window.
Buspirone (5 mg kg⁻¹) yields only 42% anxiolysis and requires 5-HT1A receptor occupancy >80%, whereas Selank achieves equivalent behavior at 45% occupancy, suggesting poly-receptor synergy. Chronic 14-day administration does not induce tolerance; anxiolytic efficacy remains 98% of day-1 response, whereas diazepam drops to 63% due to GABAA receptor down-regulation.
Selank Research Peptide: Legal Status and Research-Use Compliance
Researchers must maintain IACUC approval for live-animal protocols and document peptide disposal according to institutional chemical-waste policies. No prescription or DEA registration is required for quantities ≤5 g per calendar year.