Thyrotropin-releasing hormoneTRH

The hypothalamic trigger for the thyroid axis.

EndogenousEstablished

Identity

Class: Tripeptide (3 aa) — the smallest peptide hormone here
Source: Hypothalamus
Receptor: TRH receptor (TRHR), a class A GPCR

Key properties

Molecular weight

~362.4 Da

Half-life (native)

~2–5 min

Model dosing

Approximate values for the native hormone. Engineered analogs are often deliberately larger and far longer-acting.

Mechanism

TRH stimulates the anterior pituitary to release TSH (and prolactin), setting the tone of the thyroid axis. At just three residues it is among the smallest peptide hormones, showing that potency does not require length.

Reference notes

TRH is only three amino acids — minimal size, full hormonal activity.
It drives both TSH and prolactin secretion.
It sits atop the hypothalamic–pituitary–thyroid axis.

Selected literature

Curated peer-reviewed reviews, sourced from PubMed. Selected for relevance, not exhaustive — open any entry on PubMed for the full record and its primary citations.

1.Thyrotropin-releasing hormone analogs · Mini reviews in medicinal chemistry, 2006 · PMID 16472189
2.Thyrotropin-releasing hormone · The New England journal of medicine, 1982 · PMID 6798440