# Thymulin FAQ: Zinc Dependence, Doses, and the Research Record

> Thymulin FAQ: what it is, why it needs zinc, what doses were used in animals, how it differs from thymosin alpha-1, and what the research does and does not show. Cited answers.

Direct, cited answers on what thymulin is, why zinc switches it on, what doses were studied, and where it differs from thymosin alpha-1.

## What is thymulin?

Thymulin is a zinc-dependent nonapeptide hormone produced by thymic epithelial cells, biologically active only when bound to zinc in a 1:1 ratio [2]. Its molecular weight is 858.86 Da. Endogenously it drives T-cell differentiation and acts in a thymus-neuroendocrine axis [4]. It is not FDA-approved and is handled as a research peptide. The overview page answers [what is thymulin](/) in fuller detail.

## What is thymulin peptide?

Thymulin is the nonapeptide pyroGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn [2]. The zinc-bound form (Zn-thymulin) is the active research peptide; the zinc-free chain is inactive [1]. There is no marketed thymulin peptide product and no approved human use.

## Is thymulin the same as serum thymic factor (FTS)?

Yes — they name one molecule. Serum thymic factor (FTS, facteur thymique serique) is the original name for the zinc-free peptide. When zinc binds, FTS becomes FTS-Zn, which the 1982 authors renamed thymulin [1]. FTS is the apo-form; thymulin is the active zinc-bound form.

## How is thymulin different from thymosin alpha-1?

Thymulin is a zinc-dependent nonapeptide; thymosin alpha-1 is a different, longer thymic peptide with its own sequence and pharmacology. They are chemically and pharmacologically distinct compounds, not interchangeable, and consumer sources frequently conflate them in error [16]. A study of one is not evidence about the other — see [thymulin vs thymosin alpha-1](/) on the overview page.

## What is the amino acid sequence of thymulin?

Thymulin is the nonapeptide pyroGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn (<Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn), molecular formula C33H54N12O15, molecular weight 858.86 Da [2]. The first residue, pyroglutamate, is a cyclized blocked N-terminus.

## Why does thymulin need zinc to work?

Zinc binding in a 1:1 ratio creates the specific three-dimensional conformation required for activity [2]. The zinc-free apopeptide is inactive, and chelating the zinc (for example with Chelex 100) abolishes activity, which is restored by adding zinc back [1]. The fold is the function.

## What does thymulin do in the body?

Endogenously it drives T-lymphocyte differentiation and acts as a hypophysiotropic peptide within a thymus-neuroendocrine axis, signaling to the pituitary [2][4]. These are physiological roles studied in models. Described effects are research findings in named species, not therapeutic claims in people.

## What are the benefits of thymulin peptide?

Research describes immune-modulating and anti-inflammatory effects in animal and in-vitro models — T-cell differentiation [2], suppressed NF-kB signaling [6], and reduced inflammatory hyperalgesia in rodents [8]. No human benefits are established, and the compound is not FDA-approved [16].

## What are the benefits of thymulin?

Reported research outcomes include T-cell differentiation [2], anti-inflammatory signaling changes [6], anti-hyperalgesic effects in rodents [8], and gene-therapy reversal of established asthma in mice [7]. All are preclinical or limited-human findings in named species — not established human benefits.

## Does thymulin boost the immune system?

In models, thymulin promoted T-cell differentiation and its activity tracked zinc status [2][3]. This is described as a physiological and research effect, not a human immune-boost claim. There is no FDA-approved thymulin immune product.

## What is the dosage of thymulin peptide?

There is no established human dosage [2]. The literature reports research doses by species — for example nanogram-to-microgram amounts in rodents (1/100/1000 ng i.p.) — for laboratory study only [8]. These are study findings, not dosing guidance.

## How is thymulin administered in research?

Studied routes include intraperitoneal, subcutaneous, intracerebroventricular, intratracheal (gene therapy), intramuscular (vector), topical (a zinc-thymulin pilot), and in vitro [2][7][8][13]. The route depends on the model, and gene-therapy studies deliver a vector rather than a peptide dose [7].

## Is thymulin taken as an injection?

In animal research it has been given by injection — for example intraperitoneal and subcutaneous [8][13]. It is a research peptide with no approved human injectable product. Nothing here describes human administration.

## What is the half-life of thymulin?

As a small peptide its circulating half-life is short, but a precise human pharmacokinetic half-life is not well established in the public literature [2]. Gene-therapy approaches were developed specifically to sustain circulating thymulin because the native peptide clears quickly [5].

## What doses of thymulin were used in animal studies?

Reported research doses span nanogram-to-low-microgram amounts — for example 1, 100, and 1000 ng intraperitoneal and roughly 0.1-1 microg intracerebroventricular in rodents [8], and 3-100 microg/day subcutaneous in a radioprotection study [13]. These are study findings, not dosing guidance.

## Does thymulin reduce inflammation?

In animal and in-vitro models, thymulin was associated with reduced pro-inflammatory cytokines and suppressed NF-kB and SAPK/JNK signaling [6], and lower skin IL-1beta and NGF in an inflammatory-pain model [8]. This is a research finding, not a human anti-inflammatory treatment.

## Is thymulin studied for pain relief?

In rodent inflammatory- and neuropathic-pain models, thymulin and its analog PAT were associated with dose-dependent reductions in hyperalgesia [8][9][10]. Thymulin alone did not change baseline pain thresholds — the effect appeared only against an inflammatory background [8].

## Does thymulin act on the brain?

Yes, in research models. Intracerebroventricular thymulin-related peptide modulated central inflammation and reduced endotoxin-induced hyperalgesia and fever in rats [12], and thymulin acts as a hypophysiotropic peptide on the pituitary within the thymus-neuroendocrine axis [4].

## What is PAT, the thymulin-related peptide?

PAT (peptide analog of thymulin) is a synthetic thymulin-related peptide studied mainly for analgesic and anti-inflammatory effects in the nervous system [11]. In rats it matched thymulin's anti-hyperalgesic activity [9] and has been proposed as a neuroinflammation candidate [11].

## What research exists on thymulin?

Decades of preclinical work span immune/T-cell, anti-inflammatory, neuroinflammation/analgesia, neuroendocrine, lung, metabolic/autoimmune, and gene-therapy models, plus limited and dated human data [2][3][4][7]. Several human studies used the synthetic analog nonathymulin rather than native thymulin [15].

---

A numbers-first reading of the thymulin record — every figure pinned to its study, the 1:1 zinc-bound active form kept distinct from the inactive apopeptide and from thymosin alpha-1, and the empty human-dose and human-PK lines left openly unfilled; no clinic behind the poster and nothing here dosed, dispensed, or sold.