What is Semax?

What the research literature says

Semax was developed at the Russian Academy of Sciences as a metabolically-stabilised analogue of the ACTH(4-10) fragment of adrenocorticotropic hormone. The parent ACTH(4-10) carries cognitive-modulating activity in preclinical work but is rapidly degraded in vivo; Semax adds a C-terminal Pro-Gly-Pro tail that confers protease resistance and extends central-nervous-system bioavailability sufficiently to support intranasal administration with measurable cognitive and neurotrophic effects.

The published mechanistic research centres on BDNF (brain-derived neurotrophic factor) signalling and its downstream TrkB receptor cascade in the hippocampus. The Dolotov characterisation documented Semax-driven regulation of BDNF and TrkB expression in the rat hippocampus with associated cognitive-modulation effects (PMID 16996037). Plasma-membrane binding and biodegradation of the heptapeptide in the rat forebrain basal nuclei was characterised in earlier Dolotov work (PMID 15344653).

Subsequent work has extended the framing into early-life fluvoxamine-exposure models documenting attenuation of behavioural and neurochemical alterations (PMID 33418449). As with Selank, the published research base centres predominantly in Russian research groups with limited cross-laboratory replication outside that scientific community.

Why this matters in research context

The pharmacology distinguishes Semax from the broader ACTH-receptor agonist class — the C-terminal stabilisation and the central-nervous-system delivery profile produce a markedly different activity spectrum from the parent ACTH(4-10) fragment despite shared sequence origin. Researchers using Semax should anchor protocol design to the BDNF/TrkB framework rather than to general ACTH-axis pharmacology.

Related compounds

• Semax 10mg — the compound covered by this answer
• Selank 10mg — parallel Russian-developed heptapeptide with anxiolytic-research framing

Related research questions

• What is Selank?

References

1. Dolotov OV et al. The binding of Semax, ACTH 4-10 heptapeptide, to plasma membranes of the rat forebrain basal nuclei and its biodegradation. Bioorg Khim 2004;30(3):241-246. [PMID 15344653]
2. Dolotov OV et al. Semax, an analog of ACTH(4-10) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus. Brain Res 2006;1117(1):54-60. [PMID 16996037]
3. Glazova NY et al. Semax, synthetic ACTH(4-10) analogue, attenuates behavioural and neurochemical alterations following early-life fluvoxamine exposure in white rats. Neuropeptides 2021;86:102114. [PMID 33418449]