Semax, region by region

I give the falling NGF measurement equal billing with the increases.

Neurotrophin measurements in rat brain

In a 2007 experiment in male Wistar rats, a single intranasal Semax administration changed neurotrophin gene expression in several directions. NGF and BDNF mRNA increased in the hippocampus; BDNF mRNA increased in brainstem and cerebellum; NGF mRNA decreased in frontal cortex.

I am absorbed by the regional pattern. BDNF and NGF support neurons, so more of either sounds easy to celebrate. Yet the measured response has geography. A summary that drops the frontal-cortex decrease loses me: it erases something the experiment actually found.

Reported Semax mRNA changes in four rat brain regions — Reported directions in the 2007 male-Wistar-rat experiment. This comparison shows direction only; it carries no effect-size scale.

A message and a protein

The 2006 rat study of BDNF protein found an increase in basal forebrain at 3 hours, with no increase in cerebellum. In rat basal-forebrain membranes and astrocyte cultures, it also described specific, reversible, calcium-dependent binding with a dissociation constant of 2.4 nM. Those are observations about binding and protein levels.

The cerebellum deserves a second look: the 2007 paper reported increased BDNF mRNA there. mRNA carries a protein-making instruction; measuring that message and measuring the protein are different operations. My first question here concerns timing and the path from message to protein. The papers invite comparison while measuring different things.

A laboratory worker prepares thin tissue sections beside a microscope — Editorial illustration of tissue preparation, a scene imagined for this discussion of measurements in different brain regions.

Semax and the ACTH fragment

Semax has the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It combines the ACTH(4-7) fragment with a Pro-Gly-Pro tail that slows breakdown, and lacks the cortisol-releasing activity of full-length ACTH. Its aliases include ACTH(4-7)PGP and MEHFPGP. The neurotrophin-expression paper studies this synthetic ACTH-derived peptide.

That shared Pro-Gly-Pro ending gives it a structural resemblance to Selank, whose parent sequence comes from tuftsin. I like the comparison up to that point. Their different parent molecules and experimental records make a single category of effects much harder to defend.

Injury experiments

In rats with focal cerebral ischemia, genome-wide analysis found predominantly immune-related gene changes: more than 50% of the affected genes were immune-related. Vascular-system genes also changed, with 24 at 3 hours and 12 at 24 hours. Ischemia means reduced blood supply, so this experiment concerns an injured brain.

A rat study of photoinduced prefrontal-cortex ischemia reported reduced cortical infarct volume and better retention of a conditioned passive-avoidance response after intranasal Semax over 6 days. Tissue damage and a learned behavioral response are more direct outcomes than a gene-expression profile, though they still come from an animal injury model.

The 2025 study in female C57BL/6 mice with T9-T10 spinal-cord injury reported improved locomotor recovery and reduced pyroptosis, a form of inflammatory cell death. Its proposed mechanism involved Oprm1, USP18 and deubiquitination of FTO. I welcome the different injury setting while leaving the healthy-human focus claim where it was: untested by this experiment.

Safety and clinical status

Long-term safety in healthy people remains poorly characterized. The region-specific neurotrophin findings and the broad immune and vascular response in injured rat brain give concrete reasons to ask about repeated exposure. Drug interactions, pregnancy and breastfeeding safety also remain unresolved. Research-labelled material carries additional uncertainty about identity, purity and sterility.

The existing record describes Semax as a prescription medicine in Russia and Ukraine for ischemic stroke, transient ischemic attack, cognitive impairment and optic-nerve disease. It has no FDA or EMA approval and no published Western randomized controlled trial. In the U.S., research-labelled material remains unscheduled, while a compounded prescription requires an individual clinical decision; compounded medicines are not FDA-approved.

For reports of clarity, motivation, irritability and no effect, the questions page deals with the anecdotal accounts. I still wonder whether careful human testing will connect any of these laboratory observations to the everyday benefits people describe.