Mechanism of Action
HGF/c-Met Potentiation
Dihexa appears to potentiate HGF binding to the c-Met receptor tyrosine kinase, amplifying downstream signaling through PI3K/Akt and MAPK/ERK pathways. HGF/c-Met signaling promotes neurotrophic effects including dendritic arborization, axonal growth, and synaptic plasticity. Dihexa was reported to facilitate synaptophysin puncta formation (a marker of new synapses) at picomolar concentrations in hippocampal slice preparations.
AT4 Receptor Interactions
Early structure-activity work showed dihexa is derived from angiotensin IV (AT4) pharmacophore optimization. AT4 receptor (IRAP, insulin-regulated aminopeptidase) modulation may contribute to hippocampal memory consolidation through glucose transporter 4 trafficking. The relative contribution of AT4 vs c-Met mechanisms in vivo remains unresolved.
Research Summary
Cognitive Enhancement (Animal Models)
Preclinical OnlyRodent studies from WSU: dihexa reversed scopolamine-induced amnesia in novel object recognition and radial arm maze tasks. Aged rats showed significant spatial memory improvements comparable to young controls. Synaptophysin immunofluorescence confirmed new synapse formation in treated hippocampal neurons. Reported potency 10 million-fold greater than BDNF in facilitating synaptogenesis in culture, though this comparison requires careful interpretation.
Neurodegeneration Models
Preclinical OnlyPreliminary data in Alzheimer's mouse models (APP/PS1) showed improved maze performance. Proposed as a potential approach to neurodegenerative disease, but no IND application has been filed, and no human safety or efficacy data exists as of the current date.
Human Research Status
No Clinical DataNo Phase 1 clinical trials have been conducted. Human dosing, pharmacokinetics, blood-brain barrier penetration, safety, and efficacy are entirely unknown in humans. Community reports of cognitive enhancement are anecdotal and uncontrolled. The compound is sold by research chemical vendors for in vitro/animal research purposes only.
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Research Protocols
| Goal | Dose | Frequency | Route |
|---|---|---|---|
| Rodent cognitive studies (reference only) | 1-3 mg/kg/day IP or SC | Daily for study duration | Intraperitoneal / subcutaneous |
No validated human protocols exist. Human use is experimental with unknown safety profile. Oral bioavailability in humans is uncharacterized.
Interactions
Safety Profile
No human safety data exists. Animal studies did not report overt toxicity at research doses, but comprehensive toxicology profiling has not been published. c-Met pathway is a proto-oncogene pathway; theoretical concern exists regarding chronic potentiation and tumor promotion, though no carcinogenicity studies have been reported. Given complete absence of human clinical data, risk-benefit assessment is impossible. Not recommended for human administration outside of formal clinical trial settings.
References
- [1]Benoist CC, et al. Facilitation of hippocampus-dependent learning and long-term potentiation by dihexa. J Pharmacol Exp Ther. 2011;336(3):811-822.
- [2]Duong YT, et al. Dihexa potentiates HGF/c-Met signaling to facilitate synaptogenesis. Eur J Pharmacol. 2012;688(1-3):27-35.