Anti-aging Growth Factors Myostatin Inhibitors Under research

Follistatin 315

Also known as: FST-315

Follistatin 315 (FST-315) is another isoform derived from the same gene as Follistatin 344. Unlike FST-344, which tends to stay and act locally in the muscle where it is injected, FST-315 is primarily the isoform that circulates through the blood systemically. This means it has anabolic and myostatin-inhibitory effects distributed throughout the entire body's muscle mass, but with different clinical considerations.

Mechanism of action

Binds covalently to circulating myostatin (GDF-8), blocking it before it can inhibit cell growth.
Its systemic action can bind to other activins, playing a role in inflammation processes and ovarian follicular development.

Uses & indications

Total systemic muscle development: Investigated in severe cachexia models.
Reproductive disorders: Due to its interaction with activins.

Effects

Non-targeted muscle growth (global increase). Less popular in bodybuilding than FST-344 due to the risk of overgrowth in non-target tissues.

Considerations & contraindications

High systemic impact on endocrine axes that depend on activins, especially in women (HPG axis).
Extremely complex to dose for sports use.

Regulatory approval

Not approved. Strict laboratory use.

Dosage

Variable experimental research doses, rarely standardized or documented in humans.

Storage

Lyophilized at -20°C. Avoid violent agitation after reconstitution.

Technical data

Regulatory status Under research

Molecular weight ~34.8 kDa

Half-life Indeterminada

Administration routes Subcutánea o Intramuscular