DSIP vs Leucine Enkephalin (Leu-Enkephalin)
A neutral, side-by-side comparison of two nootropic & cognitive peptides — their mechanisms, dosing ranges, administration routes, side effects, and research evidence. For research and educational purposes only.
DSIP
DSIP (Delta Sleep Inducing Peptide) is a nonapeptide (9 amino acids) first isolated from rabbit thalamus in 1974, initially believed to directly induce slow-wave (delta) sleep. Research has since broadened its profile considerably: it modulates the HPA axis (reducing stress-driven cortisol), influences GH and LH release, demonstrates antioxidant properties, and may have cardioprotective effects. Despite decades of research, its precise receptor system remains incompletely characterized.
Full profileLeucine Enkephalin (Leu-Enkephalin)
One of the two primary endogenous enkephalins, alongside met-enkephalin. This pentapeptide (Tyr-Gly-Gly-Phe-Leu) acts primarily on δ-opioid receptors and secondarily on μ-opioid receptors. Research interests span pain modulation, neuroprotection, mood regulation, and immune system modulation. Extremely short half-life in vivo due to rapid enkephalinase degradation.
Full profile| DSIP | Leucine Enkephalin (Leu-Enkephalin) | |
|---|---|---|
| Category | Nootropic & Cognitive | Nootropic & Cognitive |
| Also known as | Delta Sleep Inducing Peptide, Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu | Leu5-enkephalin, YGGFL, L-enkephalin, endogenous opioid pentapeptide |
| Evidence | Research-stage | Research-stage |
| Dosing range | 100mcg–500mcg mcg, Once daily (evening) or every other day | 0.1mg–1mg mg, Intranasal or SC; extremely short half-life requires frequent dosing or continuous delivery |
| Administration | Subcutaneous injection, Intranasal, Intravenous (clinical studies) | Intranasal, Subcutaneous injection, Intraventricular (research only) |
| Key side effects | Generally well-tolerated, Daytime drowsiness if dosed in morning, Mild headache, Altered dream quality (common) | Tolerance development with repeated use (opioid receptor class effect), Mild euphoria (δ-opioid mediated), Nausea (at high doses), Constipation (opioid class effect at high doses) |
| Cited sources | 3 references | 2 references |
Key differences
- Administration: DSIP — Subcutaneous injection, Intranasal, Intravenous (clinical studies); Leucine Enkephalin (Leu-Enkephalin) — Intranasal, Subcutaneous injection, Intraventricular (research only).
- Dosing units differ: DSIP is dosed in mcg, Leucine Enkephalin (Leu-Enkephalin) in mg — they operate at different scales.
- Frequency: DSIP is typically Once daily (evening) or every other day; Leucine Enkephalin (Leu-Enkephalin) is Intranasal or SC; extremely short half-life requires frequent dosing or continuous delivery.
- Research depth: this profile cites 3 sources for DSIP vs 2 for Leucine Enkephalin (Leu-Enkephalin).
How each works
DSIP
DSIP does not directly trigger sleep in the simple sense originally proposed — more recent research indicates it modulates the neuroendocrine environment that facilitates sleep. Key findings: it reduces ACTH-driven cortisol elevation under stress, increases GH secretion in some models, and attenuates withdrawal severity in opioid and alcohol dependence (mechanisms unclear). DSIP demonstrates antioxidant effects and has cardioprotective properties in ischemic preconditioning models in animals. Its unique resistance to most peptidases (attributed to its unusual conformation) gives it a relatively long half-life for a nonapeptide.
Leucine Enkephalin (Leu-Enkephalin)
Leu-enkephalin was one of the first endogenous opioid peptides characterized, following the discovery of opioid receptors in 1973. It preferentially activates δ-opioid receptors (DOR) over μ-opioid receptors (MOR), producing analgesia, modulation of GABA release, and reward pathway activation. Enkephalinase (neprilysin/NEP, CD10) cleaves the Gly-Phe bond within ~2 minutes IV, necessitating stable analogues or NEP inhibitors for research applications.
This comparison aggregates public research and structured profile data for informational purposes only. It is not medical advice and does not recommend either compound for human use. Consult a qualified healthcare provider before considering any peptide.