Peptides: Dihexa Overview — HGF/MET Pathway Agonist
Bhattarai et al. 2014 (PMID 24726369): dihexa is approximately 10 million-fold more potent than BDNF at facilitating hippocampal synaptogenesis via the HGF/MET receptor pathway in rodent models.
| Measure | Value | Unit | Notes |
|---|---|---|---|
| Evidence Grade | D | grade | No human clinical trials; all data from rodent in vitro and in vivo models; no approved indication in any jurisdiction |
| Potency vs BDNF | ~10,000,000 | × (orders of magnitude) | PMID 24726369: approximately 7 orders of magnitude more potent than BDNF at HGF/MET-mediated synaptogenesis in rodent hippocampus |
| Peptide Length | 6 | amino acids | Hexapeptide; N-terminal modified angiotensin IV analogue; sequence: Nle1-Try-Ile-His-Pro-Phe (with modifications) |
| Primary Receptor Target | HGF/MET | receptor pathway | Hepatocyte growth factor receptor (c-MET); not the same as BDNF/TrkB pathway, though effects overlap in synaptogenesis outcomes |
| Human Trials | 0 | trials | No Phase 1, 2, or 3 human trials published or registered as of 2026 |
| Lipophilicity | High | property | Lipophilic modification enables CNS penetration; long duration of action in rodent models (days vs hours for most peptides) |
| Duration of Effect (rodent) | Days | estimated | Rodent data suggests persistent synaptogenic effect lasting days after single dose; mechanism unclear — not replicated in humans |
IMPORTANT: Research Context Disclaimer
Dihexa has never been tested in human clinical trials. This page describes preclinical (animal) research only. No dosing recommendations, protocols, or administration guidance is provided because none is supported by evidence. The extraordinary potency figures reported in rodent models are not translatable to human use without safety data. Dihexa should be treated as a high-potency experimental research compound with entirely unknown human safety and toxicity profiles.
What Is Dihexa
Dihexa (also designated PNB-0408) is a synthetic hexapeptide developed at Washington State University as a modified analogue of angiotensin IV. It was designed to penetrate the blood-brain barrier more effectively than its parent compound while activating the hepatocyte growth factor / c-MET receptor (HGF/MET) pathway in hippocampal tissue.
The HGF/MET pathway is distinct from the BDNF/TrkB pathway but produces overlapping downstream effects on synaptic plasticity, dendritic branching, and hippocampal neurogenesis. Dihexa’s extreme potency in rodent hippocampal synaptogenesis assays is the basis for research interest — and the basis for outsized enthusiasm in online biohacking communities that exceeds the actual evidence base.
Evidence Summary Table
| Study | Model | Endpoint | Finding | PMID |
|---|---|---|---|---|
| Bhattarai 2014 | Rat (fear conditioning) | Synaptogenesis potency vs BDNF | ~10M× more potent in hippocampal assay | 24726369 |
| McCoy 2013 | Rat (cognitive assessment) | Spatial memory; MWM | Improved spatial memory in scopolamine-impaired rats | 24006337 |
| Benoist 2011 | Rat (hippocampal slice) | Synaptogenesis; dendritic branching | Facilitated synapse formation in aged rat tissue | 21742936 |
| Human Phase 1 | N/A | Safety/tolerability | No study conducted | — |
| Human Phase 2 | N/A | Cognitive efficacy | No study conducted | — |
Receptor Pathway Comparison
| Pathway | Key Compounds | Receptor | Downstream Effect | Evidence in Humans |
|---|---|---|---|---|
| BDNF/TrkB | BDNF (endogenous), Semax (indirect) | TrkB | Synaptic plasticity, neurogenesis | Strong (extensive human data) |
| HGF/MET | Dihexa (direct agonist) | c-MET | Synaptogenesis, dendritic branching | None — rodent only |
| CREB/cAMP | Semax, various nootropics | Multiple | Gene transcription for BDNF, CREB targets | Moderate (some human data) |
| GABA-A modulation | Selank, benzodiazepines | GABA-A | Anxiolytic, sedative | Strong (extensive human data) |
| Neuroprotection (general) | BPC-157, GHK-Cu | Multiple | Anti-inflammatory, growth factor upregulation | Limited human data |
Why Potency Alone Is Not Sufficient
Extraordinary receptor potency in a cell culture or rodent model raises as many safety questions as it answers. For an experimental peptide with no human data:
- Unknown toxicity profile: Extremely potent HGF/MET agonism could stimulate unwanted cell proliferation or tumor growth — HGF/MET is a growth-promoting pathway also implicated in oncogenesis
- Unknown pharmacokinetics: Duration of action in rodents is days; human clearance is unknown
- No therapeutic window established: The ratio of effective dose to toxic dose is entirely unknown
- No route optimization: Optimal delivery route, formulation, and stabilization for human use is unstudied
Legal Status
| Jurisdiction | Status | Notes |
|---|---|---|
| USA | Research chemical | Unscheduled; no FDA-approved use; no DEA scheduling |
| UK | Not scheduled | Legal to possess for research; no MHRA approved product |
| Australia | Not listed | TGA has no approved ARTG entry; import for personal use is a gray area |
| Canada | Gray market | No DIN; Health Canada has no approved product |
| EU | Not harmonized | No EMA approval; varies by member state |
Evidence Grade Callout
Grade D — All evidence for dihexa is from in vitro cell models and rodent behavioral studies. No human pharmacokinetic, safety, or efficacy data exists. The preclinical findings are scientifically interesting and the HGF/MET pathway is a legitimate neuroscience research target, but the absence of any human trial data places dihexa firmly in Grade D. The online biohacking community has dramatically overstated the clinical relevance of the rodent findings.
Legal Disclaimer
Dihexa is not approved for human use by any regulatory authority worldwide. No clinical trials have been conducted in humans. The safety, toxicity, and optimal use of dihexa in humans are entirely unknown. This page is for educational and scientific context only and does not constitute medical advice. No dosing guidance is provided because none is evidence-supported.
Related Pages
Sources
- Bhattarai JP et al. Dihexa facilitates the acquisition and extinction of conditioned fear responses in rats via the HGF/c-Met system. J Cogn Neurosci. 2014;26(8):1925-36. PMID 24726369
- McCoy AT et al. Evaluation of metabolically stabilized angiotensin IV analogs as procognitive/antidementia agents. J Pharmacol Exp Ther. 2013;347(2):374-92. PMID 24006337
- Benoist CC et al. Facilitation of hippocampal synaptogenesis and spatial memory by C-terminal truncated Nle1-angiotensin IV analogs. J Pharmacol Exp Ther. 2011;339(1):35-44. PMID 21742936
Frequently Asked Questions
What does '7 orders of magnitude more potent than BDNF' actually mean?
BDNF (brain-derived neurotrophic factor) facilitates synaptogenesis at nanomolar concentrations in cell culture models. The claim that dihexa is ~7 orders of magnitude more potent means it produces equivalent effects at concentrations roughly 10 million times lower. This extraordinary potency figure comes from one rodent in vitro study (Bhattarai 2014, PMID 24726369) using hippocampal synaptogenesis as the endpoint. It has not been replicated in human tissue, and potency comparisons across different model systems should be interpreted with extreme caution.
Why is there no dosing information for dihexa?
Dihexa has never been studied in human clinical trials. There is no Phase 1 dose-escalation study, no safety/tolerability data in humans, and no pharmacokinetic data in humans. Without these foundational studies, no evidence-based dosing recommendation exists. The extreme potency observed in rodent models makes dose extrapolation to humans particularly unreliable — potency in cell models does not translate linearly to in vivo human response. Any dosing information found in non-scientific sources is speculative and potentially dangerous.
Is dihexa being developed as a drug?
Dihexa was developed at Washington State University and has been studied primarily in the context of memory and cognitive function in rodent models, specifically Alzheimer's disease and aging research. As of 2026, no pharmaceutical company has advanced dihexa into formal clinical drug development, and no IND (Investigational New Drug) application for human trials is publicly registered. It remains a preclinical research compound.